US Navy Dive Manual Revision 6

User Manual:

Open the PDF directly: View PDF PDF.
Page Count: 992

DownloadUS Navy Dive Manual Revision 6
Open PDF In BrowserView PDF
SS521-AG-PRO-010
0910-LP-106-0957

REVISION 6

U.S. Navy Diving Manual

Volume 1:

Diving Principles and
Policies

Volume 2:

Air Diving Operations

Volume 3:

Mixed Gas Surface
Supplied Diving
Operations

Volume 4:

Closed-Circuit and
Semiclosed Circuit
Diving Operations

Volume 5:

Diving Medicine
and Recompression
Chamber Operations

DISTRIBUTION STATEMENT A: THIS DOCUMENT HAS BEEN APPROVED FOR PUBLIC RELEASE AND SALE;
ITS DISTRIBUTION IS UNLIMITED.

SUPERSEDES SS521-AG-PRO-010, REVISION 5, Dated 15 August 2005.

Published by Direction of Commander, Naval Sea Systems Command

15 APRIL 2008

PAGE LEFT BLANK INTENTIONALLY

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

SS521-AG-PRO-010

LIST OF EFFECTIVE PAGES

Date of issue for original is:
Original  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15 April 2008
TOTAL NUMBER OF PAGES IN THIS PUBLICATION IS 992, CONSISTING OF THE
FOLLOWING:
Page No.

*Change No.

Title Page  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Title Page-2 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
A through B .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Certification Sheet .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Certification Sheet-2 blank  .  .  .  .  .  .  .  .  .  .  .
Record of Changes .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Record of Changes-2 blank . .  .  .  .  .  .  .  .  .  .
i (Foreword) .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
ii blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
iii through vii . . . . . . . . . . . . . . . . . . . . . .
viii blank . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
ix through lvii .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
lviii blank  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
lix through lxii . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Vol. 1 Title Page . . . . . . . . . . . . . . . . . . .
Vol. 1 Title Page-2 blank .  .  .  .  .  .  .  .  .  .  .  .  .
1-i through 1-xiii .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1-xiv blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1-1 through 1-31  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1-32 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
2-1 through 2-36  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-1 through 3-63  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-64 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
4-1 through 4-13  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
4-14 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
5-1 through 5-13  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
5-14 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1A-1 through 1A-16 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1B-1 through 1B-3 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Page No.

*Change No.

1B-4 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1C-1 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1C-2 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1D-1 through 1D-9 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
1D-10 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Vol. 2 Title Page . . . . . . . . . . . . . . . . . . .
Vol. 2 Title Page-2 blank .  .  .  .  .  .  .  .  .  .  .  .  .
2-i through 2-xv .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
2-xvi blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
2-xvii  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
2-xviii blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
6-1 through 6-58  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
7-1 through 7-40  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
8-1 through 8-36  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-1 through 9-84  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
10-1 through 10-13  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
10-14 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
11-1 through 11-14  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
2A-1 through 2A-3 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
2A-4 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Vol. 3 Title Page . . . . . . . . . . . . . . . . . . .
Vol. 3 Title Page-2 blank .  .  .  .  .  .  .  .  .  .  .  .  .
3-i through 3-vii .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-viii blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-ix . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-x blank  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-xi . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
3-xii blank  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
12-1 through 12-14  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

* Zero in this column indicates an original page.

List of Effective Pages	



Page No.

*Change No.

Page No.

*Change No.

13-1 through 13-13  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
13-14 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
14-1 through 14-35  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
14-36 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
15-1 through 15-39  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
15-40 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
16-1 through 16-9  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
16-10 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
Vol. 4 Title Page . . . . . . . . . . . . . . . . . . .  0
Vol. 4 Title Page-2 blank .  .  .  .  .  .  .  .  .  .  .  .  . 0
4-i through 4-vii .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
4-viii blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
4-ix . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
4-x blank  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
4-xi . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
4-xii blank  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
17-1 through 17-61  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
17-62 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
18-1 through 18-57  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
18-58 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
19-1 through 19-25  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
19-26 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
Vol. 5 Title Page . . . . . . . . . . . . . . . . . . .  0
Vol. 5 Title Page-2 blank .  .  .  .  .  .  .  .  .  .  .  .  . 0
5-i through 5-xi . . . . . . . . . . . . . . . . . . . .  0
5-xii blank  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
20-1 through 20-49  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
20-50 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
21-1 through 21-31  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
21-32 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
5A-1 through 5A-13 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
5A-14 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
5B-1 through 5B-7 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
5B-8 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
5C-1 through 5C-23 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
5C-24 blank .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 0
Index-1 through Index-12  .  .  .  .  .  .  .  .  .  .  .  . 0

* Zero in this column indicates an original page.
	

List of Effective Pages

NAVSEA TECHNICAL MANUAL CERTIFICATION SHEET
Certification Applies to:
Applicable TMINS/Pub . No .

New Manual

Revision X

1

of

1

Change

SS521-AG-PRO-010/0910-LP-106-0957

Publication Date (Da, Mo, Yr) 15 April 2008
Title: U .S . NAVY DIVING MANUAL, Revision 6

TMCR/TMSR/Specification No .:
CHANGES AND REVISIONS:
Purpose: This revision provides new procedures for decompression using air and/or oxygen .

Equipment Alteration Numbers Incorporated:
TMDER/ACN Numbers Incorporated:

Continue on reverse side or add pages as needed .

CERTIFICATION STATEMENT
This is to certify that responsible NAVSEA activities have reviewed the above identified
document for acquisition compliance, technical coverage, and printing quality . This form is
for internal NAVSEA management use only, and does not imply contractual approval or
acceptance of the technical manual by the Government, nor relieve the contractor of any
responsibility for delivering the technical manual in accordance with the contract requirement .
Authority

Name

Signature

Organization

Code

Acquisition

R . Whaley

NAVSEA

00C3

Technical

CAPT J . Gray

NAVSEA

00C3B

Printing
Release

DERIVED FROM NAVSEA 4160/8 (5 - 89)

Date

PAGE LEFT BLANK INTENTIONALLY

SS521-AG-PRO-010

RECORD OF CHANGES
CHANGE
NO.

DATE
OF
CHANGE

TITLE AND/OR BRIEF DESCRIPTION

ENTERED
BY

Flyleaf-1/(Flyleaf-2 blank)

PAGE LEFT BLANK INTENTIONALLY

Foreword

Foreword	

PAGE LEFT BLANK INTENTIONALLY

ii

Prologue

PAGE LEFT BLANK INTENTIONALLY

Safety Summary
Standard Navy Syntax

Since this manual will form the technical basis of many subsequent instructions or directives,
it utilizes the standard Navy syntax as pertains to permissive, advisory, and mandatory
language. This is done to facilitate the use of the information provided herein as a reference
for issuing Fleet Directives. The concept of word usage and intended meaning that has been
adhered to in preparing this manual is as follows:
“Shall” has been used only when application of a procedure is mandatory.
“Should” has been used only when application of a procedure is recommended.
“May” and “need not” have been used only when application of a procedure is discretionary.
“Will” has been used only to indicate futurity; never to indicate any decree of requirement for
application of a procedure.
The usage of other words has been checked against other standard nautical and naval terminology
references.
General Safety

This Safety Summary contains all specific WARNINGS and CAUTIONS appearing elsewhere
in this manual and are referenced by page number. Should situations arise that are not covered
by the general and specific safety precautions, the Commanding Officer or other authority will
issue orders, as deemed necessary, to cover the situation.
Safety Guidelines

Extensive guidance for safety can be found in the OPNAV 5100 series instruction manual,
Navy Safety Precautions.
Safety Precautions

The WARNINGS, CAUTIONS, and NOTES contained in this manual are defined as follows:
WARNING

Identifies an operating or maintenance procedure, practice, condition,
or statement, which, if not strictly observed, could result in injury to or
death of personnel.

CAUTION

Identifies an operating or maintenance procedure, practice, condition, or
statement, which, if not strictly observed, could result in damage to or
destruction of equipment or loss of mission effectiveness, or long-term
health hazard to personnel.

NOTE

Safety Summary	

An essential operating or maintenance procedure, condition, or statement,
which must be highlighted.
iii

iv

WARNING

Voluntary hyperventilation is dangerous and can lead to unconsciousness and death during breathhold dives. (Page 3-20)

WARNING

Never do a forceful Valsalva maneuver during descent. A forceful Valsalva
maneuver can result in alternobaric vertigo or barotrauma to the inner
ear. (Page 3-25)

WARNING

If decongestants must be used, check with medical personnel trained
in diving medicine to obtain medication that will not cause drowsiness
and possibly add to symptoms caused by the narcotic effect of nitrogen.
(Page 3-25)

WARNING

Reducing the oxygen partial pressure does not instantaneously reverse
the biochemical changes in the central nervous system caused by high
oxygen partial pressures. If one of the early symptoms of oxygen toxicity
occurs, the diver may still convulse up to a minute or two after being
removed from the high oxygen breathing gas. One should not assume
that an oxygen convulsion will not occur unless the diver has been off
oxygen for 2 or 3 minutes. (Page 3-44)

WARNING

CPR should not be initiated on a severely hypothermic diver unless it can
be determined that the heart has stopped or is in ventricular fibrillation.
CPR should not be initiated in a patient that is breathing. (Page 3-55)

WARNING

Do not use a malfunctioning compressor to pump diver’s breathing air or
charge diver’s air storage flasks as this may result in contamination of
the diver’s air supply. (Page 4-11)

WARNING

Welding or cutting torches may cause an explosion on penetration of
gas-filled compartments, resulting in serious injury or death. (Page 6-22)

WARNING

SCUBA equipment is not authorized for use in enclosed space diving.
(Page 6-27)

WARNING

These are the minimum personnel levels required. ORM may require these
personnel levels be increased so the diving operations can be conducted
safely. (Page 6-31)

WARNING

Skip-breathing may lead to hypercapnia and is prohibited. (Page 7-30)

WARNING

During ascent, the diver without the mouthpiece must exhale to offset
the effect of decreasing pressure on the lungs which could cause an air
embolism. (Page 7-36)

WARNING

During enclosed space diving, all divers shall be outfitted with a MK 21
MOD 1, KM-37, MK 20 MOD 0, or EXO BR MS that includes a diver-to-diver
and diver-to-topside communications system and an EGS for the diver
inside the space. (Page 8-29)

U.S. Navy Diving Manual

WARNING

For submarine ballast tanks, the divers shall not remove their diving
equipment until the atmosphere has been flushed twice with air from a
compressed air source meeting the requirements of Chapter 4, or the
submarine L.P. blower, and tests confirm that the atmosphere is safe
for breathing. Tests of the air in the enclosed space shall be conducted
hourly. Testing shall be done in accordance with NSTM 074, Volume 3,
Gas Free Engineering (S9086-CH-STM-030/CH-074) for forces afloat, and
NAVSEA-S-6470-AA-SAF-010 for shore-based facilities. If the divers smell
any unusal odors they shall immediately don their EGS. (Page 8-29)

WARNING

If the diving equipment should fail, the diver shall immediately switch to
the EGS and abort the dive. (Page 8-29)

WARNING

If job conditions call for using a steel cable or a chain as a descent line,
the Diving Officer must approve such use. (Page 8-32)

WARNING

The interval from leaving 40 fsw in the water to arriving at 50 fsw in the
chamber cannot exceed 5 minutes without incurring a penalty. (See
paragraph 9-12.6.) (Page 9-16)

WARNING

These procedures cannot be used to make repetitive dives on air following
MK 16 helium-oxygen dives.  (Page 9-29)

WARNING

Table 9-4 cannot be used when diving with equipment that maintains a
constant partial pressure of oxygen such as the MK 16 MOD 0 and the MK
16 MOD 1. Consult NAVSEA 00C for specific guidance when diving the
MK 16 at altitudes greater than 1000 feet. (Page 9-47)

WARNING

Altitudes above 10,000 feet can impose serious stress on the body resulting
in significant medical problems while the acclimatization process takes
place. Ascents to these altitudes must be slow to allow acclimatization to
occur and prophylactic drugs may be required to prevent the oocurrence
of altitude sickness. These exposures should always be planned in
consultation with a Diving Medical Officer. Commands conducting diving
operations above 10,000 feet may obtain the appropriate decompression
procedures from NAVSEA 00C. (Page 9-50)

WARNING

Mixing contaminated or non-oil free air with 100% oxygen can result in a
catastrophic fire and explosion. (Page 10-10)

WARNING

The interval from leaving 40-fsw in the water to arriving at 50-fsw in the
chamber cannot exceed 5 minutes without incurring a penalty. (See
paragraph 14-4.14.) (Page 14-6)

WARNING

The MK 16 MOD 0 UBA provides no visual warning of excess CO2 problems.
The diver should be aware of CO2 toxicity symptoms. (Page 17-5)

WARNING

Failure to adhere to these guidelines could result in serious injury or
death. (Page 17-15)

Safety Summary	

vi

WARNING

No repetitive dives are authorized after an emergency procedure requiring
a shift to the EBS. (Page 17-19)

WARNING

Hypoxia and hypercapnia may give the diver little or no warning prior to
onset of unconsciousness. (Page 17-30)

WARNING

Failure to adhere to these guidelines could result in serious injury or
death. (Page 18-14)

WARNING

Hypoxia and hypercapnia may give the diver little or no warning prior to
onset of unconsciousness. (Page 18-26)

WARNING

The MK 25 does not have a carbon dioxide-monitoring capability.
Failure to adhere to canister duration operations planning could lead to
unconsciousness and/or death. (Page 19-19)

WARNING

Drug therapy shall be administered only after consultation with a Diving
Medical Officer by qualified inside tenders adequately trained and capable
of administering prescribed medications. (Page 20-30)

WARNING

The gag valve must remain open at all times. Close only if relief valve
fails. (Page 21-20)

WARNING

This procedure is to be performed with an unmanned chamber to avoid
exposing occupants to unnecessary risks. (Page 21-21)

WARNING

Do not exceed maximum pressure rating for the pressure vessel.
(Page 21-26)

WARNING

Fire/Explosion Hazard. No matches, lighters, electrical appliances, or
flammable materials permitted in chamber. (Page 21-30)

CAUTION

When in doubt, always recompress. (Page 3-29)

CAUTION

Do not institute active rewarming with severe cases of hypothermia.
(Page 3-55)

CAUTION

GFIs require an established reference ground in order to function properly.
Cascading GFIs could result in loss of reference ground; therefore, GFIs
or equipment containing built-in GFIs should not be plugged into an
existing GFI circuit. (Page 6-21)

CAUTION

This checklist is an overview intended for use with the detailed Operating
Procedures (OPs) from the appropriate equipment O&M technical manual.
(Page 6-50)

CAUTION

Prior to use of VVDS as a buoyancy compensator, divers must be
thoroughly familiar with its use. (Page 7-9)

U.S. Navy Diving Manual

CAUTION

When diving with a Variable Volume Dry Suit, avoid overinflation and
be aware of the possibility of blowup when breaking loose from mud.
It is better to call for aid from the standby diver than to risk blowup.
(Page 8-28)

CAUTION

In very cold water, the wet suit is only a marginally effective thermal
protective measure, and its use exposes the diver to hypothermia and
restricts available bottom time. The use of alternative thermal protective
equipment should be considered in these circumstances. (Page 11-6)

CAUTION

Prior to the use of variable volume dry suits and hot water suits in cold and
ice-covered waters, divers must be trained in their use and be thoroughly
familiar with the operation of these suits. (Page 11-6)

CAUTION

There is an increased risk of CNS oxygen toxicity when diving the MK
16 MOD 1 compared to diving the MK 16 MOD 0, especially during the
descent phase of the dive. Diving supervisors and divers should be aware
that oxygen partial pressures of 1.6 ata or higher may be temporarily
experienced during descent on N2O2 dives deeper than 120 fsw (21%
oxygen diluent) and on HeO2 dives deeper than 200 fsw (12% oxygen
diluent). Refer to paragraph 18-10.1.1 for information on recognizing and
preventing CNS oxygen toxicity. (Page 18-14)

CAUTION

Defibrillation is not currently authorized at depth. (Page 20-4)

CAUTION

If the tender is outside of no-decompression limits, he should not be
brought directly to the surface. Either take the decompression stops
appropriate to the tender or lock in a new tender and decompress the
patient and new tender to the surface in the outerlock, while maintaining
the original tender at depth. (Page 20-4)

CAUTION

Inserting an airway device or bite block is not recommended while
the patient is convulsing; it is not only difficult, but may cause harm if
attempted. (Page 20-24)

CAUTION

AED’s are not currently approved for use under pressure (hyperbaric
environment) due to electrical safety concerns. (Page 20-36)

CAUTION

Acrylic view-ports should not be lubricated or come in contact with any
lubricant. Acrylic view-ports should not come in contact with any volatile
detergent or leak detector (non-ionic detergent is to be used for leak test).
When reinstalling view-port, take up retaining ring bolts until the gasket
just compresses evenly about the view-port. Do not overcompress the
gasket. (Page 21-26)

Safety Summary	

vii

PAGE LEFT BLANK INTENTIONALLY

viii

U.S. Navy Diving Manual

Table of Contents
Chap/Para

Page

1

History of Diving

1-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

1-2

1-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

1-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

1-1.3

Role of the U.S. Navy.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

SURFACE-SUPPLIED AIR DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1
1-2.1

Breathing Tubes . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-2

1-2.2

Breathing Bags. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3

1-2.3

Diving Bells. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3

1-2.4

Diving Dress Designs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3
1-2.4.1
1-2.4.2
1-2.4.3
1-2.4.4

1-2.5

Caissons. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

1-2.6

Physiological Discoveries. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-6
1-2.6.1
1-2.6.2
1-2.6.3

1-3

Lethbridge’s Diving Dress . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3
Deane’s Patented Diving Dress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4
Siebe’s Improved Diving Dress . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4
Salvage of the HMS Royal George . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

Caisson Disease (Decompression Sickness). . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Inadequate Ventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7
Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7

1-2.7

Armored Diving Suits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7

1-2.8

MK V Deep-Sea Diving Dress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-8

SCUBA DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-8
1-3.1

Open-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9
1‑3.1.1
1‑3.1.2
1‑3.1.3
1‑3.1.4

1-3.2

Rouquayrol’s Demand Regulator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9
LePrieur’s Open-Circuit SCUBA Design . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9
Cousteau and Gagnan’s Aqua-Lung . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10
Impact of SCUBA on Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10

Closed-Circuit SCUBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10
1‑3.2.1
1‑3.2.2

Fleuss’ Closed-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10
Modern Closed-Circuit Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-11

1-3.3

Hazards of Using Oxygen in SCUBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-11

1-3.4

Semiclosed-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-12
1‑3.4.1
1‑3.4.2

1-3.5

SCUBA Use During World War II . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-13
1‑3.5.1
1‑3.5.2
1‑3.5.3

Table of Contents­	

Lambertsen’s Mixed-Gas Rebreather . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-12
MK 6 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-12

Diver-Guided Torpedoes . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-13
U.S. Combat Swimming. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-14
Underwater Demolition. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-15

ix

Chap/Para
1-4

Page
MIXED-GAS DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-16
1-4.1

Nonsaturation Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-16
1‑4.1.1
1‑4.1.2
1‑4.1.3
1‑4.1.4

Diving Bells. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-20

1-4.3

Saturation Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-21

1-4.4

1-21
1-22
1-22
1-22
1-22

ADS-IV. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 1 MOD 0. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 2 MOD 0. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 2 MOD 1. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

1-25
1-25
1-25
1-26

SUBMARINE SALVAGE AND RESCUE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-26
1-5.1

USS F-4 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-26

1-5.2

USS S-51 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-27

1-5.3

USS S-4 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-27

1-5.4

USS Squalus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-28

1-5.5

USS Thresher. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-28

1-5.6

Deep Submergence Systems Project. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29

SALVAGE DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
1-6.1

World War II Era. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
1‑6.1.1
1‑6.1.2
1‑6.1.3

1-6.2

Pearl Harbor. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
USS Lafayette . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
Other Diving Missions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-30

Vietnam Era . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-30

1-7

OPEN-SEA DEEP DIVING RECORDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-30

1-8

SUMMARY . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-31

2

Underwater Physics

2-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-2

	

Advantages of Saturation Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Bond’s Saturation Theory. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Genesis Project . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Developmental Testing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Sealab Program. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

Deep Diving Systems (DDS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-24
1‑4.4.1
1‑4.4.2
1‑4.4.3
1‑4.4.4

1-6

1-16
1-18
1-19
1-20

1-4.2

1‑4.3.1
1‑4.3.2
1‑4.3.3
1‑4.3.4
1‑4.3.5

1-5

Helium-Oxygen (HeO2) Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Hydrogen-Oxygen Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Modern Surface-Supplied Mixed-Gas Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 1 MOD 0 Diving Outfit . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

2-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

PHYSICS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
2-3

2-4

Page
MATTER. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1
2-3.1

Elements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-3.2

Atoms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-3.3

Molecules . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-3.4

The Three States of Matter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

MEASUREMENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2
2-4.1

Measurement Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

2-4.2

Temperature Measurements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3
2‑4.2.1
2‑4.2.2

2-4.3
2-5

2-6

2-7

Gas Measurements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3

ENERGY . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-4
2-5.1

Conservation of Energy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2-5.2

Classifications of Energy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5

LIGHT ENERGY IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5
2-6.1

Refraction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5

2-6.2

Turbidity of Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6

2-6.3

Diffusion . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6

2-6.4

Color Visibility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6

MECHANICAL ENERGY IN DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6
2-7.1

Water Temperature and Sound. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7

2-7.2

Water Depth and Sound. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7
2‑7.2.1
2‑7.2.2

2-7.3

Diver Work and Noise . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7
Pressure Waves. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7

Underwater Explosions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
2‑7.3.1
2‑7.3.2
2‑7.3.3
2‑7.3.4
2‑7.3.5
2‑7.3.6
2‑7.3.7
2‑7.3.8

2-8

Kelvin Scale. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3
Rankine Scale . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3

Type of Explosive and Size of the Charge. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
Characteristics of the Seabed . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
Location of the Explosive Charge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Water Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
Distance from the Explosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Degree of Submersion of the Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-9
Estimating Explosion Pressure on a Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-9
Minimizing the Effects of an Explosion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10

HEAT ENERGY IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10
2-8.1

Conduction, Convection, and Radiation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10

2-8.2

Heat Transfer Rate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10

2-8.3

Diver Body Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-11

Table of Contents­	

xi

Chap/Para
2-9

Page
PRESSURE IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-11
2-9.1

Atmospheric Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-12

2-9.2

Terms Used to Describe Gas Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-12

2-9.3

Hydrostatic Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-12

2-9.4

Buoyancy . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13
2‑9.4.1
2‑9.4.2

Archimedes’ Principle. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13
Diver Buoyancy . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13

2-10 GASES IN DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-14

2-11

2-10.1

Atmospheric Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-14

2-10.2

Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.3

Nitrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.4

Helium. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.5

Hydrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.6

Neon. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.7

Carbon Dioxide. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-16

2-10.8

Carbon Monoxide. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-16

2-10.9

Kinetic Theory of Gases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-16

GAS LAWS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-17
2-11.1

Boyle’s Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-17

2-11.2

Charles’/Gay-Lussac’s Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-18

2-11.3

The General Gas Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-21

2-12 GAS MIXTURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-24
2-12.1

Dalton’s Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-24
2‑12.1.1 Expressing Small Quantities of Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-26
2‑12.1.2 Calculating Surface Equivalent Value . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-27

2-12.2

Gas Diffusion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-27

2-12.3

Humidity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-27

2-12.4

Gases in Liquids. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28

2-12.5

Solubility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28

2-12.6

Henry’s Law . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28
2‑12.6.1 Gas Tension. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28
2‑12.6.2 Gas Absorption. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28
2‑12.6.3 Gas Solubility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-29

xii

3

Underwater Physiology and Diving Disorders

3-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1
3-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

3-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

3-1.3

General. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page

3-2

THE NERVOUS SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

3-3

THE CIRCULATORY SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2
3-3.1

Anatomy . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2
3‑3.1.1
3‑3.1.2

3-4

3-3.2

Circulatory Function . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2

3-3.3

Blood Components. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-3

THE RESPIRATORY SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-5
3-4.1

Gas Exchange. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

3-4.2

Respiration Phases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-5

3-4.3

Upper and Lower Respiratory Tract . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6

3-4.4

The Respiratory Apparatus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6
3‑4.4.1
3‑4.4.2

3-5

The Heart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2
The Pulmonary and Systemic Circuits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2

The Chest Cavity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6
The Lungs . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6

3-4.5

Respiratory Tract Ventilation Definitions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-8

3-4.6

Alveolar/Capillary Gas Exchange. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-9

3-4.7

Breathing Control . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-10

3-4.8

Oxygen Consumption. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-11

RESPIRATORY PROBLEMS IN DIVING.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-11
3-5.1

Oxygen Deficiency (Hypoxia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-12
3‑5.1.1
3‑5.1.2
3‑5.1.3
3‑5.1.4

3-5.2

Causes of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-13
3-13
3-14
3-14

Carbon Dioxide Retention (Hypercapnia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-15
3‑5.2.1
3‑5.2.2
3‑5.2.3
3‑5.2.4

Causes of Hypercapnia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-15
3-16
3-17
3-18

3-5.3

Asphyxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-18

3-5.4

Drowning/Near Drowning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-18
3‑5.4.1
3‑5.4.2
3‑5.4.3
3‑5.4.4

Causes of Drowning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Drowning/Near Drowning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Near Drowning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Near Drowning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-18
3-19
3-19
3-19

3-5.5

Breathholding and Unconsciousness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-19

3-5.6

Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20
3‑5.6.1
3‑5.6.2
3‑5.6.3

3-5.7

Table of Contents­	

Causes of Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20
Symptoms of Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20
Treatment of Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20

Overbreathing the Rig. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20

xiii

Chap/Para

Page
3-5.8

Carbon Monoxide Poisoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-21
3‑5.8.1
3‑5.8.2
3‑5.8.3
3‑5.8.4

3-6

3-6.1

Prerequisites for Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-22

3-6.2

Middle Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-23

3-6.3

Causes of Sinus Squeeze . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25
Preventing Sinus Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25

3-6.4

Tooth Squeeze (Barodontalgia). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26

3-6.5

External Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-26

3-6.6

Thoracic (Lung) Squeeze.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-26

3-6.7

Face or Body Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-27

3-6.8

Inner Ear Barotrauma. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-27

MECHANICAL EFFECTS OF PRESSURE ON THE HUMAN BODY--BAROTRAUMA
DURING ASCENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-30
3-7.1

Middle Ear Overpressure (Reverse Middle Ear Squeeze) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-30

3-7.2

Sinus Overpressure (Reverse Sinus Squeeze) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-31

3-7.3

Gastrointestinal Distention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-31

PULMONARY OVERINFLATION SYNDROMES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-32
3-8.1

Arterial Gas Embolism (AGE). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-33
3‑8.1.1
3‑8.1.2
3‑8.1.3
3‑8.1.4

3-8.2

3-8.3

Causes of AGE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of AGE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of AGE. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of AGE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-33
3-34
3-34
3-35

Mediastinal and Subcutaneous Emphysema . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-35
3‑8.2.1
3‑8.2.2
3‑8.2.3
3‑8.2.4

Causes of Mediastinal and Subcutaneous Emphysema . .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Mediastinal and Subcutaneous Emphysema. .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Mediastinal and Subcutaneous Emphysema. .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Mediastinal and Subcutaneous Emphysema. .  .  .  .  .  .  .  .  .  .  .  .

3-35
3-36
3-36
3-37

Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-37
3‑8.3.1
3‑8.3.2
3‑8.3.3
3‑8.3.4

xiv

Preventing Middle Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-24
Treating Middle Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25

Sinus Squeeze . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25
3‑6.3.1
3‑6.3.2

3-8

3-21
3-21
3-22
3-22

MECHANICAL EFFECTS OF PRESSURE ON THE HUMAN BODY-BAROTRAUMA
DURING DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-22

3‑6.2.1
3‑6.2.2

3-7

Causes of Carbon Monoxide Poisoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Carbon Monoxide Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Carbon Monoxide Poisoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Carbon Monoxide Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

Causes of Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Pneumothorax . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-37
3-38
3-39
3-40

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
3-9

Page
INDIRECT EFFECTS OF PRESSURE ON THE HUMAN BODY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
3-9.1

Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
3‑9.1.1
3‑9.1.2
3‑9.1.3
3‑9.1.4

3-9.2

Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-41
3‑9.2.1
3‑9.2.2

3-9.3

Causes of Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
Symptoms of Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
Treatment of Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-41
Prevention of Nitrogen Narcosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-41

Pulmonary Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-41
Central Nervous System (CNS) Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-42

Decompression Sickness (DCS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-45
3‑9.3.1
3‑9.3.2
3‑9.3.3
3‑9.3.4
3‑9.3.5
3‑9.3.6
3‑9.3.7

Absorption and Elimination of Inert Gases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Bubble Formation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Direct Bubble Effects. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Indirect Bubble Effects. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Preventing Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-45
3-49
3-50
3-50
3-51
3-52
3-52

3-10 THERMAL PROBLEMS IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-52
3-10.1

Regulating Body Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-52

3-10.2

Excessive Heat Loss (Hypothermia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-53
3‑10.2.1
3‑10.2.2
3‑10.2.3
3‑10.2.4

3-10.3

Causes of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-53
3-53
3-54
3-55

Other Physiological Effects of Exposure to Cold Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.3.1 Caloric Vertigo . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.3.2 Diving Reflex . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.3.3 Uncontrolled Hyperventilation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56

3-10.4

Excessive Heat Gain (Hyperthermia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.4.1
3‑10.4.2
3‑10.4.3
3‑10.4.4

3-11

Causes of Hyperthermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hyperthermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hyperthermia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hyperthermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-56
3-56
3-57
3-57

SPECIAL MEDICAL PROBLEMS ASSOCIATED WITH DEEP DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-58
3-11.1

High Pressure Nervous Syndrome (HPNS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-58

3-11.2

Compression Arthralgia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-58

3-12 OTHER DIVING MEDICAL PROBLEMS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59
3-12.1

Dehydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59
3‑12.1.1 Causes of Dehydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59
3‑12.1.2 Preventing Dehydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59

3-12.2

Immersion Pulmonary Edema. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60

3-12.3

Carotid Sinus Reflex. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60

Table of Contents­	

xv

Chap/Para

Page
3-12.4

Middle Ear Oxygen Absorption Syndrome . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60
3‑12.4.1 Symptoms of Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60
3‑12.4.2 Treating Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-61

3-12.5

Underwater Trauma . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-61

3-12.6

Blast Injury . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-61

3-12.7

Otitis Externa. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-62

3-12.8

Hypoglycemia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-63

4

Dive Systems

4-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2

4-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

GENERAL INFORMATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1
4-2.1

Document Precedence. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2.2

Equipment Authorized For Navy Use (ANU). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2.3

System Certification Authority (SCA) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2.4

Planned Maintenance System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2

4-2.5

Alteration of Diving Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
4‑2.5.1
4‑2.5.2

4-2.6

Operating and Emergency Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
4‑2.6.1
4‑2.6.2
4‑2.6.3
4‑2.6.4
4‑2.6.5

4-3

4-4

xvi

Technical Program Managers for Shore-Based Systems. . . . . . . . . . . . . . . . 4-2
Technical Program Managers for Other Diving Apparatus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2

Standardized OP/EPs . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
Non-standardized OP/EPs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
OP/EP Approval Process. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-3
Format . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-3
Example. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4

DIVER’S BREATHING GAS PURITY STANDARDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4
4-3.1

Diver’s Breathing Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4

4-3.2

Diver’s Breathing Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-5

4-3.3

Diver’s Breathing Helium . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-6

4-3.4

Diver’s Breathing Nitrogen . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-6

DIVER’S AIR SAMPLING PROGRAM . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-7
4-4.1

Maintenance Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-7

4-4.2

General Air Sampling Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-8

4-4.3

NSWC-PC Air Sampling Services. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-9

4-4.4

Local Air Sampling Services. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
4-5

4-6

Page
DIVING COMPRESSORS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10
4-5.1

Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

4-5.2

Air Filtration System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

4-5.3

Lubrication. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

DIVING GAUGES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-11
4-6.1

Selecting Diving System Gauges. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-11

4-6.2

Calibrating and Maintaining Gauges. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-12

4-6.3

Helical Bourdon Tube Gauges . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-12

4-7

COMPRESSED GAS HANDLING AND STORAGE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-13

5

Dive Program Administration

5-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1
5-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-2

OBJECTIVES OF THE RECORD KEEPING AND REPORTING SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-3

RECORD KEEPING AND REPORTING DOCUMENTS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-4

COMMAND SMOOTH DIVING LOG . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-2

5-5

RECOMPRESSION CHAMBER LOG . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-7

5-6

DIVER’S PERSONAL DIVE LOG . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-10

5-7

DIVING MISHAP/CASUALTY REPORTING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-10

5-8

EQUIPMENT FAILURE OR DEFICIENCY REPORTING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-10

5-9

U.S. NAVY DIVE REPORTING SYSTEM (DRS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-11

5-10 ACCIDENT/INCIDENT EQUIPMENT INVESTIGATION REQUIREMENTS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-11
5-11

REPORTING CRITERIA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-12

5-12 ACTIONS REQUIRED . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-12

1A

5-12.1

Technical Manual Deficiency/Evaluation Report. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-13

5-12.2

Shipment of Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-13

Safe Diving Distances from Transmitting Sonar

1A-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-1
1A-2 BACKGROUND . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-1

Table of Contents­	

xvii

Chap/Para

Page

1A-3 ACTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2
1A-4 SONAR DIVING DISTANCES WORKSHEETS WITH DIRECTIONS FOR USE. .  .  .  .  .  .  .  .  .  .  . 1A-2
1A-4.1

General Information/Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-2
1A‑4.1.1 Effects of Exposure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2
1A‑4.1.2 Suit and Hood Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2
1A‑4.1.3 In­-Water Hearing vs. In-Gas Hearing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2

1A-4.2

Directions for Completing the Sonar Diving Distances Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-3

1A-5 GUIDANCE FOR DIVER EXPOSURE TO LOW-FREQUENCY SONAR (160–320 Hz). .  .  .  . 1A-16
1A-6 GUIDANCE FOR DIVER EXPOSURE TO ULTRASONIC SONAR
(250 KHz AND GREATER). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-16

1B

References . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1B-1

1C

Telephone Numbers . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1C-1

1D

List of Acronyms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1D-1

6

Operational Planning and Risk Management

6-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1

6-2

6-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1

6-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1

MISSION OBJECTIVE AND OPERATIONAL TASKS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1
6-2.1

Underwater Ship Husbandry (UWSH). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1
6‑2.1.1
6‑2.1.2
6‑2.1.3
6‑2.1.4
6-2.1.5

6-2.2

Salvage/Object Recovery. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.3

Search Missions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.4

Explosive Ordnance Disposal. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.5

Security Swims. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.6

Underwater Construction . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-4
6‑2.6.1
6‑2.6.2
6‑2.6.3

xviii

Objective of UWSH Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2
Repair Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2
Diver Training and Qualification Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2
Training Program Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3
Ascent Training and Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

Diver Training and Qualification Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5
Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5
Underwater Construction Planning Resources . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6-2.7

Demolition Missions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6-2.8

Combat Swimmer Missions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6-2.9

Enclosed Space Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
6-3

6-4

Page
GENERAL PLANNING AND ORM PROCESS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-6
6-3.1

Concept of ORM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-6

6-3.2

Risk Management Terms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-6

6-3.3

ORM Process. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-7

COLLECT and ANALYZE DATA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8
6-4.1

Information Gathering. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8

6-4.2

Planning Data. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8

6-4.3

Object Recovery. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8
6‑4.3.1

6-4.4

Data Required for All Diving Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-9
6‑4.4.1
6‑4.4.2
6‑4.4.3
6‑4.4.4

6-5

Surface Conditions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-9
Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-13
Type of Bottom. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-13
Tides and Currents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-13

IDENTIFY OPERATIONAL HAZARDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-15
6-5.1

Underwater Visibility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-16

6-5.2

Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-16

6-5.3

Warm Water Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-17
6‑5.3.1
6‑5.3.2

Operational Guidelines and Safety Precautions. . . . . . . . . . . . . . . . . . . . . . 6-17
Mission Planning Factors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-19

6-5.4

Contaminated Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-19

6-5.5

Chemical Contamination. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20

6-5.6

Biological Contamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

6-5.7

Altitude Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20

6-5.8

Underwater Obstacles. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20

6-5.9

Electrical Shock Hazards . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20
6‑5.9.1
6‑5.9.2

6-6

Searching for Objects or Underwater Sites . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8

Reducing Electrical Shock Hazards. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-21
Securing Electrical Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-21

6-5.10

Explosions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.11

Sonar. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.12

Nuclear Radiation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.13

Marine Life . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.14

Vessels and Small Boat Traffic. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.15

Territorial Waters. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24

6-5.16

Emergency Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24

SELECT DIVING TECHNIQUE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24
6-6.1

Factors to Consider when Selecting the Diving Technique. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24

6-6.2

Breathhold Diving Restrictions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27

Table of Contents­	

xix

Chap/Para

Page
6-6.3

Operational Characteristics of SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
6‑6.3.1
6‑6.3.2
6‑6.3.3
6‑6.3.4
6‑6.3.5

6-6.4

Operational Characteristics of SSDS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
6‑6.4.1
6‑6.4.2
6‑6.4.3
6‑6.4.4

6-7

6-8

Mobility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
Buoyancy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
Operational Limitations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28
Environmental Protection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

SELECT EQUIPMENT AND SUPPLIES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
6-7.1

Equipment Authorized for Navy Use. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

6-7.2

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

6-7.3

Diving Craft and Platforms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-29

6-7.4

Deep-Sea Salvage/Rescue Diving Platforms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-29

6-7.5

Small Craft . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-29

SELECT AND ASSEMBLE THE DIVING TEAM . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-30
6-8.1

Manning Levels. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-30

6-8.2

Commanding Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6-8.3

Command Diving Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6-8.4

Watchstation Diving Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6-8.5

Master Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32
6‑8.5.1
6‑8.5.2

6-8.6

Master Diver Responsibilities. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32
Master Diver Qualifications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33

Diving Supervisor . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
6‑8.6.1
6‑8.6.2
6‑8.6.3
6‑8.6.4

Pre-dive Responsibilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
Responsibilities While Operation is Underway. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
Post-dive Responsibilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
Diving Supervisor Qualifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34

6-8.7

Diving Medical Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-34

6-8.8

Diving Personnel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-34
6‑8.8.1
6‑8.8.2
6‑8.8.3
6‑8.8.4
6‑8.8.5
6‑8.8.6
6‑8.8.7
6‑8.8.8
6‑8.8.9
6‑8.8.10
6‑8.8.11

xx

Mobility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
Buoyancy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
Portability. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
Operational Limitations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27
Environmental Protection . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

Diving Personnel Responsibilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diving Personnel Qualifications. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Standby Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Buddy Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diver Tender. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Recorder. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Medical Personnel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Other Support Personnel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Cross-Training and Substitution. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Physical Condition. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Underwater Salvage or Construction Demolition Personnel . .  .  .  .  .  .  .  .  .  .  .

6-34
6-34
6-35
6-36
6-36
6-36
6-36
6-37
6-37
6-37
6-38

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page
6‑8.8.12 Blasting Plan . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-38
6‑8.8.13 Explosive Handlers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-38
6-8.9

OSHA Requirements for U.S. Navy Civilian Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-38
6‑8.9.1
6‑8.9.2
6‑8.9.3
6‑8.9.4

6-9

SCUBA Diving (Air) Restriction . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Surface Supplied Air Diving Restrictions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Mixed Gas Diving Restrictions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Recompression Chamber Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

6-39
6-39
6-39
6-40

ORGANIZE AND SCHEDULE OPERATIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-40
6-9.1

Task Planning and Scheduling . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-40

6-9.2

Post-dive Tasks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-40

6-10 BRIEF THE DIVING TEAM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41
6-10.1

Establish Mission Objective . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.2

Identify Tasks and Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.3

Review Diving Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.4

Assignment of Personnel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.5

Assistance and Emergencies. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-42

6-10.6

Notification of Ship’s Personnel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-42

6-10.7

Fouling and Entrapment.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-42

6-10.8

Equipment Failure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-43
6‑10.8.1 Loss of Gas Supply . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-43
6‑10.8.2 Loss of Communications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-43

6-10.9

Lost Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-54

6-10.10 Debriefing the Diving Team. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-54
6-11

AIR DIVING EQUIPMENT REFERENCE DATA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-54

7

SCUBA Air Diving Operations

7-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1

7-2

7-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1

7-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1

REQUIRED EQUIPMENT FOR SCUBA OPERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1
7-2.1

Equipment Authorized for Navy Use. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-2

7-2.2

Open-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-2
7‑2.2.1
7‑2.2.2
7‑2.2.3
7‑2.2.4

7-2.3

Minimum Equipment. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-7
7‑2.3.1
7‑2.3.2

Table of Contents­	

Demand Regulator Assembly. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-2
Cylinders . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-4
Cylinder Valves and Manifold Assemblies. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-6
Backpack or Harness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-7

Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-7
Life Preserver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-8

xxi

Chap/Para

Page
7‑2.3.3
7‑2.3.4
7‑2.3.5
7‑2.3.6
7‑2.3.7
7‑2.3.8

7-3

OPTIONAL EQUIPMENT FOR SCUBA OPERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10
7-3.1

Protective Clothing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-11
7‑3.1.1
7‑3.1.2
7‑3.1.3
7‑3.1.4
7‑3.1.5
7‑3.1.6
7‑3.1.7
7‑3.1.8
7‑3.1.9
7‑3.1.10

7-4

7-4.1

Duration of Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-14

7-4.2

Compressed Air from Commercial Sources . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-16

7-4.3

Methods for Charging SCUBA Cylinders . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-16

7-4.4

Operating Procedures for Charging SCUBA Tanks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-17

7-4.5

Topping off the SCUBA Cylinder . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-19

Safety Precautions for Charging and Handling Cylinders. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-19

PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-20
7-5.1

Equipment Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-20
7‑5.1.1
7‑5.1.2
7‑5.1.3
7‑5.1.4
7‑5.1.5
7‑5.1.6
7‑5.1.7
7‑5.1.8
7‑5.1.9
7‑5.1.10
7‑5.1.11
7‑5.1.12
7‑5.1.13

xxii

Wet Suits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-11
Dry Suits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-11
Gloves . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12
Writing Slate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12
Signal Flare . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12
Acoustic Beacons. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Lines and Floats. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Snorkel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Compass . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Submersible Cylinder Pressure Gauge . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-14

AIR SUPPLY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-14

7‑4.4.1

7-5

Buoyancy Compensator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-8
Weight Belt. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-9
Knife. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-9
Swim Fins. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10
Wrist Watch . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10
Depth Gauge . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10

Air Cylinders. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Harness Straps and Backpack. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Breathing Hoses. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Regulator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Life Preserver/Buoyancy Compensator (BC). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Swim Fins. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Dive Knife. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Snorkel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Weight Belt. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Submersible Wrist Watch. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Depth Gauge and Compass. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Miscellaneous Equipment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

7-21
7-21
7-21
7-21
7-22
7-22
7-22
7-23
7-23
7-23
7-23
7-23
7-23

7-5.2

Diver Preparation and Brief. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-23

7-5.3

Donning Gear. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-24

7-5.4

Predive Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-25

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
7-6

Page
WATER ENTRY AND DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
7-6.1

Water Entry. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
7‑6.1.1
7‑6.1.2
7‑6.1.3

7-7

7-6.2

Pre-descent Surface Check . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-28

7-6.3

Surface Swimming . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29

7-6.4

Descent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29

UNDERWATER PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29
7-7.1

Breathing Technique. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29

7-7.2

Mask Clearing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-30

7-7.3

Hose and Mouthpiece Clearing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-30

7-7.4

Swimming Technique . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-30

7-7.5

Diver Communications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31
7‑7.5.1
7‑7.5.2

Through-Water Communication Systems . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31
Hand and Line-Pull Signals . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31

7-7.6

Buddy Diver Responsibilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-32

7-7.7

Buddy Breathing Procedure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-32

7-7.8

Tending. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-36
7‑7.8.1
7‑7.8.2

7-8

Step-In Method. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
Rear Roll Method. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
Entering the Water from the Beach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-28

Tending with a Surface or Buddy Line.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-36
Tending with No Surface Line. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-36

7-7.9

Working with Tools . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-36

7-7.10

Adapting to Underwater Conditions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-37

ASCENT PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-37
7-8.1

Emergency Free-Ascent Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-38

7-8.2

Ascent From Under a Vessel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-38

7-8.3

Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-39

7-8.4

Surfacing and Leaving the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-40

7-9

POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-40

8

Surface Supplied Air Diving Operations

8-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-2

8-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

MK 21 MOD 1, KM-37. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1
8-2.1

Operation and Maintenance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-2.2

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-2
8‑2.2.1

Table of Contents­	

Emergency Gas Supply Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-2

xxiii

Chap/Para

Page
8‑2.2.2
8‑2.2.3

8-3

MK 20 MOD 0. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7
8-3.1

Operation and Maintenance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7

8-3.2

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7
8‑3.2.1
8‑3.2.2
8‑3.2.3

8-4

8-5

EGS Requirements for MK 20 MOD 0 Enclosed-Space Diving. .  .  .  .  .  .  .  .  .  .  . 8-7
EGS Requirements for MK 20 MOD 0 Open Water Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8
Flow Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

EXO BR MS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8
8-4.1

EXO BR MS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.2

Operations and Maintenance . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.3

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.4

EGS Requirements for EXO BR MS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.5

Flow and Pressure Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9

PORTABLE SURFACE-SUPPLIED DIVING SYSTEMS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9
8-5.1

MK 3 MOD 0 Lightweight Dive System (LWDS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9
8‑5.1.1
8‑5.1.2
8‑5.1.3

MK 3 MOD 0 Configuration 1. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9
MK 3 MOD 0 Configuration 2. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10
MK 3 MOD 0 Configuration 3. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-5.2

MK 3 MOD 1 Lightweight Dive System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-5.3

ROPER Diving Cart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-5.4

Flyaway Dive System (FADS) III. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-13

8-5.5

Oxygen Regulator Console Assembly (ORCA). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-13

8-6

ACCESSORY EQUIPMENT FOR SURFACE-SUPPLIED DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-15

8-7

SURFACE AIR SUPPLY SYSTEMS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-16
8-7.1

Requirements for Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-16
8‑7.1.1
8‑7.1.2
8‑7.1.3
8‑7.1.4
8‑7.1.5

8-7.2

8-8

Air Purity Standards. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Air Supply Flow Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Supply Pressure Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Water Vapor Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Standby Diver Air Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

8-16
8-16
8-16
8-17
8-17

Primary and Secondary Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-17
8‑7.2.1
8‑7.2.2
8‑7.2.3

xxiv

Flow Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-3
Pressure Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-4

Requirements for Operating Procedures and Emergency Procedures . .  .  . 8-18
Air Compressors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-18
High-Pressure Air Cylinders and Flasks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-21

DIVER COMMUNICATIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-22
8-8.1

Diver Intercommunication Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-22

8-8.2

Line-Pull Signals. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-23

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
8-9

Page
PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-24
8-9.1

Predive Checklist . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-24

8-9.2

Diving Station Preparation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.3

Air Supply Preparation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.4

Line Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.5

Recompression Chamber Inspection and Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.6

Predive Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-25

8-9.7

Donning Gear. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.8

Diving Supervisor Predive Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-10 WATER ENTRY AND DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-11

8-10.1

Predescent Surface Check. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-26

8-10.2

Descent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-26

UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-27
8-11.1

Adapting to Underwater Conditions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-27

8-11.2

Movement on the Bottom . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-27

8-11.3

Searching on the Bottom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-28

8-11.4

Enclosed Space Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29
8‑11.4.1
8‑11.4.2

Enclosed Space Hazards. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29
Enclosed Space Safety Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29

8-11.5

Working Around Corners. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29

8-11.6

Working Inside a Wreck . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30

8-11.7

Working With or Near Lines or Moorings . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30

8-11.8

Bottom Checks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30

8-11.9

Job Site Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30
8‑11.9.1
8‑11.9.2

Underwater Ship Husbandry Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-31
Working with Tools. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-31

8-11.10 Safety Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-31
8‑11.10.1
8‑11.10.2
8‑11.10.3
8‑11.10.4

Fouled Umbilical Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32
Fouled Descent Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-32
Falling. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32
Damage to Helmet and Diving Dress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32

8-11.11 Tending the Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32
8-11.12 Monitoring the Diver’s Movements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-33
8-12 ASCENT PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-34
8-13 SURFACE DECOMPRESSION . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35
8-13.1

Disadvantages of In-Water Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

8-13.2

Transferring a Diver to the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

Table of Contents­	

xxv

Chap/Para

Page

8-14 POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

xxvi

8-14.1

Personnel and Reporting . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

8-14.2

Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-36

9

Air Decompression

9-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1
9-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1

9-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1

9-2

THEORY OF DECOMPRESSION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1

9-3

AIR DECOMPRESSION DEFINITIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2
9-3.1

Descent Time . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.2

Bottom Time . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.3

Total Decompression Time. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.4

Total Time of Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.5

Deepest Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.6

Maximum Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.7

Stage Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.8

Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.9

Decompression Schedule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.10

Decompression Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.11

No-Decompression (No “D”) Limit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.12

No-Decompression Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.13

Decompression Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.14

Surface Interval. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.15

Residual Nitrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.16

Single Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.17

Repetitive Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.18

Repetitive Group Designator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.19

Residual Nitrogen Time. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.20

Equivalent Single Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-3.21

Equivalent Single Dive Time. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-3.22

Surface Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-3.23

Exceptional Exposure Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-4

DIVE CHARTING AND RECORDING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-5

THE AIR DECOMPRESSION TABLES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-6

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
9-6

9-7

Page
GENERAL RULES FOR THE USE OF AIR DECOMPRESSION TABLES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7
9-6.1

Selecting the Decompression Schedule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.2

Descent Rate . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.3

Ascent Rate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.4

Decompression Stop Time . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.5

Last Water Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-8

9-6.6

Eligibility for Surface Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-8

NO-DECOMPRESSION LIMITS AND REPETITIVE GROUP DESIGNATION TABLE
FOR NO-DECOMPRESSION AIR DIVES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-8
9-7.1

9-8

Optional Shallow Water No-Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-9

THE AIR DECOMPRESSION TABLE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-9
9-8.1

In-Water Decompression on Air . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-9

9-8.2

In-Water Decompression on Air and Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-11
9-8.2.1
9-8.2.2

9-8.3

Surface Decompression on Oxygen (SurDO2). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-15
9-8.3.1
9-8.3.2

9-8.4
9-9

Procedures for Shifting to 100% Oxygen at 30 or 20 fsw. . . . . . . . . . . . . . . 9-11
Air Breaks at 30 and 20 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-13

Surface Decompression on Oxygen Procedure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-15
Surface Decompression from 30 and 20 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-17

Selection of the Mode of Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-19

REPETITIVE DIVES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-21
9-9.1

Repetitive Dive Procedure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-21

9-9.2

RNT Exception Rule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-25

9-9.3

Repetitive Air-MK 16 Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-29

9-9.4

Order of Repetitive Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-30

9-10 EXCEPTIONAL EXPOSURE DIVES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-31
9-11

VARIATIONS IN RATE OF ASCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-31
9-11.1

Travel Rate Exceeded. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-31

9-11.2

Early Arrival at the First Decompression Stop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-31

9-11.3

Delays in Arriving at the First Decompression Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-32

9.11.4

Delays in Leaving a Stop or Between Decompression Stops. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-32

9-12 EMERGENCY PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-35
9-12.1

Bottom Time in Excess of the Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-35

9-12.2

Loss of Oxygen Supply in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-36

9-12.3

Contamination of Oxygen Supply with Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-37

9-12.4

CNS Oxygen Toxicity Symptoms (Non-convulsive) at 30 or 20 fsw Water Stop. .  .  .  .  . 9-37

9-12.5

Oxygen Convulsion at the 30- or 20-fsw Water Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-38

9-12.6

Surface Interval Greater than 5 Minutes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-39

Table of Contents­	

xxvii

Chap/Para

Page
9-12.7

Decompression Sickness During the Surface Interval . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-40

9-12.8

Loss of Oxygen Supply in the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-41

9-12.9

CNS Oxygen Toxicity in the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-42

9-12.10 Asymptomatic Omitted Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-12.10.1 No-Decompression Stops Required. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-12.10.2 Omitted Decompression Stops at 30 and 20 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-12.10.3 Omitted Decompression Stops Deeper than 30 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

9-42
9-43
9-44
9-44

9-12.11 Decompression Sickness in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-45
9-12.11.1 Diver Remaining in the Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-45
9-12.11.2 Diver Leaving the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13 DIVING AT ALTITUDE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13.1

Altitude Correction Procedure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13.1.1 Correction of Dive Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13.1.2 Correction of Decompression Stop Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-47

9-13.2

Need for Correction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-47

9-13.3

Depth Measurement at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-47

9-13.4

Equilibration at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-49

9-13.5

Diving at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-50
9-13.5.1 Corrections for Depth of Dive at Altitude and In-Water Stops . .  .  .  .  .  .  .  .  .  . 9-50
9-13.5.2 Corrections for Equilibration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-52

9-13.6

Repetitive Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-53

9-14 ASCENT TO ALTITUDE AFTER DIVING / FLYING AFTER DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-57

10

Nitrogen-Oxygen Diving Operations

10-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-1
10-1.1

Advantages and Disadvantages of NITROX Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-1

10-2 EQUIVALENT AIR DEPTH. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-1
10-2.1

Equivalent Air Depth Calculation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-2

10-3 OXYGEN TOXICITY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-2
10-3.1

Selecting the Proper NITROX Mixture . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-3

10-4 NITROX DIVING PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-3
10-4.1

NITROX Diving Using Equivalent Air Depths . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-3

10-4.2

SCUBA Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-4.3

Special Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-4.4

Omitted Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-4.5

Dives Exceeding the Normal Working Limit . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-5 NITROX REPETITIVE DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

xxviii

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page

10-6 NITROX DIVE CHARTING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5
10-7 FLEET TRAINING FOR NITROX. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10-8 NITROX DIVING EQUIPMENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10-8.1

Open-Circuit SCUBA Systems . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10‑8.1.1 Regulators . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10‑8.1.2 Bottles . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10-8.2

General. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10-8.3

Surface-Supplied NITROX Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10-9 EQUIPMENT CLEANLINESS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8
10-10 BREATHING GAS PURITY . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-9
10-11 NITROX MIXING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-9
10-12 NITROX MIXING, BLENDING, AND STORAGE SYSTEMS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-12

11

Ice and Cold Water Diving Operations

11-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-2

11-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

OPERATIONS PLANNING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1
11-2.1

Planning Guidelines . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-2.2

Navigational Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-2.3

SCUBA Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-2

11-2.4

SCUBA Regulators. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-2
11‑2.4.1
11‑2.4.2

Special Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3
Octopus and Redundant Regulators . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3

11-2.5

Life Preserver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3

11-2.6

Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4

11-2.7

SCUBA Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4

11-2.8

Surface-Supplied Diving System (SSDS) Considerations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4
11‑2.8.1 Advantages and Disadvantages of SSDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4
11‑2.8.2 Effect of Ice Conditions on SSDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-5

11-2.9

Suit Selection . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-5
11‑2.9.1
11‑2.9.2
11‑2.9.3

Wet Suits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-5
Variable Volume Dry Suits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-6
Extreme Exposure Suits/Hot Water Suits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-6

11-2.10 Clothing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-6
11-2.11 Ancillary Equipment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7
11-2.12 Dive Site Shelter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7

Table of Contents­	

xxix

Chap/Para
11-3

11-4

11-5

11-6

Page
PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7
11-3.1

Personnel Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7

11-3.2

Dive Site Selection Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7

11-3.3

Shelter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.4

Entry Hole. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.5

Escape Holes . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.6

Navigation Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.7

Lifelines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.8

Equipment Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-9

UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10
11-4.1

Buddy Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

11-4.2

Tending the Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

11-4.3

Standby Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

OPERATING PRECAUTIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10
11-5.1

General Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

11-5.2

Ice Conditions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-11

11-5.3

Dressing Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-11

11-5.4

On-Surface Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-11

11-5.5

In-Water Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-12

11-5.6

Postdive Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-12

EMERGENCY PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-13
11-6.1

Lost Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-13

11-6.2

Searching for a Lost Diver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-13

11-6.3

Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-14

11-7

ADDITIONAL REFERENCES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-14

2A

Optional Shallow Water Diving Tables
2-A1.1

12

Introduction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2A-1

Mixed-Gas Diving Theory

12-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-1
12-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-1

12-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-1

12-2 BOYLE’S LAW. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-1

xxx

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page

12-3 CHARLES’/GAY-LUSSAC’S LAW. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-4
12-4 THE GENERAL GAS LAW. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-7
12-5 DALTON’S LAW. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-11
12-6 HENRY’S LAW. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12-14

13

Mixed Gas Operational Planning

13-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-1
13-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-1

13-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-1

13-1.3

Additional Sources of Information. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-1

13-1.4

Complexity of Mixed Gas Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-1

13-1.5

Medical Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-1

13-2 ESTABLISH OPERATIONAL TASKS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-2
13-3 SELECT DIVING METHOD AND EQUIPMENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-2
13-3.1

Mixed Gas Diving Methods. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-3

13-3.2

Method Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-3

13-3.3

Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-4

13-3.4

Bottom Time Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-4

13-3.5

Environment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-4

13-3.6

Mobility . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-5

13-3.7

Equipment Selection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-5

13-3.8

Operational Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-6

13-3.9

Support Equipment and ROVs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-6
13‑3.9.1 Types of ROV. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-6
13‑3.9.2 ROV Capabilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-6

13-3.10 Diver’s Breathing Gas Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-7
13‑3.10.1 Gas Consumption Rates . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-7
13‑3.10.2 Surface Supplied Diving Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-7
13-4 SELECTING AND ASSEMBLING THE DIVE TEAM . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-8
13-4.1

Diver Training . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-8

13-4.2

Personnel Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-8

13-4.3

Diver Fatigue. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-8

13-5 BRIEFING THE DIVE TEAM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-10
13-6 FINAL PREPARATIONS AND SAFETY PRECAUTIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-10
13-7 RECORD KEEPING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-11

Table of Contents­	

xxxi

Chap/Para

Page

13-8 MIXED GAS DIVING EQUIPMENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-11

14

13-8.1

Minimum Required Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-11

13-8.2

Operational Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-11

13-8.3

Flyaway Dive System III Mixed Gas System (FMGS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-12

Surface-Supplied Mixed Gas Diving Procedures

14-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1
14-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1

14-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1

14-2 PLANNING THE OPERATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1
14-2.1

Depth and Exposure Limits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1

14-2.2

Ascent to Altitude . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1

14-2.3

Water Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-1

14-2.4

Gas Mixtures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-2

14-2.5

Emergency Gas Supply . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-2

14-3 SURFACE-SUPPLIED HELIUM-OXYGEN DESCENT AND ASCENT PROCEDURES. .  .  .  .  . 14-2
14-3.1

Selecting the Bottom Mix . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-2

14-3.2

Selecting the Decompression Schedule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-3

14-3.3

Travel Rates and Stop Times. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-3

14-3.4

Decompression Breathing Gases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-3

14-3.5

Special Procedures for Descent with Less than 16 Percent Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  . 14-4

14-3.6

Aborting Dive During Descent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-4

14-3.7

Procedures for Shifting to 50 Percent Helium/50 Percent Oxygen at 90 fsw. .  .  .  .  .  .  . 14-5

14-3.8

Procedures for Shifting to 100 Percent Oxygen at 30 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-5

14-3.9

Air Breaks at 30 and 20 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-5

14-3.10 Ascent from the 20-fsw Water Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-6
14-3.11 Surface Decompression on Oxygen (SurDO2). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-6
14-3.12 Variation in Rate of Ascent . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-7
14‑3.12.1
14‑3.12.2
14‑3.12.3
14‑3.12.4

Early Arrival at the First Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Delays in Arriving at the First Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Delays in Leaving a Stop or Arrival at the Next Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Delays in Travel from 40 fsw to the Surface for Surface Decompression . .

14-7
14-7
14-8
14-8

14-4 SURFACE-SUPPLIED HELIUM-OXYGEN EMERGENCY PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-9

xxxii

14-4.1

Bottom Time in Excess of the Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-9

14-4.2

Loss of Helium-Oxygen Supply on the Bottom. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-9

14-4.3

Loss of 50 Percent Oxygen Supply During In-Water Decompression . .  .  .  .  .  .  .  .  .  .  . 14-10

14-4.4

Loss of Oxygen Supply During In-Water Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-10

14-4.5

Loss of Oxygen Supply in the Chamber During Surface Decompression. . . . . . . . . . 14-11

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page
14-4.6

Decompression Gas Supply Contamination. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-11

14-4.7

CNS Oxygen Toxicity Symptoms (Nonconvulsive) at the 90-60 fsw Water Stops . .  . 14-12

14-4.8

Oxygen Convulsion at the 90-60 fsw Water Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-12

14-4.9

CNS Toxicity Symptoms (Nonconvulsive) at 50- and 40-fsw Water Stops. .  .  .  .  .  .  .  . 14-13

14-4.10 Oxygen Convulsion at the 50-40 fsw Water Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-14
14-4.11 CNS Oxygen Toxicity Symptoms (Nonconvulsive) at 30- and 20-fsw Water Stops . . 14-15
14-4.12 Oxygen Convulsion at the 30- and 20-fsw Water Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-15
14-4.13 Oxygen Toxicity Symptoms in the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-16
14-4.14 Surface Interval Greater than 5 Minutes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-16
14-4.15 Asymptomatic Omitted Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-17
14‑4.15.1 Omitted Decompression Stop Deeper Than 50 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-18
14-4.16 Symptomatic Omitted Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-18
14-4.17 Light Headed or Dizzy Diver on the Bottom . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-18
14‑4.17.1 Initial Management. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-18
14‑4.17.2 Vertigo . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-19
14-4.18 Unconscious Diver on the Bottom . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-19
14-4.19 Decompression Sickness in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-20
14‑4.19.1 Decompression Sickness Deeper than 30 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-21
14‑4.19.2 Decompression Sickness at 30 fsw and Shallower. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-21
14-4.20 Decompression Sickness During the Surface Interval . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-21
14-5 CHARTING SURFACE SUPPLIED HELIUM OXYGEN DIVES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-22
14-5.1

Charting an HeO2 Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-22

14-6 DIVING AT ALTITUDE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-22

15

Saturation Diving

15-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1
15-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1

15-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1

15-2 APPLICATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1
15-3 BASIC COMPONENTS OF A SATURATION DIVE SYSTEM . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1
15-3.1

Personnel Transfer Capsule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1
15‑3.1.1
15‑3.1.2
15‑3.1.3
15‑3.1.4
15‑3.1.5
15‑3.1.6
15‑3.1.7
15‑3.1.8

Table of Contents­	

Gas Supplies . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-1
PTC Pressurization/Depressurization System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-2
PTC Life-Support System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-3
Electrical System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-3
Communications System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-3
Strength, Power, and Communications Cables (SPCCs). . . . . . . . . . . . . . . 15-3
PTC Main Umbilical. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-3
Diver Hot Water System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-3

xxxiii

Chap/Para

Page
15-3.2

Deck Decompression Chamber (DDC). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-3
15‑3.2.1
15‑3.2.2
15‑3.2.3
15‑3.2.4
15‑3.2.5

15-3.3

DDC Life-Support System (LSS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Sanitary System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Fire Suppression System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Main Control Console (MCC). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Gas Supply Mixing and Storage. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

15-4
15-4
15-4
15-4
15-4

PTC Handling Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-4
15‑3.3.1 Handling System Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-5

15-3.4

Saturation Mixed-Gas Diving Equipment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-5

15-4 U.S. NAVY SATURATION FACILITIES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-5
15-4.1

Navy Experimental Diving Unit (NEDU), Panama City, FL. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-5

15-4.2

Naval Submarine Medical Research Laboratory (NSMRL), New London, CT. .  .  .  .  .  . 15-6

15-5 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-6
15-6 THERMAL PROTECTION SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-9
15-6.1

Diver Heating . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-9

15-6.2

Inspired Gas Heating . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-9

15-7 SATURATION DIVING UNDERWATER BREATHING APPARATUS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-10
15-8 UBA GAS USAGE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-11
15-8.1

Specific Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-11

15-8.2

Emergency Gas Supply Duration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-12

15-8.3

Gas Composition. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-13

15-9 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-14
15-10 OPERATIONAL CONSIDERATIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-14
15-10.1 Dive Team Selection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-14
15-10.2 Mission Training . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-14
15-11 SELECTION OF STORAGE DEPTH . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-14
15-12 RECORDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-15
15-12.1 Command Diving Log. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-15
15-12.2 Master Protocol. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-15
15‑12.2.1 Modifications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-16
15‑12.2.2 Elements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-16
15-12.3 Chamber Atmosphere Data Sheet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-16
15-12.4 Service Lock. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-16
15-12.5 Machinery Log/Gas Status Report . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-16
15-12.6 Operational Procedures (OPs).. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-16
15-12.7 Emergency Procedures (EPs). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-17
15-12.8 Individual Dive Record . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-17

xxxiv

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page

15-13 LOGISTICS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-17
15-14 DDC AND PTC ATMOSPHERE CONTROL. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-17
15-15 GAS SUPPLY REQUIREMENTS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-18
15-15.1 UBA Gas. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-18
15-15.2 Emergency Gas . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-18
15-15.3 Treatment Gases . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-18
15-16 ENVIRONMENTAL CONTROL. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-19
15-17 FIRE ZONE CONSIDERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-19
15-18 HYGIENE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-20
15-18.1 Personal Hygiene. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-21
15-18.2 Prevention of External Ear Infections. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-21
15-18.3 Chamber Cleanliness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-21
15-18.4 Food Preparation and Handling . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-21
15-19 ATMOSPHERE QUALITY CONTROL. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-22
15-19.1 Gaseous Contaminants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-22
15-19.2 Initial Unmanned Screening Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-22
15-20 COMPRESSION PHASE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-22
15-20.1 Establishing Chamber Oxygen Partial Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-23
15-20.2 Compression to Storage Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-24
15-20.3 Precautions During Compression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-24
15-20.4 Abort Procedures During Compression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-25
15-21 STORAGE DEPTH. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-25
15-21.1 Excursion Table Examples . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-28
15-21.2 PTC Diving Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-29
15‑21.2.1 PTC Deployment Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-29
15-22 DEEP DIVING SYSTEM (DDS) EMERGENCY PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-29
15-22.1 Loss of Chamber Atmosphere Control . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-30
15‑22.1.1
15‑22.1.2
15‑22.1.3
15‑22.1.4
15‑22.1.5

Loss of Oxygen Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Loss of Carbon Dioxide Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Atmosphere Contamination. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Interpretation of the Analysis . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Loss of Temperature Control . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

15-30
15-31
15-31
15-31
15-32

15-22.2 Loss of Depth Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-32
15-22.3 Fire in the DDC. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-32
15-22.4 PTC Emergencies. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-32

Table of Contents­	

xxxv

Chap/Para

Page

15-23 SATURATION DECOMPRESSION . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33
15-23.1 Upward Excursion Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33
15-23.2 Travel Rate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33
15-23.3 Post-Excursion Hold. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33
15-23.4 Rest Stops. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33
15-23.5 Saturation Decompression Rates . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33
15-23.6 Atmosphere Control at Shallow Depths . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-34
15-23.7 Saturation Dive Mission Abort. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-35
15‑23.7.1 Emergency Cases . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-35
15‑23.7.2 Emergency Abort Procedure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-36
15-23.8 Decompression Sickness (DCS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-37
15‑23.8.1 Type I Decompression Sickness . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-37
15‑23.8.2 Type II Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-37
15-24 POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-39

16

Breathing Gas Mixing Procedures

16-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-1
16-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-1

16-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-1

16-2 MIXING PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-1
16-2.1

Mixing by Partial Pressure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-1

16-2.2

Ideal-Gas Method Mixing Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-2

16-2.3

Adjustment of Oxygen Percentage. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-5
16‑2.3.1 Increasing the Oxygen Percentage . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-5
16‑2.3.2 Reducing the Oxygen Percentage. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-6

16-2.4

Continuous-Flow Mixing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-7

16-2.5

Mixing by Volume . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-7

16-2.6

Mixing by Weight. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-8

16-3 GAS ANALYSIS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-8

17

16-3.1

Instrument Selection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-9

16-3.2

Techniques for Analyzing Constituents of a Gas. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-9

MK 16 MOD 0 Closed-Circuit Mixed-Gas UBA Diving

17-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-1

xxxvi

17-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-1

17-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-1

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page

17-2 PRINCIPLES OF OPERATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-1
17-2.1

Diving Safety. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-2

17-2.2

Advantages of Closed-Circuit Mixed-Gas UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-2

17-2.3

Recirculation and Carbon Dioxide Removal. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-3
17‑2.3.1
17‑2.3.2
17‑2.3.3
17‑2.3.4
17‑2.3.5
17-2.3.6

Recirculating Gas. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Full Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Carbon Dioxide Scrubber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diaphragm Assembly. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Recirculation System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Gas Addition, Exhaust, and Monitoring . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

17-3
17-3
17-3
17-4
17-4
17-5

17-3 MK16 MOD 0 Closed Circuit UBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-5
17-3.1

Housing System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-5

17-3.2

Recirculation System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-5
17‑3.2.1 Closed-Circuit Subassembly . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-6
17‑3.2.2 Scrubber Functions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-6

17-3.3

Pneumatics System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-6

17-3.4

Electronics System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-6
17‑3.4.1 Oxygen Sensing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-6
17‑3.4.2 Oxygen Control . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-6
17‑3.4.3 Displays. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-7

17-4 OPERATIONAL PLANNING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-8
17-4.1

Operating Limitations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-9
17‑4.1.1
17‑4.1.2
17‑4.1.3
17‑4.1.4

17-4.2

Oxygen Flask Endurance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diluent Flask Endurance . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Canister Duration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Thermal Protection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

17-9
17-11
17-11
17-11

Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-12
17‑4.2.1
17‑4.2.2
17‑4.2.3
17‑4.2.4
17‑4.2.5
17‑4.2.6

Distance Line. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Standby Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Marking of Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diver Marker Buoy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Depth Gauge/Wrist Watch. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

17-12
17-12
17-13
17-13
17-13
17-13

17-4.3

Recompression Chamber Considerations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-13

17-4.4

Ship Safety. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-13

17-4.5

Operational Area Clearance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-13

17-5 PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-14
17-5.1

Diving Supervisor Brief. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-14

17-5.2

Diving Supervisor Check. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-14

17-6 WATER ENTRY AND DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-14

Table of Contents­	

xxxvii

Chap/Para

Page

17-7 UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-15
17-7.1

General Guidelines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-15

17-7.2

At Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-16

17-8 ASCENT PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-16
17-9 POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-16
17-10 DECOMPRESSION PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-16
17-10.1 Rules for Using 0.7 ata Constant ppO2 in Nitrogen and in Helium
Decompression Tables.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-17
17-10.2 PPO2 Variances. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-24
17-10.3 Emergency Breathing System (EBS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-24
17‑10.3.1 Emergency Decompression on Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-24
17-10.4 Asymptomatic Omitted Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-25
17-10.5 Symptomatic Omitted Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-25
17-11 MEDICAL ASPECTS OF CLOSED-CIRCUIT MIXED-GAS UBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-25
17-11.1 Central Nervous System (CNS) Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-26
17‑11.1.1
17‑11.1.2
17‑11.1.3
17‑11.1.4
17‑11.1.5
17‑11.1.6

Causes of CNS Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of CNS Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Non-Convulsive Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Underwater Convulsion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of CNS Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Off-Effect . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

17-26
17-26
17-27
17-27
17-28
17-29

17-11.2 Pulmonary Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-29
17-11.3 Oxygen Deficiency (Hypoxia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-29
17‑11.3.1
17‑11.3.2
17‑11.3.3
17‑11.3.4

Causes of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypoxic Divers Requiring Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .

17-29
17-29
17-29
17-30

17-11.4 Carbon Dioxide Toxicity (Hypercapnia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-30
17‑11.4.1
17‑11.4.2
17‑11.4.3
17‑11.4.4

Causes of Hypercapnia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

17-30
17-30
17-31
17-31

17-11.5 Chemical Injury . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-31
17‑11.5.1
17‑11.5.2
17‑11.5.3
17‑11.5.4

Causes of Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Management of a Chemical Incident. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Chemical Injury . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

17-31
17-32
17-32
17-32

17-11.6 Decompression Sickness in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-32
17‑11.6.1 Diver Remaining in Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-33
17‑11.6.2 Diver Leaving the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-33
17-11.7. Altitude Diving Procedures and Flying After Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-33
17-12 MK 16 MOD 0 DIVING EQUIPMENT REFERENCE DATA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-34
xxxviii

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
18

Page
MK 16 MOD 1 Closed-Circuit Mixed-Gas UBA Diving

18-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-1
18-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-1

18-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-1

18-2 OPERATIONAL PLANNING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-1
18-2.1

Operating Limitations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-3
18-2.1.1
18-2.1.2
18-2.1.3
18-2.1.4

18-2.2

Oxygen Flask Endurance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Effect of Cold Water Immersion on Flask Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diluent Flask Endurance . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Canister Duration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

18-4
18-6
18-6
18-6

Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-7
18-2.2.1
18-2.2.2
18-2.2.3
18-2.2.4
18-2.2.5
18-2.2.6
18-2.2.7
18-2.2.8
18-2.2.9
18-2.2.10
18-2.2.11
18-2.2.12

Safety Boat. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Buddy Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Distance Line. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Standby Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Tending Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Marking of Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diver Marker Buoy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Depth Gauge/Wrist Watch. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Thermal Protection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Approved Life Preserver or Buoyancy Compensator (BC). .  .  .  .  .  .  .  .  .  .  .  .  .
Full Face Mask (FFM) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Emergency Breathing System (EBS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

18-7
18-7
18-7
18-7
18-8
18-8
18-8
18-9
18-9
18-9
18-9
18-9

18-2.3

Recompression Chamber Considerations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-9

18-2.4

Diving Procedures for MK 16 MOD 1. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-10
18-2.4.1 EOD Standard Safety Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-10
18-2.4.2 Diving Methods. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-10

18-2.5

Ship Safety. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-11

18-2.6

Operational Area Clearance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-11

18-3 PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-11
18-3.1

Diving Supervisor Brief. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-11

18-3.2

Diving Supervisor Check. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-11

18-4 DESCENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-14
18-5 UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-14
18-5.1

General Guidelines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-14

18-5.2

At Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-15

18-6 ASCENT PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-15
18-7 DECOMPRESSION PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-15
18-7.1

Monitoring ppO2 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-16

18-7.2

Rules for Using MK 16 MOD 1 Decompression Tables . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-16

Table of Contents­	

xxxix

Chap/Para

Page
18-7.3

PPO2 Variances. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-19

18-7.4

Emergency Breathing System (EBS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-19
18-7.4.1 EBS Deployment Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-19
18-7.4.2 EBS Ascent Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-19

18-8 MULTI-DAY DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-20
18-9 ALTITUDE DIVING PROCEDURES AND FLYING AFTER DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-21
18-10 POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-21
18-11 MEDICAL ASPECTS OF CLOSED-CIRCUIT MIXED-GAS UBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-21
18-11.1 Central Nervous System (CNS) Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-21
18-11.1.1
18-11.1.2
18-11.1.3
18-11.1.4
18-11.1.5
18-11.1.6

Causes of CNS Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of CNS Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Nonconvulsive Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Underwater Convulsion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of CNS Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Off-Effect . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

18-22
18-22
18-23
18-23
18-24
18-24

18-11.2 Pulmonary Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-25
18-11.3 Oxygen Deficiency (Hypoxia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-25
18-11.3.1
18-11.3.2
18-11.3.3
18-11.3.4

Causes of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypoxic Divers Requiring Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .

18-25
18-25
18-25
18-25

18-11.4 Carbon Dioxide Toxicity (Hypercapnia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-26
18-11.4.1
18-11.4.2
18-11.4.3
18-11.4.4

Causes of Hypercapnia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

18-26
18-26
18-26
18-26

18-11.5 Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-27
18-11.5.1
18-11.5.2
18-11.5.3
18-11.5.4

Causes of Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Management of a Chemical Incident. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Chemical Injury . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

18-27
18-27
18-27
18-28

18-11.6 Omitted Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-28
18-11.6.1
18-11.6.2
18-11.6.3
18-11.6.4

At 20 fsw. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Deeper than 20 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Deeper than 20 fsw/No Recompression Chamber Available. .  .  .  .  .  .  .  .  .  .
Evidence of Decompression Sickness or Arterial Gas Embolism . .  .  .  .  .  .

18-28
18-28
18-28
18-29

18-11.7 Decompression Sickness in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-30
18-11.7.1 Diver Remaining in Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-30
18-11.7.2 Diver Leaving the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-30
18-12 MK 16 MOD 1 Diving Equipment Reference Data . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-31

xl

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para
19

Page
Closed-Circuit Oxygen UBA Diving

19-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-1
19-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-1

19-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-1

19-2 MEDICAL ASPECTS OF CLOSED-CIRCUIT OXYGEN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-1
19-2.1

Central Nervous System (CNS) Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-2
19‑2.1.1
19‑2.1.2
19‑2.1.3
19‑2.1.4
19‑2.1.5

Causes of CNS Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of CNS Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Nonconvulsive Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Underwater Convulsion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Off-Effect . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

19-2
19-2
19-3
19-3
19-4

19-2.2

Pulmonary Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-4

19-2.3

Oxygen Deficiency (Hypoxia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-5
19‑2.3.1
19‑2.3.2
19‑2.3.3
19‑2.3.4
19‑2.3.5

19-2.4

Causes of Hypoxia with the MK 25 UBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 25 UBA Purge Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Underwater Purge . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

19-5
19-5
19-5
19-5
19-5

Carbon Dioxide Toxicity (Hypercapnia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-6
19‑2.4.1 Symptoms of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-6
19‑2.4.2 Treating Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-6
19‑2.4.3 Prevention of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-7

19-2.5

Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-7
19‑2.5.1
19‑2.5.2
19‑2.5.3
19‑2.5.4

19-2.6

Causes of Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Chemical Injury. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of a Chemical Incident . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Chemical Injury . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

19-7
19-7
19-7
19-8

Middle Ear Oxygen Absorption Syndrome . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-8
19‑2.6.1
19‑2.6.2
19‑2.6.3
19‑2.6.4

Causes of Middle Ear Oxygen Absorption Syndrome . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  .

19-8
19-8
19-8
19-9

19-3 MK-25. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-9
19-3.1

Gas Flow Path. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-9
19‑3.1.1 Breathing Loop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-10

19-3.2

Operational Duration of the MK 25 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-11
19‑3.2.1 Oxygen Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-11
19‑3.2.2 Canister Duration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-11

19-3.3

Packing Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-12

19-3.4

Preventing Caustic Solutions in the Canister . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-12

19-4 CLOSED-CIRCUIT OXYGEN EXPOSURE LIMITS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-12
19-4.1

Table of Contents­	

Transit with Excursion Limits Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-12

xli

Chap/Para

Page
19-4.2

Single-Depth Oxygen Exposure Limits Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-13

19-4.3

Oxygen Exposure Limit Testing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-13

19-4.4

Individual Oxygen Susceptibility Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-14

19-4.5

Transit with Excursion Limits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-14
19‑4.5.1 Transit with Excursion Limits Definitions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-14
19‑4.5.2 Transit with Excursion Rules . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-14
19‑4.5.3 Inadvertent Excursions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-15

19-4.6

Single-Depth Limits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-15
19‑4.6.1 Single-Depth Limits Definitions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-15
19‑4.6.2 Depth/Time Limits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-16

19-4.7

Exposure Limits for Successive Oxygen Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-16
19‑4.7.1 Definitions for Successive Oxygen Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-16
19‑4.7.2 Off-Oxygen Exposure Limit Adjustments. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-16

19-4.8

Exposure Limits for Oxygen Dives Following Mixed-Gas or Air Dives . .  .  .  .  .  .  .  .  .  .  . 19-17
19‑4.8.1 Mixed-Gas to Oxygen Rule . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-17
19‑4.8.2 Oxygen to Mixed-Gas Rule . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-17

19-4.9

Oxygen Diving at High Elevations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-18

19-4.10 Flying After Oxygen Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-18
19-4.11 Combat Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-18
19-5 OPERATIONS PLANNING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-18
19-5.1

Operating Limitations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-18

19-5.2

Maximizing Operational Range. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-19

19-5.3

Training. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-19

19-5.4

Personnel Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-20

19-5.5

Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-20

19-5.6

Predive Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-21

19-6 PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-22
19-6.1

Equipment Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-22

19-6.2

Diving Supervisor Brief. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-22

19-6.3

Diving Supervisor Check. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-22
19‑6.3.1 First Phase. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-22
19‑6.3.2 Second Phase . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-22

19-7 WATER ENTRY AND DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-23
19-7.1

Purge Procedure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-23

19-7.2

Avoiding Purge Procedure Errors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-24

19-8 UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-24

xlii

19-8.1

General Guidelines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-24

19-8.2

UBA Malfunction Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-25

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page

19-9 ASCENT PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-25
19-10 POSTDIVE PROCEDURES AND DIVE DOCUMENTATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-25

20

Diagnosis and Treatment of Decompression Sickness and 
Arterial Gas Embolism

20-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-1
20-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-1

20-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-1

20-1.3

Diving Supervisor’s Responsibilities. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-1

20-1.4

Prescribing and Modifying Treatments. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-2

20-1.5

When Treatment is Not Necessary. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-2

20-1.6

Emergency Consultation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-2

20-2 ARTERIAL GAS EMBOLISM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-2
20-2.1

Diagnosis of Arterial Gas Embolism. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-3
20‑2.1.1 Symptoms of AGE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-3

20-2.2

Treating Arterial Gas Embolism . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-4

20-2.3

Resuscitation of a Pulseless Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-4

20-3 DECOMPRESSION SICKNESS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-4
20-3.1

Diagnosis of Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-5

20-3.2

Symptoms of Type I Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-5
20‑3.2.1 Musculoskeletal Pain-Only Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-5
20‑3.2.2 Cutaneous (Skin) Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-6
20‑3.2.3 Lymphatic Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-6

20-3.3

Treatment of Type I Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-6

20-3.4

Symptoms of Type II Decompression Sickness . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-6
20‑3.4.1
20‑3.4.2
20‑3.4.3
20‑3.4.4

Neurological Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Inner Ear Symptoms (“Staggers”) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Cardiopulmonary Symptoms (“Chokes”) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Differentiating Between Type II DCS and AGE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

20-7
20-7
20-7
20-7

20-3.5

Treatment of Type II Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-8

20-3.6

Decompression Sickness in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-8

20-3.7

Symptomatic Omitted Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-8

20-3.8

Altitude Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-8
20‑3.8.1 Joint Pain Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-9
20‑3.8.2 Other Symptoms and Persistent Symptoms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-9

20-4 RECOMPRESSION TREATMENT FOR DIVING DISORDERS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-9
20-4.1

Primary Objectives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-9

20-4.2

Guidance on Recompression Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-9

Table of Contents­	

xliii

Chap/Para

Page
20-4.3

Recompression Treatment When Chamber Is Available. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-9
20‑4.3.1 Recompression Treatment With Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-10
20‑4.3.2 Recompression Treatments When Oxygen Is Not Available. .  .  .  .  .  .  .  .  .  . 20-10

20-4.4

Recompression Treatment When No Recompression Chamber is Available. .  .  .  .  .  .  . 20-11
20‑4.4.1 Transporting the Patient. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-11
20‑4.4.2 In-Water Recompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-11

20-5 TREATMENT TABLES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-13
20-5.1

Air Treatment Tables. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-13

20-5.2

Treatment Table 5. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-13

20-5.3

Treatment Table 6. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-13

20-5.4

Treatment Table 6A. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-14

20-5.5

Treatment Table 4 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-14

20-5.6

Treatment Table 7. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-15
20‑5.6.1
20-5.6.2
20‑5.6.3
20‑5.6.4
20‑5.6.5
20‑5.6.6
20‑5.6.7

Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-15
Tenders.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-16
Preventing Inadvertent Early Surfacing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-16
Oxygen Breathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-16
Sleeping, Resting, and Eating . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-16
Ancillary Care. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-16
Life Support . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-17

20-5.7

Treatment Table 8. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-17

20-5.8

Treatment Table 9. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-17

20-6 RECOMPRESSION TREATMENT FOR NON-DIVING DISORDERS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-17
20-7 RECOMPRESSION CHAMBER LIFE-SUPPORT CONSIDERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-18
20-7.1

Minimum Manning Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-18

20-7.2

Optimum Manning Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-19
20‑7.2.1 Additional Personnel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-19
20‑7.2.2 Required Consultation by a Diving Medical Officer . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-19

20-7.3

Oxygen Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-19

20-7.4

Carbon Dioxide Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-19
20‑7.4.1 Carbon Dioxide Monitoring. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-20
20‑7.4.2 Carbon Dioxide Scrubbing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-20
20‑7.4.3 Carbon Dioxide Absorbent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-20

20-7.5

Temperature Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-20
20‑7.5.1 Patient Hydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-21

20-7.6

Chamber Ventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-21

20-7.7

Access to Chamber Occupants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22

20-7.8

Inside Tenders. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-22
20‑7.8.1
20‑7.8.2
20‑7.8.3
20‑7.8.4

xliv

Inside Tender Responsibilities. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
DMO or DMT Inside Tender. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Use of Diving Medical Officer as Inside Tender. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Non-Diver Inside Tender - Medical. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

20-22
20-22
20-22
20-23

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page
20‑7.8.5 Specialized Medical Care. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-23
20‑7.8.6 Inside Tender Oxygen Breathing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-23
20‑7.8.7 Tending Frequency. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-23
20-7.9

Equalizing During Descent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-23

20-7.10 Use of High Oxygen Mixes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-23
20-7.11 Oxygen Toxicity During Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-24
20‑7.11.1 Central Nervous System Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-24
20‑7.11.2 Pulmonary Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-25
20-7.12 Loss of Oxygen During Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-25
20‑7.12.1 Compensation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-25
20‑7.12.2 Switching to Air Treatment Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-26
20-7.13 Treatment at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-26
20-8 POST-TREATMENT CONSIDERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-26
20-8.1

Post-Treatment Observation Period. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-26

20-8.2

Post-Treatment Transfer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-27

20-8.3

Flying After Treatments. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-27
20‑8.3.1 Emergency Air Evacuation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-27

20-8.4

Treatment of Residual Symptoms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-28

20-8.5

Returning to Diving after Recompression Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-28

20-9 NON-STANDARD TREATMENTS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-29
20-10 RECOMPRESSION TREATMENT ABORT PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-29
20-10.1 Death During Treatment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-29
20-10.2 Impending Natural Disasters or Mechanical Failures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-30
20-11 ANCILLARY CARE AND ADJUNCTIVE TREATMENTS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-30
20-11.1 Decompression Sickness.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-31
20‑11.1.1
20‑11.1.2
20‑11.1.3
20‑11.1.4
20‑11.1.5
20‑11.1.6
20‑11.1.7

Surface Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Fluids. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Anticoagulants. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Aspirin and Other Non-Steroidal Anti-Inflammatory Drugs. .  .  .  .  .  .  .  .  .  .  .  .
Steroids . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Lidocaine . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Environmental Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

20-31
20-31
20-32
20-32
20-32
20-32
20-32

20-11.2 Arterial Gas Embolism . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-32
20‑11.2.1
20‑11.2.2
20‑11.2.3
20‑11.2.4
20‑11.2.5
20‑11.2.6

Surface Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Lidocaine . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Fluids. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Anticoagulants. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Aspirin and Other Non-Steroidal Anti-Inflammatory Drugs. .  .  .  .  .  .  .  .  .  .  .  .
Steroids . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

20-32
20-32
20-32
20-33
20-33
20-33

20-11.3 Sleeping and Eating . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-33

Table of Contents­	

xlv

Chap/Para

Page

20-12 EMERGENCY MEDICAL EQUIPMENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-33
20-12.1 Primary and Secondary Emergency Kits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-33
20-12.2 Portable Monitor-Defibrillator . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-36
20-12.3 Advanced Cardiac Life Support Drugs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-36
20-12.4 Use of Emergency Kits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-36
20-12.4.1 Modification of Emergency Kits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-36

21

Recompression Chamber Operation

21-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-1
21-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-1

21-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-1

21-1.3

Chamber Definitions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-1

21-2 DESCRIPTION . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-1
21-2.1

Basic Chamber Components . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-2

21-2.2

Fleet Modernized Double-Lock Recompression Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-2

21-2.3

Recompression Chamber Facility (RCF) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-2

21-2.4

Standard Navy Double Lock Recompression Chamber System (SNDLRCS) . .  .  .  .  .  . 21-3

21-2.5

Transportable Recompression Chamber System (TRCS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-3

21-2.6

Fly Away Recompression Chamber (FARCC) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-3

21-2.7

Emergency Evacuation Hyperbaric Stretcher (EEHS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-4

21-2.8

Standard Features . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-4
21‑2.8.1
21‑2.8.2
21‑2.8.3
21‑2.8.4
21‑2.8.5
21‑2.8.6

Labeling. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Inlet and Exhaust Ports . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Gauges. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Relief Valves. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Communications System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Lighting Fixtures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

21-4
21-4
21-4
21-5
21-5
21-5

21-3 STATE OF READINESS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-15
21-4 GAS SUPPLY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-15
21-4.1

Capacity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-15

21-5 OPERATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-17
21-5.1

Predive Checklist . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-17

21-5.2

Safety Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-17

21-5.3

General Operating Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-17
21‑5.3.1
21‑5.3.2
21‑5.3.3
21‑5.3.4

xlvi

Tender Change-Out. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Lock-In Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Lock-Out Operations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Gag Valves. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

21-20
21-20
21-20
21-20

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page
21-5.4

Ventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-20
21‑5.4.1 Chamber Ventilation Bill. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-21
21‑5.4.2 Notes on Chamber Ventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-22

21-6 CHAMBER MAINTENANCE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-23
21-6.1

Postdive Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-23

21-6.2

Scheduled Maintenance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-23
21‑6.2.1
21‑6.2.2
21‑6.2.3
21‑6.2.4
21‑6.2.5
21‑6.2.6

Inspections. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Corrosion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Painting Steel Chambers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Recompression Chamber Paint Process Instruction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Stainless Steel Chambers . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Fire Hazard Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

21-25
21-25
21-25
21-29
21-29
21-29

21-7 DIVER CANDIDATE PRESSURE TEST. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-30
21-7.1

Candidate Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-30

21-7.2

Procedure. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-31
21‑7.2.1 References. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-31

5A

Neurological Examination

5A-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-1
5A-2 INITIAL ASSESSMENT OF DIVING INJURIES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-1
5A-3 NEUROLOGICAL ASSESSMENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-2
5A-3.1

Mental Status . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-5

5A-3.2

Coordination (Cerebellar/Inner Ear Function). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-5

5A-3.3

Cranial Nerves . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-6

5A-3.4

Motor. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-7
5A‑3.4.1
5A‑3.4.2
5A‑3.4.3
5A‑3.4.4

5A-3.5

Table of Contents­	

5A-8
5A-8
5A-8
5A-8

Sensory Function . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-8
5A‑3.5.1
5A‑3.5.2
5A‑3.5.3
5A‑3.5.4
5A‑3.5.5
5A‑3.5.6
5A‑3.5.7

5A-3.6

Extremity Strength. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Muscle Size . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Muscle Tone. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Involuntary Movements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

Sensory Examination. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10
Sensations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10
Instruments. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10
Testing the Trunk . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10
Testing Limbs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10
Testing the Hands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A-10
Marking Abnormalities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10

Deep Tendon Reflexes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-10

xlvii

Chap/Para
5B

Page
First Aid

5B-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-1
5B-2 CARDIOPULMONARY RESUSCITATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-1
5B-3 CONTROL OF MASSIVE BLEEDING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-1
5B-3.1

External Arterial Hemorrhage. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-1

5B-3.2

Direct Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-1

5B-3.3

Pressure Points. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-1
5B‑3.3.1
5B‑3.3.2
5B‑3.3.3
5B‑3.3.4
5B‑3.3.5
5B‑3.3.6
5B‑3.3.7
5B‑3.3.8
5B‑3.3.9
5B‑3.3.10
5B‑3.3.11
5B‑3.3.12

5B-3.4

Pressure Point Location on Face. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Shoulder or Upper Arm . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Middle Arm and Hand . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Thigh . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Foot. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Temple or Scalp. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Neck. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location for Lower Arm. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location of the Upper Thigh . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Pressure Point Location Between Knee and Foot. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Determining Correct Pressure Point. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
When to Use Pressure Points . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

5B-2
5B-2
5B-2
5B-2
5B-2
5B-2
5B-2
5B-2
5B-2
5B-4
5B-4
5B-4

Tourniquet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-4
5B‑3.4.1
5B‑3.4.2
5B‑3.4.3
5B‑3.4.4

How to Make a Tourniquet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Tightness of Tourniquet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
After Bleeding is Under Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Points to Remember.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

5B-4
5B-5
5B-5
5B-5

5B-3.5

External Venous Hemorrhage. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-6

5B-3.6

Internal Bleeding. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-6
5B‑3.6.1 Treatment of Internal Bleeding. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-6

5B-4 SHOCK. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-6

5C

5B-4.1

Signs and Symptoms of Shock. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-6

5B-4.2

Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-7

Dangerous Marine Animals

5C-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1
5C-1.1 Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1
5C-1.2 Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1
5C-2 PREDATORY MARINE ANIMALS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1
5C-2.1 Sharks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1
5C‑2.1.1 Shark Pre-Attack Behavior. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1
5C‑2.1.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-1

xlviii

U.S. Navy Diving Manual—Volumes 1 through 5

Chap/Para

Page
5C-2.2 Killer Whales. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-3
5C‑2.2.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4
5C‑2.2.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4
5C-2.3 Barracuda. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4
5C‑2.3.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4
5C‑2.3.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4
5C-2.4 Moray Eels . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4
5C‑2.4.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-5
5C‑2.4.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-5
5C-2.5 Sea Lions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-5
5C‑2.5.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-5
5C‑2.5.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-5

5C-3 VENOMOUS MARINE ANIMALS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-6
5C-3.1 Venomous Fish (Excluding Stonefish, Zebrafish, Scorpionfish). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-6
5C‑3.1.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-6
5C‑3.1.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-6
5C-3.2 Highly Toxic Fish (Stonefish, Zebrafish, Scorpionfish) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-7
5C‑3.2.1 Prevention.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-7
5C‑3.2.2 First Aid and Treatment.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-7
5C-3.3 Stingrays. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-9
5C‑3.3.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-9
5C‑3.3.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-9
5C-3.4 Coelenterates. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-9
5C‑3.4.1
5C‑3.4.2
5C‑3.4.3
5C‑3.4.4
5C‑3.4.5
5C‑3.4.6
5C‑3.4.7

Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-10
Avoidance of Tentacles . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-10
Protection Against Jellyfish. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5C-10
First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-10
Symptomatic Treatment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11
Anaphylaxis . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11
Antivenin. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11

5C-3.5 Coral. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11
5C‑3.5.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11
5C‑3.5.2 Protection Against Coral. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11
5C‑3.5.3 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-11
5C-3.6 Octopuses. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-12
5C‑3.6.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-13
5C‑3.6.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-13
5C-3.7 Segmented Worms (Annelida) (Examples: Bloodworm, Bristleworm) . .  .  .  .  .  .  .  .  .  .  . 5C-13
5C‑3.7.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-13
5C‑3.7.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-13
5C-3.8 Sea Urchins. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-14
5C‑3.8.1 Prevention.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-14
5C‑3.8.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-14

Table of Contents­	

xlix

Chap/Para

Page
5C-3.9 Cone Shells. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-15
5C‑3.9.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-15
5C‑3.9.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-15
5C-3.10 Sea Snakes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-16
5C‑3.10.1 Sea Snake Bite Effects. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-16
5C‑3.10.2 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-17
5C‑3.10.3 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-17
5C-3.11 Sponges . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-18
5C‑3.11.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-18
5C‑3.11.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-18

5C-4 POISONOUS MARINE ANIMALS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-18
5C-4.1 Ciguatera Fish Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-18
5C‑4.1.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-19
5C‑4.1.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-19
5C-4.2 Scombroid Fish Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-19
5C‑4.2.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-20
5C‑4.2.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-20
5C-4.3 Puffer (Fugu) Fish Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-20
5C‑4.3.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-20
5C‑4.3.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-20
5C-4.4 Paralytic Shellfish Poisoning (PSP) (Red Tide). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5C-20
5C‑4.4.1 Symptoms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-21
5C‑4.4.2 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-21
5C‑4.4.3 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-21
5C-4.5 Bacterial and Viral Diseases from Shellfish . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-21
5C‑4.5.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-21
5C‑4.5.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-21
5C-4.6 Sea Cucumbers . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-22
5C‑4.6.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-22
5C‑4.6.2 First Aid and Treatment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-22
5C-4.7 Parasitic Infestation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-22
5C‑4.7.1 Prevention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-22
5C-5 REFERENCES FOR ADDITIONAL INFORMATION . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-22

	

U.S. Navy Diving Manual—Volumes 1 through 5

List of Illustrations
Figure

Page

1-1

Early Impractical Breathing Device. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-2

1-2

Assyrian Frieze (900 B.C.) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-2

1-3

Engraving of Halley’s Diving Bell. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4

1-4

Lethbridge’s Diving Suit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4

1-5

Siebe’s First Enclosed Diving Dress and Helmet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

1-6

French Caisson. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

1-7

Armored Diving Suit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7

1-8

MK 12 and MK V. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9

1-9

Fleuss Apparatus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-11

1-10

Original Davis Submerged Escape Apparatus . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-13

1-11

Lambertsen Amphibious Respiratory Unit (LARU). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-14

1-12

Emerson-Lambertsen Oxygen Rebreather. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-15

1-13

Draeger LAR V UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-15

1-14

Helium-Oxygen Diving Manifold . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-17

1-15

MK V MOD 1 Helmet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-18

1-16

MK 1 MOD 0 Diving Outfit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-20

1-17

Sealab II . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-23

1-18

U.S. Navy’s First DDS, SDS-450. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-23

1-19

DDS MK 1 Personnel Transfer Capsule . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-25

1-20

PTC Handling System, Elk River. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-25

1-21

Recovery of the Squalus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-28

2-1

Molecules . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

2-2

The Three States of Matter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

2-3

Temperature Scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2-4

The Six Forms of Energy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-4

2-5

Objects Underwater Appear Closer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5

2‑6

Kinetic Energy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-17

2‑7

Depth, Pressure, Atmosphere Graph . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-36

3-1

The Heart’s Components and Blood Flow. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-3

3-2

Respiration and Blood Circulation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-4

3-3

Inspiration Process . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-7

3-4

Lungs Viewed from Medical Aspect. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-7

3-5

Lung Volumes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-8

List of Illustrations	

li

Figure

lii

Page

3-6

Oxygen Consumption and RMV at Different Work Rates. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-12

3-7

Gross Anatomy of the Ear in Frontal Section . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-23

3-8

Location of the Sinuses in the Human Skull . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-26

3-9

Components of the Middle/Inner Ear. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-28

3-10

Pulmonary Overinflation Syndromes (POIS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-32

3-11

Arterial Gas Embolism. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-33

3-12

Mediastinal Emphysema. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-36

3-13

Subcutaneous Emphysema. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-37

3-14

Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-38

3-15

Tension Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-39

3-16

Saturation of Tissues. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-47

3-17

Desaturation of Tissues. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-49

5-1

U.S. Navy Diving Log . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-3

5-2

Equipment Accident/Incident Information Sheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-5

5-3

Failure Analysis Report (NAVSEA Form 10560/4). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-8

5‑4

Failure Analysis Report. (NAVSEA Form 10560/1). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-9

1A-1

Sonar Safe Diving Distance/Exposure Time Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-4

1A‑2

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  .  . 1A-8

1A-3

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  .  . 1A-9

1A‑4

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  . 1A-10

1A‑5

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  . 1A-11

6-1

Underwater Ship Husbandry Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2

6-2

Salvage Diving. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

6-3

Explosive Ordnance Disposal Diving. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

6-4

Underwater Construction Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6‑5

Planning Data Sources. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-9

6‑6

Environmental Assessment Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-11

6-7

Sea State Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-12

6‑8

Equivalent Wind Chill Temperature Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-14

6‑9

Pneumofathometer . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-15

6‑10

Bottom Conditions and Effects Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-16

6‑11

Water Temperature Protection Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-18

6‑12

International Code Signal Flags . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-23

6‑13

Air Diving Techniques . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-25

6‑14

Normal and Maximum Limits for Air Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-26

U.S. Navy Diving Manual—Volumes 1 through 5

Figure

Page

6‑15

MK 21 Dive Requiring Two Divers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-30

6‑16

Minimum Personnel Levels for Air Diving Stations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-31

6‑17

Master Diver Supervising Recompression Treatment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6‑18

Standby Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-35

6-19

Diving Safety and Planning Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-44

6-20

Ship Repair Safety Checklist for Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-48

6-21

Surface-Supplied Diving Operations Predive Checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-50

6‑22

Emergency Assistance Checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-53

6‑23

SCUBA General Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-55

6-24

MK 20 MOD 0 General Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-56

6-25

MK 21 MOD 1, KM-37 General Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-57

6‑26

EXO BR MS Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-58

7-1

Schematic of Demand Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

7-2

Full Face Mask . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-4

7-3

Typical Gas Cylinder Identification Markings. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-5

7-4

Life Preserver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-8

7-5

Protective Clothing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12

7-6

Cascading System for Charging SCUBA Cylinders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17

7-7

SCUBA Entry Techniques. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-27

7-8

Clearing a Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31

7-9

SCUBA Hand Signals . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-33

8-1

MK 21 MOD 1 SSDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-2

MK 20 MOD 0 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7

8-3

MK 3 MOD 0 Configuration 1 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-4

MK 3 MOD 0 Configuration 2 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-11

8-5

MK 3 MOD 0 Configuration 3 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-11

8-6

Flyaway Dive System (FADS) III. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-12

8-7

ROPER Cart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-12

8-8

Oxygen Regulator Control Assembly (ORCA) II Schematic . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-14

8-9

Oxygen Regulator Control Assembly (ORCA) II. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-14

8‑10

HP Compressor Assembly (top); MP Compressor Assembly (bottom). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-19

8-11

Communicating with Line-Pull Signals . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-23

8-12

Surface Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

9-1

Diving Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-5

9‑2

Graphic View of a Dive with Abbreviations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-6

List of Illustrations	

liii

Figure

liv

Page

9‑3

Completed Air Diving Chart: No-Decompression Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-10

9‑4

Completed Air Diving Chart: In-water Decompression on Air . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-12

9‑5

Completed Air Diving Chart: In-water Decompression on Air and Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-14

9‑6

Completed Air Diving Chart: Surface Decompression on Oxygen . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-18

9‑7

Decompression Mode Selection Flowchart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-20

9‑8

Repetitive Dive Flow Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-22

9‑9

Repetitive Dive Worksheet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-24

9‑10

Completed Air Diving Chart: First Dive of Repetitive Dive Profile. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-26

9‑11

Completed Repetitive Dive Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-27

9‑12

Completed Air Diving Chart: Second Dive of Repetitive Dive Profile . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-28

9‑13

Completed Air Diving Chart: Delay in Ascent deeper than 50 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-33

9‑14

Completed Air Diving Chart: Delay in Ascent Shallower than 50 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-34

9‑15

Diving at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-51

9‑16

Completed Diving at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-54

9‑17

Completed Air Diving Chart: Dive at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-55

9‑18

Repetitive Dive at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-56

9‑19

Completed Repetitive Dive at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-58

9‑20

Completed Air Diving Chart: First Dive of Repetitive Dive Profile at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-59

9‑21

Completed Air Diving Chart: Second Dive of Repetitive Dive Profile at Altitude. .  .  .  .  .  .  .  .  .  .  .  . 9-60

10‑1

NITROX Diving Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-6

10‑2

NITROX SCUBA Bottle Markings . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10‑3

NITROX O2 Injection System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-10

10‑4

LP Air Supply NITROX Membrane Configuration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-12

10‑5

HP Air Supply NITROX Membrane Configuration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-13

11‑1

Ice Diving with SCUBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3

11-2

Typical Ice Diving Worksite. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-9

13-1

Searching Through Aircraft Debris on the Ocean Floor. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-5

13-2

Remotely Operated Vehicle (ROV) Deep Drone. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-7

13-3

Dive Team Brief for Divers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-10

13-4

MK 21 MOD 1 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-11

13-5

FADS III Mixed Gas System (FMGS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-13

13-6

FMGS Control Console Assembly. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-13

14-1

Diving Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-23

14-2

Completed HeO2 Diving Chart: Surface Decompression Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-24

14-3

Completed HeO2 Diving Chart: In-water Decompression Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-25

U.S. Navy Diving Manual—Volumes 1 through 5

Figure

Page

14‑4

Completed HeO2 Diving Chart: Surface Decompression Dive with Hold
on Descent and Delay on Ascent . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-26

15-1

Typical Personnel Transfer Capsule Exterior . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-2

15-2

MK 21 MOD 0 with Hot Water Suit, Hot Water Shroud, and Come-Home Bottle. .  .  .  .  .  .  .  .  .  .  . 15-6

15-3

MK 22 MOD 0 with Hot Water Suit, Hot Water Shroud, and Come-Home Bottle. .  .  .  .  .  .  .  .  .  .  . 15-6

15-4

NEDU’s Ocean Simulation Facility (OSF). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-7

15-5

NEDU’s Ocean Simulation Facility Saturation Diving Chamber Complex. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-7

15-6

NEDU’s Ocean Simulation Facility Control Room. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-8

15-7

Naval Submarine Medical Research Laboratory (NSMRL). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-8

15‑8

PTC Placement Relative to Excursion Limits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-30

15‑9

Saturation Decompression Sickness Treatment Flow Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-38

16‑1

Mixing by Cascading. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-3

16‑2

Mixing with Gas Transfer System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16-4

17-1

MK 16 MOD 0 Closed-Circuit Mixed-Gas UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-1

17‑2

MK 16 MOD 0 UBA Functional Block Diagram. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-2

17‑3

UBA Breathing Bag Acts to Maintain the Diver’s Constant Buoyancy
by Responding Counter to Lung Displacement. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-4

17‑4

Underwater Breathing Apparatus MK 16 MOD 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-8

17‑5

Dive Worksheet for Repetitive 0.7 ata Constant Partial Pressure
Oxygen in Nitrogen Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-21

17‑6

MK 16 MOD 0 General Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-35

18-1

MK 16 MOD 1 Closed-Circuit Mixed-Gas UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-1

18-2

MK 16 MOD 1 Dive Record Sheet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-13

18-3

Emergency Breathing System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-20

18-4

MK 16 MOD 1 UBA General Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-31

18-5

Repetitive Dive Worksheet for MK 16 MOD 1 N202. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-34

18‑6

Repetitive Dive Worksheet for MK 16 MOD 1 HeO2 Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-44

19-1

Diver in MK-25 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-1

19‑2

MK 25 MOD 2 Operational Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-9

19‑3

Gas Flow Path of the MK 25. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-10

19-4

Example of Transit with Excursion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-13

20-1

Treatment of Arterial Gas Embolism or Serious Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-37

20-2

Treatment of Type I Decompression Sickness . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-38

20-3

Treatment of Symptom Recurrence . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-39

20-4

Treatment Table 5. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-40

20-5

Treatment Table 6. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-41

List of Illustrations	

lv

Figure

lvi

Page

20-6

Treatment Table 6A. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-42

20-7

Treatment Table 4. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-43

20-8

Treatment Table 7. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-44

20-9

Treatment Table 8. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-45

20-10

Treatment Table 9. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-46

20-11

Air Treatment Table 1A . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-47

20-12

Air Treatment Table 2A . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-48

20-13

Air Treatment Table 3 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-49

21-1

Double-Lock Steel Recompression Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-6

21‑2

Recompression Chamber Facility: RCF 6500. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-7

21‑3

Recompression Chamber Facility: RCF 5000. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-8

21‑4

Double-Lock Steel Recompression Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-9

21-5

Fleet Modernized Double-Lock Recompression Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-10

21-6

Standard Navy Double-Lock Recompression Chamber System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-11

21-7

Transportable Recompression Chamber System (TRCS).  . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-12

21‑8

Transportable Recompression Chamber (TRC). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-12

21-9

Transfer Lock (TL). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-13

21-10

Fly Away Recompression Chamber (FARCC). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-13

21-11

Fly Away Recompression Chamber . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-14

21-12

Fly Away Recompression Chamber Life Support Skid . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-14

21-13

Recompression Chamber Predive Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-18

21-14

Recompression Chamber Postdive Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-24

21-15

Pressure Test for USN Recompression Chambers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-26

5A-1a

Neurological Examination Checklist . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-3

5A-2a

Dermatomal Areas Correlated to Spinal Cord Segment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-11

5B‑1

Pressure Points. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-3

5B‑2

Applying a Tourniquet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5B-5

5C-1

Types of Sharks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-2

5C-2

Killer Whale. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-3

5C-3

Barracuda . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-4

5C-4

Moray Eel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-5

5C-5

Venomous Fish. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-6

U.S. Navy Diving Manual—Volumes 1 through 5

Figure

Page

5C-6

Highly Toxic Fish. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-8

5C-7

Stingray. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-9

5C-8

Coelenterates . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-10

5C-9

Octopus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-12

5C-10

Cone Shell. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-15

5C-11

Sea Snake. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5C-16

List of Illustrations	

lvii

PAGE LEFT BLANK INTENTIONALLY

lviii

U.S. Navy Diving Manual—Volumes 1 through 5

List of Tables
Table

Page

2‑1

Pressure Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13

2‑2

Components of Dry Atmospheric Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-14

2‑3

Partial Pressure at 1 ata . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-25

2‑4

Partial Pressure at 137 ata . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-25

2‑5

Symbols and Values . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-30

2‑6

Buoyancy (In Pounds). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑7

Formulas for Area . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑8

Formulas for Volumes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑9

Formulas for Partial Pressure/Equivalent Air Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑10

Pressure Equivalents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32

2‑11

Volume and Capacity Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-32

2‑12

Length Equivalents . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-33

2‑13

Area Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-33

2‑14

Velocity Equivalents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-33

2‑15

Mass Equivalents . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-34

2‑16

Energy or Work Equivalents . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-34

2‑17

Power Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-34

2‑18

Temperature Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-35

2-19

Atmospheric Pressure at Altitude . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-35

3‑1

Signs and Symptoms of Dropping Core Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-54

3‑2

Signs of Heat Stress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-57

4‑1

U.S. Military Diver’s Compressed Air Breathing Purity Requirements
for ANU Approved or Certified Sources. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4

4‑2

Diver’s Compressed Air Breathing Requirements if from Commercial Source. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-5

4‑3

Diver’s Compressed Oxygen Breathing Purity Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-5

4‑4

Diver’s Compressed Helium Breathing Purity Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-6

4‑5

Diver’s Compressed Nitrogen Breathing Purity Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-7

1A‑1

PEL Selection Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-3

1A‑2

Depth Reduction Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-5

1A‑3

Wet Suit Un-Hooded. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-12

1A‑4

Wet Suit Hooded. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-13

1A‑5

Helmeted. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-14

List of Tables	

lix

Table

lx

Page

1A‑6

Permissible Exposure Limit (PEL) Within a 24-hour Period for
Exposure to AN/SQQ-14, -30, ‑32 Sonars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-15

7‑1

Sample SCUBA Cylinder Data . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-6

8‑1

MK 21 MOD 1 and KM-37 Overbottom Pressure Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

8‑2

Primary Air System Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-17

8‑3

Line-Pull Signals. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-24

9‑1

Pneumofathometer Correction Factors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9‑2

Management of Extended Surface Interval and Type I Decompression
Sickness during the Surface Interval. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-41

9‑3

Management of Asymptomatic Omitted Decompression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-43

9‑4

Sea Level Equivalent Depth (fsw). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-48

9‑5

Repetitive Groups Associated with Initial Ascent to Altitude . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-50

9‑6

Required Surface Interval Before Ascent to Altitude After Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-61

9‑7

No-Decompression Limits and Repetitive Group Designators for
No-Decompression Air Dives. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-62

9‑8

Residual Nitrogen Time Table for Repetitive Air Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-63

9‑9

Air Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-64

10‑1

Equivalent Air Depth Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-4

10‑2

Oil Free Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-11

2A‑1

No-Decompression Limits and Repetitive Group Designators for Shallow Water
Air No-Decompression Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2A-2

2A‑2

Residual Nitrogen Time Table for Repetitive Shallow Water Air Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2A-3

13‑1

Average Breathing Gas Consumption Rates. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-2

13‑2

Equipment Operational Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-4

13‑3

Mixed Gas Diving Equipment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-6

13‑4

Surface Supplied Mixed Gas Dive Team. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13-9

14‑1

Pneumofathometer Correction Factors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-3

14‑2

Management of Asymptomatic Omitted Decompression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-17

14‑3

Surface-Supplied Helium-Oxygen Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14-27

15‑1

Guidelines for Minimum Inspired HeO2 Temperatures for Saturation Depths
Between 350 and 1,500 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-10

15‑2

Typical Saturation Diving Watch Stations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-15

15‑3

Chamber Oxygen Exposure Time Limits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-18

15‑4

Treatment Gases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-19

15‑5

Limits for Selected Gaseous Contaminants in Saturation Diving Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-23

15‑6

Saturation Diving Compression Rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-24

15‑7

Unlimited Duration Downward Excursion Limits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-26

U.S. Navy Diving Manual—Volumes 1 through 5

Table

Page

15‑8

Unlimited Duration Upward Excursion Limits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-27

15‑9

Saturation Decompression Rates. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-33

15‑10

Emergency Abort Decompression Times and Oxygen Partial Pressures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15-36

17‑1

Average Breathing Gas Consumption Rates and CO2 Absorbent Usage. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-10

17‑2

MK 16 MOD 0 Canister Duration Limits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-11

17‑3

MK 16 MOD 0 UBA Diving Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-12

17‑4

MK 16 MOD 0 UBA Dive Briefing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-15

17‑5

Repetitive Dive Procedures for Various Gas Mediums. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-19

17‑6

No-Decompression Limits and Repetitive Group Designation Table for
0.7 ata Constant ppO2 in Nitrogen Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-22

17‑7

Residual Nitrogen Timetable for Repetitive 0.7 ata Constant ppO2 in Nitrogen Dives . .  .  .  .  .  . 17-23

17‑8

Management of Asymptomatic Omitted Decompression MK 16 MOD 0 Diver. .  .  .  .  .  .  .  .  .  .  .  . 17-25

17‑9

Closed-Circuit Mixed-Gas UBA Decompression Table Using 0.7 ata Constant
Partial Pressure Oxygen in Nitrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-36

17‑10

Closed-Circuit Mixed-Gas UBA Decompression Table Using 0.7 ata Constant
Partial Pressure Oxygen in Helium. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17-44

18-1

MK 16 MOD 1 Operational Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-2

18-2

Personnel Requirements Chart for MK 16 MOD 1 Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-3

18-3a

Flask Endurance for 29°F Water Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-4

18-3b

Flask Endurance for 40°F Water Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-4

18-3c

Flask Endurance for 60°F Water Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-5

18-3d

Flask Endurance for 80°F Water Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-5

18-3e

Flask Endurance for 104°F Water Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-6

18-4

MK 16 MOD 1 Canister Duration Limits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-7

18-5

MK 16 MOD 1 UBA Diving Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-8

18-6

MK 16 MOD 1 UBA Dive Briefing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-12

18-7

MK 16 MOD 1 UBA Line-Pull Signals. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-12

18-8

Initial Management of Asymptomatic Omitted Decompression MK 16 MOD 1 Diver . .  .  .  .  .  .  . 18-29

18-9

No Decompression Limits and Repetitive Group Designators for MK 16 MOD 1 N2O2 Dives. . 18-32

18-10

Residual Nitrogen Timetable for MK 16 MOD 1 N2O2 Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-33

18-11

MK 16 MOD 1 N2O2 Decompression Tables. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-35

18-12

No Decompression Limits and Repetitive Group Designators for MK 16 MOD 1 HeO2 Dives.  18-42

18-13

Residual Helium Timetable for MK 16 MOD 1 HeO2 Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-43

18-14

MK 16 MOD 1 HeO2 Decompression Tables. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18-45

19‑1

Average Breathing Gas Consumption. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-11

19‑2

NAVSEA-Approved CO2 Absorbents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-12

List of Tables	

lxi

Table

lxii

Page

19‑3

Excursion Limits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-13

19‑4

Single-Depth Oxygen Exposure Limits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-14

19‑5

Adjusted Oxygen Exposure Limits for Successive Oxygen Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-17

19‑6

Closed-Circuit Oxygen Diving Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-21

19‑7

Diving Supervisor Brief . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 19-23

20‑1

Rules for Recompression Treatment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-10

20-2

Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-16

20‑3

Guidelines for Conducting Hyperbaric Oxygen Therapy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-18

20‑4

Maximum Permissible Recompression Chamber Exposure Times at
Various Temperatures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-21

20‑5

High Oxygen Treatment Gas Mixtures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-24

20‑6

Tender Oxygen Breathing Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-27

20‑7

Primary Emergency Kit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-34

20‑8

Secondary Emergency Kit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20-35

21‑1

Recompression Chamber Line Guide. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-4

21‑2

Recompression Chamber Air Supply Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 21-16

5A‑1

Extremity Strength Tests. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-9

5A‑2

Reflexes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5A-13

U.S. Navy Diving Manual—Volumes 1 through 5

VOLUME 1

Diving Principles
and Policy

1

History of Diving

2

Underwater Physics

3

Underwater Physiology
and Diving Disorders

4

Dive Systems

5

Dive Program
Administration

Appendix 1A

Safe Diving Distances from
Transmitting Sonar

Appendix 1B

References

Appendix 1C

Telephone Numbers

Appendix 1D

List of Acronyms

U.S. Navy Diving Manual

PAGE LEFT BLANK INTENTIONALLY

Volume 1 - �Table of Contents
Chap/Para

Page

1

History of Diving

1-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

1-2

1-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

1-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

1-1.3

Role of the U.S. Navy.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1

SURFACE-SUPPLIED AIR DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-1
1-2.1

Breathing Tubes . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-2

1-2.2

Breathing Bags. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3

1-2.3

Diving Bells. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3

1-2.4

Diving Dress Designs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3
1-2.4.1
1-2.4.2
1-2.4.3
1-2.4.4

1-2.5

Caissons. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

1-2.6

Physiological Discoveries. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-6
1-2.6.1
1-2.6.2
1-2.6.3

1-3

Lethbridge’s Diving Dress . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-3
Deane’s Patented Diving Dress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4
Siebe’s Improved Diving Dress . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4
Salvage of the HMS Royal George . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

Caisson Disease (Decompression Sickness). . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Inadequate Ventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7
Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7

1-2.7

Armored Diving Suits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7

1-2.8

MK V Deep-Sea Diving Dress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-8

SCUBA DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-8
1-3.1

Open-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9
1‑3.1.1
1‑3.1.2
1‑3.1.3
1‑3.1.4

1-3.2

Rouquayrol’s Demand Regulator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9
LePrieur’s Open-Circuit SCUBA Design . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9
Cousteau and Gagnan’s Aqua-Lung . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10
Impact of SCUBA on Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10

Closed-Circuit SCUBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10
1‑3.2.1
1‑3.2.2

Fleuss’ Closed-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-10
Modern Closed-Circuit Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-11

1-3.3

Hazards of Using Oxygen in SCUBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-11

1-3.4

Semiclosed-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-12
1‑3.4.1
1‑3.4.2

1-3.5

Lambertsen’s Mixed-Gas Rebreather . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-12
MK 6 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-12

SCUBA Use During World War II . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-13
1‑3.5.1
1‑3.5.2
1‑3.5.3

Table of Contents­—Volume 1	

Diver-Guided Torpedoes . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-13
U.S. Combat Swimming. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-14
Underwater Demolition. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-15

1–i

Chap/Para
1-4

Page
MIXED-GAS DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-16
1-4.1

Nonsaturation Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-16
1‑4.1.1
1‑4.1.2
1‑4.1.3
1‑4.1.4

Diving Bells. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-20

1-4.3

Saturation Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-21

1-4.4

1-21
1-22
1-22
1-22
1-22

ADS-IV. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 1 MOD 0. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 2 MOD 0. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 2 MOD 1. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

1-25
1-25
1-25
1-26

SUBMARINE SALVAGE AND RESCUE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-26
1-5.1

USS F-4 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-26

1-5.2

USS S-51 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-27

1-5.3

USS S-4 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-27

1-5.4

USS Squalus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-28

1-5.5

USS Thresher. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-28

1-5.6

Deep Submergence Systems Project. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29

SALVAGE DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
1-6.1

World War II Era. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
1‑6.1.1
1‑6.1.2
1‑6.1.3

1-6.2

Pearl Harbor. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
USS Lafayette . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-29
Other Diving Missions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-30

Vietnam Era . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-30

1-7

OPEN-SEA DEEP DIVING RECORDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-30

1-8

SUMMARY . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-31

2

Underwater Physics

2-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-2

1–ii

Advantages of Saturation Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Bond’s Saturation Theory. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Genesis Project . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Developmental Testing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Sealab Program. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

Deep Diving Systems (DDS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-24
1‑4.4.1
1‑4.4.2
1‑4.4.3
1‑4.4.4

1-6

1-16
1-18
1-19
1-20

1-4.2

1‑4.3.1
1‑4.3.2
1‑4.3.3
1‑4.3.4
1‑4.3.5

1-5

Helium-Oxygen (HeO2) Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Hydrogen-Oxygen Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Modern Surface-Supplied Mixed-Gas Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
MK 1 MOD 0 Diving Outfit . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

2-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

PHYSICS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

U.S. Navy Diving Manual—Volume 1

Chap/Para
2-3

2-4

Page
MATTER. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1
2-3.1

Elements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-3.2

Atoms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-3.3

Molecules . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-1

2-3.4

The Three States of Matter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

MEASUREMENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2
2-4.1

Measurement Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

2-4.2

Temperature Measurements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3
2‑4.2.1
2‑4.2.2

2-4.3
2-5

2-6

2-7

Gas Measurements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3

ENERGY . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-4
2-5.1

Conservation of Energy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2-5.2

Classifications of Energy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5

LIGHT ENERGY IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5
2-6.1

Refraction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5

2-6.2

Turbidity of Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6

2-6.3

Diffusion . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6

2-6.4

Color Visibility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6

MECHANICAL ENERGY IN DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-6
2-7.1

Water Temperature and Sound. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7

2-7.2

Water Depth and Sound. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7
2‑7.2.1
2‑7.2.2

2-7.3

2-9

Diver Work and Noise . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7
Pressure Waves. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-7

Underwater Explosions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
2‑7.3.1
2‑7.3.2
2‑7.3.3
2‑7.3.4
2‑7.3.5
2‑7.3.6
2‑7.3.7
2‑7.3.8

2-8

Kelvin Scale. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3
Rankine Scale . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-3

Type of Explosive and Size of the Charge. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
Characteristics of the Seabed . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
Location of the Explosive Charge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Water Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-8
Distance from the Explosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Degree of Submersion of the Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-9
Estimating Explosion Pressure on a Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-9
Minimizing the Effects of an Explosion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10

HEAT ENERGY IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10
2-8.1

Conduction, Convection, and Radiation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10

2-8.2

Heat Transfer Rate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-10

2-8.3

Diver Body Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-11

PRESSURE IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-11
2-9.1

Atmospheric Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-12

Table of Contents­—Volume 1	

1–iii

Chap/Para

Page
2-9.2

Terms Used to Describe Gas Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-12

2-9.3

Hydrostatic Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-12

2-9.4

Buoyancy . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13
2‑9.4.1
2‑9.4.2

Archimedes’ Principle. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13
Diver Buoyancy . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13

2-10 GASES IN DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-14

2-11

2-10.1

Atmospheric Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-14

2-10.2

Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.3

Nitrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.4

Helium. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.5

Hydrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.6

Neon. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-15

2-10.7

Carbon Dioxide. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-16

2-10.8

Carbon Monoxide. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-16

2-10.9

Kinetic Theory of Gases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-16

GAS LAWS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-17
2-11.1

Boyle’s Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-17

2-11.2

Charles’/Gay-Lussac’s Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-18

2-11.3

The General Gas Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-21

2-12 GAS MIXTURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-24
2-12.1

Dalton’s Law. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-24
2‑12.1.1 Expressing Small Quantities of Pressure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-26
2‑12.1.2 Calculating Surface Equivalent Value . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-27

2-12.2

Gas Diffusion. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-27

2-12.3

Humidity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-27

2-12.4

Gases in Liquids. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28

2-12.5

Solubility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28

2-12.6

Henry’s Law . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28
2‑12.6.1 Gas Tension. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28
2‑12.6.2 Gas Absorption. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-28
2‑12.6.3 Gas Solubility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-29

1–iv

3

Underwater Physiology and Diving Disorders

3-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1
3-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

3-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

3-1.3

General. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

U.S. Navy Diving Manual—Volume 1

Chap/Para

Page

3-2

THE NERVOUS SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-1

3-3

THE CIRCULATORY SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2
3-3.1

Anatomy . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2
3‑3.1.1
3‑3.1.2

3-4

3-3.2

Circulatory Function . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2

3-3.3

Blood Components. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-3

THE RESPIRATORY SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-5
3-4.1

Gas Exchange. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

3-4.2

Respiration Phases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-5

3-4.3

Upper and Lower Respiratory Tract . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6

3-4.4

The Respiratory Apparatus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6
3‑4.4.1
3‑4.4.2

3-5

The Heart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2
The Pulmonary and Systemic Circuits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-2

The Chest Cavity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6
The Lungs . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-6

3-4.5

Respiratory Tract Ventilation Definitions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-8

3-4.6

Alveolar/Capillary Gas Exchange. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-9

3-4.7

Breathing Control . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-10

3-4.8

Oxygen Consumption. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-11

RESPIRATORY PROBLEMS IN DIVING.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-11
3-5.1

Oxygen Deficiency (Hypoxia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-12
3‑5.1.1
3‑5.1.2
3‑5.1.3
3‑5.1.4

3-5.2

Causes of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypoxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypoxia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-13
3-13
3-14
3-14

Carbon Dioxide Retention (Hypercapnia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-15
3‑5.2.1
3‑5.2.2
3‑5.2.3
3‑5.2.4

Causes of Hypercapnia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypercapnia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-15
3-16
3-17
3-18

3-5.3

Asphyxia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-18

3-5.4

Drowning/Near Drowning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-18
3‑5.4.1
3‑5.4.2
3‑5.4.3
3‑5.4.4

Causes of Drowning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Drowning/Near Drowning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Near Drowning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Near Drowning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-18
3-19
3-19
3-19

3-5.5

Breathholding and Unconsciousness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-19

3-5.6

Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20
3‑5.6.1
3‑5.6.2
3‑5.6.3

3-5.7

Causes of Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20
Symptoms of Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20
Treatment of Involuntary Hyperventilation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20

Overbreathing the Rig. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-20

Table of Contents­—Volume 1	

1–v

Chap/Para

Page
3-5.8

Carbon Monoxide Poisoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-21
3‑5.8.1
3‑5.8.2
3‑5.8.3
3‑5.8.4

3-6

3-6.1

Prerequisites for Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-22

3-6.2

Middle Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-23

3-6.3

Causes of Sinus Squeeze . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25
Preventing Sinus Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25

3-6.4

Tooth Squeeze (Barodontalgia). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26

3-6.5

External Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-26

3-6.6

Thoracic (Lung) Squeeze.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-26

3-6.7

Face or Body Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-27

3-6.8

Inner Ear Barotrauma. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-27

MECHANICAL EFFECTS OF PRESSURE ON THE HUMAN BODY--BAROTRAUMA
DURING ASCENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-30
3-7.1

Middle Ear Overpressure (Reverse Middle Ear Squeeze) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-30

3-7.2

Sinus Overpressure (Reverse Sinus Squeeze) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-31

3-7.3

Gastrointestinal Distention . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-31

PULMONARY OVERINFLATION SYNDROMES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-32
3-8.1

Arterial Gas Embolism (AGE). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-33
3‑8.1.1
3‑8.1.2
3‑8.1.3
3‑8.1.4

3-8.2

3-8.3

Causes of AGE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of AGE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of AGE. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of AGE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-33
3-34
3-34
3-35

Mediastinal and Subcutaneous Emphysema . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-35
3‑8.2.1
3‑8.2.2
3‑8.2.3
3‑8.2.4

Causes of Mediastinal and Subcutaneous Emphysema . .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Mediastinal and Subcutaneous Emphysema. .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Mediastinal and Subcutaneous Emphysema. .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Mediastinal and Subcutaneous Emphysema. .  .  .  .  .  .  .  .  .  .  .  .

3-35
3-36
3-36
3-37

Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-37
3‑8.3.1
3‑8.3.2
3‑8.3.3
3‑8.3.4

1–vi

Preventing Middle Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-24
Treating Middle Ear Squeeze. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25

Sinus Squeeze . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-25
3‑6.3.1
3‑6.3.2

3-8

3-21
3-21
3-22
3-22

MECHANICAL EFFECTS OF PRESSURE ON THE HUMAN BODY-BAROTRAUMA
DURING DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-22

3‑6.2.1
3‑6.2.2

3-7

Causes of Carbon Monoxide Poisoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Carbon Monoxide Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Carbon Monoxide Poisoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Carbon Monoxide Poisoning . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

Causes of Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Pneumothorax . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-37
3-38
3-39
3-40

U.S. Navy Diving Manual—Volume 1

Chap/Para
3-9

Page
INDIRECT EFFECTS OF PRESSURE ON THE HUMAN BODY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
3-9.1

Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
3‑9.1.1
3‑9.1.2
3‑9.1.3
3‑9.1.4

3-9.2

Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-41
3‑9.2.1
3‑9.2.2

3-9.3

Causes of Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
Symptoms of Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-40
Treatment of Nitrogen Narcosis. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-41
Prevention of Nitrogen Narcosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-41

Pulmonary Oxygen Toxicity . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-41
Central Nervous System (CNS) Oxygen Toxicity. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-42

Decompression Sickness (DCS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-45
3‑9.3.1
3‑9.3.2
3‑9.3.3
3‑9.3.4
3‑9.3.5
3‑9.3.6
3‑9.3.7

Absorption and Elimination of Inert Gases. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Bubble Formation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Direct Bubble Effects. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Indirect Bubble Effects. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treating Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Preventing Decompression Sickness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-45
3-49
3-50
3-50
3-51
3-52
3-52

3-10 THERMAL PROBLEMS IN DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-52
3-10.1

Regulating Body Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-52

3-10.2

Excessive Heat Loss (Hypothermia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-53
3‑10.2.1
3‑10.2.2
3‑10.2.3
3‑10.2.4

3-10.3

Causes of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-53
3-53
3-54
3-55

Other Physiological Effects of Exposure to Cold Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.3.1 Caloric Vertigo . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.3.2 Diving Reflex . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.3.3 Uncontrolled Hyperventilation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56

3-10.4

Excessive Heat Gain (Hyperthermia). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-56
3‑10.4.1
3‑10.4.2
3‑10.4.3
3‑10.4.4

3-11

Causes of Hyperthermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Symptoms of Hyperthermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Treatment of Hyperthermia . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Prevention of Hyperthermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

3-56
3-56
3-57
3-57

SPECIAL MEDICAL PROBLEMS ASSOCIATED WITH DEEP DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-58
3-11.1

High Pressure Nervous Syndrome (HPNS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-58

3-11.2

Compression Arthralgia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-58

3-12 OTHER DIVING MEDICAL PROBLEMS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59
3-12.1

Dehydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59
3‑12.1.1 Causes of Dehydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59
3‑12.1.2 Preventing Dehydration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-59

3-12.2

Immersion Pulmonary Edema. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60

3-12.3

Carotid Sinus Reflex. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60

Table of Contents­—Volume 1	

1–vii

Chap/Para

Page
3-12.4

Middle Ear Oxygen Absorption Syndrome . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60
3‑12.4.1 Symptoms of Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-60
3‑12.4.2 Treating Middle Ear Oxygen Absorption Syndrome. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-61

3-12.5

Underwater Trauma . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-61

3-12.6

Blast Injury . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-61

3-12.7

Otitis Externa. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-62

3-12.8

Hypoglycemia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-63

4

Dive Systems

4-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2

4-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

GENERAL INFORMATION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1
4-2.1

Document Precedence. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2.2

Equipment Authorized For Navy Use (ANU). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2.3

System Certification Authority (SCA) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-1

4-2.4

Planned Maintenance System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2

4-2.5

Alteration of Diving Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
4‑2.5.1
4‑2.5.2

4-2.6

Operating and Emergency Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
4‑2.6.1
4‑2.6.2
4‑2.6.3
4‑2.6.4
4‑2.6.5

4-3

4-4

4-5

Standardized OP/EPs . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
Non-standardized OP/EPs. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2
OP/EP Approval Process. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-3
Format . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-3
Example. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4

DIVER’S BREATHING GAS PURITY STANDARDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4
4-3.1

Diver’s Breathing Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4

4-3.2

Diver’s Breathing Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-5

4-3.3

Diver’s Breathing Helium . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-6

4-3.4

Diver’s Breathing Nitrogen . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-6

DIVER’S AIR SAMPLING PROGRAM . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-7
4-4.1

Maintenance Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-7

4-4.2

General Air Sampling Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-8

4-4.3

NSWC-PC Air Sampling Services. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-9

4-4.4

Local Air Sampling Services. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

DIVING COMPRESSORS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10
4-5.1

1–viii

Technical Program Managers for Shore-Based Systems. . . . . . . . . . . . . . . . 4-2
Technical Program Managers for Other Diving Apparatus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-2

Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

U.S. Navy Diving Manual—Volume 1

Chap/Para

4-6

Page
4-5.2

Air Filtration System . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

4-5.3

Lubrication. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-10

DIVING GAUGES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-11
4-6.1

Selecting Diving System Gauges. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-11

4-6.2

Calibrating and Maintaining Gauges. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-12

4-6.3

Helical Bourdon Tube Gauges . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-12

4-7

COMPRESSED GAS HANDLING AND STORAGE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-13

5

Dive Program Administration

5-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1
5-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-2

OBJECTIVES OF THE RECORD KEEPING AND REPORTING SYSTEM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-3

RECORD KEEPING AND REPORTING DOCUMENTS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-1

5-4

COMMAND SMOOTH DIVING LOG . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-2

5-5

RECOMPRESSION CHAMBER LOG . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-7

5-6

DIVER’S PERSONAL DIVE LOG . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-10

5-7

DIVING MISHAP/CASUALTY REPORTING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-10

5-8

EQUIPMENT FAILURE OR DEFICIENCY REPORTING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-10

5-9

U.S. NAVY DIVE REPORTING SYSTEM (DRS) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-11

5-10 ACCIDENT/INCIDENT EQUIPMENT INVESTIGATION REQUIREMENTS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-11
5-11

REPORTING CRITERIA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-12

5-12 ACTIONS REQUIRED . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-12

1A

5-12.1

Technical Manual Deficiency/Evaluation Report. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-13

5-12.2

Shipment of Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-13

Safe Diving Distances from Transmitting Sonar

1A-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-1
1A-2 BACKGROUND . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-1
1A-3 ACTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2

Table of Contents­—Volume 1	

1–ix

Chap/Para

Page

1A-4 SONAR DIVING DISTANCES WORKSHEETS WITH DIRECTIONS FOR USE. .  .  .  .  .  .  .  .  .  .  . 1A-2
1A-4.1

General Information/Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-2
1A‑4.1.1 Effects of Exposure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2
1A‑4.1.2 Suit and Hood Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2
1A‑4.1.3 In­-Water Hearing vs. In-Gas Hearing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-2

1A-4.2

Directions for Completing the Sonar Diving Distances Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-3

1A-5 GUIDANCE FOR DIVER EXPOSURE TO LOW-FREQUENCY SONAR (160–320 Hz). .  .  .  . 1A-16
1A-6 GUIDANCE FOR DIVER EXPOSURE TO ULTRASONIC SONAR
(250 KHz AND GREATER). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-16

1–x

1B

References . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1B-1

1C

Telephone Numbers . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1C-1

1D

List of Acronyms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1D-1

U.S. Navy Diving Manual—Volume 1

Volume 1 - �List of Illustrations
Figure

Page

1-1

Early Impractical Breathing Device. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-2

1-2

Assyrian Frieze (900 B.C.) . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-2

1-3

Engraving of Halley’s Diving Bell. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4

1-4

Lethbridge’s Diving Suit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-4

1-5

Siebe’s First Enclosed Diving Dress and Helmet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

1-6

French Caisson. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-5

1-7

Armored Diving Suit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-7

1-8

MK 12 and MK V. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-9

1-9

Fleuss Apparatus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-11

1-10

Original Davis Submerged Escape Apparatus . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-13

1-11

Lambertsen Amphibious Respiratory Unit (LARU). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-14

1-12

Emerson-Lambertsen Oxygen Rebreather. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-15

1-13

Draeger LAR V UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-15

1-14

Helium-Oxygen Diving Manifold . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-17

1-15

MK V MOD 1 Helmet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-18

1-16

MK 1 MOD 0 Diving Outfit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-20

1-17

Sealab II . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-23

1-18

U.S. Navy’s First DDS, SDS-450. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-23

1-19

DDS MK 1 Personnel Transfer Capsule . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-25

1-20

PTC Handling System, Elk River. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-25

1-21

Recovery of the Squalus. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1-28

2-1

Molecules . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

2-2

The Three States of Matter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-2

2-3

Temperature Scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2-4

The Six Forms of Energy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-4

2-5

Objects Underwater Appear Closer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-5

2‑6

Kinetic Energy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-17

2‑7

Depth, Pressure, Atmosphere Graph . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-36

3-1

The Heart’s Components and Blood Flow. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-3

3-2

Respiration and Blood Circulation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-4

3-3

Inspiration Process . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-7

3-4

Lungs Viewed from Medical Aspect. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-7

3-5

Lung Volumes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-8

List of Illustrations—Volume 1	

1–xi

Figure

1–xii

Page

3-6

Oxygen Consumption and RMV at Different Work Rates. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-12

3-7

Gross Anatomy of the Ear in Frontal Section . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-23

3-8

Location of the Sinuses in the Human Skull . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-26

3-9

Components of the Middle/Inner Ear. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-28

3-10

Pulmonary Overinflation Syndromes (POIS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-32

3-11

Arterial Gas Embolism. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-33

3-12

Mediastinal Emphysema. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-36

3-13

Subcutaneous Emphysema. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-37

3-14

Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-38

3-15

Tension Pneumothorax. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-39

3-16

Saturation of Tissues. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-47

3-17

Desaturation of Tissues. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-49

5-1

U.S. Navy Diving Log . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-3

5-2

Equipment Accident/Incident Information Sheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-5

5-3

Failure Analysis Report (NAVSEA Form 10560/4). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-8

5‑4

Failure Analysis Report. (NAVSEA Form 10560/1). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5-9

1A-1

Sonar Safe Diving Distance/Exposure Time Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-4

1A‑2

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  .  . 1A-8

1A-3

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  .  . 1A-9

1A‑4

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  . 1A-10

1A‑5

Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example). .  .  .  .  .  .  .  .  .  .  . 1A-11

U.S. Navy Diving Manual—Volume 1

Volume 1 - List of Tables
Table

Page

2‑1

Pressure Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-13

2‑2

Components of Dry Atmospheric Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-14

2‑3

Partial Pressure at 1 ata . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-25

2‑4

Partial Pressure at 137 ata . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-25

2‑5

Symbols and Values . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-30

2‑6

Buoyancy (In Pounds). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑7

Formulas for Area . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑8

Formulas for Volumes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑9

Formulas for Partial Pressure/Equivalent Air Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-31

2‑10

Pressure Equivalents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32

2‑11

Volume and Capacity Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-32

2‑12

Length Equivalents . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-33

2‑13

Area Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-33

2‑14

Velocity Equivalents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-33

2‑15

Mass Equivalents . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-34

2‑16

Energy or Work Equivalents . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-34

2‑17

Power Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-34

2‑18

Temperature Equivalents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-35

2-19

Atmospheric Pressure at Altitude . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2-35

3‑1

Signs and Symptoms of Dropping Core Temperature. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-54

3‑2

Signs of Heat Stress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3-57

4‑1

U.S. Military Diver’s Compressed Air Breathing Purity Requirements
for ANU Approved or Certified Sources. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-4

4‑2

Diver’s Compressed Air Breathing Requirements if from Commercial Source. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-5

4‑3

Diver’s Compressed Oxygen Breathing Purity Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-5

4‑4

Diver’s Compressed Helium Breathing Purity Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-6

4‑5

Diver’s Compressed Nitrogen Breathing Purity Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4-7

1A‑1

PEL Selection Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-3

1A‑2

Depth Reduction Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-5

1A‑3

Wet Suit Un-Hooded. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-12

1A‑4

Wet Suit Hooded. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-13

1A‑5

Helmeted. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1A-14

1A‑6

Permissible Exposure Limit (PEL) Within a 24-hour Period for
Exposure to AN/SQQ-14, -30, ‑32 Sonars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-15

List of Tables—Volume 1	

1–xiii

PAGE LEFT BLANK INTENTIONALLY

1–xiv

U.S. Navy Diving Manual—Volume 1

CHAPTER 1

History of Diving
1-1

INTRODUCTION
1-1.1

Purpose. This chapter provides a general history of the development of military

diving operations.
1-1.2

Scope. This chapter outlines the hard work and dedication of a number of

individuals who were pioneers in the development of diving technology. As with
any endeavor, it is important to build on the discoveries of our predecessors and
not repeat mistakes of the past.

1-1.3

1-2

Role of the U.S. Navy. The U.S. Navy is a leader in the development of modern
diving and underwater operations. The general requirements of national defense
and the specific require­ments of underwater reconnaissance, demolition, ordnance
disposal, construction, ship maintenance, search, rescue and salvage operations
repeatedly give impetus to training and development. Navy diving is no longer
limited to tactical combat operations, wartime salvage, and submarine sinkings.
Fleet diving has become increasingly important and diversified since World War
II. A major part of the diving mission is inspecting and repairing naval vessels to
minimize downtime and the need for dry-docking. Other aspects of fleet diving
include recovering practice and research torpedoes, installing and repairing
underwater electronic arrays, underwater construction, and locating and recovering
downed aircraft.

SURFACE-SUPPLIED AIR DIVING

The origins of diving are firmly rooted in man’s need and desire to engage in mari­
time commerce, to conduct salvage and military operations, and to expand the
frontiers of knowledge through exploration, research, and development.
Diving, as a profession, can be traced back more than 5,000 years. Early divers
confined their efforts to waters less than 100 feet deep, performing salvage work
and harvesting food, sponges, coral, and mother-of-pearl. A Greek historian,
Herodotus, recorded the story of a diver named Scyllis, who was employed by the
Persian King Xerxes to recover sunken treasure in the fifth century B.C.
From the earliest times, divers were active in military operations. Their missions
included cutting anchor cables to set enemy ships adrift, boring or punching holes
in the bottoms of ships, and building harbor defenses at home while attempting
to destroy those of the enemy abroad. Alexander the Great sent divers down to
remove obstacles in the harbor of the city of Tyre, in what is now Lebanon, which
he had taken under siege in 332 B.C.
Other early divers developed an active salvage industry centered around the major
shipping ports of the eastern Mediterranean. By the first century B.C., operations
CHAPTER 1­—History of Diving	

1-1

in one area had become so well organized that a payment scale for salvage work
was established by law, acknowledging the fact that effort and risk increased with
depth. In 24 feet of water, the divers could claim a one-half share of all goods
recovered. In 12 feet of water, they were allowed a one-third share, and in 3 feet,
only a one-tenth share.
1-2.1

Breathing Tubes. The most obvious and crucial step to broadening a diver’s

capabilities was providing an air supply that would permit him to stay underwater.
Hollow reeds or tubes extending to the surface allowed a diver to remain submerged
for an extended period, but he could accomplish little in the way of useful work.
Breathing tubes were employed in military operations, permitting an undetected
approach to an enemy stronghold (Figure 1-1).
At first glance, it seemed logical that a longer breathing tube was the only require­
ment for extending a diver’s range. In fact, a number of early designs used leather
hoods with long flexible tubes supported at the surface by floats. There is no record,
however, that any of these devices were actually constructed or tested. The result
may well have been the drowning of the diver. At a depth of 3 feet, it is nearly
impossible to breathe through a tube using only the body’s natural respira­tory
ability, as the weight of the water exerts a total force of almost 200 pounds on
the diver’s chest. This force increases steadily with depth and is one of the most
important factors in diving. Successful diving operations require that the pressure
be overcome or eliminated. Throughout history, imaginative devices were designed
to overcome this problem, many by some of the greatest minds of the time. At first,
the problem of pressure underwater was not fully understood and the designs were
impractical.

Figure 1-1. Early Impractical Breathing Device.
This 1511 design shows the diver’s head encased
in a leather bag with a breathing tube extending to
the surface. 

1-2

Figure 1-2. Assyrian Frieze (900 B.C.).

U.S. Navy Diving Manual—Volume 1

1-2.2

Breathing Bags. An entire series of designs was based on the idea of a breathing

bag carried by the diver. An Assyrian frieze of the ninth century B.C. shows what
appear to be divers using inflated animal skins as air tanks. However, these men
were probably swim­mers using skins for flotation. It would be impossible to
submerge while holding such an accessory (Figure 1-2).
A workable diving system may have made a brief appearance in the later Middle
Ages. In 1240, Roger Bacon made reference to “instruments whereby men can
walk on sea or river beds without danger to themselves.”
1-2.3

Diving Bells. Between 1500 and 1800 the diving bell was developed, enabling

divers to remain underwater for hours rather than minutes. The diving bell is a
bell-shaped appa­ratus with the bottom open to the sea.
The first diving bells were large, strong tubs weighted to sink in a vertical posi­tion,
trapping enough air to permit a diver to breathe for several hours. Later diving bells
were suspended by a cable from the surface. They had no significant underwater
maneuverability beyond that provided by moving the support ship. The diver could
remain in the bell if positioned directly over his work, or could venture outside for
short periods of time by holding his breath.
The first reference to an actual practical diving bell was made in 1531. For several
hundred years thereafter, rudimentary but effective bells were used with regu­larity.
In the 1680s, a Massachusetts-born adventurer named William Phipps modified the
diving bell technique by supplying his divers with air from a series of weighted,
inverted buckets as they attempted to recover treasure valued at $200,000.
In 1690, the English astronomer Edmund Halley developed a diving bell in which
the atmosphere was replenished by sending weighted barrels of air down from the
surface (Figure 1-3). In an early demonstration of his system, he and four compan­
ions remained at 60 feet in the Thames River for almost 1½ hours. Nearly 26 years
later, Halley spent more than 4 hours at 66 feet using an improved version of his
bell.
1-2.4

Diving Dress Designs. With an increasing number of military and civilian wrecks

littering the shores of Great Britain each year, there was strong incentive to develop
a diving dress that would increase the efficiency of salvage operations.

1-2.4.1

Lethbridge’s Diving Dress. In 1715, Englishman John Lethbridge developed

a one-man, completely enclosed diving dress (Figure 1-4). The Lethbridge
equipment was a reinforced, leather-covered barrel of air, equipped with a glass
porthole for viewing and two arm holes with watertight sleeves. Wearing this gear,
the occupant could accomplish useful work. This apparatus was lowered from a
ship and maneuvered in the same manner as a diving bell.

Lethbridge was quite successful with his invention and participated in salvaging
a number of European wrecks. In a letter to the editor of a popular magazine in
1749, the inventor noted that his normal operating depth was 10 fathoms (60 feet),

CHAPTER 1­—History of Diving	

1-3

Figure 1-3. Engraving of Halley’s
Diving Bell.

Figure 1-4. Lethbridge’s Diving Suit.

with about 12 fathoms the maximum, and that he could remain underwater for 34
minutes.
Several designs similar to Lethbridge’s were used in succeeding years. However,
all had the same basic limitation as the diving bell—the diver had little freedom
because there was no practical way to continually supply him with air. A true
tech­nological breakthrough occurred at the turn of the 19th century when a handoperated pump capable of delivering air under pressure was developed.
1-2.4.2

1-2.4.3

Deane’s Patented Diving Dress. Several men produced a successful apparatus at
the same time. In 1823, two salvage operators, John and Charles Deane, patented
the basic design for a smoke apparatus that permitted firemen to move about in
burning buildings. By 1828, the apparatus evolved into Deane’s Patent Diving
Dress, consisting of a heavy suit for protection from the cold, a helmet with viewing
ports, and hose connections for delivering surface-supplied air. The helmet rested
on the diver’s shoulders, held in place by its own weight and straps to a waist belt.
Exhausted or surplus air passed out from under the edge of the helmet and posed
no problem as long as the diver was upright. If he fell, however, the helmet could
quickly fill with water. In 1836, the Deanes issued a diver’s manual, perhaps the
first ever produced.
Siebe’s Improved Diving Dress. Credit for developing the first practical diving

dress has been given to Augustus Siebe. Siebe’s initial contribution to diving was
a modification of the Deane outfit. Siebe sealed the helmet to the dress at the collar
by using a short, waist-length waterproof suit and added an exhaust valve to the
system (Figure 1-5). Known as Siebe’s Improved Diving Dress, this apparatus is
the direct ancestor of the MK V standard deep-sea diving dress.

1-4

U.S. Navy Diving Manual—Volume 1

1-2.4.4

Salvage of the HMS Royal George. By 1840, sev­

eral types of diving dress were being used in actual
diving operations. At that time, a unit of the British
Royal Engineers was engaged in removing the
remains of the sunken warship, HMS Royal George.
The warship was fouling a major fleet anchorage
just outside Portsmouth, England. Colonel William
Pasley, the officer in charge, de­cided that his
operation was an ideal opportunity to formally test
and evaluate the various types of ap­paratus. Wary
of the Deane apparatus because of the possibility of
helmet flooding, he formally rec­ommended that the
Siebe dress be adopted for future operations.
When Pasley’s project was completed, an official
government historian noted that “of the seasoned
divers, not a man escaped the repeated attacks
of rheumatism and cold.” The divers had been
Figure 1-5. Siebe’s First
Enclosed Diving Dress and
working for 6 or 7 hours a day, much of it spent
Helmet.
at depths of 60 to 70 feet. Pasley and his men did
not realize the implications of the observation.
What appeared to be rheumatism was instead a symptom of a far more serious
physiological problem that, within a few years, was to become of great importance
to the diving profession.
1-2.5

Caissons. At the same time that a practical diving dress was being perfected,
inventors were working to improve the diving bell by increasing its size and
adding high-capacity air pumps that could deliver enough pressure to keep water
entirely out of the bell’s interior. The improved pumps soon led to the construction
of chambers large enough to permit several men to engage in dry work on the
bottom. This was particularly advantageous for projects such as excavating bridge
footings or constructing tunnel sections where long periods of work were required.
These dry chambers were known as caissons, a French word meaning “big boxes”
(Figure 1-6).

Figure 1-6. French Caisson. 
This caisson could be floated
over the work site and
lowered to the bottom by
flooding the side tanks.

CHAPTER 1­—History of Diving	

1-5

Caissons were designed to provide ready access from the surface. By using an
air lock, the pressure inside could be maintained while men or materials could be
passed in and out. The caisson was a major step in engineering technology and its
use grew quickly.
1-2.6

Physiological Discoveries.

1-2.6.1

Caisson Disease (Decompression Sickness). With the increasing use of caissons,

a new and unexplained malady began to affect the caisson workers. Upon returning
to the surface at the end of a shift, the divers frequently would be struck by dizzy
spells, breathing difficulties, or sharp pains in the joints or abdomen. The sufferer
usually recovered, but might never be completely free of some of the symptoms.
Caisson workers often noted that they felt better working on the job, but wrongly
attributed this to being more rested at the beginning of a shift.
As caisson work extended to larger projects and to greater operating pressures, the
physiological problems increased in number and severity. Fatalities occurred with
alarming frequency. The malady was called, logically enough, caisson disease.
However, workers on the Brooklyn Bridge project in New York gave the sickness
a more descriptive name that has remained—the “bends.”
Today the bends is the most well-known danger of diving. Although men had been
diving for thousands of years, few men had spent much time working under great
atmospheric pressure until the time of the caisson. Individuals such as Pasley, who
had experienced some aspect of the disease, were simply not prepared to look for
anything more involved than indigestion, rheumatism, or arthritis.

1-2.6.1.1

Cause of Decompression Sickness. The actual cause of caisson disease was first

clinically described in 1878 by a French physiologist, Paul Bert. In studying the
effect of pressure on human physi­ology, Bert determined that breathing air under
pressure forced quantities of nitrogen into solution in the blood and tissues of the
body. As long as the pressure remained, the gas was held in solution. When the
pressure was quickly released, as it was when a worker left the caisson, the nitrogen
returned to a gaseous state too rapidly to pass out of the body in a natural manner.
Gas bubbles formed throughout the body, causing the wide range of symptoms
associated with the disease. Paralysis or death could occur if the flow of blood to a
vital organ was blocked by the bubbles.
1-2.6.1.2

Prevention and Treatment of Decompression Sickness. Bert recommended that

cais­son workers gradually decompress and divers return to the surface slowly. His
studies led to an immediate improvement for the caisson workers when they discovered
their pain could be relieved by returning to the pressure of the caisson as soon as the
symptom appeared.

Within a few years, specially designed recompression chambers were being placed
at job sites to provide a more controlled situation for handling the bends. The pres­
sure in the chambers could be increased or decreased as needed for an individual
worker. One of the first successful uses of a recompression chamber was in 1879

1-6

U.S. Navy Diving Manual—Volume 1

during the construction of a subway tunnel under the Hudson River between New
York and New Jersey. The recompression chamber markedly reduced the number
of serious cases and fatalities caused by the bends.
Bert’s recommendation that divers ascend gradually and steadily was not a
complete success, however; some divers continued to suffer from the bends. The
general thought at the time was that divers had reached the practical limits of the
art and that 120 feet was about as deep as anyone could work. This was because
of the repeated incidence of the bends and diver inefficiency beyond that depth.
Occasionally, divers would lose consciousness while working at 120 feet.
1-2.6.2

Inadequate Ventilation. J.S. Haldane, an English physiologist, conducted experi­

ments with Royal Navy divers from 1905 to 1907. He determined that part of the
problem was due to the divers not adequately ventilating their helmets, causing
high levels of carbon dioxide to accumulate. To solve the problem, he established
a standard supply rate of flow (1.5 cubic feet of air per minute, measured at the
pressure of the diver). Pumps capable of maintaining the flow and ventilating the
helmet on a continuous basis were used.
Haldane also composed a set of diving tables that established a method of decom­
pression in stages. Though restudied and improved over the years, these tables
remain the basis of the accepted method for bringing a diver to the surface.
As a result of Haldane’s studies, the practical operating depth for air divers was
extended to slightly more than 200 feet. The limit was not imposed by physiolog­
ical factors, but by the capabilities of the hand-pumps available to provide the air
supply.
1-2.6.3

Nitrogen Narcosis. Divers soon were moving into

deeper water and another unexplained malady began
to appear. The diver would appear intoxicated,
sometimes feeling euphoric and frequently losing
judgment to the point of forgetting the dive’s
purpose. In the 1930s this “rapture of the deep”
was linked to nitrogen in the air breathed under
higher pressures. Known as nitrogen narcosis, this
condition occurred because nitrogen has anesthetic
properties that become progressively more severe
with increasing air pres­sure. To avoid the problem,
special breathing mixtures such as helium-oxygen
were developed for deep diving (see section 1‑4,
Mixed-Gas Diving).
1-2.7

Armored Diving Suits. Numerous inventors, many

with little or no under­water experience, worked to
create an armored diving suit that would free the
diver from pressure problems (Figure 1‑7). In an
armored suit, the diver could breathe air at normal
atmospheric pressure and descend to great depths
CHAPTER 1­—History of Diving	

Figure 1-7. Armored
Diving Suit.

1-7

without any ill effects. The barrel diving suit, de­signed by John Lethbridge in 1715,
had been an armored suit in essence, but one with a limited operating depth.
The utility of most armored suits was questionable. They were too clumsy for the
diver to be able to accomplish much work and too complicated to provide protec­
tion from extreme pressure. The maximum anticipated depth of the various suits
developed in the 1930s was 700 feet, but was never reached in actual diving. More
recent pursuits in the area of armored suits, now called one-atmosphere diving
suits, have demonstrated their capability for specialized underwater tasks to 2,000
feet of saltwater (fsw).
1-2.8

MK V Deep-Sea Diving Dress. By 1905, the Bureau of Construction and Repair

had designed the MK V Diving Helmet which seemed to address many of the
problems encountered in diving. This deep-sea outfit was designed for extensive,
rugged diving work and provided the diver maximum physical protection and
some maneuverability.
The 1905 MK V Diving Helmet had an elbow inlet with a safety valve that
allowed air to enter the helmet, but not to escape back up the umbilical if the air
supply were interrupted. Air was expelled from the helmet through an exhaust
valve on the right side, below the port. The exhaust valve was vented toward the
rear of the helmet to prevent escaping bubbles from interfering with the diver’s
field of vision.

By 1916, several improvements had been made to the helmet, including a rudi­
mentary communications system via a telephone cable and a regulating valve
operated by an interior push button. The regulating valve allowed some control of
the atmospheric pressure. A supplementary relief valve, known as the spitcock, was
added to the left side of the helmet. A safety catch was also incorporated to keep
the helmet attached to the breast plate. The exhaust valve and the communi­cations
system were improved by 1927, and the weight of the helmet was decreased to be
more comfortable for the diver.
After 1927, the MK V changed very little. It remained basically the same helmet
used in salvage operations of the USS S-51 and USS S-4 in the mid-1920s. With
its associated deep-sea dress and umbilical, the MK V was used for all submarine
rescue and salvage work undertaken in peacetime and practically all salvage work
undertaken during World War II. The MK V Diving Helmet was the standard U.S.
Navy diving equipment until succeeded by the MK 12 Surface-Supplied Diving
System (SSDS) in February 1980 (see Figure 1‑8). The MK 12 was replaced by the
MK 21 in December 1993.
1-3

SCUBA DIVING

The diving equipment developed by Charles and John Deane, Augustus Siebe, and
other inventors gave man the ability to remain and work underwater for extended
periods, but movement was greatly limited by the requirement for surface-supplied
air. Inventors searched for methods to increase the diver’s movement without
increasing the hazards. The best solution was to provide the diver with a portable,
1-8

U.S. Navy Diving Manual—Volume 1

Figure 1-8. MK 12 and MK V.

self-contained air supply. For many years the self-contained underwater breathing
apparatus (SCUBA) was only a theoretical possibility. Early attempts to supply
self-contained compressed air to divers were not successful due to the limi­tations
of air pumps and containers to compress and store air at sufficiently high pressure.
SCUBA development took place gradually, however, evolving into three basic
types:
n Open-circuit SCUBA (where the exhaust is vented directly to the surrounding
water),
n Closed-circuit SCUBA (where the oxygen is filtered and recirculated), and
n Semiclosed-circuit SCUBA (which combines features of the open- and closedcircuit types).
1-3.1

1‑3.1.1

1‑3.1.2

Open-Circuit SCUBA. In the open-circuit apparatus, air is inhaled from a supply
cylinder and the exhaust is vented directly to the surrounding water.
Rouquayrol’s Demand Regulator. The first and highly necessary component of
an open-circuit apparatus was a demand regulator. Designed early in 1866 and
patented by Benoist Rouquayrol, the regulator adjusted the flow of air from the
tank to meet the diver’s breathing and pressure requirements. However, because
cylinders strong enough to contain air at high pressure could not be built at the time,
Rouquayrol adapted his regulator to surface-supplied diving equipment and the
technology turned toward closed-circuit designs. The application of Rouquayrol’s
concept of a demand regulator to a successful open-circuit SCUBA was to wait
more than 60 years.
LePrieur’s Open-Circuit SCUBA Design. The thread of open-circuit development
was picked up in 1933. Commander LePrieur, a French naval officer, constructed
an open-circuit SCUBA using a tank of compressed air. However, LePrieur did not
include a demand regulator in his design and, the diver’s main effort was diverted
to the constant manual control of his air supply. The lack of a demand regulator,

CHAPTER 1­—History of Diving	

1-9

coupled with extremely short endurance, severely limited the practical use of
LePrieur’s apparatus.
1‑3.1.3

Cousteau and Gagnan’s Aqua-Lung. At the same time that actual combat opera­

tions were being carried out with closed-circuit apparatus, two Frenchmen
achieved a significant breakthrough in open-circuit SCUBA design. Working in
a small Mediterranean village, under the diffi­cult and restrictive conditions of
German-occupied France, Jacques-Yves Cousteau and Emile Gagnan combined
an improved demand regulator with high-pressure air tanks to create the first truly
efficient and safe open-circuit SCUBA, known as the Aqua-Lung. Cousteau and
his companions brought the Aqua-Lung to a high state of development as they
explored and photographed wrecks, devel­oping new diving techniques and testing
their equipment.
The Aqua-Lung was the culmination of hundreds of years of progress, blending
the work of Rouquayol, LePrieur, and Fleuss, a pioneer in closed-circuit SCUBA
development. Cousteau used his gear successfully to 180 fsw without significant
difficulty and with the end of the war the Aqua-Lung quickly became a commer­cial
success. Today the Aqua-Lung is the most widely used diving equipment, opening
the underwater world to anyone with suitable training and the funda­mental physical
abilities.
1‑3.1.4

Impact of SCUBA on Diving. The underwater freedom brought about by the
development of SCUBA led to a rapid growth of interest in diving. Sport diving has
become very popular, but science and commerce have also benefited. Biologists,
geologists and archaeolo­gists have all gone underwater, seeking new clues to
the origins and behavior of the earth, man and civilization as a whole. An entire
industry has grown around commercial diving, with the major portion of activity
in offshore petroleum production.

After World War II, the art and science of diving progressed rapidly, with emphasis
placed on improving existing diving techniques, creating new methods, and
developing the equipment required to serve these methods. A complete gener­ation
of new and sophisticated equipment took form, with substantial improvements
being made in both open and closed-circuit apparatus. However, the most significant
aspect of this technological expansion has been the closely linked development of
saturation diving techniques and deep diving systems.
1-3.2

Closed-Circuit SCUBA. The basic closed-circuit system, or oxygen rebreather, uses

a cylinder of 100 percent oxygen that supplies a breathing bag. The oxygen used
by the diver is recirculated in the apparatus, passing through a chemical filter that
removes carbon dioxide. Oxygen is added from the tank to replace that consumed
in breathing. For special warfare operations, the closed-circuit system has a major
advantage over the open-circuit type: it does not produce a telltale trail of bubbles
on the surface.

1‑3.2.1

Fleuss’ Closed-Circuit SCUBA. Henry A. Fleuss developed the first commercially

practical closed-circuit SCUBA between 1876 and 1878 (Figure 1‑9). The Fleuss
device consisted of a watertight rubber face mask and a breathing bag connected to
1-10

U.S. Navy Diving Manual—Volume 1

a copper tank of 100 percent oxygen charged to 450 psi. By using oxygen instead
of compressed air as the breathing medium, Fleuss eliminated the need for highstrength tanks. In early models of this apparatus, the diver controlled the makeup
feed of fresh oxygen with a hand valve.
Fleuss successfully tested his apparatus in 1879. In the
first test, he remained in a tank of water for about an
hour. In the second test, he walked along a creek bed at
a depth of 18 feet. During the second test, Fleuss turned
off his oxygen feed to see what would happen. He was
soon unconscious, and suffered gas embolism as his
tenders pulled him to the surface. A few weeks after his
recovery, Fleuss made arrangements to put his recircu­
lating design into commercial production.
In 1880, the Fleuss SCUBA figured prominently in a
highly publicized achievement by an English diver,
Alexander Lambert. A tunnel under the Severn River
flooded and Lambert, wearing a Fleuss apparatus, walked
1,000 feet along the tunnel, in complete dark­ness, to
close several crucial valves.
1‑3.2.2

Modern Closed-Circuit Systems. As development of the

Figure 1-9. Fleuss

closed-circuit design continued, the Fleuss equipment
Apparatus.
was improved by adding a demand regulator and tanks
capable of holding oxygen at more than 2,000 psi. By
World War I, the Fleuss SCUBA (with modifications) was the basis for subma­rine
escape equipment used in the Royal Navy. In World War II, closed-circuit units
were widely used for combat diving operations (see paragraph 1‑3.5.2).
Some modern closed-circuit systems employ a mixed gas for breathing and elec­
tronically senses and controls oxygen concentration. This type of apparatus retains
the bubble-free characteristics of 100-percent oxygen recirculators while signifi­
cantly improving depth capability.
1-3.3

Hazards of Using Oxygen in SCUBA. Fleuss had been unaware of the serious

problem of oxygen toxicity caused by breathing 100 percent oxygen under pressure.
Oxygen toxicity apparently was not encountered when he used his apparatus in
early shallow water experiments. The danger of oxygen poisoning had actually
been discovered prior to 1878 by Paul Bert, the physiologist who first proposed
controlled decompression as a way to avoid the bends. In laboratory experiments
with animals, Bert demonstrated that breathing oxygen under pressure could lead
to convulsions and death (central nervous system oxygen toxicity).

In 1899, J. Lorrain Smith found that breathing oxygen over prolonged periods of
time, even at pressures not sufficient to cause convulsions, could lead to pulmo­nary
oxygen toxicity, a serious lung irritation. The results of these experiments, however,
were not widely publicized. For many years, working divers were unaware of the
dangers of oxygen poisoning.
CHAPTER 1­—History of Diving	

1-11

The true seriousness of the problem was not apparent until large numbers of combat
swimmers were being trained in the early years of World War II. After a number of
oxygen toxicity accidents, the British established an operational depth limit of 33
fsw. Additional research on oxygen toxicity continued in the U.S. Navy after the
war and resulted in the setting of a normal working limit of 25 fsw for 75 minutes
for the Emerson oxygen rebreather. A maximum emergency depth/time limit of 40
fsw for 10 minutes was also allowed.
These limits eventually proved operationally restrictive, and prompted the Navy
Experimental Diving Unit to reexamine the entire problem of oxygen toxicity
in the mid-1980s. As a result of this work, more liberal and flexible limits were
adopted for U.S. Navy use.
1-3.4

1‑3.4.1

Semiclosed-Circuit SCUBA. The semiclosed-circuit SCUBA combines features
of the open and closed-circuit systems. Using a mixture of gases for breathing,
the apparatus recycles the gas through a carbon dioxide removal canister and
continually adds a small amount of oxygen-rich mixed gas to the system from a
supply cylinder. The supply gas flow is preset to satisfy the body’s oxygen demand;
an equal amount of the recirculating mixed-gas stream is continually exhausted to
the water. Because the quantity of makeup gas is constant regardless of depth, the
semiclosed-circuit SCUBA provides significantly greater endurance than opencircuit systems in deep diving.
Lambertsen’s Mixed-Gas Rebreather. In the late 1940s, Dr. C.J. Lambertsen
proposed that mixtures of nitrogen or helium with an elevated oxygen content be
used in SCUBA to expand the depth range beyond that allowed by 100-percent
oxygen rebreathers, while simulta­neously minimizing the requirement for
decompression.

In the early 1950s, Lambertsen introduced the FLATUS I, a semiclosed-circuit
SCUBA that continually added a small volume of mixed gas, rather than pure
oxygen, to a rebreathing circuit. The small volume of new gas provided the oxygen
necessary for metabolic consumption while exhaled carbon dioxide was absorbed
in an absorbent canister. Because inert gas, as well as oxygen, was added to the rig,
and because the inert gas was not consumed by the diver, a small amount of gas
mixture was continuously exhausted from the rig.
1‑3.4.2

MK 6 UBA. In 1964, after significant development work, the Navy adopted a

semiclosed-circuit, mixed-gas rebreather, the MK 6 UBA, for combat swimming
and EOD operations. Decompression procedures for both nitrogen-oxygen and
helium-oxygen mixtures were developed at the Navy Experimental Diving Unit.
The apparatus had a maximum depth capability of 200 fsw and a maximum
endurance of 3 hours depending on water temperature and diver activity. Because
the appa­ratus was based on a constant mass flow of mixed gas, the endurance was
independent of the diver’s depth.
In the late 1960s, work began on a new type of mixed-gas rebreather technology,
which was later used in the MK 15 and MK 16 UBAs. In this UBA, the oxygen
partial pressure was controlled at a constant value by an oxygen sensing and addi­
1-12

U.S. Navy Diving Manual—Volume 1

tion system. As the diver consumed oxygen, an oxygen sensor detected the fall in
oxygen partial pressure and signaled an oxygen valve to open, allowing a small
amount of pure oxygen to be admitted to the breathing circuit from a cylinder.
Oxygen addition was thus exactly matched to metabolic consumption. Exhaled
carbon dioxide was absorbed in an absorption canister. The system had the endur­
ance and completely closed-circuit characteristics of an oxygen rebreather without
the concerns and limitations associated with oxygen toxicity.
Beginning in 1979, the MK 6 semiclosed-circuit underwater breathing apparatus
(UBA) was phased out by the MK 15 closed-circuit, constant oxygen partial
pres­sure UBA. The Navy Experimental Diving Unit developed decompression
procedures for the MK 15 with nitrogen and helium in the early 1980s. In 1985, an
improved low magnetic signature version of the MK 15, the MK 16, was approved
for Explosive Ordnance Disposal (EOD) team use.
1-3.5

SCUBA Use During World War II. Although closed-circuit equipment was restricted

to shallow-water use and carried with it the potential danger of oxygen toxicity, its
design had reached a suitably high level of efficiency by World War II. During the
war, combat swimmer breathing units were widely used by navies on both sides
of the conflict. The swimmers used various modes of underwater attack. Many
notable successes were achieved including the sinking of several battleships,
cruisers, and merchant ships.
1‑3.5.1

Diver-Guided Torpedoes. Italian divers, using

closed-circuit gear, rode chariot torpedoes
fitted with seats and manual controls in
repeated attacks against British ships. In
1936, the Italian Navy tested a chariot torpedo
system in which the divers used a descendant
of the Fleuss SCUBA. This was the Davis
Lung (Figure 1‑10). It was originally designed
as a submarine es­cape device and was later
manufactured in Italy under a license from
the English patent holders.
British divers, carried to the scene of action
in midget submarines, aided in placing
explosive charges under the keel of the
German battleship Tirpitz. The British began
Figure 1-10. Original Davis
their chariot program in 1942 using the Davis
Submerged Escape Apparatus.
Lung and exposure suits. Swimmers using the
MK 1 chariot dress quickly discovered that
the steel oxygen bottles adversely affected the compass of the chariot torpedo.
Aluminum oxygen cylin­ders were not readily available in England, but German
aircraft used aluminum oxygen cylinders that were almost the same size as the steel
cylinders aboard the chariot torpedo. Enough aluminum cylinders were salvaged
from downed enemy bombers to supply the British forces.

CHAPTER 1­—History of Diving	

1-13

Changes introduced in the MK 2 and MK 3 diving dress involved improvements in
valving, faceplate design, and arrangement of components. After the war, the MK 3
became the standard Royal Navy shallow water diving dress. The MK 4 dress was
used near the end of the war. Unlike the MK 3, the MK 4 could be supplied with
oxygen from a self-contained bottle or from a larger cylinder carried in the chariot.
This gave the swimmer greater endurance, yet preserved freedom of movement
independent of the chariot torpedo.
In the final stages of the war, the Japanese employed an underwater equivalent of
their kamikaze aerial attack—the kaiten diver-guided torpedo.
1‑3.5.2

U.S. Combat Swimming. There were two groups of U.S. combat swimmers

during World War II: Naval beach reconnaissance swimmers and U.S. operational
swimmers. Naval beach reconnaissance units did not normally use any breathing
devices, although several models existed.

U.S. operational swimmers, however,
under the Office of Strategic Services,
developed and applied advanced methods
for true self-contained diver-submersible
operations. They employed the Lambertsen
Amphibious Respiratory Unit (LARU), a
rebreather invented by Dr. C.J. Lambertsen
(see Figure 1‑11). The LARU was a closedcircuit oxygen UBA used in special warfare
operations where a complete absence of
exhaust bubbles was required. Following
World War II, the Emerson-Lambertsen
Oxygen Rebreather replaced the LARU
(Figure 1‑12). The Emerson Unit was
used exten­sively by Navy special warfare
divers until 1982, when it was replaced by
the Draeger Lung Automatic Regenerator
(LAR) V. The LAR V is the standard unit
now used by U.S. Navy combat swim­mers
(see Figure 1-13).

Figure 1-11. Lambertsen Amphibious
Respiratory Unit (LARU).

Today Navy combat swimmers are organized into two separate groups, each
with specialized training and missions. The Explosive Ordnance Disposal (EOD)
team handles, defuses, and disposes of munitions and other explosives. The Sea,
Air and Land (SEAL) special warfare teams make up the second group of Navy
combat swimmers. SEAL team members are trained to operate in all of these envi­
ronments. They qualify as parachutists, learn to handle a range of weapons, receive
intensive training in hand-to-hand combat, and are expert in SCUBA and other
swimming and diving techniques. In Vietnam, SEALs were deployed in special
counter-insurgency and guerrilla warfare operations. The SEALs also participated

1-14

U.S. Navy Diving Manual—Volume 1

Figure 1-12. Emerson-Lambertsen
Oxygen Rebreather.

Figure 1-13. Draeger LAR V UBA.

in the space program by securing flotation collars to returned space capsules and
assisting astronauts during the helicopter pickup.
1‑3.5.3

Underwater Demolition. The Navy’s Underwater Demolition Teams (UDTs) were
created when bomb disposal experts and Seabees (combat engineers) teamed
together in 1943 to devise methods for removing obstacles that the Germans were
placing off the beaches of France. The first UDT combat mission was a daylight
reconnaissance and demolition project off the beaches of Saipan in June 1944. In
March of 1945, preparing for the invasion of Okinawa, one underwater demolition
team achieved the exceptional record of removing 1,200 underwater obstacles in 2
days, under heavy fire, without a single casualty.

Because suitable equipment was not readily available, diving apparatus was not
extensively used by the UDT during the war. UDT experimented with a modified
Momsen lung and other types of breathing apparatus, but not until 1947 did the
Navy’s acquisition of Aqua-Lung equipment give impetus to the diving aspect of
UDT operations. The trail of bubbles from the open-circuit apparatus limited the
type of mission in which it could be employed, but a special SCUBA platoon of
UDT members was formed to test the equipment and determine appropriate uses
for it.
Through the years since, the mission and importance of the UDT has grown. In the
Korean Conflict, during the period of strategic withdrawal, the UDT destroyed an
entire port complex to keep it from the enemy. The UDTs have since been incor­
porated into the Navy Seal Teams.

CHAPTER 1­—History of Diving	

1-15

1-4

MIXED-GAS DIVING

Mixed-gas diving operations are conducted using a breathing medium other than
air. This medium may consist of:
 Nitrogen and oxygen in proportions other than those found in the atmosphere
 A mixture of other inert gases, such as helium, with oxygen.
The breathing medium can also be 100 percent oxygen, which is not a mixed gas,
but which requires training for safe use. Air may be used in some phases of a
mixed-gas dive.
Mixed-gas diving is a complex undertaking. A mixed-gas diving operation requires
extensive special training, detailed planning, specialized and advanced equipment
and, in many applications, requires extensive surface-support personnel and
facilities. Because mixed-gas operations are often conducted at great depth or for
extended periods of time, hazards to personnel increase greatly. Divers studying
mixed-gas diving must first be qualified in air diving operations.
In recent years, to match basic operational requirements and capabilities, the U.S.
Navy has divided mixed-gas diving into two categories:
 Nonsaturation diving without a pressurized bell to a maximum depth of 300
fsw, and
 Saturation diving for dives of 150 fsw and greater depth or for extended bottom
time missions.
The 300-foot limit is based primarily on the increased risk of decompression sick­
ness when nonsaturation diving techniques are used deeper than 300 fsw.
1-4.1

Nonsaturation Diving.

1‑4.1.1

Helium-Oxygen (HeO2) Diving. An inventor named Elihu Thomson theorized that

helium might be an appropriate substitute for the nitrogen in a diver’s breathing
supply. He estimated that at least a 50-percent gain in working depth could be
achieved by substituting helium for nitrogen. In 1919, he suggested that the U.S.
Bureau of Mines investigate this possibility. Thomson directed his suggestion to
the Bureau of Mines rather than the Navy Department, since the Bureau of Mines
held a virtual world monopoly on helium marketing and distribution.
1‑4.1.1.1

Experiments with Helium-Oxygen Mixtures. In 1924, the Navy and the Bureau of

Mines jointly sponsored a series of experi­ments using helium-oxygen mixtures.
The preliminary work was conducted at the Bureau of Mines Experimental Station
in Pittsburgh, Pennsylvania. Figure 1‑14 is a picture of an early Navy heliumoxygen diving manifold.

1-16

U.S. Navy Diving Manual—Volume 1

Figure 1-14. Helium-Oxygen Diving Manifold.

The first experiments showed no detrimental effects on test animals or humans
from breathing a helium-oxygen mixture, and decompression time was shortened.
The principal physiological effects noted by divers using helium-oxygen were:
 Increased sensation of cold caused by the high thermal conductivity of helium
 The high-pitched distortion or “Donald Duck” effect on human speech that
resulted from the acoustic properties and reduced density of the gas
These experiments clearly showed that helium-oxygen mixtures offered great
advantages over air for deep dives. They laid the foundation for developing the
reliable decompression tables and specialized apparatus, which are the corner­
stones of modern deep diving technology.
In 1937, at the Experimental Diving Unit research facility, a diver wearing a deepsea diving dress with a helium-oxygen breathing supply was compressed in a
chamber to a simulated depth of 500 feet. The diver was not told the depth and
when asked to make an estimate of the depth, the diver reported that it felt as if
he were at 100 feet. During decompression at the 300-foot mark, the breathing
mixture was switched to air and the diver was troubled immediately by nitrogen
narcosis.
The first practical test of helium-oxygen came in 1939, when the submarine USS
Squalus was salvaged from a depth of 243 fsw. In that year, the Navy issued
decompression tables for surface-supplied helium-oxygen diving.

CHAPTER 1­—History of Diving	

1-17

1‑4.1.1.2

MK V MOD 1 Helmet. Because helium was

expensive and ship­board supplies were
limited, the standard MK V MOD 0 opencircuit helmet was not economical for
surface-supplied helium-oxygen diving.
After experi­menting with several different
designs, the U.S. Navy adopted the
semiclosed-circuit MK V MOD 1 (Figure
1‑15).
The MK V MOD 1 helmet was equipped
with a carbon dioxide absorption canister and
venturi-powered recirculator assembly. Gas
in the helmet was continu­ously recirculated
through the carbon dioxide scrubber
assembly by the venturi. By removing carbon
dioxide by scrubbing rather than ventilating
the helmet, the fresh gas flow into the helmet
was reduced to the amount required to
replenish oxygen. The gas consumption of
the semiclosed-circuit MK V MOD 1 was
approximately 10 percent of that of the opencircuit MK V MOD 0.

Figure 1-15. MK V MOD 1 Helmet.

The MK V MOD 1, with breastplate and recirculating gas canister, weighed
approximately 103 pounds compared to 56 pounds for the standard air helmet and
breastplate. It was fitted with a lifting ring at the top of the helmet to aid in hatting
the diver and to keep the weight off his shoulders until he was lowered into the
water. The diver was lowered into and raised out of the water by a diving stage
connected to an onboard boom.
1‑4.1.1.3

Civilian Designers. U.S. Navy divers were not alone in working with mixed gases

or helium. In 1937, civilian engineer Max Gene Nohl reached 420 feet in Lake
Michigan while breathing helium-oxygen and using a suit of his own design. In
1946, civilian diver Jack Browne, designer of the lightweight diving mask that
bears his name, made a simulated helium-oxygen dive of 550 feet. In 1948, a
British Navy diver set an open-sea record of 540 fsw while using war-surplus
helium provided by the U.S.

1‑4.1.2

Hydrogen-Oxygen Diving. In countries where the availability of helium was

more restricted, divers experi­mented with mixtures of other gases. The most
notable example is that of the Swedish engineer Arne Zetterstrom, who worked
with hydrogen-oxygen mixtures. The explosive nature of such mixtures was well
known, but it was also known that hydrogen would not explode when used in a
mixture of less than 4 percent oxygen. At the surface, this percentage of oxygen
would not be sufficient to sustain life; at 100 feet, however, the oxygen partial
pressure would be the equivalent of 16 percent oxygen at the surface.

1-18

U.S. Navy Diving Manual—Volume 1

Zetterstrom devised a simple method for making the transition from air to
hydrogen-oxygen without exceeding the 4-percent oxygen limit. At the 100-foot
level, he replaced his breathing air with a mixture of 96 percent nitrogen and 4
percent oxygen. He then replaced that mixture with hydrogen-oxygen in the same
proportions. In 1945, after some successful test dives to 363 feet, Zetterstrom
reached 528 feet. Unfortunately, as a result of a misunderstanding on the part of his
topside support personnel, he was brought to the surface too rapidly. Zetter­strom
did not have time to enrich his breathing mixture or to adequately decompress and
died as a result of the effects of his ascent.
1‑4.1.3

Modern Surface-Supplied Mixed-Gas Diving. The U.S. Navy and the Royal Navy

continued to develop procedures and equip­ment for surface-supplied heliumoxygen diving in the years following World War II. In 1946, the Admiralty
Experimental Diving Unit was established and, in 1956, during open-sea tests
of helium-oxygen diving, a Royal Navy diver reached a depth of 600 fsw. Both
navies conducted helium-oxygen decompression trials in an attempt to develop
better procedures.
In the early 1960s, a young diving enthusiast from Switzerland, Hannes Keller,
proposed techniques to attain great depths while minimizing decompression
requirements. Using a series of gas mixtures containing varying concentrations
of oxygen, helium, nitrogen, and argon, Keller demonstrated the value of elevated
oxygen pressures and gas sequencing in a series of successful dives in mountain
lakes. In 1962, with partial support from the U.S. Navy, he reached an open-sea
depth of more than 1,000 fsw off the California coast. Unfortunately, this dive was
marred by tragedy. Through a mishap unrelated to the technique itself, Keller lost
consciousness on the bottom and, in the subsequent emergency decompression,
Keller’s companion died of decompression sickness.
By the late 1960s, it was clear that surface-supplied diving deeper than 300 fsw
was better carried out using a deep diving (bell) system where the gas sequencing
techniques pioneered by Hannes Keller could be exploited to full advantage, while
maintaining the diver in a state of comfort and security. The U.S. Navy developed
decompression procedures for bell diving systems in the late 1960s and early
1970s. For surface-supplied diving in the 0-300 fsw range, attention was turned to
developing new equipment to replace the cumbersome MK V MOD 1 helmet.

CHAPTER 1­—History of Diving	

1-19

1‑4.1.4

MK 1 MOD 0 Diving Outfit. The new

equipment development proceeded along
two parallel paths, developing open-circuit
demand breathing systems suitable for deep
helium-oxygen diving, and developing an
improved recirculating helmet to replace the
MK V MOD 1. By the late 1960s, engineering
improvements in demand regulators had
reduced breathing resis­tance on deep dives
to acceptable levels. Masks and helmets
incorporating the new regulators became
commercially avail­able. In 1976, the U.S.
Navy approved the MK 1 MOD 0 Lightweight,
Mixed-Gas Diving Outfit for dives to 300 fsw
on helium-oxygen (Figure 1‑16). The MK 1
MOD 0 Diving Outfit incorporated a full face
mask (bandmask) featuring a demand opencircuit breathing regulator and a backpack for
an emergency gas supply. Surface contact was
maintained through an umbilical that included
Figure 1-16. MK 1 MOD 0
the breathing gas hose, communications
Diving Outfit.
cable, lifeline strength member and pneumo­
fathometer hose. The diver was dressed in a
dry suit or hot water suit depending on water
temperature. The equipment was issued as a lightweight diving outfit in a system
with sufficient equipment to support a diving operation employing two working
divers and a standby diver. The outfit was used in conjunction with an open diving
bell that replaced the traditional diver’s stage and added additional safety. In 1990,
the MK 1 MOD 0 was replaced by the MK 21 MOD 1 (Superlite 17 B/NS) demand
helmet. This is the lightweight rig in use today.
In 1985, after an extensive development period, the direct replacement for the
MK V MOD 1 helmet was approved for Fleet use. The new MK 12 Mixed-Gas
Surface-Supplied Diving System (SSDS) was similar to the MK 12 Air SSDS,
with the addition of a backpack assembly to allow operation in a semiclosed-circuit
mode. The MK 12 system was retired in 1992 after the introduction of the MK 21
MOD 1 demand helmet.
1-4.2

Diving Bells. Although open, pressure-balanced diving bells have been used for

several centu­ries, it was not until 1928 that a bell appeared that was capable of
maintaining internal pressure when raised to the surface. In that year, Sir Robert
H. Davis, the British pioneer in diving equipment, designed the Submersible
Decompression Chamber (SDC). The vessel was conceived to reduce the time a
diver had to remain in the water during a lengthy decompression.
The Davis SDC was a steel cylinder capable of holding two men, with two inwardopening hatches, one on the top and one on the bottom. A surface-supplied diver
was deployed over the side in the normal mode and the bell was lowered to a

1-20

U.S. Navy Diving Manual—Volume 1

depth of 60 fsw with the lower hatch open and a tender inside. Surface-supplied air
ventilated the bell and prevented flooding. The diver’s deep decompression stops
were taken in the water and he was assisted into the bell by the tender upon arrival
at 60 fsw. The diver’s gas supply hose and communications cable were removed
from the helmet and passed out of the bell. The lower door was closed and the bell
was lifted to the deck where the diver and tender were decompressed within the
safety and comfort of the bell.
By 1931, the increased decompression times associated with deep diving and the
need for diver comfort resulted in the design of an improved bell system. Davis
designed a three-compartment deck decompression chamber (DDC) to which the
SDC could be mechanically mated, permitting the transfer of the diver under pres­
sure. The DDC provided additional space, a bunk, food and clothing for the diver’s
comfort during a lengthy decompression. This procedure also freed the SDC for
use by another diving team for continuous diving operations.
The SDC-DDC concept was a major advance in diving safety, but was not applied
to American diving technology until the advent of saturation diving. In 1962, E. A.
Link employed a cylindrical, aluminum SDC in conducting his first open-sea satu­
ration diving experiment. In his experiments, Link used the SDC to transport the
diver to and from the sea floor and a DDC for improved diver comfort. American
diving had entered the era of the Deep Diving System (DDS) and advances
and applications of the concept grew at a phenomenal rate in both military and
commercial diving.
1-4.3

Saturation Diving. As divers dove deeper and attempted more ambitious

underwater tasks, a safe method to extend actual working time at depth became
crucial. Examples of satu­ration missions include submarine rescue and salvage,
sea bed implantments, construction, and scientific testing and observation. These
types of operations are characterized by the need for extensive bottom time and,
consequently, are more efficiently conducted using saturation techniques.
1‑4.3.1

Advantages of Saturation Diving. In deep diving operations, decompression is the

most time-consuming factor. For example, a diver working for an hour at 200 fsw
would be required to spend an additional 3 hours and 20 minutes in the water
undergoing the necessary decompression.
However, once a diver becomes saturated with the gases that make decompression
necessary, the diver does not need additional decompression. When the blood and
tissues have absorbed all the gas they can hold at that depth, the time required for
decompression becomes constant. As long as the depth is not increased, additional
time on the bottom is free of any additional decompression.

If a diver could remain under pressure for the entire period of the required task, the
diver would face a lengthy decompression only when completing the project. For
a 40-hour task at 200 fsw, a saturated diver would spend 5 days at bottom pressure
and 2 days in decompression, as opposed to spending 40 days making 1‑hour dives
with long decompression periods using conventional methods.

CHAPTER 1­—History of Diving	

1-21

The U.S. Navy developed and proved saturation diving techniques in its Sealab
series. Advanced saturation diving techniques are being developed in ongoing
programs of research and development at the Navy Experimental Diving Unit
(NEDU), Navy Submarine Medical Research Laboratory (NSMRL), and many
institutional and commercial hyperbaric facilities. In addition, saturation diving
using Deep Diving Systems (DDS) is now a proven capability.
1‑4.3.2

1‑4.3.3

Bond’s Saturation Theory. True scientific impetus was first given to the saturation
concept in 1957 when a Navy diving medical officer, Captain George F. Bond,
theorized that the tissues of the body would eventually become saturated with inert
gas if exposure time was long enough. Bond, then a commander and the director
of the Submarine Medical Center at New London, Connecticut, met with Captain
Jacques-Yves Cousteau and determined that the data required to prove the theory
of saturation diving could be developed at the Medical Center.
Genesis Project. With the support of the U.S. Navy, Bond initiated the Genesis

Project to test the theory of saturation diving. A series of experiments, first with
test animals and then with humans, proved that once a diver was saturated, further
extension of bottom time would require no additional decompression time. Project
Genesis proved that men could be sustained for long periods under pressure, and
what was then needed was a means to put this concept to use on the ocean floor.

1‑4.3.4

Developmental Testing. Several test dives were conducted in the early 1960s:

 The first practical open-sea demonstrations of saturation diving were undertaken
in September 1962 by Edward A. Link and Captain Jacques-Yves Cousteau.
 Link’s Man-in-the-Sea program had one man breathing helium-oxygen at 200
fsw for 24 hours in a specially designed diving system.
 Cousteau placed two men in a gas-filled, pressure-balanced underwater habitat
at 33 fsw where they stayed for 169 hours, moving freely in and out of their
deep-house.
 Cousteau’s Conshelf One supported six men breathing nitrogen-oxygen at 35
fsw for 7 days.
 In 1964, Link and Lambertsen conducted a 2-day exposure of two men at 430
fsw.
 Cousteau’s Conshelf Two experiment maintained a group of seven men for 30
days at 36 fsw and 90 fsw with excursion dives to 330 fsw.
1‑4.3.5

Sealab Program. The best known U.S. Navy experimental effort in saturation

diving was the Sealab program.

1-22

U.S. Navy Diving Manual—Volume 1

1‑4.3.5.1

Sealabs I and II. After completing the Genesis Project, the Office of Naval

Research, the Navy Mine Defense Laboratory and Bond’s small staff of volunteers
gathered in Panama City, Florida, where construction and testing of the Sealab I
habitat began in December 1963.

In 1964, Sealab I placed four men underwater for 10 days at an average depth of
192 fsw. The habitat was eventually raised to 81 fsw, where the divers were trans­
ferred to a decompression chamber that was hoisted aboard a four-legged offshore
support structure.
In 1965, Sealab II put three teams of ten men each in a habitat at 205 fsw. Each
team spent 15 days at depth and one man, Astronaut Scott Carpenter, remained for
30 days (see Figure 1‑17).
1‑4.3.5.2

Sealab III. The follow-on seafloor experiment, Sealab III, was planned for

600 fsw. This huge undertaking required not only extensive development and
testing of equipment but also assessment of human tolerance to high-pressure
environments.

To prepare for Sealab III, 28 helium-oxygen saturation dives were performed at
the Navy Experimental Diving Unit to depths of 825 fsw between 1965 and 1968.
In 1968, a record-breaking excursion dive to 1,025 fsw from a saturation depth of
825 fsw was performed at the Navy Experimental Diving Unit (NEDU). The cul­
mination of this series of dives was a 1,000 fsw, 3-day saturation dive conducted
jointly by the U.S. Navy and Duke University in the hyperbaric chambers at Duke.
This was the first time man had been saturated at 1,000 fsw. The Sealab III prepa­
ration experiments showed that men could readily perform useful work at pressures
up to 31 atmospheres and could be returned to normal pressure without harm.

Figure 1-17. Sealab II.

CHAPTER 1­—History of Diving	

Figure 1-18. U.S. Navy’s First DDS, SDS-450.

1-23

Reaching the depth intended for the Sealab III habitat required highly specialized
support, including a diving bell to transfer divers under pressure from the habitat to
a pressurized deck decompression chamber. The experiment, however, was marred
by tragedy. Shortly after being compressed to 600 fsw in February 1969, Aquanaut
Berry Cannon convulsed and drowned. This unfortunate accident ended the Navy’s
involvement with sea­floor habitats.
1‑4.3.5.3

Continuing Research. Research and development continues to extend the depth
limit for saturation diving and to improve the diver’s capability. The deepest
dive attained by the U.S. Navy to date was in 1979 when divers from the NEDU
completed a 37-day, 1,800 fsw dive in its Ocean Simulation Facility. The world
record depth for experimental saturation, attained at Duke University in 1981, is
2,250 fsw, and non-Navy open sea dives have been completed to in excess of 2300
fsw. Experiments with mixtures of hydrogen, helium, and oxygen have begun and
the success of this mixture was demonstrated in 1988 in an open-sea dive to 1,650
fsw.

Advanced saturation diving techniques are being developed in ongoing programs
of research and development at NEDU, Navy Submarine Medical Research Labo­
ratory (NSMRL), and many institutional and commercial hyperbaric facilities. In
addition, saturation diving using Deep Diving Systems (DDS) is now a proven
capability.
1-4.4

Deep Diving Systems (DDS). Experiments in saturation technique required
substantial surface support as well as extensive underwater equipment. DDS are a
substantial improvement over previous methods of accomplishing deep undersea
work. The DDS is readily adaptable to saturation techniques and safely maintains
the saturated diver under pressure in a dry environment. Whether employed for
saturation or nonsaturation diving, the Deep Diving System totally eliminates
long decompression periods in the water where the diver is subjected to extended
environmental stress. The diver only remains in the sea for the time spent on a
given task. Additional benefits derived from use of the DDS include eliminating
the need for underwater habitats and increasing operational flexibility for the
surface-support ship.

The Deep Diving System consists of a Deck Decompression Chamber (DDC)
mounted on a surface-support ship. A Personnel Transfer Capsule (PTC) is mated
to the DDC, and the combination is pressurized to a storage depth. Two or more
divers enter the PTC, which is unmated and lowered to the working depth. The
interior of the capsule is pressurized to equal the pressure at depth, a hatch is
opened, and one or more divers swim out to accomplish their work. The divers
can use a self-contained breathing apparatus with a safety tether to the capsule, or
employ a mask and an umbilical that provides breathing gas and communications.
Upon completing the task, the divers enters the capsule, close the hatch and return
to the support ship with the interior of the PTC still at the working pressure. The
capsule is hoisted aboard and mated to the pressurized DDC. The divers enter the
larger, more comfortable DDC via an entry lock. They remain in the DDC until

1-24

U.S. Navy Diving Manual—Volume 1

they must return to the undersea job site. Decompression is carried out comfort­ably
and safely on the support ship.
The Navy developed four deep diving systems: ADS-IV, MK 1 MOD 0, MK 2
MOD 0, and MK 2 MOD 1.
1‑4.4.1

1‑4.4.2

ADS-IV. Several years prior to the Sealab I experiment, the Navy successfully
deployed the Advanced Diving System IV (ADS-IV) (see Figure 1‑18). The ADSIV was a small deep diving system with a depth capability of 450 fsw. The ADSIV was later called the SDS-450.
MK 1 MOD 0. The MK 1 MOD 0 DDS was a small system intended to be used on

the new ATS-1 class salvage ships, and underwent operational evaluation in 1970.
The DDS consisted of a Personnel Transfer Capsule (PTC) (see Figure 1‑19), a
life-support system, main control console and two deck decompression chambers
to handle two teams of two divers each. This system was also used to operationally
evaluate the MK 11 UBA, a semiclosed-circuit mixed-gas apparatus, for saturation
diving. The MK 1 MOD 0 DDS conducted an open-sea dive to 1,148 fsw in 1975.
The MK 1 DDS was not installed on the ATS ships as originally planned, but
placed on a barge and assigned to Harbor Clearance Unit Two. The system went
out of service in 1977.

Figure 1-19. DDS MK 1 Personnel Transfer Capsule.

1‑4.4.3

Figure 1-20. PTC Handling System, Elk River.

MK 2 MOD 0. The Sealab III experiment required a much larger and more capable

deep diving system than the MK 1 MOD 0. The MK 2 MOD 0 was constructed
and installed on the support ship Elk River (IX-501). With this system, divers could
be saturated in the deck chamber under close observation and then transported
to the habitat for the stay at depth, or could cycle back and forth between the
deck chamber and the seafloor while working on the exterior of the habitat. The

CHAPTER 1­—History of Diving	

1-25

bell could also be used in a non-pressurized observation mode. The divers would
be transported from the habitat to the deck decompression chamber, where final
decompression could take place under close observation.
1‑4.4.4

1-5

MK 2 MOD 1. Experience gained with the MK 2 MOD 0 DDS on board Elk River
(IX-501) (see Figure 1‑20) led to the development of the MK 2 MOD 1, a larger,
more sophisti­cated DDS. The MK 2 MOD 1 DDS supported two four-man teams
for long term saturation diving with a normal depth capability of 850 fsw. The
diving complex consisted of two complete systems, one at starboard and one at
port. Each system had a DDC with a life-support system, a PTC, a main control
console, a strength-power-communications cable (SPCC) and ship support. The
two systems shared a helium-recovery system. The MK 2 MOD 1 was installed on
the ASR 21 Class submarine rescue vessels.

SUBMARINE SALVAGE AND RESCUE

At the beginning of the 20th century, all major navies turned their attention toward
developing a weapon of immense potential—the military submarine. The highly
effective use of the submarine by the German Navy in World War I heightened this
interest and an emphasis was placed on the submarine that continues today.
The U.S. Navy had operated submarines on a limited basis for several years prior
to 1900. As American technology expanded, the U.S. submarine fleet grew rapidly.
However, throughout the period of 1912 to 1939, the development of the Navy’s F,
H, and S class boats was marred by a series of accidents, collisions, and sinkings.
Several of these submarine disasters resulted in a correspondingly rapid growth in
the Navy diving capability.
Until 1912, U.S. Navy divers rarely went below 60 fsw. In that year, Chief Gunner
George D. Stillson set up a program to test Haldane’s diving tables and methods
of stage decompression. A companion goal of the program was to improve Navy
diving equipment. Throughout a 3-year period, first diving in tanks ashore and then
in open water in Long Island Sound from the USS Walkie, the Navy divers went
progressively deeper, eventually reaching 274 fsw.
1-5.1

USS F-4. The experience gained in Stillson’s program was put to dramatic use

in 1915 when the submarine USS F-4 sank near Honolulu, Hawaii. Twenty-one
men lost their lives in the accident and the Navy lost its first boat in 15 years
of submarine oper­ations. Navy divers salvaged the submarine and recovered the
bodies of the crew. The salvage effort incorporated many new techniques, such as
using lifting pontoons. What was most remarkable, however, was that the divers
completed a major salvage effort working at the extreme depth of 304 fsw, using
air as a breathing mixture. The decompression requirements limited bottom time
for each dive to about 10 minutes. Even for such a limited time, nitrogen narcosis
made it difficult for the divers to concentrate on their work.
The publication of the first U.S. Navy Diving Manual and the establishment of a
Navy Diving School at Newport, Rhode Island, were the direct outgrowth of expe­
rience gained in the test program and the USS F-4 salvage. When the U.S. entered
1-26

U.S. Navy Diving Manual—Volume 1

World War I, the staff and graduates of the school were sent to Europe, where they
conducted various salvage operations along the coast of France.
The physiological problems encountered in the salvage of the USS F-4 clearly
demonstrated the limitations of breathing air during deep dives. Continuing concern
that submarine rescue and salvage would be required at great depth focused Navy
attention on the need for a new diver breathing medium.
1-5.2

USS S-51. In September of 1925, the USS S-51 submarine was rammed by a

passenger liner and sunk in 132 fsw off Block Island, Rhode Island. Public pressure
to raise the submarine and recover the bodies of the crew was intense. Navy diving
was put in sharp focus, realizing it had only 20 divers who were qualified to go
deeper than 90 fsw. Diver training programs had been cut at the end of World War
I and the school had not been reinstituted.
Salvage of the USS S-51 covered a 10-month span of difficult and hazardous diving,
and a special diver training course was made part of the operation. The submarine
was finally raised and towed to the Brooklyn Navy Yard in New York.
Interest in diving was high once again and the Naval School, Diving and Salvage,
was reestablished at the Washington Navy Yard in 1927. At the same time, the
Navy brought together its existing diving technology and experimental work by
shifting the Experimental Diving Unit (EDU), which had been working with the
Bureau of Mines in Pennsylvania, to the Navy Yard as well. In the following years,
EDU developed the U.S. Navy Air Decompression Tables, which have become
the accepted world standard and continued developmental work in helium-oxygen
breathing mixtures for deeper diving.
Losing the USS F-4 and USS S-51 provided the impetus for expanding the Navy’s
diving ability. However, the Navy’s inability to rescue men trapped in a disabled
submarine was not confronted until another major submarine disaster occurred.

1-5.3

USS S-4. In 1927, the Navy lost the submarine USS S-4 in a collision with the

Coast Guard cutter USS Paulding. The first divers to reach the submarine in 102
fsw, 22 hours after the sinking, exchanged signals with the men trapped inside.
The submarine had a hull fitting designed to take an air hose from the surface,
but what had looked feasible in theory proved too difficult in reality. With stormy
seas causing repeated delays, the divers could not make the hose connection until
it was too late. All of the men aboard the USS S-4 had died. Even had the hose
connection been made in time, rescuing the crew would have posed a significant
problem.
The USS S-4 was salvaged after a major effort and the fate of the crew spurred
several efforts toward preventing a similar disaster. LT C.B. Momsen, a subma­
rine officer, developed the escape lung that bears his name. It was given its first
operational test in 1929 when 26 officers and men successfully surfaced from an
intentionally bottomed submarine.

CHAPTER 1­—History of Diving	

1-27

1-5.4

USS Squalus. The Navy pushed for development of a rescue chamber that was

essentially a diving bell with special fittings for connection to a submarine deck
hatch. The apparatus, called the McCann-Erickson Rescue Chamber, was proven
in 1939 when the USS Squalus, carrying a crew of 50, sank in 243 fsw. The rescue
chamber made four trips and safely brought 33 men to the surface. (The rest of
the crew, trapped in the flooded after-section of the submarine, had perished in the
sinking.)

The USS Squalus was raised by salvage divers (see Figure 1‑21). This salvage
and rescue operation marked the first operational use of HeO2 in salvage diving.
One of the primary missions of salvage divers was to attach a down-haul cable
for the Submarine Rescue Chamber (SRC). Following renovation, the submarine,
renamed USS Sailfish, compiled a proud record in World War II.

Figure 1-21. Recovery of the Squalus.

1-5.5

USS Thresher. Just as the loss of the USS F-4, USS S-51, USS S-4 and the sinking

of the USS Squalus caused an increased concern in Navy diving in the 1920s and
1930s, a submarine disaster of major proportions had a profound effect on the
development of new diving equipment and techniques in the postwar period. This
was the loss of the nuclear attack submarine USS Thresher and all her crew in
April 1963. The submarine sank in 8,400 fsw, a depth beyond the survival limit of
the hull and far beyond the capability of any existing rescue apparatus.
An extensive search was initiated to locate the submarine and determine the cause
of the sinking. The first signs of the USS Thresher were located and photographed
a month after the disaster. Collection of debris and photographic coverage of the
wreck continued for about a year.
Two special study groups were formed as a result of the sinking. The first was a
Court of Inquiry, which attributed probable cause to a piping system failure. The

1-28

U.S. Navy Diving Manual—Volume 1

second, the Deep Submergence Review Group (DSRG), was formed to assess the
Navy’s undersea capabilities. Four general areas were examined—search, rescue,
recovery of small and large objects, and the Man-in-the-Sea concept. The basic
recommendations of the DSRG called for a vast effort to improve the Navy’s
capabilities in these four areas.
1-5.6

Deep Submergence Systems Project. Direct action on the recommendations of

the DSRG came with the formation of the Deep Submergence Systems Project
(DSSP) in 1964 and an expanded interest regarding diving and undersea activity
throughout the Navy.

Submarine rescue capabilities have been substantially improved with the develop­
ment of the Deep Submergence Rescue Vehicle (DSRV) which became operational
in 1972. This deep-diving craft is air-transportable, highly instru­mented, and
capable of diving to 5,000 fsw and rescues to 2,500 fsw.
Three additional significant areas of achievement for the Deep Submergence
Systems Project have been that of Saturation Diving, the development of Deep
Diving Systems, and progress in advanced diving equipment design.
1-6

SALVAGE DIVING
1-6.1
1‑6.1.1

World War II Era.
Pearl Harbor. Navy divers were plunged into the war with the Japanese raid on
Pearl Harbor. The raid began at 0755 on 7 December 1941; by 0915 that same
morning, the first salvage teams were cutting through the hull of the overturned
battleship USS Oklahoma to rescue trapped sailors. Teams of divers worked to
recover ammuni­tion from the magazines of sunken ships, to be ready in the event
of a second attack.

The immense salvage effort that followed at Pearl Harbor was highly successful.
Most of the 101 ships in the harbor at the time of the attack sustained damage. The
battleships, one of the primary targets of the raid, were hardest hit. Six battleships
were sunk and one was heavily damaged. Four were salvaged and returned to the
fleet for combat duty; the former battleships USS Arizona and USS Utah could not
be salvaged. The USS Oklahoma was righted and refloated but sank en route to a
shipyard in the U.S.
Battleships were not the only ships salvaged. Throughout 1942 and part of
1943, Navy divers worked on destroyers, supply ships, and other badly needed
vessels, often using makeshift shallow water apparatus inside water and gas-filled
compartments. In the Pearl Harbor effort, Navy divers spent 16,000 hours under­
water during 4,000 dives. Contract civilian divers contributed another 4,000 diving
hours.
1‑6.1.2

USS Lafayette. While divers in the Pacific were hard at work at Pearl Harbor,

a major challenge was presented to the divers on the East Coast. The interned
French passenger liner Normandie (rechristened as the USS Lafayette) caught fire

CHAPTER 1­—History of Diving	

1-29

alongside New York City’s Pier 88. Losing stability from the tons of water poured
on the fire, the ship capsized at her berth.
The ship had to be salvaged to clear the vitally needed pier. The Navy took advan­tage
of this unique training opportunity by instituting a new diving and salvage school
at the site. The Naval Training School (Salvage) was established in September
1942 and was transferred to Bayonne, New Jersey in 1946.
1‑6.1.3

1-6.2

Other Diving Missions. Salvage operations were not the only missions assigned
to Navy divers during the war. Many dives were made to inspect sunken enemy
ships and to recover mate­rials such as code books or other intelligence items. One
Japanese cruiser yielded not only $500,000 in yen, but also provided valuable
information concerning plans for the defense of Japan against the anticipated
Allied invasion.
Vietnam Era. Harbor Clearance Unit One (HCU 1) was commissioned 1 February

1966 to provide mobile salvage capability in direct support of combat operations
in Vietnam. Homeported at Naval Base Subic Bay, Philippines, HCU 1 was dedi­
cated primarily to restoring seaports and rivers to navigable condition following
their loss or diminished use through combat action.
Beginning as a small cadre of personnel, HCU 1 quickly grew in size to over 260
personnel, as combat operations in littoral environment intensified. At its peak, the
unit consisted of five Harbor Clearance teams of 20 to 22 personnel each and a
varied armada of specialized vessels within the Vietnam combat zone.
As their World War II predecessors before them, the salvors of HCU 1 left an
impressive legacy of combat salvage accomplishments. HCU 1 salvaged hundreds
of small craft, barges, and downed aircraft; refloated many stranded U.S. Military
and merchant vessels; cleared obstructed piers, shipping channels, and bridges; and
performed numerous underwater repairs to ships operating in the combat zone.
Throughout the colorful history of HCU 1 and her East Coast sister HCU 2, the vital
role salvage forces play in littoral combat operations was clearly demon­strated.
Mobile Diving and Salvage Unit One and Two, the modern-day descendants of
the Vietnam era Harbor Clearance Units, have a proud and distin­guished history of
combat salvage operations.
1-7

OPEN-SEA DEEP DIVING RECORDS

Diving records have been set and broken with increasing regularity since the early
1900s:
 1915. The 300-fsw mark was exceeded. Three U.S. Navy divers, F. Crilley,
W.F. Loughman, and F.C. Nielson, reached 304 fsw using the MK V dress.
 1972. The MK 2 MOD 0 DDS set the in-water record of 1,010 fsw.
 1975. Divers using the MK 1 Deep Dive System descended to 1,148 fsw.

1-30

U.S. Navy Diving Manual—Volume 1

 1977. A French dive team broke the open-sea record with 1,643 fsw.
 1981. The deepest salvage operation made with divers was 803 fsw when
British divers retrieved 431 gold ingots from the wreck of HMS Edinburgh,
sunk during World War II.
 Present. Commercial open water diving operations to over 1,000 fsw.
1-8

SUMMARY

Throughout the evolution of diving, from the earliest breath-holding sponge diver
to the modern saturation diver, the basic reasons for diving have not changed.
National defense, commerce, and science continue to provide the underlying basis
for the development of diving. What has changed and continues to change radi­cally
is diving technology.
Each person who prepares for a dive has the opportunity and obligation to take
along the knowledge of his or her predecessors that was gained through difficult
and dangerous experience. The modern diver must have a broad understanding of
the physical properties of the undersea environment and a detailed knowledge of his
or her own physiology and how it is affected by the environment. Divers must learn
to adapt to environmental conditions to successfully carry out their missions.
Much of the diver’s practical education will come from experience. However,
before a diver can gain this experience, he or she must build a basic foundation
from certain principles of physics, chemistry and physiology and must understand
the application of these principles to the profession of diving.

CHAPTER 1­—History of Diving	

1-31

PAGE LEFT BLANK INTENTIONALLY

1-32

U.S. Navy Diving Manual—Volume 1

CHAPTER 2

Underwater Physics
2-1

INTRODUCTION
2-1.1

Purpose. This chapter describes the laws of physics as they affect humans in the

water.
2-1.2

2-2

Scope. A thorough understanding of the principles outlined in this chapter is
essential to safe and effective diving performance.

PHYSICS

Humans readily function within the narrow atmospheric envelope present at the
earth’s surface and are seldom concerned with survival requirements. Outside the
boundaries of the envelope, the environment is hostile and our existence depends
on our ability to counteract threatening forces. To function safely, divers must
understand the characteristics of the subsea environment and the techniques that
can be used to modify its effects. To accomplish this, a diver must have a basic
knowledge of physics—the science of matter and energy. Of particular importance
to a diver are the behavior of gases, the principles of buoyancy, and the properties
of heat, light, and sound.
2-3

MATTER

Matter is anything that occupies space and has mass, and is the building block of
the physical world. Energy is required to cause matter to change course or speed.
The diver, the diver’s air supply, everything that supports him or her, and the
surrounding environment is composed of matter.
2-3.1

Elements. An element is the simplest form of matter that exhibits distinct physical

and chem­ical properties. An element cannot be broken down by chemical means
into other, more basic forms. Scientists have identified more than 100 elements
in the phys­ical universe. Elements combine to form the more than four million
substances known to man.
2-3.2

Atoms. The atom is the smallest particle of matter that carries the specific properties

of an element. Atoms are made up of electrically charged particles known as
protons, neutrons, and electrons. Protons have a positive charge, neutrons have a
neutral charge, and electrons have a negative charge.

2-3.3

Molecules. Molecules are formed when atoms group together (Figure 2-1).
Molecules usually exhibit properties different from any of the contributing atoms.
For example, when two hydrogen atoms combine with one oxygen atom, a new
substance—water—is formed. Some molecules are active and try to combine with
many of the other molecules that surround them. Other molecules are inert and

CHAPTER 2­ — Underwater Physics	

2-1

H atom

O2 molecule
(2 oxygen atoms)

O atom

H2O molecule
(2 hydrogen atoms
+ 1 oxygen atom)

Figure 2-1. Molecules. Two similar atoms
combine to form an oxygen molecule
while the atoms of two different elements,
hydrogen and oxygen, combine to form a
water molecule.

Solid

Liquid

Gas

Figure 2-2. The Three States of Matter.

do not naturally combine with other substances. The presence of inert elements
in breathing mixtures is important when calculating a diver’s decompression
obligations.
2-3.4

The Three States of Matter. Matter can exist in one of three natural states: solid,

liquid, or gas (Figure 2-2). A solid has a definite size and shape. A liquid has a
definite volume, but takes the shape of the container. Gas has neither definite shape
nor volume, but will expand to fill a container. Gases and liquids are collectively
referred to as fluids.

The physical state of a substance depends primarily upon temperature and partially
upon pressure. A solid is the coolest of the three states, with its molecules rigidly
aligned in fixed patterns. The molecules move, but their motion is like a constant
vibration. As heat is added the molecules increase their motion, slip apart from
each other and move around; the solid becomes a liquid. A few of the mole­cules
will spontaneously leave the surface of the liquid and become a gas. When the
substance reaches its boiling point, the molecules are moving very rapidly in all
directions and the liquid is quickly transformed into a gas. Lowering the temperature
reverses the sequence. As the gas molecules cool, their motion is reduced and the
gas condenses into a liquid. As the temperature continues to fall, the liquid reaches
the freezing point and transforms to a solid state.
2-4

MEASUREMENT

Physics relies heavily upon standards of comparison of one state of matter or
energy to another. To apply the principles of physics, divers must be able to employ
a variety of units of measurement.
2-4.1

Measurement Systems. Two systems of measurement are widely used throughout

the world. Although the English System is commonly used in the United States,
the most common system of measurement in the world is the International System
of Units. The Interna­tional System of Units, or SI system, is a modernized metric
system designated in 1960 by the General Conference on Weights and Measures.
The SI system is decimal based with all its units related, so that it is not necessary
2-2

U.S. Navy Diving Manual — Volume 1

to use calcula­tions to change from one unit to another. The SI system changes one
of its units of measurement to another by moving the decimal point, rather than by
the lengthy calculations necessary in the English System. Because measurements
are often reported in units of the English system, it is important to be able to convert
them to SI units. Measurements can be converted from one system to another by
using the conversion factors in Table 2-10 through 2-18.
2-4.2

Temperature Measurements. While the English System of weights and measures

uses the Fahrenheit (°F) temperature scale, the Celsius (°C) scale is the one most
commonly used in scien­tific work. Both scales are based upon the freezing and
boiling points of water. The freezing point of water is 32°F or 0°C; the boiling
point of water is 212°F or 100°C. Temperature conversion formulas and charts are
found in Table 2-18.
Absolute temperature values are used
when employing the ideal gas laws.
The absolute temperature scales are
based upon absolute zero. Absolute
zero is the lowest temperature that
could possibly be reached at which all
molecular motion would cease (Figure
2‑3).
2‑4.2.1

212° F

100° C

373 K

672o R

32° F

0° C

273 K

492 R

o

Kelvin Scale. One example of an

absolute tempera­ture scale is the Kelvin
scale, which has the same size degrees
as the Celsius scale. The freezing point
of water is 273°K and boiling point
of water is 373°K. Use this formula
to convert from Celsius to absolute
temperature (Kelvin):

Figure 2-3. Temperature Scales. 
Fahrenheit, Celsius, Kelvin, and Rankine
temperature scales showing the freezing
and boiling points of water.

Kelvin (K) = °C + 273.
2‑4.2.2

Rankine Scale. The Rankine scale is another absolute temperature scale, which

has the same size degrees as the Fahrenheit scale. The freezing point of water is
492°R and the boiling point of water is 672°R. Use this formula to convert from
Fahrenheit to absolute temperature (degrees Rankine, °R):
°R = °F + 460
2-4.3

Gas Measurements. When measuring gas, actual cubic feet (acf) of a gas refers to

the quantity of a gas at ambient conditions. The most common unit of measurement
for gas in the United States is standard cubic feet (scf). Standard cubic feet relates
the quantity measurement of a gas under pressure to a specific condition. The
specific condi­tion is a common basis for comparison. For air, the standard cubic
foot is measured at 60°F and 14.696 psia.

CHAPTER 2­ — Underwater Physics	

2-3

2-5

ENERGY

Energy is the capacity to do work. The six basic types of energy are mechanical,
heat, light, chemical, electromagnetic, and nuclear, and may appear in a variety
of forms (Figure 2‑4). Energy is a vast and complex aspect of physics beyond the
scope of this manual. Consequently, this chapter only covers a few aspects of light,
heat, and mechanical energy because of their unusual effects underwater and their
impact on diving.

Figure 2-4. The Six Forms of Energy.

2-4

U.S. Navy Diving Manual — Volume 1

2-5.1

2-5.2

Conservation of Energy. The Law of the Conservation of Energy, formulated in
the 1840s, states that energy in the universe can neither be created nor destroyed.
Energy can be changed, however, from one form to another.
Classifications of Energy. The two general classifications of energy are potential

energy and kinetic energy. Potential energy is due to position. An automobile
parked on a hill with its brakes set possesses potential energy. Kinetic energy is
energy of motion. An automobile rolling on a flat road possesses kinetic energy
while it is moving.

2-6

LIGHT ENERGY IN DIVING

Refraction, turbidity of the water, salinity, and pollution all contribute to the
distance, size, shape, and color perception of underwater objects. Divers must
understand the factors affecting underwater visual perception, and must realize
that distance perception is very likely to be inaccurate.
2-6.1

Refraction. Light passing from an object
bends as it passes through the diver’s
faceplate and the air in his mask (Figure 25). This phenomenon is called refraction,
and occurs because light travels faster in
air than in water. Although the refraction
that occurs between the water and the
air in the diver’s face mask produces
undesir­able perceptual inaccuracies, air
is essential for vision. When a diver loses
his face mask, his eyes are immersed in
water, which has about the same refrac­
tive index as the eye. Consequently, the
light is not focused normally and the
diver’s vision is reduced to a level that
would be classified as legally blind on
the surface.

Water

Figure 2-5. Objects Underwater
Appear Closer.

Refraction can make objects appear closer
than they really are. A distant object will appear to be approximately three-quarters
of its actual distance. At greater distances, the effects of refraction may be reversed,
making objects appear farther away than they actually are. Reduced brightness and
contrast combine with refrac­tion to affect visual distance relationships.
Refraction can also affect perception of size and shape. Generally, underwater
objects appear to be about 30 percent larger than they actually are. Refraction
effects are greater for objects off to the side in the field of view. This distortion
interferes with hand-eye coordination, and explains why grasping objects under­
water is sometimes difficult for a diver. Experience and training can help a diver
learn to compensate for the misinterpretation of size, distance, and shape caused
by refraction.

CHAPTER 2­ — Underwater Physics	

2-5

2-6.2

Turbidity of Water. Water turbidity can also profoundly influence underwater

vision and distance perception. The more turbid the water, the shorter the distance
at which the reversal from underestimation to overestimation occurs. For example,
in highly turbid water, the distance of objects at 3 or 4 feet may be overestimated;
in moder­ately turbid water, the change might occur at 20 to 25 feet and in very
clear water, objects as far away as 50 to 70 feet might appear closer than they
actually are. Generally speaking, the closer the object, the more it will appear to be
too close, and the more turbid the water, the greater the tendency to see it as too far
away.
2-6.3

2-6.4

Diffusion. Light scattering is intensified underwater. Light rays are diffused and
scattered by the water molecules and particulate matter. At times diffusion is helpful
because it scatters light into areas that otherwise would be in shadow or have no
illumination. Normally, however, diffusion interferes with vision and underwater
photography because the backscatter reduces the contrast between an object and
its background. The loss of contrast is the major reason why vision underwater is
so much more restricted than it is in air. Similar degrees of scattering occur in air
only in unusual conditions such as heavy fog or smoke.
Color Visibility. Object size and distance are not the only characteristics distorted

underwater. A variety of factors may combine to alter a diver’s color perception.
Painting objects different colors is an obvious means of changing their visibility
by enhancing their contrast with the surroundings, or by camouflaging them to
merge with the back­ground. Determining the most and least visible colors is much
more complicated underwater than in air.
Colors are filtered out of light as it enters the water and travels to depth. Red light
is filtered out at relatively shallow depths. Orange is filtered out next, followed
by yellow, green, and then blue. Water depth is not the only factor affecting the
filtering of colors. Salinity, turbidity, size of the particles suspended in the water,
and pollution all affect the color-filtering properties of water. Color changes vary
from one body of water to another, and become more pronounced as the amount of
water between the observer and the object increases.
The components of any underwater scene, such as weeds, rocks, and encrusting
animals, generally appear to be the same color as the depth or viewing range
increases. Objects become distinguishable only by differences in brightness and
not color. Contrast becomes the most important factor in visibility; even very
large objects may be undetectable if their brightness is similar to that of the
background.
2-7

MECHANICAL ENERGY IN DIVING

Mechanical energy mostly affects divers in the form of sound. Sound is a periodic
motion or pressure change transmitted through a gas, a liquid, or a solid. Because
liquid is denser than gas, more energy is required to disturb its equilibrium. Once
this disturbance takes place, sound travels farther and faster in the denser medium.
Several aspects of sound underwater are of interest to the working diver.

2-6

U.S. Navy Diving Manual — Volume 1

2-7.1

Water Temperature and Sound. In any body of water, there may be two or more

distinct contiguous layers of water at different temperatures; these layers are
known as thermoclines. The colder a layer of water, the greater its density. As
the difference in density between layers increases, the sound energy transmitted
between them decreases. This means that a sound heard 50 meters from its source
within one layer may be inaudible a few meters from its source if the diver is in
another layer.
2-7.2

Water Depth and Sound. In shallow water or in enclosed spaces, reflections and

reverberations from the air/water and object/water interfaces produce anomalies
in the sound field, such as echoes, dead spots, and sound nodes. When swimming
in shallow water, among coral heads, or in enclosed spaces, a diver can expect
periodic losses in acoustic communication signals and disruption of acoustic
navigation beacons. The problem becomes more pronounced as the frequency of
the signal increases.
Because sound travels so quickly underwater (4,921 feet per second), human ears
cannot detect the difference in time of arrival of a sound at each ear. Consequently,
a diver cannot always locate the direction of a sound source. This disadvantage can
have serious consequences for a diver or swimmer trying to locate an object or a
source of danger, such as a powerboat.

2‑7.2.1

Diver Work and Noise. Open-circuit SCUBA affects sound reception by producing
high noise levels at the diver’s head and by creating a screen of bubbles that
reduces the effective sound pressure level (SPL). When several divers are working
in the same area, the noise and bubbles affect communication signals more for
some divers than for others, depending on the position of the divers in relation to
the communicator and to each other.

A neoprene wet suit is an effective barrier to sound above 1,000 Hz and it becomes
more of a barrier as frequency increases. This problem can be overcome by exposing
a small area of the head either by cutting holes at the ears of the suit or by folding
a small flap away from the surface.
2‑7.2.2

Pressure Waves. Sound is transmitted through water as a series of pressure waves.

High-intensity sound is transmitted by correspondingly high-intensity pressure
waves. A high-pressure wave transmitted from the water surrounding a diver to
the open spaces within the body (ears, sinuses, lungs) may increase the pressure
within these open spaces, causing injury. Underwater explosions and sonar can
create high-intensity sound or pressure waves. Low intensity sonar, such as depth
finders and fish finders, do not produce pressure waves intense enough to endanger
divers. However, anti-submarine sonar-equipped ships do pulse dangerous, highintensity pressure waves.

It is prudent to suspend diving operations if a high-powered sonar transponder
is being operated in the area. When using a diver-held pinger system, divers are
advised to wear the standard ¼-inch neoprene hood for ear protection. Experi­ments
have shown that such a hood offers adequate protection when the ultrasonic pulses
are of 4-millisecond duration, repeated once per second for acoustic source levels
CHAPTER 2­ — Underwater Physics	

2-7

up to 100 watts, at head-to-source distances as short as 0.5 feet (Pence and Sparks,
1978).
2-7.3

Underwater Explosions. An underwater explosion creates a series of waves that

are transmitted as hydraulic shock waves in the water, and as seismic waves in the
seabed. The hydraulic shock wave of an underwater explosion consists of an initial
wave followed by further pressure waves of diminishing intensity. The initial
high-intensity shock wave is the result of the violent creation and liberation of a
large volume of gas, in the form of a gas pocket, at high pressure and temperature.
Subsequent pressure waves are caused by rapid gas expansion in a non-compress­
ible environment, causing a sequence of contractions and expansions as the gas
pocket rises to the surface.
The initial high-intensity shock wave is the most dangerous; as it travels outward
from the source of the explosion, it loses its intensity. Less severe pressure waves
closely follow the initial shock wave. Considerable turbulence and movement of
the water in the area of the explosion are evident for an extended time after the
detonation.
2‑7.3.1

Type of Explosive and Size of the Charge. Some explosives have characteristics

of high brisance (shattering power in the immediate vicinity of the explosion) with
less power at long range, while the bri­sance of others is reduced to increase their
power over a greater area. Those with high brisance generally are used for cutting
or shattering purposes, while high-power, low-­brisance explosives are used in
depth charges and sea mines where the target may not be in immediate contact and
the ability to inflict damage over a greater area is an advantage. The high-brisance
explosives create a high-level shock and pressure waves of short duration over
a limited area. Low brisance explosives create a less intense shock and pressure
waves of long duration over a greater area.
2‑7.3.2

Characteristics of the Seabed. Aside from the fact that rock or other bottom debris

may be propelled through the water or into the air with shallow-placed charges,
bottom conditions can affect an explosion’s pressure waves. A soft bottom tends
to dampen reflected shock and pressure waves, while a hard, rock bottom may
amplify the effect. Rock strata, ridges and other topographical features of the
seabed may affect the direction of the shock and pressure waves, and may also
produce secondary reflecting waves.
2‑7.3.3

Location of the Explosive Charge. Research has indicated that the magnitude of

shock and pressure waves generated from charges freely suspended in water is
considerably greater than that from charges placed in drill holes in rock or coral.
2‑7.3.4

2‑7.3.5

Water Depth. At great depth, the shock and pressure waves are drawn out by the
greater water volume and are thus reduced in intensity. An explosion near the
surface is not weakened to the same degree.
Distance from the Explosion. In general, the farther away from the explosion, the

greater the attenuation of the shock and pressure waves and the less the intensity.
This factor must be considered in the context of bottom conditions, depth of

2-8

U.S. Navy Diving Manual — Volume 1

water, and reflection of shock and pressure waves from underwater structures and
topographical features.
2‑7.3.6

Degree of Submersion of the Diver. A fully submerged diver receives the total

effect of the shock and pressure waves passing over the body. A partially submerged
diver whose head and upper body are out of the water, may experience a reduced
effect of the shock and pressure waves on the lungs, ears, and sinuses. However,
air will transmit some portion of the explosive shock and pressure waves. The
head, lungs, and intestines are the parts of the body most vulnerable to the pressure
effects of an explosion. A pres­sure wave of 500 pounds per square inch is sufficient
to cause serious injury to the lungs and intestinal tract, and one greater than 2,000
pounds per square inch will cause certain death. Even a pressure wave of 500
pounds per square inch could cause fatal injury under certain circumstances.
2‑7.3.7

Estimating Explosion Pressure on a Diver. There are various formulas for
estimating the pressure wave resulting from an explosion of TNT. The equations
vary in format and the results illustrate that the technique for estimation is only an
approximation. Moreover, these formulas relate to TNT and are not applicable to
other types of explosives.

The formula below (Greenbaum and Hoff, 1966) is one method of estimating the
pressure on a diver resulting from an explosion of tetryl or TNT.

13, 0003 W
P=
r
Where:
P
=
W =
r
=

pressure on the diver in pounds per square inch
weight of the explosive (TNT) in pounds
range of the diver from the explosion in feet

Sample Problem. Determine the pressure exerted by a 45-pound charge at a

distance of 80 feet.

1. Substitute the known values.

13, 0003 45
P=
80
2. Solve for the pressure exerted.

13, 0003 45
80
13, 000 × 3.56
=
80
= 578.5

P=

Round up to 579 psi.

CHAPTER 2­ — Underwater Physics	

2-9

A 45-pound charge exerts a pressure of 579 pounds per square inch at a distance
of 80 feet.
2‑7.3.8

Minimizing the Effects of an Explosion. When expecting an underwater blast, the

diver shall get out of the water and out of range of the blast whenever possible.
If the diver must be in the water, it is prudent to limit the pressure he experiences
from the explosion to less than 50 pounds per square inch. To minimize the effects,
the diver can position himself with feet pointing toward and head directly away
from the explosion. The head and upper section of the body should be out of the
water or the diver should float on his back with his head out of the water.
2-8

HEAT ENERGY IN DIVING

Heat is crucial to man’s environmental balance. The human body functions within
only a very narrow range of internal temperature and contains delicate mecha­nisms
to control that temperature.
Heat is a form of energy associated with and proportional to the molecular motion
of a substance. It is closely related to temperature, but must be distinguished from
temperature because different substances do not necessarily contain the same heat
energy even though their temperatures are the same.
Heat is generated in many ways. Burning fuels, chemical reactions, friction, and
electricity all generate heat. Heat is transmitted from one place to another by
conduction, convection, and radiation.
2-8.1

Conduction, Convection, and Radiation. Conduction is the transmission of heat by
direct contact. Because water is an excellent heat conductor, an unprotected diver
can lose a great deal of body heat to the surrounding water by direct conduction.

Convection is the transfer of heat by the movement of heated fluids. Most home
heating systems operate on the principle of convection, setting up a flow of air
currents based on the natural tendency of warm air to rise and cool air to fall. A
diver seated on the bottom of a tank of water in a cold room can lose heat not only
by direct conduction to the water, but also by convection currents in the water. The
warmed water next to his body will rise and be replaced by colder water passing
along the walls of the tank. Upon reaching the surface, the warmed water will lose
heat to the cooler surroundings. Once cooled, the water will sink only to be warmed
again as part of a continuing cycle.
Radiation is heat transmission by electromagnetic waves of energy. Every warm
object gives off waves of electromagnetic energy, which is absorbed by cool
objects. Heat from the sun, electric heaters, and fireplaces is primarily radiant
heat.
2-8.2

2-10

Heat Transfer Rate. To divers, conduction is the most significant means of
transmitting heat. The rate at which heat is transferred by conduction depends on
two basic factors:

U.S. Navy Diving Manual — Volume 1

 The difference in temperature between the warmer and cooler material
 The thermal conductivity of the materials
Not all substances conduct heat at the same rate. Iron, helium, and water are
excel­lent heat conductors while air is a very poor conductor. Placing a poor heat
conductor between a source of heat and another substance insulates the substance
and slows the transfer of heat. Materials such as wool and foam rubber insulate the
human body and are effective because they contain thousands of pockets of trapped
air. The air pockets are too small to be subject to convective currents, but block
conductive transfer of heat.
2-8.3

Diver Body Temperature. A diver will start to become chilled when the water
temperature falls below a seemingly comfortable 70°F (21°C). Below 70°F, a
diver wearing only a swim­ming suit loses heat to the water faster than his body
can replace it. Unless he is provided some protection or insulation, he may quickly
experience difficulties. A chilled diver cannot work efficiently or think clearly, and
is more susceptible to decompression sickness.

Suit compression, increased gas density, thermal conductivity of breathing gases,
and respiratory heat loss are contributory factors in maintaining a diver’s body
temperature. Cellular neoprene wet suits lose a major portion of their insulating
properties as depth increases and the material compresses. As a consequence, it is
often necessary to employ a thicker suit, a dry suit, or a hot water suit for extended
exposures to cold water.
The heat transmission characteristics of an individual gas are directly proportional
to its density. Therefore, the heat lost through gas insulating barriers and respira­
tory heat lost to the surrounding areas increase with depth. The heat loss is further
aggravated when high thermal conductivity gases, such as helium-oxygen, are used
for breathing. The respiratory heat loss alone increases from 10 percent of the body’s
heat generating capacity at one ata (atmosphere absolute), to 28 percent at 7 ata,
to 50 percent at 21 ata when breathing helium-oxygen. Under these circum­stances,
standard insulating materials are insufficient to maintain body temperatures and
supplementary heat must be supplied to the body surface and respiratory gas.
2-9

PRESSURE IN DIVING

Pressure is defined as a force acting upon a particular area of matter. It is typically
measured in pounds per square inch (psi) in the English system and Newton per
square centimeter (N/cm2) in the System International (SI). Underwater pressure is
a result of the weight of the water above the diver and the weight of the atmo­sphere
over the water. There is one concept that must be remembered at all times—any
diver, at any depth, must be in pressure balance with the forces at that depth. The
body can only function normally when the pressure difference between the forces
acting inside of the diver’s body and forces acting outside is very small. Pressure,
whether of the atmosphere, seawater, or the diver’s breathing gases, must always
be thought of in terms of maintaining pressure balance.

CHAPTER 2­ — Underwater Physics	

2-11

2-9.1

Atmospheric Pressure. Given that one atmosphere is equal to 33 feet of sea water

or 14.7 psi, 14.7 psi divided by 33 feet equals 0.445 psi per foot. Thus, for every
foot of sea water, the total pressure is increased by 0.445 psi. Atmospheric pressure
is constant at sea level; minor fluctuations caused by the weather are usually
ignored. Atmospheric pressure acts on all things in all directions.

Most pressure gauges measure differential pressure between the inside and outside
of the gauge. Thus, the atmospheric pressure does not register on the pressure gauge
of a cylinder of compressed air. The initial air in the cylinder and the gauge are
already under a base pressure of one atmosphere (14.7 psi or 10N/cm2). The gauge
measures the pressure difference between the atmosphere and the increased air
pressure in the tank. This reading is called gauge pressure and for most purposes
it is sufficient.
In diving, however, it is important to include atmospheric pressure in computa­
tions. This total pressure is called absolute pressure and is normally expressed in
units of atmospheres. The distinction is important and pressure must be identified
as either gauge (psig) or absolute (psia). When the type of pressure is identified
only as psi, it refers to gauge pressure. Table 2‑10 contains conversion factors for
pressure measurement units.
2-9.2

Terms Used to Describe Gas Pressure. Four terms are used to describe gas

pressure:
 Atmospheric. Standard atmosphere, usually expressed as 10N/cm2, 14.7 psi, or
one atmosphere absolute (1 ata).
 Barometric. Essentially the same as atmospheric but varying with the weather
and expressed in terms of the height of a column of mercury. Standard pressure
is equal to 29.92 inches of mercury, 760 millimeters of mercury, or 1013
millibars.
 Gauge. Indicates the difference between atmospheric pressure and the pressure
being measured.
 Absolute. The total pressure being exerted, i.e., gauge pressure plus atmospheric
pressure.
2-9.3

Hydrostatic Pressure. The water on the surface pushes down on the water

below and so on down to the bottom where, at the greatest depths of the ocean
(approximately 36,000 fsw), the pressure is more than 8 tons per square inch
(1,100 ata). The pressure due to the weight of a water column is referred to as
hydrostatic pressure.
The pressure of seawater at a depth of 33 feet equals one atmosphere. The absolute
pressure, which is a combination of atmospheric and water pressure for that depth,
is two atmospheres. For every additional 33 feet of depth, another atmosphere of
pressure (14.7 psi) is encountered. Thus, at 99 feet, the absolute pressure is equal

2-12

U.S. Navy Diving Manual — Volume 1

to four atmospheres. Table 2‑1 and Figure 2‑7 shows how pressure increases with
depth.
Table 2‑1. Pressure Chart.
Depth Gauge Pressure

Atmospheric Pressure

Absolute Pressure

0

One Atmosphere

1 ata (14.7 psia)

33 fsw

+ One Atmosphere

2 ata (29.4 psia)

66 fsw

+ One Atmosphere

3 ata (44.1 psia)

99 fsw

+ One Atmosphere

4 ata (58.8 psia)

The change in pressure with depth is so pronounced that the feet of a 6-foot tall
person standing underwater are exposed to pressure that is almost 3 pounds per
square inch greater than that exerted at his head.
2-9.4

Buoyancy. Buoyancy is the force that makes objects float. It was first defined by

the Greek mathematician Archimedes, who established that “Any object wholly or
partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid
displaced by the object.” This is known as Archimedes’ Principle and applies to all
objects and all fluids.

2‑9.4.1

Archimedes’ Principle. According to Archimedes’ Principle, the buoyancy of a

submerged body can be established by subtracting the weight of the submerged
body from the weight of the displaced liquid. If the total displacement (the weight
of the displaced liquid) is greater than the weight of the submerged body, the
buoyancy is positive and the body will float or be buoyed upward. If the weight
of the body is equal to that of the displaced liquid, the buoyancy is neutral and the
body will remain suspended in the liquid. If the weight of the submerged body is
greater than that of the displaced liquid, the buoyancy is negative and the body
will sink.
The buoyant force on an object is dependent upon the density of the substance it
is immersed in (weight per unit volume). Fresh water has a density of 62.4 pounds
per cubic foot. Sea water is heavier, having a density of 64.0 pounds per cubic
foot. Thus an object is buoyed up by a greater force in seawater than in fresh water,
making it easier to float in the ocean than in a fresh water lake.
2‑9.4.2

Diver Buoyancy. Lung capacity has a significant effect on buoyancy of a diver.

A diver with full lungs displaces a greater volume of water and, therefore, is
more buoyant than with deflated lungs. Individual differences that may affect
the buoyancy of a diver include bone structure, bone weight, and body fat. These
differences explain why some individuals float easily while others do not.
A diver can vary his buoyancy in several ways. By adding weight to his gear,
he can cause himself to sink. When wearing a variable volume dry suit, he can
increase or decrease the amount of air in his suit, thus changing his displacement

CHAPTER 2­ — Underwater Physics	

2-13

and thereby his buoyancy. Divers usually seek a condition of neutral to slightly
negative buoyancy. Negative buoyancy gives a diver in a helmet and dress a better
foothold on the bottom. Neutral buoyancy enhances a SCUBA diver’s ability to
swim easily, change depth, and hover.
2-10

GASES IN DIVING

Knowledge of the properties and behavior of gases, especially those used for
breathing, is vitally important to divers.
2-10.1

Atmospheric Air. The most common gas used in diving is atmospheric air, the
composition of which is shown in Table 2-2. Any gases found in concentrations
different than those in Table 2-2 or that are not listed in Table 2-2 are considered
contaminants. Depending on weather and location, many industrial pollutants may
be found in air. Carbon monoxide is the most commonly encountered and is often
present around air compressor engine exhaust. Care must be taken to exclude the
pollut­ants from the diver’s compressed air by appropriate filtering, inlet location,
and compressor maintenance. Water vapor in varying quantities is present in
compressed air and its concentration is important in certain instances.

Table 2‑2. Components of Dry Atmospheric Air.
Concentration
Component

Percent by Volume

Nitrogen

78.084

Oxygen

20.9476

Carbon Dioxide

0.038

Argon

0.0934

Neon

Parts per Million (ppm)

380

18.18

Helium

5.24

Krypton

1.14

Xenon

0.08

Hydrogen

0.5

Methane

2.0

Nitrous Oxide

0.5

For most purposes and computations, diving air may be assumed to be composed
of 79 percent nitrogen and 21 percent oxygen. Besides air, varying mixtures of
oxygen, nitrogen, and helium are commonly used in diving. While these gases are
discussed separately, the gases themselves are almost always used in some mixture.
Air is a naturally occurring mixture of most of them. In certain types of diving
applications, special mixtures may be blended using one or more of the gases with
oxygen.

2-14

U.S. Navy Diving Manual — Volume 1

2-10.2

Oxygen. Oxygen (O2) is the most important of all gases and is one of the most

abundant elements on earth. Fire cannot burn without oxygen and people cannot
survive without oxygen. Atmospheric air contains approximately 21 percent
oxygen, which exists freely in a diatomic state (two atoms paired off to make one
mole­cule). This colorless, odorless, tasteless, and active gas readily combines
with other elements. From the air we breathe, only oxygen is actually used by the
body. The other 79 percent of the air serves to dilute the oxygen. Pure 100 percent
oxygen is often used for breathing in hospitals, aircraft, and hyperbaric medical
treatment facilities. Sometimes 100 percent oxygen is used in shallow diving oper­
ations and certain phases of mixed-gas diving operations. However, breathing pure
oxygen under pressure may induce the serious problems of oxygen toxicity.
2-10.3

Nitrogen. Like oxygen, nitrogen (N2) is diatomic, colorless, odorless, and tasteless,
and is a component of all living organisms. Unlike oxygen, it will not support life
or aid combustion and it does not combine easily with other elements. Nitrogen
in the air is inert in the free state. For diving, nitrogen may be used to dilute
oxygen. Nitrogen is not the only gas that can be used for this purpose and under
some conditions it has severe disadvantages as compared to other gases. Nitrogen
narcosis, a disorder resulting from the anesthetic properties of nitrogen breathed
under pressure, can result in a loss of orientation and judgment by the diver. For
this reason, compressed air, with its high nitrogen content, is not used below a
specified depth in diving operations.

2-10.4

Helium. Helium (He) is a colorless, odorless, and tasteless gas, but it is monatomic

(exists as a single atom in its free state). It is totally inert. Helium is a rare element,
found in air only as a trace element of about 5 parts per million (ppm). Helium
coexists with natural gas in certain wells in the southwestern United States,
Canada, and Russia. These wells provide the world’s supply. When used in diving
to dilute oxygen in the breathing mixture, helium does not cause the same problems
associ­ated with nitrogen narcosis, but it does have unique disadvantages. Among
these is the distortion of speech which takes place in a helium atmosphere. The
“Donald Duck” effect is caused by the acoustic properties of helium and it impairs
voice communications in deep diving. Another negative characteristic of helium is
its high thermal conductivity which can cause rapid loss of body and respiratory
heat.
2-10.5

Hydrogen. Hydrogen (H2) is diatomic, colorless, odorless, and tasteless, and is so

active that it is rarely found in a free state on earth. It is, however, the most abundant
element in the visible universe. The sun and stars are almost pure hydrogen. Pure
hydrogen is violently explosive when mixed with air in proportions that include
a presence of more than 5.3 percent oxygen. Hydrogen has been used in diving
(replacing nitrogen for the same reasons as helium) but the hazards have limited
this to little more than experimentation.
2-10.6

Neon. Neon (Ne) is inert, monatomic, colorless, odorless, and tasteless, and is

found in minute quantities in the atmosphere. It is a heavy gas and does not exhibit
the narcotic properties of nitrogen when used as a breathing medium. Because
it does not cause the speech distortion problem associated with helium and has

CHAPTER 2­ — Underwater Physics	

2-15

superior thermal insulating properties, it has been the subject of some experimental
diving research.
2-10.7

Carbon Dioxide. Carbon dioxide (CO2) is colorless, odorless, and tasteless when

found in small percentages in the air. In greater concentrations it has an acid taste
and odor. Carbon dioxide is a natural by-product of animal and human respiration,
and is formed by the oxidation of carbon in food to produce energy. For divers,
the two major concerns with carbon dioxide are control of the quantity in the
breathing supply and removal of the exhaust after breathing. Carbon dioxide
can cause unconsciousness when breathed at increased partial pressure. In high
concentra­tions the gas can be extremely toxic. In the case of closed and semiclosed
breathing apparatus, the removal of excess carbon dioxide generated by breathing
is essential to safety.
2-10.8

Carbon Monoxide. Carbon monoxide (CO) is a colorless, odorless, tasteless,

and poisonous gas whose presence is difficult to detect. Carbon monoxide is
formed as a product of incomplete fuel combustion, and is most commonly
found in the exhaust of internal combustion engines. A diver’s air supply can be
contaminated by carbon monoxide when the compressor intake is placed too close
to the compressor’s engine exhaust. The exhaust gases are sucked in with the air
and sent on to the diver, with potentially disastrous results. Carbon monoxide
seriously interferes with the blood’s ability to carry the oxygen required for the
body to function normally. The affinity of carbon monoxide for hemoglobin is
approximately 210 times that of oxygen. Carbon monoxide dissociates from
hemoglobin at a much slower rate than oxygen.

2-10.9

Kinetic Theory of Gases. On the surface of the earth the constancy of the

atmosphere’s pressure and compo­sition tend to be accepted without concern. To the
diver, however, the nature of the high pressure or hyperbaric, gaseous environment
assumes great importance. The basic explanation of the behavior of gases under all
variations of temperature and pressure is known as the kinetic theory of gases.

The kinetic theory of gases states: “The kinetic energy of any gas at a given tem­
perature is the same as the kinetic energy of any other gas at the same tempera­ture.”
Consequently, the measurable pressures of all gases resulting from kinetic activity
are affected by the same factors.
The kinetic energy of a gas is related to the speed at which the molecules are
mov­ing and the mass of the gas. Speed is a function of temperature and mass is a
function of gas type. At a given temperature, molecules of heavier gases move at a
slower speed than those of lighter gases, but their combination of mass and speed
results in the same kinetic energy level and impact force. The measured impact
force, or pressure, is representative of the kinetic energy of the gas. This is illus­
trated in Figure 2‑6.

2-16

U.S. Navy Diving Manual — Volume 1

(a)

(b)

(c)

HEAT

Figure 2‑6. Kinetic Energy. The kinetic energy of the molecules inside the container (a) produces a constant
pressure on the internal surfaces. As the container volume is decreased (b), the molecules per unit volume
(density) increase and so does the pressure. As the energy level of the molecules increases from the addition
of thermal energy (heat), so does the pressure (c).

2-11

GAS LAWS

Gases are subject to three closely interrelated factors—temperature, pressure,
and volume. As the kinetic theory of gases points out, a change in one of these
factors must result in some measurable change in the other factors. Further, the
theory indicates that the kinetic behavior of any one gas is the same for all gases or
mixtures of gases. Consequently, basic laws have been established to help predict
the changes that will be reflected in one factor as the conditions of one or both of
the other factors change. A diver needs to know how changing pressure will effect
the air in his suit and lungs as he moves up and down in the water. He must be able
to determine whether an air compressor can deliver an adequate supply of air to a
proposed operating depth. He also needs to be able to interpret the reading on the
pressure gauge of his tanks under varying conditions of temperature and pressure.
The answers to such questions are calculated using a set of rules called the gas
laws. This section explains the gas laws of direct concern to divers.
2-11.1

Boyle’s Law. Boyle’s law states that at constant temperature, the absolute pressure

and the volume of gas are inversely proportional. As pressure increases the gas
volume is reduced; as the pressure is reduced the gas volume increases. Boyle’s
law is important to divers because it relates to change in the volume of a gas caused
by the change in pressure, due to depth, which defines the relationship of pressure
and volume in breathing gas supplies.

The formula for Boyle’s law is: C = P × V
Where:
C
=
P
=
V
=

a constant
absolute pressure
volume

CHAPTER 2­ — Underwater Physics	

2-17

Boyle’s law can also be expressed as: P1V1 = P2V2
Where:
P1 =
V1 =
P2 =
V2 =

initial pressure
initial volume
final pressure
final volume

When working with Boyle’s law, pressure may be measured in atmospheres abso­
lute. To calculate pressure using atmospheres absolute:
psig + 14.7 psi
Depth fsw + 33 fsw
Pata =
Pata =
or
14.7 psi
33 fsw
Sample Problem 1. An open diving bell with a volume of 24 cubic feet is to be
lowered into the sea from a support craft. No air is supplied to or lost from the bell.
Calculate the volume of the air in the bell at 99 fsw.
1. Rearrange the formula for Boyle’s law to find the final volume (V2):

V2 =

P1V1
P2

2. Calculate the final pressure (P2) at 99 fsw:

99 fsw + 33 fsw
33 fsw
= 4 ata

P2 =

3. Substitute known values to find the final volume:

1ata × 24 ft 3
4 ata
3
= 6 ft

V2 =

The volume of air in the open bell has been compressed to 6 ft3 at 99 fsw.
2-11.2

Charles’/Gay-Lussac’s Law. When working with Boyle’s law, the temperature

of the gas is a constant value. However, temperature significantly affects the
pressure and volume of a gas. Charles’/Gay-Lussac’s law describes the physical
relationships of temperature upon volume and pressure. Charles’/Gay-Lussac’s
law states that at a constant pressure, the volume of a gas is directly proportional
to the change in the absolute temperature. If the pressure is kept constant and
the absolute temperature is doubled, the volume will double. If the temperature
decreases, volume decreases. If volume instead of pressure is kept constant (i.e.,
heating in a rigid container), then the absolute pressure will change in proportion
to the absolute temperature.

2-18

U.S. Navy Diving Manual — Volume 1

The formulas for expressing Charles’/Gay-Lussac’s law are as follows.
For the relationship between volume and temperature:

V1 V2
=
T1 T2
Where:
T1 =
T2 =
V1 =
V2 =

Pressure is constant
initial temperature (absolute)
final temperature (absolute)
initial volume
final volume

And, for the relationship between pressure and temperature:

P1 P2
=
T1 T2
Where:
P1 =
P2 =
T1 =
T2 =

Volume is constant
initial pressure (absolute)
final pressure (absolute)
initial temperature (absolute)
final temperature (absolute)

Sample Problem 1. An open diving bell of 24 cubic feet capacity is lowered into

the ocean to a depth of 99 fsw. The surface temperature is 80°F, and the temperature
at depth is 45°F. From the sample problem illustrating Boyle’s law, we know that
the volume of the gas was compressed to 6 cubic feet when the bell was lowered
to 99 fsw. Apply Charles’/Gay-Lussac’s law to determine the volume when it is
effected by temperature.
1. Convert Fahrenheit temperatures to absolute temperatures (Rankine):

°R = °F + 460
T1 = 80°F + 460
= 540°R
T2 = 45°F + 460
= 505°R
2. Transpose the formula for Charles’/Gay-Lussac’s law to solve for the final volume

(V2):

V2 =

V1T2
T1

CHAPTER 2­ — Underwater Physics	

2-19

3. Substitute known values to solve for the final volume (V2):

6 ft.3 × 505
V2 =
540
= 5.61 ft.3
The volume of the gas at 99 fsw is 5.61 ft3.
Sample Problem 2. A 6-cubic-foot flask is charged to 3000 psig and the temperature
in the flask room is 72° F. A fire in an adjoining space causes the temperature in the
flask room to reach 170° F. What will happen to the pressure in the flask?
1. Convert gauge pressure unit to atmospheric pressure unit:

P1 =
=

3000 psig + 14.7 psi
3014.7 psia

2. Convert Fahrenheit temperatures to absolute temperatures (Rankine):

°R =

°F + 460

T1 =

72°F + 460

=
T2 =
=

532°R
170°F + 460
630°R

3. Transpose the formula for Gay-Lussac’s law to solve for the final pressure (P2):

P2 =

P1T2
T1

4. Substitute known values and solve for the final pressure (P2):

3014.7 × 630
532
1, 899, 261
=
532
= 3570.03 psia − 14 .7
= 3555.33 psig

P2 =

2-20

U.S. Navy Diving Manual — Volume 1

The pressure in the flask increased from 3000 psig to 3555.33 psig. Note that
the pressure increased even though the flask’s volume and the volume of the gas
remained the same.
This example also shows what would happen to a SCUBA cylinder that was filled
to capacity and left unattended in the trunk of an automobile or lying in direct
sunlight on a hot day.
2-11.3

The General Gas Law. Boyle, Charles, and Gay-Lussac demonstrated that

temperature, volume, and pres­sure affect a gas in such a way that a change in one
factor must be balanced by corresponding change in one or both of the others.
Boyle’s law describes the rela­tionship between pressure and volume, Charles’/
Gay-Lussac’s law describes the relationship between temperature and volume and
the relationship between temperature and pressure. The general gas law combines
the laws to predict the behavior of a given quantity of gas when any of the factors
change.
P1V1 P2 V2
The formula for expressing the general gas law is: T = T
1
2
Where:
P1
=
V1 =
T1 =
P2
=
V2 =
T2 =

initial pressure (absolute)
initial volume
initial temperature (absolute)
final pressure (absolute)
final volume
final temperature (absolute)

Two simple rules must be kept in mind when working with the general gas law:
 There can be only one unknown value.
 The equation can be simplified if it is known that a value remains unchanged
(such as the volume of an air cylinder) or that the change in one of the variables
is of little consequence. In either case, cancel the value out of both sides of the
equation to simplify the computations.
Sample Problem 1. Your ship has been assigned to salvage a sunken LCM landing

craft located in 130 fsw. An exploratory dive, using SCUBA, is planned to survey
the wreckage. The SCUBA cylinders are charged to 2,250 psig, which raises the
temperature in the tanks to 140 °F. From experience in these waters, you know
that the temperature at the operating depth will be about 40°F. Apply the general
gas law to find what the gauge reading will be when you first reach the bottom.
(Assume no loss of air due to breathing.)
1. Simplify the equation by eliminating the variables that will not change. The volume

of the tank will not change, so V1 and V2 can be eliminated from the formula in this
problem:

CHAPTER 2­ — Underwater Physics	

2-21

P1 P2
=
T1 T2
2. Calculate the initial pressure by converting the gauge pressure unit to the

atmospheric pressure unit:
P1 =
=

2,250 psig + 14.7
2,264.7 psia

3. Convert Fahrenheit temperatures to Rankine (absolute) temperatures:

Conversion formula: °R = °F + 460
T1 =
=
T2 =
=

140° F + 460
600° R
40° F + 460
500° R

4. Rearrange the formula to solve for the final pressure (P2):

P2 =

P1T2
T1

5. Fill in known values:

2,264.7 psia × 500°R
600°R
= 1887.25 psia

P2 =

6. Convert final pressure (P2) to gauge pressure:

P2 = 1,887.25 psia − 14.7
= 1, 872.55 psia
The gauge reading when you reach bottom will be 1,872.55 psig.
Sample Problem 2. During the survey dive for the operation outlined in Sample
Problem 1, the divers determined that the damage will require a simple patch. The
Diving Supervisor elects to use surface-supplied MK 21 equipment. The compressor
discharge capacity is 60 cubic feet per minute, and the air temperature on the deck
of the ship is 80°F.

2-22

U.S. Navy Diving Manual — Volume 1

Apply the general gas law to determine whether the compressor can deliver the
proper volume of air to both the working diver and the standby diver at the oper­
ating depth and temperature.
1. Calculate the absolute pressure at depth (P2):

130 fsw + 33 fsw
33 fsw
= 4.93 ata

P2 =

2. Convert Fahrenheit temperatures to Rankine (absolute) temperatures:

Conversion formula:
°R =

°F + 460

T1 =

80°F + 460

=
T2 =
=

540°R
40°F + 460
500°R

3. Rearrange the general gas law formula to solve for the volume of air at depth

(V2):

V2 =

P1V1T2
P2 T1

4. Substitute known values and solve:

1 ata × 60 cfm × 500°R
4.93 ata × 540°R
= 11.26 acfm at bottom conditions

V2 =

Based upon an actual volume (displacement) flow requirement of 1.4 acfm for a
deep-sea diver, the compressor capacity is sufficient to support the working and
standby divers at 130 fsw.
Sample Problem 3. Find the actual cubic feet of air contained in a 700-cubic inch

internal volume cylinder pressurized to 3,000 psi.

1. Simplify the equation by eliminating the variables that will not change. The

temperature of the tank will not change so T1 and T2 can be eliminated from the
formula in this problem:

P1V1 = P2V2

CHAPTER 2­ — Underwater Physics	

2-23

2. Rearrange the formula to solve for the initial volume:

V1 =

P2 V2
P1

Where:
P1 =

14.7 psi

P2 =

3,000 psi + 14.7 psi

V2 =

700 in3

3. Fill in the known values and solve for V1:

V1 =

3014.7 psia × 700 in 3
14.7 psi

= 143, 557.14 in 3
4. Convert V1 to cubic feet:

143,557.14 in 3
3
3
(1728 in = 1 ft )
1728 in 3
= 83.07 scf

V1 =

2-12

GAS MIXTURES

If a diver used only one gas for all underwater work, at all depths, then the general
gas law would suffice for most of his necessary calculations. However, to accom­
modate use of a single gas, oxygen would have to be chosen because it is the only
one that provides life support. But 100 percent oxygen can be dangerous to a diver
as depth and breathing time increase. Divers usually breathe gases in a mixture,
either air (21 percent oxygen, 78 percent nitrogen, 1 percent other gases) or oxygen
with one of the inert gases serving as a diluent for the oxygen. The human body has
a wide range of reactions to various gases under different conditions of pressure
and for this reason another gas law is required to help compute the differ­ences
between breathing at the surface and breathing under pressure.
2-12.1

Dalton’s Law. Dalton’s law states: “The total pressure exerted by a mixture of

gases is equal to the sum of the pressures of each of the different gases making up
the mixture, with each gas acting as if it alone was present and occupied the total
volume.”
In a gas mixture, the portion of the total pressure contributed by a single gas is
called the partial pressure (pp) of that gas. An easily understood example is that of a
container at atmospheric pressure (14.7 psi). If the container were filled with oxygen
alone, the partial pressure of the oxygen would be one atmosphere. If the same

2-24

U.S. Navy Diving Manual — Volume 1

container at 1 atm were filled with dry air, the partial pressures of all the constituent
gases would contribute to the total partial pressure, as shown in Table 2‑3.
If the same container was filled with air to 2,000 psi (137 ata), the partial pressures of
the various components would reflect the increased pressure in the same proportion
as their percentage of the gas, as illustrated in Table 2‑4.
Table 2‑3. Partial Pressure at 1 ata.
Gas

Percent of Component

Atmospheres Partial Pressure

N2

78.08

0.7808

O2

20.95

0.2095

CO2

.03

0.0003

Other

.94

0.0094

Total

100.00

1.0000

Table 2‑4. Partial Pressure at 137 ata.
Gas

Percent of Component

Atmospheres Partial Pressure

N2

78.08

106.97

O2

20.95

28.70

CO2

.03

0.04

Other

.94

1.29

Total

100.00

137.00

The formula for expressing Dalton’s law is:

PTotal = pp A + pp B + pp C + …
Where: A, B, and C are gases and

pp A =

PTotal × %VolA
1.00

Another method of arriving at the same conclusion is to use the T formula. When
using the T formula, there can be only one unknown value. Then it is merely a
case of multiplying across, or dividing up to solve for the unknown value. The T
formula is illustrated as:

partial pressure
atmosphere(s) absolute  % volume (in decimal form)

CHAPTER 2­ — Underwater Physics	

2-25

Sample Problem 1. Use the T formula to calculate oxygen partial pressure given

10 ata and 16 percent oxygen.
1. Fill in the known values:

pp
10  .16
2. Multiply the pressure by the volume to solve for the oxygen partial pressure (pp):

1.6 ppO 2
10  .16
The oxygen partial pressure is 1.6.
Sample Problem 2. What happens to the breathing mixture at the operating depth

of 130 fsw (4.93 ata)? The air compressor on the ship is taking in air at the surface,
at normal pressure and normal mixture, and sending it to the diver at pressure
sufficient to provide the necessary balance. The composition of air is not changed,
but the quantity being delivered to the diver is five times what he was breathing
on the surface. More molecules of oxygen, nitrogen, and carbon dioxide are all
compressed into the same volume at the higher pressure. Use Dalton’s law to
determine the partial pressures at depth.

1. Calculate the oxygen partial pressure at depth.

ppO2

=

.21 (surface) × 4.93 ata

=

1.03 ata

2. Calculate the nitrogen partial pressure at depth.

ppN2

=

.79 (surface) × 4.93 ata

=

3.89 ata

3. Calculate the carbon dioxide partial pressure at depth.

ppCO2 =
=
2‑12.1.1

.0003 (surface) × 4.93 ata
.0014 ata

Expressing Small Quantities of Pressure. Expressing partial pressures of gases

in atmospheres absolute (ata) is the most common method employed in large
quantities of pressure. Partial pressures of less than 0.1 atmosphere are usually
expressed in millimeters of mercury (mmHg). At the surface, atmospheric pressure
is equal to 1 ata or 14.7 psia or 760 mmHg. The formula used to calculate the
ppCO2 at 130 fsw in millimeters of mercury is:

2-26

U.S. Navy Diving Manual — Volume 1

760mmHg
0.03
× 4.93 ata ×
100
1 ata
= 1.12mmHg

ppCO 2 =

2‑12.1.2

Calculating Surface Equivalent Value. From the previous calculations, it is

apparent that the diver is breathing more molecules of oxygen breathing air at
130 fsw than he would be if using 100 percent oxygen at the surface. He is also
inspiring five times as many carbon dioxide molecules as he would breathing
normal air on the surface. If the surface air were contaminated with 2 percent
(0.02 ata) carbon dioxide, a level that could be readily accommodated by a normal
person at one ata, the partial pressure at depth would be dangerously high—0.0986
ata (0.02 x 4.93 ata). This partial pres­sure is commonly referred to as a surface
equivalent value (sev) of 10 percent carbon dioxide. The formula for calculating
the surface equivalent value is:

pp at depth (in ata) × 100%
1 ata
0.0986 ata
=
× 100%
1 ata
= 9.86% CO 2

sev =

2-12.2

Gas Diffusion. Another physical effect of partial pressures and kinetic activity is

that of gas diffu­sion. Gas diffusion is the process of intermingling or mixing of gas
molecules. If two gases are placed together in a container, they will eventually mix
completely even though one gas may be heavier. The mixing occurs as a result of
constant molecular motion.
An individual gas will move through a permeable membrane (a solid that permits
molecular transmission) depending upon the partial pressure of the gas on each side
of the membrane. If the partial pressure is higher on one side, the gas mole­cules
will diffuse through the membrane from the higher to the lower partial pressure
side until the partial pressure on sides of the membrane are equal. Mole­cules are
actually passing through the membrane at all times in both directions due to kinetic
activity, but more will move from the side of higher concentration to the side of
lower concentration.
Body tissues are permeable membranes. The rate of gas diffusion, which is related
to the difference in partial pressures, is an important consideration in determining
the uptake and elimination of gases in calculating decompression tables.
2-12.3

Humidity. Humidity is the amount of water vapor in gaseous atmospheres. Like
other gases, water vapor behaves in accordance with the gas laws. However,
unlike other gases encountered in diving, water vapor condenses to its liquid state
at temperatures normally encountered by man.

Humidity is related to the vapor pressure of water, and the maximum partial pres­
sure of water vapor in the gas is governed entirely by the temperature of the gas.

CHAPTER 2­ — Underwater Physics	

2-27

As the gas temperature increases, more molecules of water can be maintained in
the gas until a new equilibrium condition and higher maximum partial pressure are
established. As a gas cools, water vapor in the gas condenses until a lower partial
pressure condition exists regardless of the total pressure of the gas. The tempera­
ture at which a gas is saturated with water vapor is called the dewpoint.
In proper concentrations, water vapor in a diver’s breathing gas can be beneficial to
the diver. Water vapor moistens body tissues, thus keeping the diver comfort­able.
As a condensing liquid, however, water vapor can freeze and block air passageways
in hoses and equipment, fog a diver’s faceplate, and corrode his equipment.
2-12.4

Gases in Liquids. When a gas comes in contact with a liquid, a portion of the gas
molecules enters into solution with the liquid. The gas is said to be dissolved in
the liquid. Solubility is vitally important because significant amounts of gases are
dissolved in body tissues at the pressures encountered in diving.

2-12.5

Solubility. Some gases are more soluble (capable of being dissolved) than others,

and some liquids and substances are better solvents (capable of dissolving another
substance) than others. For example, nitrogen is five times more soluble in fat than
it is in water.
Apart from the individual characteristics of the various gases and liquids, tempera­
ture and pressure greatly affect the quantity of gas that will be absorbed. Because a
diver is always operating under unusual conditions of pressure, understanding this
factor is particularly important.
2-12.6

Henry’s Law. Henry’s law states: “The amount of any given gas that will dissolve

in a liquid at a given temperature is directly proportional to the partial pressure of
that gas.” Because a large percentage of the human body is water, the law simply
states that as one dives deeper and deeper, more gas will dissolve in the body
tissues and that upon ascent, the dissolved gas must be released.
2‑12.6.1

Gas Tension. When a gas-free liquid is first exposed to a gas, quantities of gas

molecules rush to enter the solution, pushed along by the partial pressure of the
gas. As the mole­cules enter the liquid, they add to a state of gas tension. Gas
tension is a way of identifying the partial pressure of that gas in the liquid.
The difference between the gas tension and the partial pressure of the gas outside
the liquid is called the pressure gradient. The pressure gradient indicates the rate at
which the gas enters or leaves the solution.
2‑12.6.2

2-28

Gas Absorption. At sea level, the body tissues are equilibrated with dissolved
nitrogen at a partial pressure equal to the partial pressure of nitrogen in the lungs.
Upon exposure to altitude or increased pressure in diving, the partial pressure of
nitrogen in the lungs changes and tissues either lose or gain nitrogen to reach a
new equilibrium with the nitrogen pressure in the lungs. Taking up nitrogen in
tissues is called absorp­tion or uptake. Giving up nitrogen from tissues is termed
elimination or offgassing. In air diving, nitrogen absorption occurs when a diver

U.S. Navy Diving Manual — Volume 1

is exposed to an increased nitrogen partial pressure. As pressure decreases, the
nitrogen is elimi­nated. This is true for any inert gas breathed.
Absorption consists of several phases, including transfer of inert gas from the lungs
to the blood and then from the blood to the various tissues as it flows through the
body. The gradient for gas transfer is the partial pressure difference of the gas
between the lungs and blood and between the blood and the tissues.
The volume of blood flowing through tissues is small compared to the mass of the
tissue, but over a period of time the gas delivered to the tissue causes it to become
equilibrated with the gas carried in the blood. As the number of gas molecules
in the liquid increases, the tension increases until it reaches a value equal to the
partial pressure. When the tension equals the partial pressure, the liquid is satu­rated
with the gas and the pressure gradient is zero. Unless the temperature or pressure
changes, the only molecules of gas to enter or leave the liquid are those which may,
in random fashion, change places without altering the balance.
The rate of equilibration with the blood gas depends upon the volume of blood
flow and the respective capacities of blood and tissues to absorb dissolved gas. For
example, fatty tissues hold significantly more gas than watery tissues and will thus
take longer to absorb or eliminate excess inert gas.
2‑12.6.3

Gas Solubility. The solubility of gases is affected by temperature—the lower the

temperature, the higher the solubility. As the temperature of a solution increases,
some of the dissolved gas leaves the solution. The bubbles rising in a pan of water
being heated (long before it boils) are bubbles of dissolved gas coming out of
solution.

The gases in a diver’s breathing mixture are dissolved into his body in proportion
to the partial pressure of each gas in the mixture. Because of the varied solubility
of different gases, the quantity of a particular gas that becomes dissolved is also
governed by the length of time the diver is breathing the gas at the increased pres­
sure. If the diver breathes the gas long enough, his body will become saturated.
The dissolved gas in a diver’s body, regardless of quantity, depth, or pressure,
remains in solution as long as the pressure is maintained. However, as the diver
ascends, more and more of the dissolved gas comes out of solution. If his ascent
rate is controlled (i.e., through the use of the decompression tables), the dissolved
gas is carried to the lungs and exhaled before it accumulates to form significant
bubbles in the tissues. If, on the other hand, he ascends suddenly and the pressure
is reduced at a rate higher than the body can accommodate, bubbles may form,
disrupt body tissues and systems, and produce decompression sickness.

CHAPTER 2­ — Underwater Physics	

2-29

Table 2‑5. Symbols and Values.
Symbol
°F

Degrees Fahrenheit

°C

Degrees Celsius

°R

Degrees Rankine

A

Area

C

Circumference

D

Depth of Water

H

Height

L

Length

P

Pressure

r

Radius

T

Temperature

t

Time

V

Volume

W

Width

Dia

Diameter

Dia

2

Diameter Squared

Dia

3

Diameter Cubed

�

3.1416

ata

Atmospheres Absolute

pp

Partial Pressure

psi

Pounds per Square Inch

psig

Pounds per Square Inch Gauge

psia

Pounds per Square Inch Absolute

fsw

Feet of Sea Water

fpm

Feet per Minute

scf

Standard Cubic Feet

BTU

British Thermal Unit

cm

3

kw hr
mb

2-30

Value

Cubic Centimeter
Kilowatt Hour
Millibars

U.S. Navy Diving Manual — Volume 1

Table 2‑6. Buoyancy (In Pounds).
Fresh Water

(V cu ft x 62.4) - Weight of Unit

Salt Water

(V cu ft x 64) - Weight of Unit

Table 2‑7. Formulas for Area.
Square or Rectangle

A=LxW

Circle

A = 0.7854 x Dia2
or
A = πr2

Table 2‑8. Formulas for Volumes.
Compartment

V=LxWxH

Sphere

= π x 4/3 x r 3
= 0.5236 x Dia3

Cylinder

V=πxr2xL
= π x 1/4 x Dia2 x L
= 0.7854 x Dia2 x L

Table 2‑9. Formulas for Partial Pressure/Equivalent Air Depth.
Partial Pressure Measured in psi

 %V 
pp = (D + 33 fsw) × 0.445 psi × 

 100% 

Partial Pressure Measured in ata

pp =

Partial Pressure Measured in fsw

pp = (D + 33 fsw) ×

T formula for Measuring Partial Pressure

pp
ata  %

Equivalent Air Depth for N2O2 Diving Measured in fsw

 (1.0 − O2 %)(D + 33) 
EAD = 
 − 33
.79



Equivalent Air Depth for N2O2 Diving Measured in meters

 (1.0 − O2 %)(M + 10) 
EAD = 
 − 10
.79



CHAPTER 2­ — Underwater Physics	

D + 33 fsw
%V
×
33 fsw
100%
%V
100%

2-31

Table 2‑10. Pressure Equivalents.
Columns of Mercury
at 0°C
Atmospheres

Bars

10 Newton Pounds
Per Square Per Square
Meters
Centimeter Inch

Columns of Water*
at 15°C

Inches

Meters

Inches

Feet
(FW)

Feet
(FSW)

1

1.01325

1.03323

14.696

0.76

29.9212

10.337

406.966

33.9139

33.066

0.986923

1

1.01972

14.5038

0.750062

29.5299

10.2018

401.645

33.4704

32.6336

0.967841

0.980665

1

14.2234

0.735559

28.959

10.0045

393.879

32.8232

32.0026

0.068046

0.068947

0.070307

1.31579

1.33322

1.35951

0.0334211

0.0338639

0.0345316

0.491157

0.0254

1

0.345473

13.6013

1.13344

1.1051

0.09674

0.09798

0.099955

1.42169

0.073523

2.89458

1

39.37

3.28083

3.19881

0.002456

0.002489

0.002538

0.03609

0.001867

0.073523

0.02540

1

0.08333

0.08125

0.029487

0.029877

0.030466

0.43333

0.02241

0.882271

0.304801

12

1

0.975

0.030242

0.030643

0.031247

0.44444

0.022984

0.904884

0.312616

12.3077

1.02564

1

1

0.0517147

19.33369

1

2.03601
39.37

0.703386
13.6013

27.6923
535.482

2.30769

2.25

44.6235

43.5079

1.  Fresh Water (FW) = 62.4 lbs/ft3; Salt Water (fsw) = 64.0 lbs/ft3.
2.  The SI unit for pressure is Kilopascal (KPA)—1KG/CM2 = 98.0665 KPA and by definition 1 BAR = 100.00 KPA @ 4ºC.
3. In the metric system, 10 MSW is defined as 1 BAR. Note that pressure conversion from MSW to FSW is different than length
conversion; i.e., 10 MSW = 32.6336 FSW and 10 M = 32.8083 feet.

Table 2‑11. Volume and Capacity Equivalents.
Cubic
Centimeters

Cubic
Inches

Cubic
Feet

1

.061023

3.531 x 10-5
10-4

Cubic
Yards

Milliliters

Liters

Pint

Quart

Gallon

1.3097 x 10-6

.999972

9.9997 x 10-4

2.113 x 10-3

1.0567 x 10-3

2.6417x 10-4

10-5

16.3867

0.0163867

0.034632

0.017316

4.329 x 10-3

16.3872

1

5.787 x

28317

1728

1

0.037037

28316.2

28.3162

59.8442

29.9221

7.48052

764559

46656

27

1

764538

764.538

1615.79

807.896

201.974

1.00003

0.0610251

3.5315 x 10-5

1.308 x 10-6

1

0.001

2.1134 x 10-3

1.0567 x 10-3

2.6418 x 10-4

1.05671

0.264178

1000.03

61.0251

0.0353154

2.1434 x

1.308 x

10-3

1000

1

2.11342

10-4

473.179

28.875

0.0167101

6.1889 x

473.166

0.473166

1

0.5

0.125

946.359

57.75

0.0334201

1.2378 x 10-3

946.332

0.946332

2

1

0.25

3785.43

231

0.133681

49511 x 10-3

3785.33

3.78533

8

4

1

2-32

U.S. Navy Diving Manual — Volume 1

Table 2‑12. Length Equivalents.
Centimeters

Inches

Feet

Yards

Meters

Fathom

Kilometers

Miles

Int. Nautical
Miles

1

0.3937

0.032808

0.010936

0.01

5.468 x 10-3

0.00001

6.2137 x 10-5

5.3659 x 10-6

2.54001

1

0.08333

0.027778

0.025400

0.013889

2.540 x 10-5

1.5783 x 10-5

1.3706 x 10-5

10-4

1.6447 x 10-4

10-4

30.4801

12

1

0.33333

0.304801

0.166665

3.0480 x

1.8939 x

91.4403

36

3

1

0.914403

0.5

9.144 x 10-4

5.6818 x 10-4

4.9341 x 10-4

100

39.37

3.28083

1.09361

1

0.5468

0.001

6.2137 x 10-4

5.3959 x 10-4

182.882

72

6

2

1.82882

1

1.8288 x 10-3

1.1364 x 10-3

9.8682 x 10-4

100000

39370

3280.83

1093.61

1000

546.8

1

0.62137

0.539593

160935

63360

5280

1760

1609.35

80

1.60935

1

0.868393

185325

72962.4

6080.4

2026.73

1853.25

1013.36

1.85325

1.15155

1

Table 2‑13. Area Equivalents.
Square
Meters

Square
Centimeters

Square
Inches

Square
Feet

1

10000

1550

10.7639

Square
Yards

2.471 x 10-4

1.19599
10-3

10-4

3.861 x 10-11

1

0.155

1.0764 x

6.4516 x 10-4

6.45163

1

6.944 x 10-3

7.716 x 10-4

1.594 x 10-7

2.491 x 10-10

0.092903

929.034

144

1

0.11111

2.2957 x 10-5

3.578 x 10-8

0.836131

8361.31

9

1

2.0661 x 10-4

3.2283 x 10-7

43560

4840

1

1.5625 x 10-3

2.7878 x 107

3.0976 x 106

640

1

1296

4046.87

4.0469 x

2.59 x 106

2.59 x 1010

6.2726 x

106

4.0145 x 109

2.471 x

3.861 x 10-7

10-8

0.0001

107

1.196 x

Square
Miles

Acres

Table 2‑14. Velocity Equivalents.
Centimeters
Per Second

Meters
Per Second

Meters
Per Minute

Kilometers
Per Hour

Feet
Per Second

Feet
Per Minute

Miles
Per Hour

Knots

1

0.01

0.6

0.036

0.0328083

1.9685

0.0223639

0.0194673

100

1

60

3.6

3.28083

196.85

2.23693

1.9473

1.66667

0.016667

1

0.06

0.0546806

3.28083

0.0372822

0.0324455

27.778

0.27778

16.667

1

0.911343

54.6806

0.62137

0.540758

30.4801

0.304801

18.288

1.09728

1

60

0.681818

0.593365

0.5080

5.080 x 10-3

0.304801

0.018288

0.016667

1

0.0113636

9.8894 x 10-3

44.7041

0.447041

26.8225

1.60935

1.4667

88

1

0.870268

51.3682

0.513682

30.8209

1.84926

1.6853

101.118

1.14907

1

CHAPTER 2­ — Underwater Physics	

2-33

Table 2‑15. Mass Equivalents.
Kilograms

Grams

Grains

Ounces

Pounds

1

1000

15432.4

35.274

2.20462

0.001
6.4799 x

1
10-5

15432.4

0.035274
10-3

2.2046 x

10-3

1.4286 x

10-4

Tons (short)

Tons (long)

Tons (metric)

1.1023 x 10-3

9.842 x 10-4

0.001

1.1023 x

10-6

10-7

7.1429 x

10-8

9.842 x

6.4799 x 10-8

0.6047989

1

2.2857 x

0.0283495

28.3495

437.5

1

0.0625

3.125 x 10-5

2.790 x 10-5

2.835 x 10-5

0.453592

453.592

7000

16

1

0.0005

4.4543 x 10-4

4.5359 x 10-4

32000

2000

1

0.892857

0.907185

35840

2240

1.12

1

1.01605

35274

2204.62

1.10231

984206

1

907.185

907185

1016.05

1.016 x

1000

106

1.4 x
106

107

1.568 x

107

1.5432 x 107

6.3776 x

0.000001

10-8

Table 2‑16. Energy or Work Equivalents.
International
Joules

Ergs

Foot Pounds

1

107

0.737682

Horse Power
Hours

Kilo Calories

BTUs

2.778 x 10-7

3.7257 10-7

2.3889 x 10-4

9.4799 x 10-4

10-7

1

7.3768 x

1.3566

1.3556 x 107

1

3.766 x 10-7

5.0505 x 10-7

3.238 x 10-4

1.285 x 10-3

3.6 x 106

3.6 x 1013

2.6557 x 106

1

1.34124

860

3412.76

2.684 x 106

2.684 x 1013

1.98 x 106

0.745578

1

641.197

2544.48

1

3.96832

0.251996

1

4186.04

4.186 x

1054.87

1010

1.0549 x

1010

10-8

International
Kilowatt
Hours

3087.97
778.155

2.778 x

10-14

1.163 x

10-3

2.930 x

10-4

3.726 x

1.596 x
3.93 x

10-14

10-3

10-4

2.389 x

10-11

9.4799 x 10-11

Table 2‑17. Power Equivalents.
Horse
Power

International
Kilowatts

International
Joules/
Second

Kg-M
Second

Foot lbs.
Per Second

IT Calories
Per Second

BTUs
Per Second

1

0.745578

745.578

76.0404

550

178.11

0.7068

1

1000

101.989

737.683

238.889

0.947989

0.001

1

0.101988

0.737682

0.238889

9.4799 x 10-4

0.0131509

9.805 x 10-3

9.80503

1

7.233

2.34231

9.2951 x 10-3

1.8182 x 10-3

1.3556 x 10-3

1.3556

0.138255

1

0.323837

1.2851 x 10-3

10-3

10-3

4.18605

0.426929

3.08797

1

3.9683 x 10-3

1054.86

107.584

778.155

251.995

1

1.34124
1.3412 x

5.6145 x
1.41483

2-34

10-3

4.1861 x
1.05486

U.S. Navy Diving Manual — Volume 1

Table 2‑18. Temperature Equivalents.
°C = (°F − 32) ×

Conversion Formulas:

5
9

9
°F = ( × °C) + 32
5

°C

°F

°C

°F

°C

°F

°C

°F

°C

°F

°C

°F

°C

°F

-100
-98
-96
-94
-92

-148.0
-144.4
-140.8
-137.2
-133.6

-60
-58
-56
-54
-52

-76.0
-72.4
-68.8
-65.2
-61.6

-20
-18
-16
-14
-12

-4.0
-0.4
3.2
6.8
10.4

20
22
24
26
28

68.0
71.6
75.2
78.8
82.4

60
62
64
66
68

140.0
143.6
147.2
150.8
154.4

100
102
104
106
108

212.0
215.6
219.2
222.8
226.4

140
142
144
146
148

284.0
287.6
291.2
294.8
298.4

-90
-88
-86
-84
-82

-130.0
-126.4
-122.8
-119.2
-115.6

-50
-48
-46
-44
-42

-58.0
-54.4
-50.8
-47.2
-43.6

-10
-8
-6
-4
-2

14.0
17.6
21.2
24.8
28.4

30
32
34
36
38

86.0
89.6
93.2
96.8
100.4

70
72
74
76
78

158.0
161.6
165.2
168.8
172.4

110
112
114
116
118

230.0
233.6
237.2
240.8
244.4

150
152
154
156
158

302.0
305.6
309.2
312.8
316.4

-80
-78
-76
-74
-72

-112.0
-108.4
-104.8
-101.2
-97.6

-40
-38
-36
-34
-32

-40.0
-36.4
-32.8
-29.2
-25.6

0
2
4
6
8

32
35.6
39.2
42.8
46.4

40
42
44
46
48

104.0
107.6
111.2
114.8
118.4

80
82
84
86
88

176.0
179.6
183.2
186.8
190.4

120
122
124
126
128

248.0
251.6
255.2
258.8
262.4

160
162
164
166
168

320.0
323.6
327.2
330.8
334.4

-70
-68
-66
-64
-62

-94.0
-90.4
-86.8
-83.2
-79.6

-30
-28
-26
-24
-22

-22.0
-18.4
-14.8
-11.2
-7.6

10
12
14
16
18

50.0
53.6
57.2
60.8
64.4

50
52
54
56
58

122.0
125.6
129.2
132.8
136.4

90
92
94
96
98

194.0
197.6
201.2
204.8
208.4

130
132
134
136
138

266.0
269.6
273.2
276.8
280.4

170
172
174
176
178

338.0
341.6
345.2
348.8
352.4

Table 2-19. Atmospheric Pressure at Altitude.
Atmospheric Pressure
Altitude
in Feet

Atmospheres
absolute

Millimeters
of Mercury

Pounds per
sq. in. absolute

Millibars

Kilopascals

500

0.982

746.4

14.43

995.1

99.51

1000

0.964

732.9

14.17

977.2

97.72

1500

0.947

719.7

13.92

959.5

95.95

2000

0.930

706.7

13.66

942.1

94.21

2500

0.913

693.8

13.42

925.0

92.50

3000

0.896

681.1

13.17

908.1

90.81

3500

0.880

668.7

12.93

891.5

89.15

4000

0.864

656.4

12.69

875.1

87.51

4500

0.848

644.3

12.46

859.0

85.90

5000

0.832

632.4

12.23

843.1

84.31

5500

0.817

620.6

12.00

827.4

82.74

6000

0.801

609.0

11.78

812.0

81.20

6500

0.786

597.7

11.56

796.8

79.68

7000

0.772

586.4

11.34

781.9

78.19

7500

0.757

575.4

11.13

767.1

76.71

8000

0.743

564.5

10.92

752.6

75.26

8500

0.729

553.8

10.71

738.3

73.83

9000

0.715

543.3

10.50

724.3

72.43

9500

0.701

532.9

10.30

710.4

71.04

10000

0.688

522.7

10.11

696.8

69.68

CHAPTER 2­ — Underwater Physics	

2-35

Depth, Pressure, Atmosphere
300

10

290
280
270

9

260
250
240

8

230
220
210

7

200
180

DEPTH
FSW

170

6

160
150
140

5

ATMOSPHERE
ABSOLUTE

190

130
120
100

4

90
80
70

3

60
50
40

2

30
20
10

1

0
0

10

20

30

40

50

60

70

80

90

100

110

120

130

PRESSURE PSIG

Figure 2‑7. Depth, Pressure, Atmosphere Graph.

2-36

U.S. Navy Diving Manual — Volume 1

CHAPTER 3

Underwater Physiology and Diving
Disorders
3-1

INTRODUCTION
3-1.1

Purpose. This chapter provides basic information on the changes in human anatomy

and physiology that occur while working in the underwater environment. It also
discusses the diving disorders that result when these anatomical or physiological
changes exceed the limits of adaptation.

3-1.2

Scope. Anatomy is the study of the structure of the organs of the body. Physiology

is the study of the processes and functions of the body. This chapter explains
the basic anatomical and physiological changes that occur when diver enters the
water and is subject to increased ambient pressure. A diver’s knowledge of these
changes is as important as his knowledge of diving gear and procedures. When the
changes in normal anatomy or physiology exceed the limits of adaptation, one or
more patho­logical states may emerge. These pathological states are called diving
disorders and are also discussed in this chapter. Safe diving is only possible when
the diver fully understands the fundamental processes at work on the human body
in the underwater environment.
3-1.3

General. A body at work requires coordinated functioning of all organs and systems.
The heart pumps blood to all parts of the body, the tissue fluids exchange dissolved
materials with the blood, and the lungs keep the blood supplied with oxygen and
cleared of excess carbon dioxide. Most of these processes are controlled directly by
the brain, nervous system, and various glands. The individual is generally unaware
that these functions are taking place.

As efficient as it is, the human body lacks effective ways of compensating for many
of the effects of increased pressure at depth and can do little to keep its internal
environment from being upset. Such external effects set definite limits on what a
diver can do and, if not understood, can give rise to serious accidents.
3-2

THE NERVOUS SYSTEM

The nervous system coordinates all body functions and activities. The nervous
system comprises the brain, spinal cord, and a complex network of nerves that
course through the body. The brain and spinal cord are collectively referred to as
the central nervous system (CNS). Nerves originating in the brain and spinal cord
and traveling to peripheral parts of the body form the peripheral nervous system
(PNS). The peripheral nervous system consists of the cranial nerves, the spinal
nerves, and the sympathetic nervous system. The peripheral nervous system is
involved in regulating cardiovascular, respiratory, and other automatic body func­
tions. These nerve trunks also transmit nerve impulses associated with sight,

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-1

hearing, balance, taste, touch, pain, and temperature between peripheral sensors
and the spinal cord and brain.
3-3

THE CIRCULATORY SYSTEM

The circulatory system consists of the heart, arteries, veins, and capillaries. The
circulatory system carries oxygen, nutrients, and hormones to every cell of the
body, and carries away carbon dioxide, waste chemicals, and heat. Blood circulates
through a closed system of tubes that includes the lung and tissue capillaries, heart,
arteries, and veins.
3-3.1

Anatomy. Every part of the body is completely interwoven with intricate networks

of extremely small blood vessels called capillaries. The very large surface areas
required for ample diffusion of gases in the lungs and tissues are provided by the
thin walls of the capillaries. In the lungs, capillaries surround the tiny air sacs
(alveoli) so that the blood they carry can exchange gases with air.
3‑3.1.1

The Heart. The heart (Figure 3‑1) is the muscular pump that propels the blood

throughout the system. It is about the size of a closed fist, hollow, and made up
almost entirely of muscle tissue that forms its walls and provides the pumping
action. The heart is located in the front and center of the chest cavity between the
lungs, directly behind the breastbone (sternum).
The interior of the heart is divided lengthwise into halves, separated by a wall of
tissue called a septum. The two halves have no direct connection to each other.
Each half is divided into an upper chamber (the atrium), which receives blood from
the veins of its circuit and a lower chamber (the ventricle) which takes blood from
the atrium and pumps it away via the main artery. Because the ventricles do most
of the pumping, they have the thickest, most muscular walls. The arteries carry
blood from the heart to the capillaries; the veins return blood from the capil­laries
to the heart. Arteries and veins branch and rebranch many times, very much like
a tree. Trunks near the heart are approximately the diameter of a human thumb,
while the smallest arterial and venous twigs are microscopic. Capillaries provide
the connections that let blood flow from the smallest branch arteries (arte­rioles)
into the smallest veins (venules).
3‑3.1.2

The Pulmonary and Systemic Circuits. The circulatory system consists of two

circuits with the same blood flowing through the body. The pulmonary circuit
serves the lung capillaries; the systemic circuit serves the tissue capillaries. Each
circuit has its own arteries and veins and its own half of the heart as a pump.
In complete circulation, blood first passes through one circuit and then the other,
going through the heart twice in each complete circuit.

3-3.2

Circulatory Function. Blood follows a continuous circuit through the human

body. Blood leaving a muscle or organ capillary has lost most of its oxygen and
is loaded with carbon dioxide. The blood flows through the body’s veins to the
main veins in the upper chest (the superior and inferior vena cava). The superior
vena cava receives blood from the upper half of the body; the inferior vena cava
receives blood from areas of the body below the diaphragm. The blood flows

3-2

U.S. Navy Diving Manual — Volume 1

Head and Upper
Extremities
Brachiocephalic Trunk
Superior Vena Cava

Left Common Carotid Artery
Left Subclavian Artery
Arch of Aorta

Right Pulmonary Artery

Left Pulmonary Artery

Right
Lung

Left
Lung
Left Pulmonary Veins

Right Pulmonary Veins

Left Atrium
Right Atrium

Left Ventricle

Right Ventricle
Inferior Vena Cava

Thoracic Aorta

Trunk and Lower
Extremities

Figure 3-1. The Heart’s Components and Blood Flow.

through the main veins into the right atrium and then through the tricuspid valve
into the right ventricle.
The next heart contraction forces the blood through the pulmonic valve into the
pulmonary artery. The blood then passes through the arterial branchings of the
lungs into the pulmonary capillaries, where gas transfer with air takes place. By
diffusion, the blood exchanges inert gas as well as carbon dioxide and oxygen with
the air in the lungs. The blood then returns to the heart via the pulmonary venous
system and enters the left atrium.
The next relaxation finds it going through the mitral valve into the left ventricle
to be pumped through the aortic valve into the main artery (aorta) of the systemic
circuit. The blood then flows through the arteries branching from the aorta,
into successively smaller vessels until reaching the capillaries, where oxygen
is exchanged for carbon dioxide. The blood is now ready for another trip to the
lungs and back again. Figure 3‑2 shows how the pulmonary circulatory system is
arranged.
The larger blood vessels are somewhat elastic and have muscular walls. They
stretch and contract as blood is pumped from the heart, maintaining a slow but
adequate flow (perfusion) through the capillaries.
3-3.3

Blood Components. The average human body contains approximately five liters

of blood. Oxygen is carried mainly in the red corpuscles (red blood cells). There
are approximately 300 million red corpuscles in an average-sized drop of blood.
CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-3

Capillaries

O2

CO2

Terminal
bronchiole
CO2

Alveoli

Artery

O2

Venules Vein

Figure 3-2. Respiration and Blood Circulation.  The lung’s gas exchange system is
essentially three pumps.  The thorax, a gas pump, moves air through the trachea and
bronchi to the lung’s air sacs. These sacs, the alveoli, are shown with and without their
covering of pulmonary capillaries. The heart’s right ventricle, a fluid pump, moves blood
that is low in oxygen and high in carbon dioxide into the pulmonary capillaries.  Oxygen
from the air diffuses into the blood while carbon dioxide diffuses from the blood into the air
in the lungs. The oxygenated blood moves to the left ventricle, another fluid pump, which
sends the blood via the arterial system to the systemic capillaries which deliver oxygen to
and collect carbon dioxide from the body’s cells.

These corpuscles are small, disc-shaped cells that contain hemoglobin to carry
oxygen. Hemoglobin is a complex chemical compound containing iron. It can
form a loose chemical combi­nation with oxygen, soaking it up almost as a sponge
soaks up liquid. Hemoglobin is bright red when it is oxygen-rich; it becomes
increasingly dark as it loses oxygen. Hemoglobin gains or loses oxygen depending
upon the partial pressure of oxygen to which it is exposed. Hemoglobin takes up
about 98 percent of the oxygen it can carry when it is exposed to the normal partial
pressure of oxygen in the lungs. Because the tissue cells are using oxygen, the
partial pressure (tension) in the tissues is much lower and the hemoglobin gives up
much of its oxygen in the tissue capillaries.
Acids form as the carbon dioxide dissolves in the blood. Buffers in the blood
neutralize the acids and permit large amounts of carbon dioxide to be carried away
to prevent excess acidity. Hemoglobin also plays an important part in transporting
carbon dioxide. The uptake or loss of carbon dioxide by blood depends mainly
upon the partial pressure (or tension) of the gas in the area where the blood is
exposed. For example, in the peripheral tissues, carbon dioxide diffuses into the
blood and oxygen diffuses into the tissues.

3-4

U.S. Navy Diving Manual — Volume 1

Blood also contains infection-fighting white blood cells, and platelets, which are
cells essential in blood coagulation. Plasma is the colorless, watery portion of the
blood. It contains a large amount of dissolved material essential to life. The blood
also contains several substances, such as fibrinogen, associated with blood clot­ting.
Without the clotting ability, even the slightest bodily injury could cause death.
3-4

THE RESPIRATORY SYSTEM

Every cell in the body must obtain energy to maintain its life, growth, and func­
tion. Cells obtain their energy from oxidation, which is a slow, controlled burning
of food materials. Oxidation requires fuel and oxygen. Respiration is the process
of exchanging oxygen and carbon dioxide during oxidation and releasing energy
and water.
3-4.1

Gas Exchange. Few body cells are close enough to the surface to have any chance

of obtaining oxygen and expelling carbon dioxide by direct air diffusion. Instead,
the gas exchange takes place via the circulating blood. The blood is exposed to
air over a large diffusing surface as it passes through the lungs. When the blood
reaches the tissues, the small capillary vessels provide another large surface where
the blood and tissue fluids are in close contact. Gases diffuse readily at both ends
of the circuit and the blood has the remarkable ability to carry both oxygen and
carbon dioxide. This system normally works so well that even the deepest cells of
the body can obtain oxygen and get rid of excess carbon dioxide almost as readily
as if they were completely surrounded by air.

If the membrane surface in the lung, where blood and air come close together,
were just an exposed sheet of tissue like the skin, natural air currents would keep
fresh air in contact with it. Actually, this lung membrane surface is many times
larger than the skin area and is folded and compressed into the small space of the
lungs that are protected inside the bony cage of the chest. This makes it necessary
to continually move air in and out of the space. The processes of breathing and the
exchange of gases in the lungs are referred to as ventilation and pulmonary gas
exchange, respectively.
3-4.2

Respiration Phases. The complete process of respiration includes six important

phases:
1. Ventilation of the lungs with fresh air
2. Exchange of gases between blood and air in lungs
3. Transport of gases by blood
4. Exchange of gases between blood and tissue fluids
5. Exchange of gases between the tissue fluids and cells
6. Use and production of gases by cells

If any one of the processes stops or is seriously hindered, the affected cells cannot
function normally or survive for any length of time. Brain tissue cells, for example,

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-5

stop working almost immediately and will either die or be permanently injured in
a few minutes if their oxygen supply is completely cut off.
The respiratory system is a complex of organs and structures that performs the
pulmonary ventilation of the body and the exchange of oxygen and carbon dioxide
between the ambient air and the blood circulating through the lungs. It also warms
the air passing into the body and assists in speech production by providing air to
the larynx and the vocal chords. The respiratory tract is divided into upper and
lower tracts.
3-4.3

Upper and Lower Respiratory Tract. The upper respiratory tract consists of the

nose, nasal cavity, frontal sinuses, maxillary sinuses, larynx, and trachea. The
upper respiratory tract carries air to and from the lungs and filters, moistens and
warms air during each inhalation.
The lower respiratory tract consists of the left and right bronchi and the lungs,
where the exchange of oxygen and carbon dioxide occurs during the respiratory
cycle. The bronchi divide into smaller bronchioles in the lungs, the bronchioles
divide into alveolar ducts, the ducts into alveolar sacs, and the sacs into alveoli. The
alveolar sacs and the alveoli present about 850 square feet of surface area for the
exchange of oxygen and carbon dioxide that occurs between the internal alve­olar
surface and the tiny capillaries surrounding the external alveolar wall.
3-4.4

The Respiratory Apparatus. The mechanics of taking fresh air into the lungs

(inspiration or inhalation) and expelling used air from the lungs (expiration or
exhalation) is diagrammed in Figure 3-3. By elevating the ribs and lowering the
diaphragm, the volume of the lung is increased. Thus, according to Boyle’s Law,
a lower pressure is created within the lungs and fresh air rushes in to equalize this
lowered pressure. When the ribs are lowered again and the diaphragm rises to its
original position, a higher pressure is created within the lungs, expelling the used
air.
3‑4.4.1

The Chest Cavity. The chest cavity does not have space between the outer lung
surfaces and the surrounding chest wall and diaphragm. Both surfaces are covered
by membranes; the visceral pleura covers the lung and the parietal pleura lines the
chest wall. These pleurae are separated from each other by a small amount of fluid
that acts as a lubri­cant to allow the membranes to slide freely over themselves as
the lungs expand and contract during respiration.

3‑4.4.2

The Lungs. The lungs are a pair of light, spongy organs in the chest and are the

main component of the respiratory system (see Figure 3‑4). The highly elastic
lungs are the main mechanism in the body for inspiring air from which oxygen is
extracted for the arte­rial blood system and for exhaling carbon dioxide dispersed
from the venous system. The lungs are composed of lobes that are smooth and
shiny on their surface. The lungs contain millions of small expandable air sacs
(alveoli) connected to air passages. These passages branch and rebranch like the

3-6

U.S. Navy Diving Manual — Volume 1

Spinal Column

First Rib
Vertebrae
Deep Inspiration

Seventh Rib
Ordinary Inspiration

Quiet Inspiration

Inspiration

Expiration

Figure 3-3. Inspiration Process. Inspiration involves both raising the rib cage (left panel) and lowering the
diaphragm (right panel). Both movements enlarge the volume of the thoracic cavity and draw air into the lung.

Apex
Upper Lobes
Pulmonary
Arteries

Horizontal
Fissure

Right Bronchus
Left Bronchus

Root

Costal
Surface
Cardiac
Notch or
Impression

Pulmonary Veins
Middle Lobe

Lower Lobes

Oblique
Fissure

Oblique
Fissure

Base

Right Lung

Left Lung

Figure 3-4. Lungs Viewed from Medical Aspect.

twigs of a tree. Air entering the main airways of the lungs gains access to the
entire surface of these alveoli. Each alveolus is lined with a thin membrane and is
surrounded by a network of very small vessels that make up the capillary bed of
the lungs. Most of the lung membrane has air on one side of it and blood on the
other; diffusion of gases takes place freely in either direction.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-7

Inspiratory
reserve
volume
Vital
capacity

Expiratory
reserve
volume

Tidal
volume

Total
lung
capacity

Residual volume
Figure 3-5. Lung Volumes. The heavy line is a tracing, derived from a subject breathing
to and from a sealed recording bellows. Following several normal tidal breaths, the subject
inhales maximally, then exhales maximally. The volume of air moved during this maximal
effort is called the vital capacity.  During exercise, the tidal volume increases, using part
of the inspiratory and expiratory reserve volumes. The tidal volume, however, can never
exceed the vital capacity. The residual volume is the amount of air remaining in the lung
after the most forceful expiration. The sum of the vital capacity and the residual volume is
the total lung capacity.

3-4.5

Respiratory Tract Ventilation Definitions. Ventilation of the respiratory system
establishes the proper composition of gases in the alveoli for exchange with the
blood. The following definitions help in understanding respiration (Figure 3-5).
Respiratory Cycle. The respiratory cycle is one complete breath consisting of an

inspiration and exhalation, including any pause between the movements.
Respiratory Rate. The number of complete respiratory cycles that take place in

1 minute is the respiratory rate. An adult at rest normally has a respiratory rate of
approximately 12 to 16 breaths per minute.
Total Lung Capacity. The total lung capacity (TLC) is the total volume of air that
the lungs can hold when filled to capacity. TLC is normally between five and six
liters.

Vital Capacity. Vital capacity is the volume of air that can be expelled from the
lungs after a full inspiration. The average vital capacity is between four and five
liters.
Tidal Volume. Tidal volume is the volume of air moved in or out of the lungs during

a single normal respiratory cycle. The tidal volume generally averages about onehalf liter for an adult at rest. Tidal volume increases considerably during physical
exertion, and may be as high as 3 liters during severe work.

3-8

U.S. Navy Diving Manual — Volume 1

Respiratory Minute Volume. The respiratory minute volume (RMV) is the total

amount of air moved in or out of the lungs in a minute. The respiratory minute
volume is calculated by multiplying the tidal volume by the respiratory rate.
RMV varies greatly with the body’s activity. It is about 6 to 10 liters per minute at
complete rest and may be over 100 liters per minute during severe work.
Maximal Breathing Capacity and Maximum Ventilatory Volume. The maximum

breathing capacity (MBC) and maximum voluntary ventilation (MVV) are the
greatest respiratory minute volumes that a person can produce during a short
period of extremely forceful breathing. In a healthy young man, they may average
as much as 180 liters per minute (the range is 140 to 240 liters per minute).
Maximum Inspiratory Flow Rate and Maximum Expiratory Flow Rate. The maxi-

mum inspiratory flow rate (MIFR) and maximum expiratory flow rate (MEFR) are
the fastest rates at which the body can move gases in and out of the lungs. These
rates are important in designing breathing equipment and computing gas use under
various workloads. Flow rates are usually expressed in liters per second.
Respiratory Quotient. Respiratory quotient (RQ) is the ratio of the amount

of carbon dioxide produced to the amount of oxygen consumed during cellular
processes per unit time. This value ranges from 0.7 to 1.0 depending on diet and
physical exertion and is usually assumed to be 0.9 for calculations. This ratio is
significant when calculating the amount of carbon dioxide produced as oxygen is
used at various workloads while using a closed-circuit breathing apparatus. The
duration of the carbon dioxide absorbent canister can then be compared to the
duration of the oxygen supply.
Respiratory Dead Space. Respiratory dead space refers to the part of the respira­
tory system that has no alveoli, and in which little or no exchange of gas between
air and blood takes place. It normally amounts to less than 0.2 liter. Air occupying
the dead space at the end of expiration is rebreathed in the following inspiration.
Parts of a diver’s breathing apparatus can add to the volume of the dead space and
thus reduce the proportion of the tidal volume that serves the purpose of respira­
tion. To compensate, the diver must increase his tidal volume. The problem can
best be visualized by using a breathing tube as an example. If the tube contains
one liter of air, a normal exhalation of about one liter will leave the tube filled with
used air from the lungs. At inhalation, the used air will be drawn right back into
the lungs. The tidal volume must be increased by more than a liter to draw in the
needed fresh supply, because any fresh air is diluted by the air in the dead space.
Thus, the air that is taken into the lungs (inspired air) is a mixture of fresh and dead
space gases.
3-4.6

Alveolar/Capillary Gas Exchange. Within the alveolar air spaces, the composition

of the air (alveolar air) is changed by the elimination of carbon dioxide from the
blood, the absorption of oxygen by the blood, and the addition of water vapor. The
air that is exhaled is a mixture of alveolar air and the inspired air that remained in
the dead space.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-9

The blood in the capillary bed of the lungs is exposed to the gas pressures of alve­
olar air through the thin membranes of the air sacs and the capillary walls. With
this exposure taking place over a vast surface area, the gas pressure of the blood
leaving the lungs is approximately equal to that present in alveolar air.
When arterial blood passes through the capillary network surrounding the cells in
the body tissues it is exposed to and equalizes with the gas pressure of the tissues.
Some of the blood’s oxygen is absorbed by the cells and carbon dioxide is picked
up from these cells. When the blood returns to the pulmonary capillaries and is
exposed to the alveolar air, the partial pressures of gases between the blood and the
alveolar air are again equalized.
Carbon dioxide diffuses from the blood into the alveolar air, lowering its partial
pressure, and oxygen is absorbed by the blood from the alveolar air, increasing its
partial pressure. With each complete round of circulation, the blood is the medium
through which this process of gas exchange occurs. Each cycle normally requires
approximately 20 seconds.
3-4.7

Breathing Control. The amount of oxygen consumed and carbon dioxide produced

increases mark­edly when a diver is working. The amount of blood pumped through
the tissues and the lungs per minute increases in proportion to the rate at which
these gases must be transported. As a result, more oxygen is taken up from the
alveolar air and more carbon dioxide is delivered to the lungs for disposal. To
maintain proper blood levels, the respiratory minute volume must also change in
proportion to oxygen consumption and carbon dioxide output.
Changes in the partial pressure (concentration) of oxygen and carbon dioxide
(ppO2 and ppCO2) in the arterial circulation activate central and peripheral
chemoreceptors. These chemoreceptors are attached to important arteries. The
most important are the carotid bodies in the neck and aortic bodies near the heart.
The chemoreceptor in the carotid artery is activated by the ppCO2 in the blood and
signals the respiratory center in the brain stem to increase or decrease respiration.
The chemoreceptor in the aorta causes the aortic body reflex. This is a normal
chemical reflex initiated by decreased oxygen concentration and increased carbon
dioxide concentration in the blood. These changes result in nerve impulses that
increase respiratory activity. Low oxygen tension alone does not increase breathing
markedly until dangerous levels are reached. The part played by chemoreceptors is
evident in normal processes such as breathholding.
As a result of the regulatory process and the adjustments they cause, the blood
leaving the lungs usually has about the same oxygen and carbon dioxide levels
during work that it did at rest. The maximum pumping capacity of the heart (blood
circulation) and respiratory system (ventilation) largely determines the amount of
work a person can do.

3-10

U.S. Navy Diving Manual — Volume 1

3-4.8

Oxygen Consumption. A diver’s oxygen consumption is an important factor

when determining how long breathing gas will last, the ventilation rates required
to maintain proper helmet oxygen level, and the length of time a canister will
absorb carbon dioxide. Oxygen consumption is a measure of energy expenditure
and is closely linked to the respi­ratory processes of ventilation and carbon dioxide
production.
Oxygen consumption is measured in liters per minute (l/min) at Standard Temper­
ature (0°C, 32°F) and Pressure (14.7 psia, 1 ata), Dry Gas (STPD). These rates of
oxygen consumption are not depth dependent. This means that a fully charged MK
16 oxygen bottle containing 360 standard liters (3.96 scf) of usable gas will last
225 minutes at an oxygen consumption rate of 1.6 liters per minute at any depth,
provided no gas leaks from the rig.
Minute ventilation, or respiratory minute volume (RMV), is measured at BTPS
(body temperature 37°C/98.6°F, ambient barometric pressure, saturated with water
vapor at body temperature) and varies depending on a person’s activity level,
as shown in Figure 3‑6. Surface RMV can be approximated by multiplying the
oxygen consumption rate by 25. Although this 25:1 ratio decreases with increasing
gas density and high inhaled oxygen concentrations, it is a good rule-of-thumb
approximation for computing how long the breathing gas will last.
Unlike oxygen consumption, the amount of gas a diver inhales is depth dependent.
At the surface, a diver swimming at 0.5 knot inhales 20 l/min of gas. A SCUBA
cylinder containing 71.2 standard cubic feet (scf) of air (approximately 2,000
stan­dard liters) lasts approximately 100 minutes. At 33 fsw, the diver still inhales
20 l/min at BTPS, but the gas is twice as dense; thus, the inhalation would be
approxi­mately 40 standard l/min and the cylinder would last only half as long, or
50 minutes. At three atmospheres, the same cylinder would last only one-third as
long as at the surface.
Carbon dioxide production depends only on the level of exertion and can be
assumed to be independent of depth. Carbon dioxide production and RQ are used
to compute ventilation rates for chambers and free-flow diving helmets. These
factors may also be used to determine whether the oxygen supply or the duration of
the CO2 absorbent will limit a diver’s time in a closed or semi-closed system.
3-5

RESPIRATORY PROBLEMS IN DIVING.

Physiological problems often occur when divers are exposed to the pressures of
depth. However, some of the difficulties related to respiratory processes can occur
at any time because of an inadequate supply of oxygen or inadequate removal of
carbon dioxide from the tissue cells. Depth may modify these problems for the
diver, but the basic difficulties remain the same. Fortunately, the diver has normal
physiological reserves to adapt to environmental changes and is only marginally
aware of small changes. The extra work of breathing reduces the diver’s ability to
do heavy work at depth, but moderate work can be done with adequate equipment
at the maximum depths currently achieved in diving.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-11

Figure 3-6. Oxygen Consumption and RMV at Different Work Rates.

3-5.1

Oxygen Deficiency (Hypoxia). Hypoxia, is an abnormal deficiency of oxygen in

the arterial blood. Severe hypoxia will impede the normal function of cells and
eventually kill them. The brain is the most vulnerable organ in the body to the
effects of hypoxia.
The partial pressure of oxygen (ppO2) determines whether the amount of oxygen
in a breathing medium is adequate. Air contains approximately 21 percent oxygen
and provides an ample ppO2 of about 0.21 ata at the surface. A drop in ppO2 below
0.16 ata causes the onset of hypoxic symptoms. Most individuals become hypoxic
to the point of helplessness at a ppO2 of 0.11 ata and unconscious at a ppO2 of 0.10
ata. Below this level, permanent brain damage and eventually death will occur. In

3-12

U.S. Navy Diving Manual — Volume 1

diving, a lower percentage of oxygen will suffice as long as the total pressure is
sufficient to maintain an adequate ppO2. For example, 5 percent oxygen gives a
ppO2 of 0.20 ata for a diver at 100 fsw. On ascent, however, the diver would rapidly
experience hypoxia if the oxygen percentage were not increased.
3‑5.1.1

3‑5.1.2

Causes of Hypoxia. The causes of hypoxia vary, but all interfere with the normal
oxygen supply to the body. For divers, interference of oxygen delivery can be
caused by:
■

Improper line up of breathing gases resulting in a low partial pressure of oxygen
in the breathing gas supply.

■

Partial or complete blockage of the fresh gas injection orifice in a semiclosedcircuit UBA. Failure of the oxygen addition valve in closed circuit rebreathers
like the MK 16.

■

Inadequate purging of breathing bags in closed-circuit oxygen rebreathers like
the MK 25.

■

Blockage of all or part of the air passages by vomitus, secretions, water, or
foreign objects.

■

Collapse of the lung due to pneumothorax.

■

Paralysis of the respiratory muscles from spinal cord injury.

■

Accumulation of fluid in the lung tissues (pulmonary edema) due to diving
in cold water while overhydrated, negative pressure breathing, inhalation of
water in a near drowning episode, or excessive accumulation of venous gas
bubbles in the lung during decompression. The latter condition is referred to
as “chokes”. Pulmonary edema causes a mismatch of alveolar ventilation and
pulmonary blood flow and decreases the rate of transfer of oxygen across the
alveolar capillary membrane.

■

Carbon monoxide poisoning. Carbon monoxide interferes with the transport of
oxygen by the hemoglobin in red blood cells and blocks oxygen utilization at
the cellular level.

■

Breathholding. During a breathhold the partial pressure of oxygen in the lung
falls progressively as the body continues to consume oxygen. If the breathhold
is long enough, hypoxia will occur.

Symptoms of Hypoxia. The symptoms of hypoxia include:
■

Loss of judgment

■

Lack of concentration

■

Lack of muscle control

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-13

■

Inability to perform delicate or skill-requiring tasks

■

Drowsiness

■

Weakness

■

Agitation

■

Euphoria

■

Loss of consciousness

Brain tissue is by far the most susceptible to the effects of hypoxia. Unconscious­
ness and death can occur from brain hypoxia before the effects on other tissues
become very prominent.
There is no reliable warning of the onset of hypoxia. It can occur unexpectedly,
making it a particularly serious hazard. A diver who loses his air supply is in danger
of hypoxia, but he immediately knows he is in danger and usually has time to do
something about it. He is much more fortunate than a diver who gradually uses up
the oxygen in a closed-circuit rebreathing rig and has no warning of impending
unconsciousness.
When hypoxia develops, pulse rate and blood pressure increase as the body tries
to offset the hypoxia by circulating more blood. A small increase in breathing may
also occur. A general blueness (cyanosis) of the lips, nail beds, and skin may occur
with hypoxia. This may not be noticed by the diver and often is not a reliable indi­
cator of hypoxia, even for the trained observer at the surface. The same signs could
be caused by prolonged exposure to cold water.
If hypoxia develops gradually, symptoms of interference with brain function will
appear. None of these symptoms, however, are sufficient warning and very few
people are able to recognize the mental effects of hypoxia in time to take correc­tive
action.
3‑5.1.3

Treatment of Hypoxia. A diver suffering from severe hypoxia must be rescued

promptly. Treat with basic first aid and 100% oxygen. If a victim of hypoxia is
given gas with adequate oxygen content before his breathing stops, he usually
regains consciousness shortly and recovers completely. For SCUBA divers, this
usually involves bringing the diver to the surface. For surface-supplied mixedgas divers, it involves shifting the gas supply to alternative banks and ventilating
the helmet or chamber with the new gas. Refer to Volume 4 for information on
treatment of hypoxia arising in specific operational environments for dives
involving semi-closed and closed-circuit rebreathers.

3‑5.1.4

Prevention of Hypoxia. Because of its insidious nature and potentially fatal

outcome, preventing hypoxia is essential. In open-circuit SCUBA and helmets,
hypoxia is unlikely unless the supply gas has too low an oxygen content. On

3-14

U.S. Navy Diving Manual — Volume 1

mixed-gas operations, strict atten­tion must be paid to gas analysis, cylinder lineups
and predive checkout procedures. In closed and semi-closed circuit rebreathers,
a malfunction can cause hypoxia even though the proper gases are being used.
Electronically controlled, fully closed-circuit Underwater Breathing Apparatus
(UBAs), like the MK 16, have oxygen sensors to read out oxygen partial
pressure, but divers must be constantly alert to the possibility of hypoxia from a
UBA malfunction. To prevent hypoxia, oxygen sensors should be monitored
closely throughout the dive. MK 25 UBA breathing bags should be purged
in accordance with Operating Procedures (OPs). Recently surfaced mixed-gas
chambers should not be entered until after they are thoroughly ventilated with air.
3-5.2

Carbon Dioxide Retention (Hypercapnia). Hypercapnia is an abnormally high

level of carbon dioxide in the blood and body tissues.
3‑5.2.1

Causes of Hypercapnia. In diving operations, hypercapnia is generally the result

of a buildup of carbon dioxide in the breathing supply or an inadequate respiratory
minute volume. The principal causes are:
■

Excess carbon dioxide levels in compressed air supplies due to improper
placement of the compressor inlet.

■

Inadequate ventilation of surface-supplied helmets or UBAs.

■

Failure of carbon dioxide absorbent canisters to absorb carbon dioxide or
incorrect installation of breathing hoses in closed or semi-closed circuit
UBAs.

■

Inadequate lung ventilation in relation to exercise level. The latter may be
caused by skip breathing, increased apparatus dead space, excessive breathing
resistance, or increased oxygen partial pressure.

Excessive breathing resistance is an important cause of hypercapnia and arises
from two sources: flow resistance and static lung load. Flow resistance results from
the flow of dense gas through tubes, hoses, and orifices in the diving equip­ment
and through the diver’s own airways. As gas density increases, a larger driving
pressure must be applied to keep gas flowing at the same rate. The diver has to
exert higher negative pressures to inhale and higher positive pressures to exhale.
As ventilation increases with increasing levels of exercise, the necessary driving
pressures increase. Because the respiratory muscles can only exert so much effort
to inhale and exhale, a point is reached when further increases cannot occur. At this
point, metabolically produced carbon dioxide is not adequately eliminated and increases in the blood and tissues, causing symptoms of hyper­capnia. Symptoms of
hypercapnia usually become apparent when divers attempt heavy work at depths
deeper then 120 FSW on air or deeper than 850 FSW on helium-oxygen. At very
great depths (1,600-2,000 FSW), shortness of breath and other signs of carbon dioxide toxicity may occur even at rest.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-15

Static lung load is the result of breathing gas being supplied at a different pressure
than the hydrostatic pressure surrounding the lungs. For example, when swimming
horizontally with a single-hose regulator, the regulator diaphragm is lower than the
mouth and the regulator supplies gas at a slight positive pressure once the demand
valve has opened. If the diver flips onto his back, the regulator diaphragm is shallower than his mouth and the regulator supplies gas at a slightly negative pressure.
Inhalation is harder but exhalation is easier because the exhaust ports are above the
mouth and at a slightly lower pressure.
Static lung loading is more apparent in closed and semi-closed circuit underwater
breathing apparatus such as the MK 25 and MK 16. When swimming horizontally
with the MK 16, the diaphragm on the diver’s back is shallower than the lungs and
the diver feels a negative pressure at the mouth. Exhalation is easier than inhala­
tion. If the diver flips onto his back, the diaphragm is below the lungs and the diver
feels a positive pressure at the mouth. Inhalation becomes easier than exhala­tion.
Static lung load is an important contributor to hypercapnia.
Excessive breathing resistance may cause shortness of breath and a sensation of
labored breathing (dyspnea) without any increase in blood carbon dioxide level. In
this case, the sensation of shortness of breath is due to activation of pressure and
stretch receptors in the airways, lungs, and chest wall rather than activation of the
chemoreceptors in the brain stem and carotid and aortic bodies. Usually, both types
of activation are present when breathing resistance is excessive.
3‑5.2.2

Symptoms of Hypercapnia. Hypercapnia affects the brain differently than hypoxia

does. However, it can result in similar symptoms. Symptoms of hypercapnia
include:

3-16

■

Increased breathing rate

■

Shortness of breath, sensation of difficult breathing or suffocation (dyspnea)

■

Confusion or feeling of euphoria

■

Inability to concentrate

■

Increased sweating

■

Drowsiness

■

Headache

■

Loss of consciousness

■

Convulsions

U.S. Navy Diving Manual — Volume 1

The increasing level of carbon dioxide in the blood stimulates the respiratory center
to increase the breathing rate and volume. The pulse rate also often increases. On
dry land, the increased breathing rate is easily noticed and uncom­fortable enough
to warn the victim before the rise in ppCO2 becomes dangerous. This is usually not
the case in diving. Factors such as water temperature, work rate, increased breathing resistance, and an elevated ppO2 in the breathing mixture may produce changes
in respiratory drive that mask changes caused by excess carbon dioxide. This is especially true in closed-circuit UBAs, particularly 100-percent oxygen rebreathers.
In cases where the ppO2 is above 0.5 ata, the short­ness of breath usually associated
with excess carbon dioxide may not be prominent and may go unnoticed by the
diver, especially if he is breathing hard because of exertion. In these cases the diver
may become confused and even slightly euphoric before losing consciousness. For
this reason, a diver must be particularly alert for any marked change in his breathing comfort or cycle (such as shortness of breath or hyperventilation) as a warning
of hypercapnia. A similar situation can occur in cold water. Exposure to cold water
often results in an increase in respiratory rate. This increase can make it difficult
for the diver to detect an increase in respiratory rate related to a buildup of carbon
dioxide.
Injury from hypercapnia is usually due to secondary effects such as drowning or
injury caused by decreased mental function or unconsciousness. A diver who loses
consciousness because of excess carbon dioxide in his breathing medium and does
not inhale water generally revives rapidly when given fresh air and usually feels
normal within 15 minutes. The after effects rarely include symptoms more serious
than headache, nausea, and dizziness. Permanent brain damage and death are much
less likely than in the case of hypoxia. If breathing resistance was high, the diver
may note some respiratory muscle soreness post-dive.
Excess carbon dioxide also dilates the arteries of the brain. This may partially
explain the headaches often associated with carbon dioxide intoxication, though
these headaches are more likely to occur following the exposure than during it.
The increase in blood flow through the brain, which results from dilation of the
arteries, is thought to explain why carbon dioxide excess speeds the onset of CNS
oxygen toxicity. Excess carbon dioxide during a dive is also believed to increase
the likelihood of decompression sickness, but the reasons are less clear.
The effects of nitrogen narcosis and hypercapnia are additive. A diver under the
influence of narcosis will probably not notice the warning signs of carbon dioxide
intoxication. Hypercapnia in turn will intensify the symptoms of narcosis.
3‑5.2.3

Treatment of Hypercapnia. Hypercapnia is treated by:
■

Decreasing the level of exertion to reduce CO2 production

■

Increasing helmet and lung ventilation to wash out excess CO2

■

Shifting to an alternate breathing source or aborting the dive if defective
equipment is the cause.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-17

Because the first sign of hypercapnia may be unconsciousness and it may not be
readily apparent whether the cause is hypoxia or hypercapnia. It is important to
rule out hypoxia first because of the significant potential for brain damage in hypoxia. Hypercapnia may cause unconsciousness, but by itself will not injure the
brain permanently.
3‑5.2.4

Prevention of Hypercapnia. In surface-supplied diving, hypercapnia is prevented

by ensuring that gas supplies do not contain excess carbon dioxide, by maintaining
proper manifold pressure during the dive and by ventilating the helmet frequently
with fresh gas. For dives deeper than 150 fsw, helium-oxygen mixtures should be
used to reduce breathing resistance. In closed or semiclosed-circuit UBAs, hypercapnia is prevented by carefully filling the CO2 absorbent canister and limiting
dive duration to estab­lished canister duration limits. For dives deeper than 150 fsw,
helium-oxygen mixtures should be used to reduce breathing resistance.
3-5.3

Asphyxia. Asphyxia is a condition where breathing stops and both hypoxia and

hypercapnia occur simultaneously. Asphyxia will occur when there is no gas to
breathe, when the airway is completely obstructed, when the respiratory muscles
become para­lyzed, or when the respiratory center fails to send out impulses to
breathe. Running out of air is a common cause of asphyxia in SCUBA diving.
Loss of the gas supply may also be due to equipment failure, for example regulator
freeze up. Divers who become unconscious as a result of hypoxia, hypercapnia,
or oxygen toxicity may lose the mouthpiece and suffer asphyxia. Obstruction of
the airway can be caused by injury to the windpipe, the tongue falling back in the
throat during unconsciousness, or the inhalation of water, saliva, vomitus or a foreign body. Paralysis of the respiratory muscles may occur with high cervical spinal
cord injury due to trauma or decompression sickness. The respiratory center in the
brain stem may become non-functional during a prolonged episode of hypoxia.
3-5.4

Drowning/Near Drowning. Drowning is fluid induced asphyxia. Near drowning

is the term used when a victim is successfully resuscitated following a drowning
episode.
3‑5.4.1

Causes of Drowning. A swimmer or diver can fall victim to drowning because of

overexertion, panic, inability to cope with rough water, exhaustion, or the effects
of cold water or heat loss. Drowning in a hard-hat diving rig is rare. It can happen
if the helmet is not properly secured and comes off, or if the diver is trapped in a
head-down position with a water leak in the helmet. Normally, as long as the diver
is in an upright position and has a supply of air, water can be kept out of the helmet
regardless of the condition of the suit. Divers wearing lightweight or SCUBA gear
can drown if they lose or ditch their mask or mouthpiece, run out of air, or inhale
even small quantities of water. This could be the direct result of failure of the air
supply, or panic in a hazardous situation. The SCUBA diver, because of direct exposure to the environment, can be affected by the same conditions that may cause
a swimmer to drown.

3-18

U.S. Navy Diving Manual — Volume 1

3‑5.4.2

3‑5.4.3

Symptoms of Drowning/Near Drowning.
■

Unconsciousness

■

Pulmonary edema

■

Increased respiratory rate.

Treatment of Near Drowning.
■

Assess airway, breathing, and circulation.

■

Rescue breathing should be started as soon as possible, even before the victim
is removed from the water.

■

Give 100 percent oxygen by mask.

■

Call for assistance from qualified medical personnel and transport to nearest
medical facility for evaluation.

Victims of near drowning who have no neurological symptoms should be evalu­
ated by a Diving Medical Officer for pulmonary aspiration. Pneumonia is the classic result of near drowning.
3‑5.4.4

Prevention of Near Drowning. Drowning is best prevented by thoroughly training

divers in safe diving practices and carefully selecting diving personnel. A trained
diver should not easily fall victim to drowning. However, overconfidence can give
a feeling of false security that might lead a diver to take dangerous risks.

3-5.5

Breathholding and Unconsciousness. Most people can hold their breath approxi-

mately 1 minute, but usually not much longer without training or special preparation. At some time during a breath­holding attempt, the desire to breathe becomes
uncontrollable. The demand to breathe is signaled by the respiratory center responding to the increasing levels of carbon dioxide in the arterial blood and peripheral chemoreceptors responding to the corresponding fall in arterial oxygen
partial pressure. If the breathhold is preceded by a period of voluntary hyperventilation, the breathhold can be much longer. Voluntary hyperventilation lowers body
stores of carbon dioxide below normal (a condition known as hypocapnia), without significantly increasing oxygen stores. During the breathhold, it takes an appreciable time for the body stores of carbon dioxide to return to the normal level
then to rise to the point where breathing is stimulated. During this time the oxygen partial pressure may fall below the level necessary to maintain consciousness.
This is a common cause of breathholding accidents in swimming pools. Extended
breathholding after hyper­ventilation is not a safe procedure.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-19

WARNING

Voluntary hyperventilation is dangerous and can lead to unconsciousness and death during breathhold dives.

Another hazard of breathhold diving is the possible loss of consciousness from
hypoxia during ascent. Air in the lungs is compressed during descent, raising the
oxygen partial pressure. The increased ppO2 readily satisfies the body’s oxygen
demand during descent and while on the bottom, even though a portion is being
consumed by the body. During ascent, the partial pressure of the remaining oxygen
is reduced rapidly as the hydrostatic pressure on the body lessens. If the ppO2
falls below 0.10 ata (10% sev), unconsciousness may result. This danger is further
heightened when hyperventilation has eliminated normal body warning signs of
carbon dioxide accumulation and allowed the diver to remain on the bottom for a
longer period of time. Refer to Chapter 6 for breathhold diving restrictions.
3-5.6

3‑5.6.1

Involuntary Hyperventilation. Hyperventilation is the term applied to breathing
more than is necessary to keep the body’s carbon dioxide tensions at proper level.
Hyperventilation may be volun­tary (for example, to increase breathholding time)
or involuntary. In involuntary hyperventilation, the diver is either unaware that he
is breathing excessively, or is unable to control his breathing.
Causes of Involuntary Hyperventilation. Involuntary hyperventilation can be

triggered by fear experienced during stressful situations. It can also be initiated by
the slight “smothering sensation” that accom­panies an increase in equipment dead
space, an increase in static lung loading, or an increase in breathing resistance. Cold
water exposure can add to the sensation of needing to breathe faster and deeper.
Divers using SCUBA equipment for the first few times are likely to hyperventilate
to some extent because of anxiety.
3‑5.6.2

Symptoms of Involuntary Hyperventilation. Hyperventilation may lead to a

biochemical imbalance that gives rise to dizziness, tingling of the extremities, and
spasm of the small muscles of the hands and feet. Hyperventilating over a long
period, produces additional symptoms such as weak­ness, headaches, numbness,
faintness, and blurring of vision. The diver may experience a sensation of “air
hunger” even though his ventilation is more than enough to eliminate carbon
dioxide. All these symptoms can be easily confused with symptoms of CNS oxygen
toxicity.
3‑5.6.3

Treatment of Involuntary Hyperventilation. Hyperventilation victims should

be encouraged to relax and slow their breathing rates. The body will correct
hyperventilation naturally.
3-5.7

3-20

Overbreathing the Rig. “Overbreathing the Rig” is a special term divers apply to
an episode of acute hypercapnia that develops when a diver works at a level greater
than his UBA can support. When a diver starts work, or abruptly increases his
workload, the increase in respiratory minute ventilation lags the increase in oxygen
consumption and carbon dioxide production by several minutes. When the RMV
demand for that workload finally catches up, the UBA may not be able to supply
the gas necessary despite extreme respiratory efforts on the part of the diver. Acute
hyper­capnia with marked respiratory distress ensues. Even if the diver stops work

U.S. Navy Diving Manual — Volume 1

to lower the production of carbon dioxide, the sensation of shortness of breath may
persist or even increase for a short period of time. When this occurs, the inexperi­
enced diver may panic and begin to hyperventilate. The situation can rapidly
develop into a malicious cycle of severe shortness of breath and uncontrollable
hyperventilation. In this situation, if even a small amount of water is inhaled, it
can cause a spasm of the muscles of the larynx (voice box), called a laryngospasm,
followed by asphyxia and possible drowning.
The U.S. Navy makes every effort to ensure that UBA meet adequate breathing
standards to minimize flow resistance and static lung loading problems. However,
all UBA have their limitations and divers must have sufficient experience to
recognize those limitations and pace their work accordingly. Always increase
workloads gradually to insure that the UBA can match the demand for increased
lung ventilation. If excessive breathing resistance is encountered, slow or stop the
pace of work until a respiratory comfort level is achieved. If respiratory distress
occurs following an abrupt increase in workload, stop work and take even controlled
breaths until the sensation of respiratory distress subsides. If the situa­tion does not
improve, abort the dive.
3-5.8

Carbon Monoxide Poisoning. The body produces carbon monoxide as a part of

the process of normal metabo­lism. Consequently, there is always a small amount
of carbon monoxide present in the blood and tissues. Carbon monoxide poisoning
occurs when levels of carbon monoxide in the blood and tissues rise above these
normal values due to the pres­ence of carbon monoxide in the diver’s gas supply.
Carbon monoxide not only blocks hemoglobin’s ability to delivery oxygen to the
cells, causing cellular hypoxia, but also poisons cellular metabolism directly.
3‑5.8.1

Causes of Carbon Monoxide Poisoning. Carbon monoxide is not found in any

significant quantity in fresh air. Carbon monoxide poisoning is usually caused by
a compressor’s intake being too close to the exhaust of an internal combustion
engine or malfunction of a oil lubricated compressor. Concentrations as low as
0.002 ata (2,000 ppm, or 0.2%) can prove fatal.

3‑5.8.2

Symptoms of Carbon Monoxide Poisoning. The symptoms of carbon monoxide

poisoning are almost identical to those of hypoxia. When toxicity develops
gradually the symptoms are:
■

Headache

■

Dizziness

■

Confusion

■

Nausea

■

Vomiting

■

Tightness across the forehead

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-21

When carbon monoxide concentrations are high enough to cause rapid onset of
poisoning, the victim may not be aware of any symptoms before he becomes
unconscious.
Carbon monoxide poisoning is particularly treacherous because conspicuous
symptoms may be delayed until the diver begins to ascend. While at depth, the
greater partial pressure of oxygen in the breathing supply forces more oxygen into
solution in the blood plasma. Some of this additional oxygen reaches the cells and
helps to offset the hypoxia. In addition, the increased partial pressure of oxygen
forcibly displaces some carbon monoxide from the hemoglobin. During ascent,
however, as the partial pressure of oxygen diminishes, the full effect of carbon
monoxide poisoning is felt.
3‑5.8.3

Treatment of Carbon Monoxide Poisoning. The immediate treatment of carbon

monoxide poisoning consists of getting the diver to fresh air and seeking medical
attention. Oxygen, if available, shall be administered immediately and while
transporting the patient to a hyperbaric or medical treatment facility. Hyperbaric
oxygen therapy is the definitive treatment of choice and transportation for
recompression should not be delayed except to stabilize the serious patient.
Divers with severe symptoms (i.e. severe headache, mental status changes, any
neurological symptoms, rapid heart rate) should be treated using Treatment Table
6.
3‑5.8.4

Prevention of Carbon Monoxide Poisoning. Locating compressor intakes away

from engine exhausts and maintaining air compressors in the best possible
mechanical condition can prevent carbon monoxide poisoning. When carbon
monoxide poisoning is suspected, isolate the suspect breathing gas source, and
forward gas samples for analysis as soon as possible.
3-6

MECHANICAL EFFECTS OF PRESSURE ON THE HUMAN BODY-BAROTRAUMA
DURING DESCENT

Barotrauma, or damage to body tissues from the mechanical effects of pressure,
results when pressure differentials between body cavities and the hydrostatic pres­
sure surrounding the body, or between the body and the diving equipment, are not
equalized properly. Barotrauma most frequently occurs during descent, but may
also occur during ascent. Barotrauma on descent is called squeeze. Barotrauma on
ascent is called reverse squeeze.
3-6.1

Prerequisites for Squeeze. For squeeze to occur during descent the following five

conditions must be met:

3-22

■

There must be a gas-filled space. Any gas-filled space within the body (such as
a sinus cavity) or next to the body (such as a face mask) can damage the body
tissues when the gas volume changes because of increased pressure.

■

The gas-filled space must have rigid walls. If the walls are collapsible like a
balloon, no damage will be done by compression.

U.S. Navy Diving Manual — Volume 1

Incus

Semicircular
Canals
Vestibular Nerve

Facial Nerve
Cochlear Nerve
Cochlea
Round
Window
Eustachian Tubes

Malleus
Tympanic
Stapes
Membrane
at Oval
Window
External Auditory
Canal

Figure 3-7. Gross Anatomy of the Ear in Frontal Section.

3-6.2

■

The gas-filled space must be enclosed. If gas or liquid can freely enter the
space as the gas volume changes, no damage will occur.

■

The space must have lining membrane with an arterial blood supply and venous
drainage that penetrates the space from the outside. This allows blood to be
forced into the space to compensate for the change in pressure.

■

There must be a change in ambient pressure.

Middle Ear Squeeze. Middle ear squeeze is the most common type of barotrauma.
The anatomy of the ear is illustrated in Figure 3-7. The eardrum completely seals off
the outer ear canal from the middle ear space. As a diver descends, water pressure
increases on the external surface of the drum. To counterbalance this pressure, the
air pressure must reach the inner surface of the eardrum. This is accomplished by
the passage of air through the narrow eustachian tube that leads from the nasal
passages to the middle ear space. When the eustachian tube is blocked by mucous,
the middle ear meets four of the requirements for barotrauma to occur (gas filled
space, rigid walls, enclosed space, penetrating blood vessels).

As the diver continues his descent, the fifth requirement (change in ambient pres­
sure) is attained. As the pressure increases, the eardrum bows inward and initially
equalizes the pressure by compressing the middle ear gas. There is a limit to this
stretching capability and soon the middle ear pressure becomes lower than the
external water pressure, creating a relative vacuum in the middle ear space. This
negative pressure causes the blood vessels of the eardrum and lining of the middle
ear to first expand, then leak and finally burst. If descent continues, either the

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-23

eardrum ruptures, allowing air or water to enter the middle ear and equalize the
pressure, or blood vessels rupture and cause sufficient bleeding into the middle ear
to equalize the pressure. The latter usually happens.
The hallmark of middle ear squeeze is sharp pain caused by stretching of the
eardrum. The pain produced before rupture of the eardrum often becomes intense
enough to prevent further descent. Simply stopping the descent and ascending a
few feet usually brings about immediate relief.
If descent continues in spite of the pain, the eardrum may rupture. When rupture
occurs, this pain will diminish rapidly. Unless the diver is in hard hat diving dress,
the middle ear cavity may be exposed to water when the ear drum ruptures. This
exposes the diver to a possible middle ear infection and, in any case, prevents
the diver from diving until the damage is healed. If eardrum rupture occurs, the
dive shall be aborted. At the time of the rupture, the diver may experience the
sudden onset of a brief but violent episode of vertigo (a sensation of spinning). This
can completely disorient the diver and cause nausea and vomiting. This vertigo is
caused by violent disturbance of the malleus, incus, and stapes, or by cold water
stimulating the balance mechanism of the inner ear. The latter situation is referred
to as caloric vertigo and may occur from simply having cold or warm water enter
one ear and not the other. The eardrum does not have to rupture for caloric vertigo
to occur. It can occur as the result of having water enter one ear canal when swim­
ming or diving in cold water. Fortunately, these symptoms quickly pass when the
water reaching the middle ear is warmed by the body. Suspected cases of eardrum
rupture shall be referred to medical personnel.
3‑6.2.1

Preventing Middle Ear Squeeze. Diving with a partially blocked eustachian tube
increases the likelihood of middle ear squeeze. Divers who cannot clear their ears
on the surface should not dive. Medical personnel shall examine divers who have
trouble clearing their ears before diving. The possibility of barotrauma can be
virtually eliminated if certain precautions are taken. While descending, stay ahead
of the pressure. To avoid collapse of the eustachian tube and to clear the ears,
frequent adjustments of middle ear pressure must be made by adding gas through
the eustachian tubes from the back of the nose. If too large a pressure difference
develops between the middle ear pressure and the external pressure, the eustachian
tube collapses as it becomes swollen and blocked. For some divers, the eustachian
tube is open all the time so no conscious effort is necessary to clear their ears.
For the majority, however, the eustachian tube is normally closed and some action
must be taken to clear the ears. Many divers can clear by yawning, swallowing, or
moving the jaw around.

Some divers must gently force gas up the eustachian tube by closing their mouth,
pinching their nose and exhaling. This is called a Valsalva maneuver. If too large
a relative vacuum exists in the middle ear, the eustachian tube collapses and no
amount of forceful clearing will open it. If a squeeze is noticed during descent,
the diver shall stop, ascend a few feet and gently perform a Valsalva maneuver. If
clearing cannot be accomplished as described above, abort the dive.

3-24

U.S. Navy Diving Manual — Volume 1

WARNING

Never do a forceful Valsalva maneuver during descent. A forceful Valsalva
maneuver can result in alternobaric vertigo or barotrauma to the inner
ear (see below).

WARNING

If decongestants must be used, check with medical personnel trained in
diving medicine to obtain medication that will not cause drowsiness and
possibly add to symptoms caused by the narcotic effect of nitrogen.

3‑6.2.2

Treating Middle Ear Squeeze. Upon surfacing after a middle ear squeeze, the

diver may complain of pain, full­ness in the ear, hearing loss, or even mild vertigo.
Occasionally, the diver may have a bloody nose, the result of blood being forced
out of the middle ear space and into the nasal cavity through the eustachian tube
by expanding air in the middle ear. The diver shall report symptoms of middle ear
squeeze to the diving supervisor and seek medical attention. Treatment consists
of taking decongestants, pain medication if needed, and cessation of diving until
the damage is healed. If the eardrum has ruptured antibiotics may be prescribed as
well. Never administer medications directly into the external ear canal if a ruptured
eardrum is suspected or confirmed unless done in direct consultation with an ear,
nose, and throat (ENT) medical specialist.
3-6.3

Sinus Squeeze. Sinuses are located within hollow spaces of the skull bones and

are lined with a mucous membrane continuous with that of the nasal cavity (Figure
3-8). The sinuses are small air pockets connected to the nasal cavity by narrow
passages. If pressure is applied to the body and the passages to any of these sinuses
are blocked by mucous or tissue growths, pain will soon be experienced in the
affected area. The situation is very much like that described for the middle ear.
3‑6.3.1

Causes of Sinus Squeeze. When the air pressure in these sinuses is less than the
pressure applied to the tissues surrounding these incompressible spaces, the same
relative effect is produced as if a vacuum were created within the sinuses: the
lining membranes swell and, if severe enough, hemorrhage into the sinus spaces.
This process repre­sents nature’s effort to balance the relative negative air pressure
by filling the space with swollen tissue, fluid, and blood. The sinus is actually
squeezed. The pain produced may be intense enough to halt the diver’s descent.
Unless damage has already occurred, a return to normal pressure will bring
about immediate relief. If such difficulty has been encountered during a dive, the
diver may often notice a small amount of bloody nasal discharge on reaching the
surface.

3‑6.3.2

Preventing Sinus Squeeze. Divers should not dive if any signs of nasal congestion

or a head cold are evident. The effects of squeeze can be limited during a dive by
halting the descent and ascending a few feet to restore the pressure balance. If the
space cannot be equal­ized by swallowing or blowing against a pinched-off nose,
the dive must be aborted.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-25

Frontal Sinus

Orbit

Ethmoidal Sinus

Nasal Cavity

Maxillary Sinus
Sphenoid Sinus

Nasal Septum

Figure 3-8. Location of the Sinuses in the Human Skull.

3-6.4

Tooth Squeeze (Barodontalgia). Tooth squeeze occurs when a small pocket of

gas, generated by decay, is lodged under a poorly fitted or cracked filling. If this
pocket of gas is completely isolated, the pulp of the tooth or the tissues in the tooth
socket can be sucked into the space causing pain. If additional gas enters the tooth
during descent and does not vent during ascent, it can cause the tooth to crack
or the filling to be dislodged. Prior to any dental work, personnel shall identify
themselves as divers to the dentist.

3-6.5

External Ear Squeeze. A diver who wears ear plugs, has an infected external ear
(external otitis), has a wax-impacted ear canal, or wears a tight-fitting wet suit
hood, can develop an external ear squeeze. The squeeze occurs when gas trapped
in the external ear canal remains at atmospheric pressure while the external water
pressure increases during descent. In this case, the eardrum bows outward (opposite
of middle ear squeeze) in an attempt to equalize the pressure difference and may
rupture. The skin of the canal swells and hemorrhages, causing considerable pain.

Ear plugs must never be worn while diving. In addition to creating the squeeze,
they may be forced deep into the ear canal. When a hooded suit must be worn, air
(or water in some types) must be allowed to enter the hood to equalize pressure in
the ear canal.
3-6.6

Thoracic (Lung) Squeeze. When making a breathhold dive, it is possible to reach

a depth at which the air held in the lungs is compressed to a volume somewhat
smaller than the normal residual volume of the lungs. At this volume, the chest
wall becomes stiff and incompressible. If the diver descends further, the additional
pressure is unable to compress the chest walls, force additional blood into the blood
vessels in the chest, or elevate the diaphragm further. The pressure in the lung
becomes negative with respect to the external water pressure. Injury takes the form
of squeeze. Blood and tissue fluids are forced into the lung alveoli and air passages

3-26

U.S. Navy Diving Manual — Volume 1

where the air is under less pressure than the blood in the surrounding vessels. This
amounts to an attempt to relieve the negative pressure within the lungs by partially
filling the air space with swollen tissue, fluid, and blood. Considerable lung damage
results and, if severe enough, may prove fatal. If the diver descends still further,
death will occur as a result of the collapse of the chest. Breathhold diving shall be
limited to controlled, training situations or special operational situations involving
well-trained personnel at shallow depths.
A surface-supplied diver who suffers a loss of gas pressure or hose rupture with
failure of the nonreturn valve may suffer a lung squeeze, if his depth is great
enough, as the surrounding water pressure compresses his chest.
3-6.7

Face or Body Squeeze. SCUBA face masks, goggles, and certain types of exposure

suits may cause squeeze under some conditions. Exhaling through the nose can
usually equalize the pressure in a face mask, but this is not possible with goggles.
Goggles shall only be used for surface swimming. The eye and the eye socket
tissues are the most seriously affected tissues in an instance of face mask or goggle
squeeze. When using exposure suits, air may be trapped in a fold in the garment
and may lead to some discomfort and possibly a minor case of hemorrhage into the
skin from pinching.
3-6.8

Inner Ear Barotrauma. The inner ear contains no gas and therefore cannot be

“squeezed” in the same sense that the middle ear and sinuses can. However,
the inner ear is located next to the middle ear cavity and is affected by the same
conditions that lead to middle ear squeeze. To understand how the inner ear could
be damaged as a result of pressure imbalances in the middle ear, it is first necessary
to understand the anatomy of the middle and inner ear.
The inner ear contains two important organs, the cochlea and the vestibular appa­
ratus. The cochlea is the hearing sense organ; damage to the cochlea will result in
hearing loss and ringing in the ear (tinnitus). The vestibular apparatus is the balance
organ; damage to the vestibular apparatus will result in vertigo and unsteadiness.
There are three bones in the middle ear: the malleus, the incus, and the stapes.
They are also commonly referred to as the hammer, anvil, and stirrup, respectively
(Figure 3‑9). The malleus is connected to the eardrum (tympanic membrane) and
transmits sound vibrations to the incus, which in turn transmits these vibrations to
the stapes, which relays them to the inner ear. The stapes transmits these vibrations
to the inner ear fluid through a membrane-covered hole called the oval window.
Another membrane-covered hole called the round window connects the inner ear
with the middle ear and relieves pressure waves in the inner ear caused by move­ment
of the stapes. When the stapes drives the oval window inward, the round window
bulges outward to compensate. The fluid-filled spaces of the inner ear are also
connected to the fluid spaces surrounding the brain by a narrow passage called the
cochlear aqueduct. The cochlear aqueduct can transmit increases in cerebrospinal
fluid pressure to the inner ear. When Valsalva maneuvers are performed to equalize
middle ear and sinus pressure, cerebrospinal fluid pressure increases.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-27

Incus
Malleus
Tensor tympani
Tympanic
Membrane

Stapedius
Muscle

Stapes

Oval
Window

Eustachian
Tube

Figure 3-9. Components of the Middle/Inner Ear.

If middle ear pressure is not equalized during descent, the inward bulge of the
eardrum is transmitted to the oval window by the middle ear bones. The stapes
pushes the oval window inward. Because the inner ear fluids are incompressible,
the round window correspondingly bulges outward into the middle ear space. If
this condition continues, the round window may rupture spilling inner ear fluids
into the middle ear and leading to a condition know as inner ear barotrauma with
perilymph fistula. Fistula is a medical term for a hole in a membrane; the fluid
in the inner ear is called perilymph. Rupture of the oval or round windows may
also occur when middle ear pressures are suddenly and forcibly equalized. When
equalization is sudden and forceful, the eardrum moves rapidly from a position of
bulging inward maximally to bulging outward maximally. The positions of the oval
and round windows are suddenly reversed Inner ear pressure is also increased by
transmission of the Valsalva-induced increase in cerebrospinal fluid pressure. This
puts additional stresses on these two membranes. Either the round or oval window
may rupture. Rupture of the round window is by far the most common. The oval
window is a tougher membrane and is protected by the foot­plate of the stapes.
Even if rupture of the round or oval window does not occur, the pressure waves
induced in the inner ear during these window movements may lead to disruption
of the delicate cells involved in hearing and balance. This condi­tion is referred to
inner ear barotrauma without perilymph fistula.
The primary symptoms of inner ear barotrauma are persistent vertigo and hearing
loss. Vertigo is the false sensation of motion. The diver feels that he is moving
with respect to his environment or that the environment is moving with respect to
him, when in fact no motion is taking place. The vertigo of inner ear barotrauma is
generally described as whirling, spinning, rotating, tilting, rocking, or undu­lating.
This sensation is quite distinct from the more vague complaints of dizziness or

3-28

U.S. Navy Diving Manual — Volume 1

lightheadedness caused by other conditions. The vertigo of inner ear barotrauma
is often accompanied by symptoms that may or may not be noticed depending
on the severity of the insult. These include nausea, vomiting, loss of balance,
incoordination, and a rapid jerking movement of the eyes, called nystagmus. Vertigo
may be accentuated when the head is placed in certain posi­tions. The hearing loss
of inner ear barotrauma may fluctuate in intensity and sounds may be distorted.
Hearing loss is accompanied by ringing or roaring in the affected ear. The diver
may also complain of a sensation of bubbling in the affected ear.
Symptoms of inner ear barotrauma usually appear abruptly during descent, often
as the diver arrives on the bottom and performs his last equalization maneuver.
However, the damage done by descent may not become apparent until the dive
is over. A common scenario is for the diver to rupture a damaged round window
while lifting heavy weights or having a bowel movement post dive. Both these
activities increase cerebrospinal fluid pressure and this pressure increase is trans­
mitted to the inner ear. The round window membrane, weakened by the trauma
suffered during descent, bulges into the middle ear space under the influence of the
increased cerebrospinal fluid pressure and ruptures.
All cases of suspected inner ear barotrauma should be referred to an ear, nose and
throat (ENT) physician as soon as possible. Treatment of inner ear barotrauma
ranges from bed rest with head elevation to exploratory surgery, depending on
the severity of the symptoms and whether a perilymph fistula is suspected. Any
hearing loss or vertigo occurring within 72 hours of a hyperbaric exposure should
be evaluated as a possible case of inner ear barotrauma.
When either hearing loss or vertigo develop after the diver has surfaced, it may
be impossible to tell whether the symptoms are caused by inner ear barotrauma,
decompression sickness or arterial gas embolism. For the latter two conditions,
recompression treatment is mandatory. Although it might be expected that
recompression treatment would further damage to the inner ear in a case of
barotrauma and should be avoided, experience has shown that recompression is
generally not harmful provided a few simple precautions are followed. The diver
should be placed in a head up position and compressed slowly to allow adequate
time for middle ear equalization. Clearing maneuvers should be gentle. The diver
should not be exposed to excessive positive or negative pressure when breathing
oxygen on the built-in breathing system (BIBS) mask. Always recompress the
diver if there is any doubt about the cause of post-dive hearing loss or vertigo.
CAUTION

When in doubt, always recompress.
Frequent oscillations in middle ear pressure associated with difficult clearing may
lead to a transient vertigo. This condition is called alternobaric vertigo of descent.
Vertigo usually follows a Valsalva maneuver, often with the final clearing episode
just as the diver reaches the bottom. Symptoms typically last less than a minute but
can cause significant disorientation during that period. Descent should be halted
until the vertigo resolves. Once the vertigo resolves, the dive may be continued.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-29

Alternobaric vertigo is a mild form of inner ear barotrauma in which no lasting
damage to the inner ear occurs.
3-7

MECHANICAL EFFECTS OF PRESSURE ON THE HUMAN BODY--BAROTRAUMA
DURING ASCENT

During ascent gases expand according to Boyle’s Law. If the excess gas is not
vented from enclosed spaces, damage to those spaces may result.
3-7.1

Middle Ear Overpressure (Reverse Middle Ear Squeeze). Expanding gas in the

middle ear space during ascent ordinarily vents out through the eustachian tube. If
the tube becomes blocked, pressure in the middle ear rela­tive to the external water
pressure increases. To relieve this pressure, the eardrum bows outward causing
pain. If the overpressure is significant, the eardrum may rupture. If rupture occurs,
the middle ear will equalize pressure with the surrounding water and the pain will
disappear. However, there may be a transient episode of intense vertigo as cold
water enters the middle ear space.
The increased pressure in the middle ear may also affect the inner ear balance
mechanism, leading to a condition called alternobaric vertigo of ascent. Alter­
nobaric vertigo occurs when the middle ear space on one side is overpressurized
while the other side is equalizing normally. The onset of vertigo is usually sudden
and may be preceded by pain in the ear that is not venting excess pressure. Alter­
nobaric vertigo usually lasts for only a few minutes, but may be incapacitating
during that time. Relief is usually abrupt and may be accompanied by a hissing
sound in the affected ear as it equalizes. Alternobaric vertigo during ascent will
disappear immediately if the diver halts his ascent and descends a few feet.
Increased pressure in the middle ear can also produce paralysis of the facial muscles,
a condition known as facial baroparesis. In some individuals, the facial nerve is
exposed to middle ear pressure as it traverses the temporal bone. If the middle ear
fails to vent during ascent, the overpressure can shut off the blood supply to the
nerve causing it to stop transmitting neural impulses to the facial muscles on the
affected side. Generally, a 10 to 30 min period of overpressure is necessary for
symptoms to occur. Full function of the facial muscles returns 5-10 min after the
overpressure is relieved.
Increased pressure in the middle ear can also cause structural damage to the inner
ear, a condition known as inner ear barotrauma of ascent. The bulging ear drum
pulls the oval window outward into the middle ear space through the action of the
middle ear bones. The round window correspondingly bulges inward. This inward
deflection can be enhanced if the diver further increases middle ear pressure by
performing a Valsalva maneuver. The round window may rupture causing inner
ear fluids to spill into the middle ear space. The symptoms of marked hearing loss
and sustained vertigo are identical to the symptoms experienced with inner ear
barotrauma during descent.

3-30

U.S. Navy Diving Manual — Volume 1

A diver who has a cold or is unable to equalize the ears is more likely to develop
reverse middle ear squeeze. There is no uniformly effective way to clear the ears
on ascent. Do not perform a Valsalva maneuver on ascent, as this will increase the
pressure in the middle ear, which is the direct opposite of what is required. The
Valsalva maneuver can also lead to the possibility of an arterial gas embolism.
If pain in the ear or vertigo develops on ascent, the diver should halt the ascent,
descend a few feet to relieve the symptoms and then continue his ascent at a slower
rate. Several such attempts may be necessary as the diver gradually works his way
to the surface. If symptoms of sustained hearing loss or vertigo appear during
ascent, or shortly after ascent, it may be impossible to tell whether the symptoms
are arising from inner ear barotrauma or from decompression sickness or arterial
gas embolism. Recompression therapy is always indicated unless there is 100%
certainty that the condition is inner ear barotrauma.
3-7.2

Sinus Overpressure (Reverse Sinus Squeeze). Overpressure is caused when gas

is trapped within the sinus cavity. A fold in the sinus-lining membrane, a cyst, or
an outgrowth of the sinus membrane (polyp) may act as a check valve and prevent
gas from leaving the sinus during ascent. Sharp pain in the area of the affected
sinus results from the increased pressure. The pain is usually sufficient to stop
the diver from ascending. Pain is immediately relieved by descending a few feet.
From that point, the diver should titrate himself slowly to the surface in a series of
ascents and descents just as with a reverse middle ear squeeze.
When overpressure occurs in the maxillary sinus, the blood supply to the infraor­
bital nerve may be reduced, leading to numbness of the lower eyelid, upper lip,
side of the nose, and cheek on the affected side. This numbness will resolve spon­
taneously when the sinus overpressure is relieved.
3-7.3

Gastrointestinal Distention. Divers may occasionally experience abdominal
pain during ascent because of gas expansion in the stomach or intestines. This
condition is caused by gas being generated in the intestines during a dive, or by
swallowing air (aerophagia). These pockets of gas will usually work their way out
of the system through the mouth or anus. If not, distention will occur.

If the pain begins to pass the stage of mild discomfort, ascent should be halted and
the diver should descend slightly to relieve the pain. The diver should then attempt
to gently burp or release the gas anally. Overzealous attempts to belch should be
avoided as they may result in swallowing more air. Abdominal pain following fast
ascents shall be evaluated by a Diving Medical Officer.
To avoid intestinal gas expansion:
■

Do not dive with an upset stomach or bowel.

■

Avoid eating foods that are likely to produce intestinal gas.

■

Avoid a steep, head-down angle during descent to minimize the amount of air
swallowed.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-31

Figure 3-10. Pulmonary Overinflation Syndromes (POIS). Leaking of gas into the pulmo­
nary interstitial tissue causes no symptoms unless further leaking occurs. If gas enters
the arterial circulation, potentially fatal arterial gas embolism may occur. Pneumothorax
occurs if gas accumulates between the lung and chest wall and if accumulation continues
without venting, then tension pneumothorax may result.

3-8

PULMONARY OVERINFLATION SYNDROMES

Pulmonary overinflation syndromes are a group of barotrauma-related diseases
caused by the expansion of gas trapped in the lung during ascent (reverse squeeze)
or overpressurization of the lung with subsequent overexpansion and rupture of
the alveolar air sacs. Excess pressure inside the lung can also occur when a diver
presses the purge button on a single-hose regulator while taking a breath. The two
main causes of alveolar rupture are:
■

Excessive pressure inside the lung caused by positive pressure

■

Failure of expanding gas to escape from the lung during ascent

Pulmonary overinflation from expanding gas failing to escape from the lung during
ascent can occur when a diver voluntarily or involuntarily holds his breath during
ascent. Localized pulmonary obstructions that can cause air trapping, such as
asthma or thick secretions from pneumonia or a severe cold, are other causes. The
conditions that bring about these incidents are different from those that produce
lung squeeze and they most frequently occur during free and buoyant ascent
training or emergency ascent from dives made with lightweight diving equipment
or SCUBA.
The clinical manifestations of pulmonary overinflation depend on the location
where the free air collects. In all cases, the first step is rupture of the alveolus with
a collection of air in the lung tissues, a condition known as interstitial emphysema.
Interstitial emphysema causes no symptoms unless further distribution of the air
occurs. Gas may find its way into the chest cavity or arterial circulation. These
conditions are depicted in Figure 3‑10.
3-32

U.S. Navy Diving Manual — Volume 1

Figure 3-11. Arterial Gas Embolism.

3-8.1

Arterial Gas Embolism (AGE). Arterial gas embolism (AGE), sometimes simply

called gas embolism, is an obstruction of blood flow caused by gas bubbles (emboli)
entering the arterial circulation. Obstruction of the arteries of the brain and heart
can lead to death if not promptly relieved (see Figure 3-11).
3‑8.1.1

Causes of AGE. AGE is caused by the expansion of gas taken into the lungs while

breathing under pressure and held in the lungs during ascent. The gas might have
been retained in the lungs by choice (voluntary breathholding) or by accident
(blocked air passages). The gas could have become trapped in an obstructed portion
of the lung that has been damaged from some previous disease or accident; or the
diver, reacting with panic to a difficult situation, may breathhold without realizing
it. If there is enough gas and if it expands sufficiently, the pressure will force gas
through the alveolar walls into surrounding tissues and into the bloodstream. If the
gas enters the arterial circulation, it will be dispersed to all organs of the body. The
organs that are especially susceptible to arterial gas embolism and that are respon­
sible for the life-threatening symptoms are the central nervous system (CNS) and
the heart. In all cases of arterial gas embolism, associated pneumothorax is possible
and should not be overlooked. Exhaustion of air supply and the need for an emer­
gency ascent is the most common cause of AGE.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-33

3‑8.1.2

Symptoms of AGE
■

Unconsciousness

■

Paralysis

■

Numbness

■

Weakness

■

Extreme fatigue

■

Large areas of abnormal sensations (Paresthesias)

■

Difficulty in thinking

■

Vertigo

■

Convulsions

■

Vision abnormalities

■

Loss of coordination

■

Nausea and or vomiting

■

Hearing abnormalities

■

Sensation similar to that of a blow to the chest during ascent

■

Bloody sputum

■

Dizziness

■

Personality changes

■

Loss of control of bodily functions

■

Tremors

Symptoms of subcutaneous/medistinal emphysema, pneumothorax and/or pneu­
mopericardium may also be present (see below). In all cases of arterial gas
embolism, the possible presence of these associated conditions should not be
overlooked.
3‑8.1.3

3-34

Treatment of AGE.
■

Basic first aid (ABC)

■

100 percent oxygen

U.S. Navy Diving Manual — Volume 1

3‑8.1.4

■

Immediate recompression

■

See Volume 5 for more specific information regarding treatment.

Prevention of AGE. The risk of arterial gas embolism can be substantially reduced

or eliminated by paying careful attention to the following:
■

Every diver must receive intensive training in diving physics and physiology,
as well as instruction in the correct use of diving equipment. Particular attention
must be given to the training of SCUBA divers, because SCUBA operations
produce a comparatively high incidence of embolism accidents.

■

A diver must never interrupt breathing during ascent from a dive in which
compressed gas has been breathed.

■

A diver must exhale continuously while making an emergency ascent. The rate
of exhalation must match the rate of ascent. For a free ascent, where the diver
uses natural buoyancy to be carried toward the surface, the rate of exhalation
must be great enough to prevent embolism, but not so great that positive
buoyancy is lost. In a uncontrolled or buoyant ascent, where a life preserver,
dry suit or buoyancy compensator assists the diver, the rate of ascent may far
exceed that of a free ascent. The exhalation must begin before the ascent and
must be a strong, steady, and forceful. It is difficult for an untrained diver to
execute an emergency ascent properly. It is also often dangerous to train a diver
in the proper technique.

n The diver must not hesitate to report any ill­ness, especially respiratory illness
such as a cold, to the Diving Supervisor or Diving Medical Personnel prior to
diving.
3-8.2

Mediastinal and Subcutaneous Emphysema. Mediastinal emphysema, also called

pneumomediastinum, occurs when gas is forced through torn lung tissue into the
loose mediastinal tissues in the middle of the chest surrounding the heart, the
trachea, and the major blood vessels (see Figure 3-12). Subcutaneous emphysema
occurs when that gas subsequently migrates into the subcutaneous tissues of the
neck (Figure 3-13). Mediastinal emphysema is a pre-requisite for subcutaneous
emphysema.
3‑8.2.1

Causes of Mediastinal and Subcutaneous Emphysema. Mediastinal/subcutaneous
emphysema is caused by over inflation of the whole lung or parts of the lung due
to:
■

Breath holding during ascent

■

Positive pressure breathing such as ditch and don exercises

■

Drown proofing exercises

■

Cough during surface swimming

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-35

Figure 3-12. Mediastinal Emphysema.

3-36

3‑8.2.2

Symptoms of Mediastinal and Subcutaneous Emphysema. Mild cases are often
unnoticed by the diver. In more severe cases, the diver may experience mild to
moderate pain under the breastbone, often described as dull ache or feeling of
tightness. The pain may radiate to the shoulder or back and may increase upon
deep inspiration, coughing, or swallowing. The diver may have a feeling of fullness
around the neck and may have difficulty in swallowing. His voice may change in
pitch. An observer may note a swelling or apparent inflation of the diver’s neck.
Movement of the skin near the windpipe or about the collar bone may produce a
cracking or crunching sound (crepitation).

3‑8.2.3

Treatment of Mediastinal and Subcutaneous Emphysema. Suspicion of mediastinal or subcutaneous emphysema warrants prompt referral to medical personnel
to rule out the coexistence of arterial gas embolism or pneu­mothorax. The latter two conditions require more aggressive treatment. Treatment of mediastinal
or subcutaneous emphysema with mild symptoms consists of breathing 100 percent oxygen at the surface. If symptoms are severe, shallow recompression may be
beneficial. Recompression should only be carried out upon the recommendation of
a Diving Medical Officer who has ruled out the occurrence of pneumothorax. Recompression is performed with the diver breathing 100 percent oxygen and using
the shallowest depth of relief (usually 5 or 10 feet). An hour of breathing oxygen

U.S. Navy Diving Manual — Volume 1

Figure 3-13. Subcutaneous Emphysema.

should be sufficient for resolution, but longer stays may be necessary. Decompression will be dictated by the tender’s decompression obli­gation. The appropriate
air table should be used, but the ascent rate should not exceed 1 foot per minute.
In this specific case, the delay in ascent should be included in bottom time when
choosing the proper decompression table.
3‑8.2.4

Prevention of Mediastinal and Subcutaneous Emphysema. The strategies for pre-

venting mediastinal/subcutaneous emphysema are identical to the strategies for
preventing arterial gas embolism. Breathe normally during ascent. If emergency
ascent is required, exhale continuously. Mediastinal/subcuta­neous emphysema is
particularly common after ditch and don exercises. Avoid positive pressure breathing
situations during such exercises. The mediastinal/subcutaneous emphysema that is
seen during drown proofing exercises and during surface swimming unfortunately
is largely unavoidable.
3-8.3

Pneumothorax. A pneumothorax is air trapped in the pleural space between the

lung and the chest wall (Figure 3-14).
3‑8.3.1

Causes of Pneumothorax. A pneumothorax occurs when the lung surface ruptures
and air spills into the space between the lung and chest wall. Lung rupture can

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-37

Figure 3-14. Pneumothorax.

result from a severe blow to the chest or from overpressurization of the lung. In
its usual manifesta­tion, called a simple pneumothorax, a one-time leakage of air
from the lung into the chest partially collapses the lung, causing varying degrees
of respiratory distress. This condition normally improves with time as the air is
reabsorbed. In severe cases of collapse, the air must be removed with the aid of a
tube or catheter.
In certain instances, the damaged lung may allow air to enter but not exit the pleural
space. Successive breathing gradually enlarges the air pocket. This is called a
tension pneumothorax (Figure 3‑15) because of the progressively increasing tension
or pressure exerted on the lung and heart by the expanding gas. If uncorrected, this
force presses on the involved lung, causing it to completely collapse. The lung, and
then the heart, are pushed toward the opposite side of the chest, which impairs both
respiration and circulation.
A simple pneumothorax that occurs while the diver is at depth can be converted to
a tension pneumothorax by expansion of the gas pocket during ascent. Although a
ball valve like mechanism that allows air to enter the pleural cavity but not escape
is not present, the result is the same. The mounting tension collapses the lung on
the affected side and pushes the heart and lung to the opposite side of the chest.
3‑8.3.2

3-38

Symptoms of Pneumothorax. The onset of a simple pneumothorax is accompanied
by a sudden, sharp chest pain, followed by shortness of breath, labored breathing,

U.S. Navy Diving Manual — Volume 1

Organ
Shift
Heart

Figure 3-15. Tension Pneumothorax.

rapid heart rate, a weak pulse, and anxiety. The normal chest movements associated
with respiration may be reduced on the affected side and breath sounds may be
difficult to hear with a stethoscope.
The symptoms of tension pneumothorax are similar to simple pneumothorax, but
become progressively more intense over time. As the heart and lungs are displaced
to the opposite side of the chest, blood pressure falls along with the arterial oxygen
partial pressure. Cyanosis (a bluish discoloration) of the skin appears. If left
untreated, shock and death will ensue. Tension pneumothorax is a true medical
emergency.
3‑8.3.3

Treatment of Pneumothorax. A diver believed to be suffering from pneumothorax

must be thoroughly examined for the possible co-existence of arterial gas embolism.
This is covered more fully in Volume 5.
A small pneumothorax (less than 15%) normally will improve with time as the
air in the pleural space is reabsorbed spontaneously. A larger pneumothorax
may require active treatment. Mild pneumothorax can be treated by breathing
100 percent oxygen. Cases of pneumothorax that demonstrate cardio-respiratory
compromise may require the insertion of a chest tube, largebore intravenous (IV)
catheter, or other device designed to remove intrathoracic gas (gas around the
lung). Only personnel trained in the use of these and the other accessory devices
(one-way valves, underwater suction, etc.) necessary to safety decompress the

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-39

thoracic cavity should insert them. Divers recompressed for treatment of arterial
gas embolism or decompression sickness, who also have a pneumothorax, will
experience relief upon recompression. A chest tube or other device with a oneway relief valve may need to be inserted at depth to prevent expansion of the
trapped gas during subsequent ascent. A tension pneumothorax should always be
suspected if the diver’s condition deteriorates rapidly during ascent, especially if
the symptoms are respiratory. If a tension pneumothorax is found, recompress to
depth of relief until the thoracic cavity can be properly vented. Pneumothorax,
if present in combination with arterial gas embolism or decompression sickness,
should not prevent immediate recompression therapy. However, a pneumothorax
may need to be vented as described before ascent from treatment depth. In cases of
tension pneumothorax, this procedure may be lifesaving. Volume 5 fully discusses
the treatment of simple and tension pneumothorax.
3‑8.3.4

Prevention of Pneumothorax. The strategies for avoiding pneumothorax are the

same as those for avoiding arte­rial gas embolism. Breathe normally during ascent.
If forced to perform an emergency ascent, exhale continuously
3-9

INDIRECT EFFECTS OF PRESSURE ON THE HUMAN BODY

The conditions previously described occur because of differences in pressure that
damage body structures in a direct, mechanical manner. The indirect or secondary
effects of pressure are the result of changes in the partial pressure of individual
gases in the diver’s breathing medium. The mechanisms of these effects include
saturation and desaturation of body tissues with dissolved gas and the modifica­tion
of body functions by abnormal gas partial pressures.
3-9.1

3‑9.1.1

Nitrogen Narcosis. Nitrogen narcosis is the state of euphoria and exhilaration that
occurs when a diver breathes a gas mixture with a nitrogen partial pressure greater
than 4 ata.
Causes of Nitrogen Narcosis. Breathing nitrogen at high partial pressures has

a narcotic effect on the central nervous system that causes euphoria and impairs
the diver’s ability to think clearly. The narcotic effect begins at a nitrogen partial
pressure of approximately 4 ata and increases in severity as the partial pressure
is increased beyond that point. A nitrogen partial pressure of 8 ata causes very
marked impairment; partial pres­sures in excess of 10 ata may lead to hallucinations
and unconsciousness. For a dive on air, narcosis usually appears at a depth of
approximately 130 fsw, is very prominent at a depth of 200 fsw, and becomes
disabling at deeper depths.
There is a wide range of individual susceptibility to narcosis. There is also some
evidence that adaptation occurs on repeated exposures. Some divers, particularly
those experienced in deep operations with air, can often work as deep as 200 fsw
without serious difficulty. Others cannot.
3‑9.1.2

Symptoms of Nitrogen Narcosis. The symptoms of nitrogen narcosis include:
■

3-40

Loss of judgment or skill

U.S. Navy Diving Manual — Volume 1

■

A false feeling of well-being

■

Lack of concern for job or safety

■

Apparent stupidity

■

Inappropriate laughter

■

Tingling and vague numbness of the lips, gums, and legs

Disregard for personal safety is the greatest hazard of nitrogen narcosis. Divers may
display abnormal behavior such as removing the regulator mouthpiece or swimming
to unsafe depths without regard to decompression sickness or air supply.
3‑9.1.3

Treatment of Nitrogen Narcosis. The treatment for nitrogen narcosis is to bring the

diver to a shallower depth where the effects are not felt. The narcotic effects will
rapidly dissipate during the ascent. There is no hangover associated with nitrogen
narcosis.
3‑9.1.4

Prevention of Nitrogen Narcosis. Experienced and stable divers may be reasonably
productive and safe at depths where others fail. They are familiar with the extent to
which nitrogen narcosis impairs performance. They know that a strong conscious
effort to continue the dive requires unusual care, time, and effort to make even
the simplest observations and decisions. Any relaxation of conscious effort can
lead to failure or a fatal blunder. Experience, frequent exposure to deep diving,
and training may enable divers to perform air dives as deep as 180-200 fsw, but
novices and susceptible individuals should remain at shallower depths or dive with
helium-oxygen mixtures.

Helium is widely used in mixed-gas diving as a substitute for nitrogen to prevent
narcosis. Helium has not demonstrated narcotic effects at any depth tested by the
U.S. Navy. Diving with helium-oxygen mixtures is the only way to prevent nitrogen
narcosis. Helium-oxygen mixtures should be considered for any dive in excess of
150 fsw.
3-9.2

Oxygen Toxicity. Exposure to a partial pressure of oxygen above that encountered

in normal daily living may be toxic to the body. The extent of the toxicity is
dependent upon both the oxygen partial pressure and the exposure time. The higher
the partial pressure and the longer the exposure, the more severe the toxicity. The
two types of oxygen toxicity experienced by divers are pulmonary oxygen toxicity
and central nervous system (CNS) oxygen toxicity.
3‑9.2.1

Pulmonary Oxygen Toxicity. Pulmonary oxygen toxicity, sometimes called low

pressure oxygen poisoning, can occur whenever the oxygen partial pressure
exceeds 0.5 ata. A 12 hour exposure to a partial pressure of 1 ata will produce mild
symptoms and measurable decreases in lung function. The same effect will occur
with a 4 hour exposure at a partial pressure of 2 ata.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-41

Long exposures to higher levels of oxygen, such as administered during Recom­
pression Treatment Tables 4, 7, and 8, may produce pulmonary oxygen toxicity.
The symptoms of pulmonary oxygen toxicity may begin with a burning sensation
on inspiration and progress to pain on inspiration. During recompression treat­
ments, pulmonary oxygen toxicity may have to be tolerated in patients with severe
neurological symptoms to effect adequate treatment. In conscious patients, the
pain and coughing experienced with inspiration eventually limit further exposure
to oxygen. Unconscious patients who receive oxygen treatments do not feel pain
and it is possible to subject them to exposures resulting in permanent lung damage
or pneumonia. For this reason, care must be taken when administering 100 percent
oxygen to unconscious patients even at surface pressure.
Return to normal pulmonary function gradually occurs after the exposure is termi­
nated. There is no specific treatment for pulmonary oxygen toxicity.
The only way to avoid pulmonary oxygen toxicity completely is to avoid the
long exposures to moderately elevated oxygen partial pressures that produce it.
However, there is a way of extending tolerance. If the oxygen exposure is period­
ically interrupted by a short period of time at low oxygen partial pressure, the total
exposure time needed to produce a given level of toxicity can be increased signifi­
cantly. This is the basis for the “air breaks” commonly seen in both decompression
and recompression treatment tables.
3‑9.2.2

3‑9.2.2.1

Central Nervous System (CNS) Oxygen Toxicity. Central nervous system (CNS)
oxygen toxicity, sometimes called high pressure oxygen poisoning, can occur
whenever the oxygen partial pressure exceeds 1.3 ata in a wet diver or 2.4 ata in a
dry diver. The reason for the marked increase in susceptibility in a wet diver is not
completely understood. At partial pressures above the respective 1.3 ata wet and
2.4 ata dry thresholds, the risk of CNS toxicity is dependent on the oxygen partial
pressure and the exposure time. The higher the partial pressure and the longer the
exposure time, the more likely CNS symptoms will occur. This gives rise to partial
pressure of oxygen-exposure time limits for various types of diving.
Factors Affecting the Risk of CNS Oxygen Toxicity. A number of factors are

known to influence the risk of CNS oxygen toxicity:

Individual Susceptibility. Susceptibility to CNS oxygen toxicity varies markedly
from person to person. Individual susceptibility also varies markedly from time to
time and for this reason divers may experience CNS oxygen toxicity at exposure
times and pressures previously tolerated. Individual variability makes it difficult to
set oxygen exposure limits that are both safe and practical.
CO2 Retention. Hypercapnia greatly increases the risk of CNS toxicity probably
through its effect on increasing brain blood flow and consequently brain oxygen
levels. Hypercapnia may result from an accumulation of CO2 in the inspired gas
or from inadequate ventilation of the lungs. The latter is usually due to increased
breathing resistance or a suppression of respiratory drive by high inspired ppO2.
Hypercapnia is most likely to occur on deep dives and in divers using closed and
semi-closed circuit rebreathers.
3-42

U.S. Navy Diving Manual — Volume 1

Exercise. Exercise greatly increases the risk of CNS toxicity, probably by increasing
the degree of CO2 retention. Exposure limits must be much more conservative for
exercising divers than for resting divers.
Immersion in Water. Immersion in water greatly increases the risk of CNS toxicity.
The precise mechanism for the big increase in risk over comparable dry chamber
exposures is unknown, but may involve a greater tendency for diver CO2 retention
during immersion. Exposure limits must be much more conservative for immersed
divers than for dry divers.
Depth. Increasing depth is associated with an increased risk of CNS toxicity even
though ppO2 may remain unchanged. This is the situation with UBAs that control
the oxygen partial pressure at a constant value, like the MK 16. The precise mech­
anism for this effect is unknown, but is probably more than just the increase in gas
density and concomitant CO2 retention. There is some evidence that the inert gas
component of the gas mixture accelerates the formation of damaging oxygen free
radicals. Exposure limits for mixed gas diving must be more conservative than for
pure oxygen diving.
Intermittent Exposure. Periodic interruption of high ppO2 exposure with a 5-15
min exposure to low ppO2 will reduce the risk of CNS toxicity and extend the total
allowable exposure time to high ppO2. This technique is most often employed in
hyperbaric treatments and surface decompression.
Because of these modifying influences, allowable oxygen exposure times vary
from situation to situation and from diving system to diving system. In general,
closed and semi-closed circuit rebreathing systems require the lowest partial pres­
sure limits, whereas surface-supplied open-circuit systems permit slightly higher
limits. Allowable oxygen exposure limits for each system are discussed in later
chapters.
3‑9.2.2.2

Symptoms of CNS Oxygen Toxicity. The most serious direct consequence of

oxygen toxicity is convulsions. Some­times recognition of early symptoms may
provide sufficient warning to permit reduction in oxygen partial pressure and
prevent the onset of more serious symp­toms. The warning symptoms most often
encountered also may be remembered by the mnemonic VENTIDC:
V:

Visual symptoms. Tunnel vision, a decrease in diver’s peripheral vision, and
other symptoms, such as blurred vision, may occur.

E:

Ear symptoms. Tinnitus, any sound perceived by the ears but not resulting
from an external stimulus, may resemble bells ringing, roaring, or a
machinery-like pulsing sound.

N:

Nausea or spasmodic vomiting. These symptoms may be intermittent.

T:

Twitching and tingling symptoms. Any of the small facial muscles, lips, or
muscles of the extremities may be affected. These are the most frequent and
clearest symptoms.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-43

I:

Irritability. Any change in the diver’s mental status including confusion,
agitation, and anxiety.

D:

Dizziness. Symptoms include clumsiness, incoordination, and unusual
fatigue.

C:

Convulsions. The first sign of CNS oxygen toxicity may be convulsions that
occur with little or no warning.

Warning symptoms may not always appear and most are not exclusively symp­toms
of oxygen toxicity. Muscle twitching is perhaps the clearest warning, but it may
occur late, if at all. If any of these warning symptoms occur, the diver should take
immediate action to lower the oxygen partial pressure.
A convulsion, the most serious direct consequence of CNS oxygen toxicity, may
occur suddenly without being preceded by any other symptom. During a convul­
sion, the individual loses consciousness and his brain sends out uncontrolled nerve
impulses to his muscles. At the height of the seizure, all of the muscles are stimu­
lated at once and lock the body into a state of rigidity. This is referred to as the
tonic phase of the convulsion. The brain soon fatigues and the number of impulses
slows. This is the clonic phase and the random impulses to various muscles may
cause violent thrashing and jerking for a minute or so.
After the convulsive phase, brain activity is depressed and a postconvulsive
(postictal) depression follows. During this phase, the patient is usually uncon­
scious and quiet for a while, then semiconscious and very restless. He will then
usually sleep on and off, waking up occasionally though still not fully rational. The
depression phase sometimes lasts as little as 15 minutes, but an hour or more is not
uncommon. At the end of this phase, the patient often becomes suddenly alert and
complains of no more than fatigue, muscular soreness, and possibly a headache.
After an oxygen-toxicity convulsion, the diver usually remembers clearly the
events up to the moment when consciousness was lost, but remembers nothing of
the convulsion itself and little of the postictal phase.
3‑9.2.2.3

WARNING

3-44

Treatment of CNS Oxygen Toxicity. A diver who experiences the warning
symptoms of oxygen toxicity shall inform the Diving Supervisor immediately. The
following actions can be taken to lower the oxygen partial pressure:
■

Ascend

■

Shift to a breathing mixture with a lower oxygen percentage

■

In a recompression chamber, remove the mask.

Reducing the oxygen partial pressure does not instantaneously reverse
the biochemical changes in the central nervous system caused by high
oxygen partial pressures. If one of the early symptoms of oxygen toxicity
occurs, the diver may still convulse up to a minute or two after being
removed from the high oxygen breathing gas. One should not assume

U.S. Navy Diving Manual — Volume 1

that an oxygen convulsion will not occur unless the diver has been off
oxygen for 2 or 3 minutes.

Despite its rather alarming appearance, the convulsion itself is usually not much
more than a strenuous muscular workout for the victim. The possible danger of
hypoxia during breathholding in the tonic phase is greatly reduced because of the
high partial pressure of oxygen in the tissues and brain. If a diver convulses, the UBA
should be ventilated immediately with a gas of lower oxygen content, if possible. If
depth control is possible and the gas supply is secure (helmet or full face mask), the
diver should be kept at depth until the convulsion subsides and normal breathing
resumes. If an ascent must take place, it should be done as slowly as possible to
reduce the risk of an arterial gas embolism. A diver surfacing unconscious because
of an oxygen convulsion must be treated as if suffering from arterial gas embolism.
Arterial gas embolism cannot be ruled out in an uncon­scious diver.
If the convulsion occurs in a recompression chamber, it is important to keep the
individual from thrashing against hard objects and being injured. Complete restraint
of the individual’s movements is neither necessary nor desirable. The oxygen mask
shall be removed immediately. It is not necessary to force the mouth open to insert
a bite block while a convulsion is taking place. After the convulsion subsides and
the mouth relaxes, keep the jaw up and forward to maintain a clear airway until the
diver regains consciousness. Breathing almost invariably resumes spontaneously.
Management of CNS oxygen toxicity during recompression therapy is discussed
fully in Volume 5.
If a convulsing diver is prevented from drowning or causing other injury to himself,
full recovery with no lasting effects can be expected within 24 hours. Susceptibility
to oxygen toxicity does not increase as a result of a convulsion, although divers
may be more inclined to notice warning symptoms during subse­quent exposures
to oxygen.
3‑9.2.2.4

3-9.3

3‑9.3.1

Prevention of CNS Oxygen Toxicity. The actual mechanism of CNS oxygen
toxicity remains unknown in spite of many theories and much research. Preventing
oxygen toxicity is important to divers. When use of high pressures of oxygen is
advantageous or necessary, divers should take sensible precautions, such as being
sure the breathing apparatus is in good order, observing depth-time limits, avoiding
excessive exertion, and heeding abnormal symptoms that may appear. Interruption
of oxygen breathing with peri­odic “air” breaks can extend the exposure time to
high oxygen partial pressures significantly. Air breaks are routinely incorporated
into recompression treatment tables and some decompression tables.
Decompression Sickness (DCS). A diver’s blood and tissues absorb additional
nitrogen (or helium) from the lungs when at depth. If a diver ascends too fast this
excess gas will separate from solu­tion and form bubbles. These bubbles produce
mechanical and biochemical effects that lead to a condition known as decompression sickness.
Absorption and Elimination of Inert Gases. The average human body at sea level

contains about 1 liter of nitrogen. All of the body tissues are saturated with nitro-

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-45

gen at a partial pressure equal to the partial pressure in the alveoli, about 0.79 ata.
If the partial pressure of nitrogen changes because of a change in the pressure or
composition of the breathing mixture, the pressure of the nitrogen dissolved in
the body gradually attains a matching level. Additional quantities of nitrogen are
absorbed or eliminated, depending on the partial pressure gradient, until the partial
pressure of the gas in the lungs and in the tissues is equal. If a diver breathes helium, a similar process occurs.
As described by Henry’s Law, the amount of gas that dissolves in a liquid is almost
directly proportional to the partial pressure of the gas. If one liter of inert gas is
absorbed at a pressure of one atmosphere, then two liters are absorbed at two atmospheres and three liters at three atmospheres, etc.
The process of taking up more inert gas is called absorption or saturation. The process of giving up inert gas is called elimination or desaturation. The chain of events
is essentially the same in both processes even though the direction of exchange is
opposite.
Shading in diagram (Figure 3‑16) indicates saturation with nitrogen or helium under increased pressure. Blood becomes saturated on passing through lungs, and
tissues are saturated in turn via blood. Those with a large supply (as in A above) are
saturated much more rapidly than those with poor blood supply (C) or an unusually
large capacity for gas, as fatty tissues have for nitrogen. In very abrupt ascent from
depth, bubbles may form in arterial blood or in “fast” tissue (A) even through the
body as a whole is far from saturation. If enough time elapses at depth, all tissues
will become equally saturated, as shown in lower diagram.
3‑9.3.1.1

Saturation of Tissues. The sequence of events in the process of saturation can be

illustrated by consid­ering what happens in the body of a diver taken rapidly from
the surface to a depth of 100 fsw (Figure 3‑16). To simplify matters, we can say
that the partial pressure of nitrogen in his blood and tissues on leaving the surface
is roughly 0.8 ata. When the diver reaches 100 fsw, the alveolar nitrogen pressure
in his lungs will be about 0.8 × 4 ata = 3.2 ata, while the blood and tissues remain
temporarily at 0.8 ata. The partial pressure difference or gradient between the alveolar air and the blood and tissues is thus 3.2 minus 0.8, or 2.4 ata. This gradient
is the driving force that makes the molecules of nitrogen move by diffusion from
one place to another. Consider the following 10 events and factors in the diver at
100 fsw:
1. As blood passes through the alveolar capillaries, nitrogen molecules move from the

alveolar air into the blood. By the time the blood leaves the lungs, it has reached
equilibrium with the new alveolar nitrogen pressure. It now has a nitrogen tension
(partial pressure) of 3.2 ata and contains about four times as much nitrogen as
before. When this blood reaches the tissues, there is a similar gradient and nitrogen
molecules move from the blood into the tissues until equilibrium is reached.

3-46

U.S. Navy Diving Manual — Volume 1

SATURATION OF TISSUES
Lung
Capillary
Bed

Venous Return
Right
Heart
Pump

A

B

C

Arterial Supply

Left
Heart
Pump

Lung
Capillary
Bed

Venous Return
Right
Heart
Pump

Left
Heart
Pump

A

B

C

Arterial Supply

Figure 3-16. Saturation of Tissues. Shading in diagram indicates saturation with nitrogen
or helium under increased pressure. Blood becomes saturated on passing through lungs,
and tissues are saturated in turn via blood. Those with a large supply (as in A above) are
saturated much more rapidly than those with poor blood supply (C) or an unusually large
capacity for gas, as fatty tissues have for nitrogen. In very abrupt ascent from depth,
bubbles may form in arterial blood or in “fast” tissue (A) even through the body as a whole
is far from saturation. If enough time elapses at depth, all tissues will become equally
saturated, as shown in lower diagram. 

2. The volume of blood in a tissue is relatively small compared to the volume of the

tissue and the blood can carry only a limited amount of nitrogen. Because of this,
the volume of blood that reaches a tissue over a short period of time loses its excess
nitrogen to the tissue without greatly increasing the tissue nitrogen pressure.

3. When the blood leaves the tissue, the venous blood nitrogen pressure is equal to

the new tissue nitrogen pressure. When this blood goes through the lungs, it again
reaches equilibrium at 3.2 ata.
4. When the blood returns to the tissue, it again loses nitrogen until a new equilibrium

is reached.
5. As the tissue nitrogen pressure rises, the blood-tissue gradient decreases, slowing

the rate of nitrogen exchange. The rate at which the tissue nitrogen partial pressure increases, therefore, slows as the process proceeds. However, each volume
of blood that reaches the tissue gives up some nitrogen which increases the tissue

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-47

partial pressure until complete saturation, in this case at 3.2 ata of nitrogen, is
reached.
6. Tissues that have a large blood supply in proportion to their own volume have

more nitrogen delivered to them in a certain amount of time and therefore approach
complete saturation more rapidly than tissues that have a poor blood supply.
7. All body tissues are composed of lean and fatty components. If a tissue has an

unusually large capacity for nitrogen, it takes the blood longer to deliver enough
nitrogen to saturate it completely. Nitrogen is about five times as soluble (capable
of being dissolved) in fat as in water. Therefore, fatty tissues require much more
nitrogen and much more time to saturate them completely than lean (watery)
tissues do, even if the blood supply is ample. Adipose tissue (fat) has a poor blood
supply and therefore saturates very slowly.
8. At 100 fsw, the diver’s blood continues to take up more nitrogen in the lungs and

to deliver more nitrogen to tissues, until all tissues have reached saturation at a
pressure of 3.2 ata of nitrogen. A few watery tissues that have an excellent blood
supply will be almost completely saturated in a few minutes. Others, like fat with
a poor blood supply, may not be completely saturated unless the diver is kept at
100 fsw for 72 hours or longer.
9. If kept at a depth of 100 fsw until saturation is complete, the diver’s body contains

about four times as much nitrogen as it did at the surface. Divers of average size
and fatness have about one liter of dissolved nitrogen at the surface and about
four liters at 100 fsw. Because fat holds about five times as much nitrogen as lean
tissues, much of a diver’s nitrogen content is in his fatty tissue.
10. An important fact about nitrogen saturation is that the process requires the same

length of time regardless of the nitrogen pressure involved. For example, if the
diver had been taken to 33 fsw instead of 100, it would have taken just as long to
saturate him completely and to bring his nitrogen pressures to equilibrium. In this
case, the original gradient between alveolar air and the tissues would have been
only 0.8 ata instead of 2.4 ata. Because of this, the amount of nitrogen delivered
to tissues by each round of blood circulation would have been smaller from the
beginning. Less nitrogen would have to be delivered to saturate him at 33 fsw, but
the slower rate of delivery would cause the total time required to be the same.

When any other inert gas, such as helium, is used in the breathing mixture, the
body tissues become saturated with that gas in the same process as for nitrogen.
However, the time required to reach saturation is different for each gas. This is
because the blood and tissue solubilities are different for the different inert gases.
Helium, for example, is much less soluble in fat than nitrogen is.
3‑9.3.1.2

Desaturation of Tissues. The process of desaturation is the reverse of saturation

(Figure 3‑17). If the partial pressure of the inert gas in the lungs is reduced, either
through a reduction in the diver’s depth or a change in the breathing medium, the
new pressure gradient induces the nitrogen to diffuse from the tissues to the blood,
from the blood to the gas in the lungs, and then out of the body with the expired
breath. Some parts of the body desaturate more slowly than others for the same

3-48

U.S. Navy Diving Manual — Volume 1

DESATURATION OF TISSUES
Lung
Capillary
Bed

Venous Return
Right
Heart
Pump

A

B

C

Arterial Supply

Left
Heart
Pump

Lung
Capillary
Bed

Venous Return
Right
Heart
Pump

Left
Heart
Pump

A

B

C

Arterial Supply

Figure 3-17. Desaturation of Tissues. The desaturation process is essentially the reverse
of saturation. When pressure of inert gas is lowered, blood is cleared of excess gas as
it goes through the lungs. Blood then removes gas from the tissues at rates depending
on amount of blood that flows through them each minute. Tissues with poor blood supply
(as in C in upper sketch) or large gas capacity will lag behind and may remain partially
saturated after others have cleared (see lower diagram). 

reason that they saturate more slowly: poor blood supply or a greater capacity
to store inert gas. Washout of excess inert gas from these “slow” tissues will lag
behind washout from the faster tissues.
3‑9.3.2

Bubble Formation. Inert gas may separate from physical solution and form bub-

bles if the partial pres­sure of the inert gas in blood and tissues exceeds the ambient
pressure by more than a critical amount. During descent and while the diver is on
the bottom, blood and tissue inert gas partial pressures increase significantly as
tissue saturation takes place, but the inert gas pressure always remains less than
the ambient pres­sure surrounding the diver. Bubbles cannot form in this situation.
During ascent the converse is true. Blood and tissue inert gas pressures fall as the
tissues desatu­rate, but blood and tissue inert gas pressures can exceed the ambient
pressure if the rate of ascent is faster than the rate at which tissues can equilibrate.
Consider an air diver fully saturated with nitrogen at a depth of 100 fsw. All body
tissues have a nitrogen partial pressure of 3.2 ata. If the diver were to quickly ascend to the surface, the ambient pressure surrounding his tissues would be reduced
to 1 ata. Assuming that ascent was fast enough not to allow for any tissue desaturation, the nitrogen pressure in all the tissues would be 2.2 ata greater than the ambient pres­sure (3.2 ata - 1 ata). Under this circumstance bubbles can form.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-49

Bubble formation can be avoided if the ascent is controlled in such a way that the
tissue inert gas pressure never exceeds the ambient pressure by more than the crit­
ical amount. This critical amount, called the allowable supersaturation, varies from
tissue to tissue and from one inert gas to another. A decompression table shows the
time that must be spent at various decompression stops on the way to the surface
to allow each tissue to desaturate to the point where its allowable supersaturation
is not exceeded.
3‑9.3.3

Direct Bubble Effects. Bubbles forming in the tissues (autochthonous bubbles)

and in the bloodstream (circulating bubbles) may exert their effects directly in
several ways:
■

Autochthonous bubbles can put pressure on nerve endings, stretch and tear
tissue leading to hemorrhage, and increase pressure in the tissue leading to
slowing or cessation of incoming blood flow. These are thought to be the
primary mechanisms for injury in Spinal Cord, Musculoskeletal, and Inner Ear
DCS.

■

Venous bubbles can partially or completely block the veins draining various
organs leading to reduced organ blood flow (venous obstruction). Venous
obstruction in turn leads to tissue hypoxia, cell injury and death. This is one of
the secondary mechanisms of injury in Spinal Cord DCS.

■

Venous bubbles carried to the lung as emboli (called venous gas emboli or VGE)
can partially block the flow of blood through the lung leading to fluid build up
(pulmonary edema) and decreased gas exchange. The result is systemic hypoxia
and hypercarbia. This is the mechanism of damage in Pulmonary DCS.

■

Arterial bubbles can act as emboli blocking the blood supply of almost any
tissue leading to hypoxia, cell injury and death. Arterial gas embolism and
autochotonous bubble formation are thought be the primary mechanisms of
injury in Cerebral (brain) DCS.

The damage done by the direct bubble effect occurs within a relatively short
period of time (a few minutes to hours). The primary treatment for these effects
is recompression. Recompression will compress the bubble to a smaller diameter,
restore blood flow, decrease venous congestion, and improve gas exchange in
the lungs and tissues. It also increases the speed at which the bubbles outgas and
collapse.
3‑9.3.4

Indirect Bubble Effects. Bubbles may also exert their effects indirectly because a

bubble acts like a foreign body. The body reacts as it would if there were a cinder
in the eye or a splinter in the hand. The body’s defense mechanisms become alerted
and try to eliminate the foreign body. Typical reactions include:
■

3-50

Blood vessels become “leaky” due to damage to the endothelial lining cells
and chemical release. Blood plasma leaks out while blood cells remain inside.
The blood becomes thick and more difficult to pump. Organ blood flow is
reduced.

U.S. Navy Diving Manual — Volume 1

■

The platelet system becomes active and the platelets gather at the site of the
bubble causing a clot to form.

■

The injured tissue releases fats that clump together in the bloodstream. These
fat clumps act as emboli, causing tissue hypoxia.

■

Injured tissues release histamine and histamine-like substances, causing edema,
which leads to allergic-type problems of shock and respiratory distress.

Indirect bubble effects take place over a longer period of time than the direct
bubble effects. Because the non-compressible clot replaces a compressible bubble,
recompression alone is not enough. To restore blood flow and relieve hypoxia,
hyperbaric treatment and other therapies are often required.
3‑9.3.5

Symptoms of Decompression Sickness. Decompression sickness is generally

divided into two categories. Type I decom­pression sickness involves the
skin, lymphatic system, muscles and joints and is not life threatening. Type II
decompression sickness (also called serious decom­pression sickness) involves the
nervous system, respiratory system, or circulatory system. Type II decompression
sickness may become life threatening. Because the treatment of Type I and Type
II decompression sickness may be different, it is important to distinguish between
these two types. Symptoms of Type I and Type II decompression sickness may be
present at the same time.
When the skin is involved, the symptoms are itching or burning usually accompa­
nied by a rash. Involvement of the lymphatic system produces swelling of regional
lymph nodes or an extremity. Involvement of the musculoskeletal system produces
pain, which in some cases can be excruciating. Bubble formation in the brain can
produce blindness, dizziness, paralysis and even unconsciousness and convulsion.
When the spinal cord is involved, paralysis and/or loss of feeling occur. Bubbles
in the inner ear produce hearing loss and vertigo. Bubbles in the lungs can cause
coughing, shortness of breath, and hypoxia, a condition referred to as “the chokes.”
This condition may prove fatal. A large number of bubbles in the circula­tion can
lead to cardiovascular collapse and death. Unusual fatigue or exhaustion after a
dive is probably due to bubbles in unusual locations and the biochemical changes
they have induced. While not attributable to a specific organ system, unusual
fatigue is a definite symptom of decompression sickness.
3‑9.3.5.1

Time Course of Symptoms. Decompression sickness usually occurs after surfacing.

If the dive is particularly arduous or decompression has been omitted, however, the
diver may experience decompression sickness before reaching the surface.

After surfacing, there is a latency period before symptoms appear. This may be
as short as several minutes to as long as several days. Long, shallow dives are
gener­ally associated with longer latencies than deep, short dives. For most dives,
the onset of decompression sickness can be expected within several hours of
surfacing.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-51

3‑9.3.6

Treating Decompression Sickness. Treatment of decompression sickness is

accomplished by recompression. This involves putting the victim back under
pressure to reduce the size of the bubbles to cause them to go back into solution and
to supply extra oxygen to the hypoxic tissues. Treatment is done in a recompression
chamber, but can sometimes be accomplished in the water if a chamber cannot
be reached in a reasonable period of time. Recompression in the water is not
recommended, but if undertaken, must be done following specified procedures.
Further discussion of the symptoms of decompression sickness and a complete
discussion of treatment are presented in Volume 5.
3‑9.3.7

Preventing Decompression Sickness. Prevention of decompression sickness is

generally accomplished by following the decompression tables. However, individual
susceptibility or unusual conditions, either in the diver or in connection with the
dive, produces a small percentage of cases even when proper dive procedures are
followed meticulously. To be abso­lutely free of decompression sickness under all
possible circumstances, the decompression time specified would have to be far in
excess of that normally needed. On the other hand, under ideal circumstances, some
individuals can ascend safely in less time than the tables specify. This must not be
taken to mean that the tables contain an unnecessarily large safety factor. The tables
represent the minimum workable decompression time that permits average divers
to surface safely from normal working dives without an unacceptable incidence of
decom­pression sickness.
3-10

THERMAL PROBLEMS IN DIVING

The human body functions effectively within a relatively narrow range of internal
temperature. The average, or normal, core temperature of 98.6°F (37°C) is main­
tained by natural mechanisms of the body, aided by artificial measures such as the
use of protective clothing or environmental conditioning when external conditions
tend toward cold or hot extremes.
Thermal problems, arising from exposure to various temperatures of water, pose
a major consideration when planning operational dives and selecting equipment.
Bottom time may be limited more by a diver’s intolerance to heat or cold than his
exposure to increased oxygen partial pressures or the amount of decompression
required.
The diver’s thermal status will affect the rate of inert gas uptake and elimination.
Recent studies suggest divers who are warm on the bottom but cold during decom­
pression may more susceptible to decompression sickness. This may require
modification of a diver’s decompression schedule. Rewarming before a repetitive
dive is as important as accounting for residual nitrogen levels.
3-10.1

Regulating Body Temperature. The metabolic processes of the body constantly

generate heat. If heat is allowed to build up inside the body, damage to the cells can
occur. To maintain internal temperature at the proper level, the body must lose heat
equal to the amount it produces.

3-52

U.S. Navy Diving Manual — Volume 1

Heat transfer is accomplished in several ways. The blood, while circulating through
the body, picks up excess heat and carries it to the lungs, where some of it is lost
with the exhaled breath. Heat is also transferred to the surface of the skin, where
much of it is dissipated through a combination of conduction, convection, and
radiation. Moisture released by the sweat glands cools the surface of the body as it
evaporates and speeds the transfer of heat from the blood to the surrounding air. If
the body is working hard and generating greater than normal quantities of heat, the
blood vessels nearest the skin dilate to permit more of the heated blood to reach the
body surfaces, and the sweat glands increase their activity.
Maintaining proper body temperature is particularly difficult for a diver working
underwater. The principal temperature control problem encountered by divers is
keeping the body warm. The high thermal conductivity of water, coupled with
the normally cool-to-cold waters in which divers operate, can result in rapid and
excessive heat loss.
3-10.2

Excessive Heat Loss (Hypothermia). Hypothermia is a lowering of the core

temperature of the body. Immersion hypoth­ermia is a potential hazard whenever
diving operations take place in cool to cold waters. A diver’s response to
immersion in cold water depends on the degree of thermal protection worn and
water temperature. A water temperature of approxi­mately 91°F (33°C) is required
to keep an unprotected, resting man at a stable temperature. The unprotected diver
will be affected by excessive heat loss and become chilled within a short period of
time in water temperatures below 72°F (23°C).
3‑10.2.1

3‑10.2.2

Causes of Hypothermia. Hypothermia in diving occurs when the difference
between the water and body temperature is large enough for the body to lose
more heat than it produces. Exer­cise normally increases heat production and body
temperature in dry conditions. Paradoxically, exercise in cold water may cause
the body temperature to fall more rapidly. Any movement that stirs the water in
contact with the skin creates turbu­lence that carries off heat (convection). Heat loss
is caused not only by convection at the limbs, but also by increased blood flow into
the limbs during exercise. Continual movement causes the limbs to resemble the
internal body core rather than the insulating superficial layer. These two conflicting
effects result in the core temperature being maintained or increased in warm water
and decreased in cold water.
Symptoms of Hypothermia. In mild cases, the victim will experience uncontrolled

shivering, slurred speech, imbalance, and/or poor judgment. Severe cases of
hypothermia are characterized by loss of shivering, impaired mental status,
irregular heartbeat, and/or very shallow pulse or respirations. This is a medical
emergency. The signs and symp­toms of falling core temperature are given in Table
3‑1, though individual responses to falling core temperature will vary. At extremely
low temperatures or with prolonged immersion, body heat loss reaches a point at
which death occurs.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-53

Table 3‑1. Signs and Symptoms of Dropping Core Temperature.
Core Temperature
°F
°C

3‑10.2.3

Symptoms

98

37

Cold sensations, skin vasoconstriction, increased muscle tension,
increased oxygen consumption

97

36

Sporadic shivering suppressed by voluntary movements, gross
shivering in bouts, further increase in oxygen consumption,
uncontrollable shivering

95

35

Voluntary tolerance limit in laboratory experiments, mental
confusion, impairment of rational thought, possible drowning,
decreased will to struggle

93

34

Loss of memory, speech impairment, sensory function impairment,
motor performance impairment

91

33

Hallucinations, delusions, partial loss of consciousness, shivering
impaired

90

32

Heart rhythm irregularities, motor performance grossly impaired

88

31

Shivering stopped, failure to recognize familiar people

86

30

Muscles rigid, no response to pain

84

29

Loss of consciousness

80

27

Ventricular fibrillation (ineffective heartbeat), muscles flaccid

79

26

Death

Treatment of Hypothermia. To treat mild hypothermia, passive and active
rewarming measures may be used and should be continued until the victim is
sweating. Rewarming techniques include:

Passive:
■

Remove all wet clothing.

■

Wrap victim in a blanket (preferably wool).

■

Place in an area protected from wind.

■

If possible, place in a warm area (i.e. galley).

Active:
■

Warm shower or bath.

■

Place in a very warm space (i.e., engine room).

To treat severe hypothermia avoid any exercise, keep the victim lying down,
initiate only passive rewarming, and immediately transport to the nearest medical
treatment facility.

3-54

U.S. Navy Diving Manual — Volume 1

CAUTION

Do not institute active rewarming with severe cases of hypothermia.

WARNING

CPR should not be initiated on a severely hypothermic diver unless it can
be determined that the heart has stopped or is in ventricular fibrillation.
CPR should not be initiated in a patient that is breathing.

3‑10.2.4

Prevention of Hypothermia. The body’s ability to tolerate cold environments is
due to natural insulation and a built-in means of heat regulation. Temperature is
not uniform throughout the body. It is more accurate to consider the body in terms
of an inner core where a constant or uniform temperature prevails and a superficial
region through which a tempera­ture gradient exists from the core to the body
surface. Over the trunk of the body, the thickness of the superficial layer may be
1 inch (2.5 cm). The extremities become a superficial insulating layer when their
blood flow is reduced to protect the core.

Once in the water, heat loss through the superficial layer is lessened by the reduc­tion
of blood flow to the skin. The automatic, cold-induced vasoconstriction (narrowing
of the blood vessels) lowers the heat conductance of the superficial layer and acts
to maintain the heat of the body core. Unfortunately, vasoconstric­tive regulation of
heat loss has only a narrow range of protection. When the extremities are initially
put into very cold water, vasoconstriction occurs and the blood flow is reduced to
preserve body heat. After a short time, the blood flow increases and fluctuates up
and down for as long as the extremities are in cold water. As circulation and heat
loss increase, the body temperature falls and may continue falling, even though
heat production is increased by shivering.
Much of the heat loss in the trunk area is transferred over the short distance from
the deep organs to the body surface by physical conduction, which is not under any
physiological control. Most of the heat lost from the body in moderately cold water
is from the trunk and not the limbs.
Hypothermia can be insidious and cause problems without the diver being aware
of it. The diver should wear appropriate thermal protection based upon the water
temperature and expected bottom time (See Chapter 6). Appropriate dress can
greatly reduce the effects of heat loss and a diver with proper dress can work in
very cold water for reasonable periods of time. Acclimatization, adequate hydra­
tion, experience, and common sense all play a role in preventing hypothermia.
Provide the diver and topside personnel adequate shelter from the elements.
Adequate predive hydration is essential.
Heat loss through the respiratory tract becomes an increasingly significant factor
in deeper diving. Inhaled gases are heated in the upper respiratory tract and more
energy is required to heat the denser gases encountered at depth. In fact, a severe
respiratory insult can develop if a diver breathes unheated gas while making a
deep saturation dive in cold water. Respiratory gas heating is required in such
situations.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-55

3-10.3

Other Physiological Effects of Exposure to Cold Water. In addition to hypothermia,

other responses to exposure to cold water create poten­tial hazards for the diver.
3‑10.3.1

Caloric Vertigo. The eardrum does not have to rupture for caloric vertigo to occur.

Caloric vertigo can occur simply as the result of having water enter the external ear
canal on one side but not the other. The usual cause is a tight fitting wet suit hood
that allows cold water access to one ear, but not the other. It can also occur when
one external canal is obstructed by wax. Caloric vertigo may occur suddenly upon
entering cold water or when passing through thermoclines. The effect is usually
short lived, but while present may cause significant disorientation and nausea.
3‑10.3.2

3‑10.3.3

Diving Reflex. Sudden exposure of the face to cold water or immersion of the whole
body in cold water may cause an immediate slowing of the heart rate (bradycardia)
and intense constriction of the peripheral blood vessels. Sometimes abnormal heart
rhythms accompany the bradycardia. This response is known as the diving reflex.
Removing or losing a facemask in cold water can trigger the diving reflex. It is still
not known whether cardiac arrhythmias associated with the diving reflex contribute
to diving casualties. Until this issue is resolved, it is prudent for divers to closely
monitor each other when changing rigs underwater or buddy breathing.
Uncontrolled Hyperventilation. If a diver with little or no thermal protection is

suddenly plunged into very cold water, the effects are immediate and disabling.
The diver gasps and his respiratory rate and tidal volume increase. His breathing
becomes so rapid and uncontrolled that he cannot coordinate his breathing and
swimming movements. The lack of breathing control makes survival in rough
water very unlikely.

3-56

3-10.4

Excessive Heat Gain (Hyperthermia). Hyperthermia is a raising of the core
temperature of the body. Hyperthermia should be considered a potential risk
any time air temperature exceeds 90°F or water temperature is above 82°F. An
individual is considered to have developed hyperthermia when core temperature
rises 1.8°F (1°C) above normal (98.6°F, 37°C). The body core temperature should
not exceed 102.2°F (39°C). By the time the diver’s core temperature approaches
102°F noticeable mental confusion may be present.

3‑10.4.1

Causes of Hyperthermia. Divers are susceptible to hyperthermia when they are
unable to dissipate their body heat. This may result from high water temperatures,
protective garments, rate of work, and the duration of the dive. Predive heat
exposure may lead to signifi­cant dehydration and put the diver at greater risk of
hyperthermia.

3‑10.4.2

Symptoms of Hyperthermia. Signs and symptoms of hyperthermia can vary among
individuals. Since a diver might have been in water that may not be considered
hot, support personnel must not rely solely on classical signs and symptoms of
heat stress for land exposures. Table 3‑2 lists commonly encountered signs and
symptoms of heat stress in diving. In severe cases of hyperthermia (severe heat
exhaustion or heat stroke), the victim will experience disorientation, tremors, loss
of consciousness and/or seizures.

U.S. Navy Diving Manual — Volume 1

Table 3‑2. Signs of Heat Stress.

Least Severe

High breathing rate
Feeling of being hot, uncomfortable
Low urine output
Inability to think clearly
Fatigue
Light-headedness or headache
Nausea
Muscle cramps
Sudden rapid increase in pulse rate
Disorientation, confusion
Exhaustion
Collapse

Most Severe

3‑10.4.3

Death

Treatment of Hyperthermia. The treatment of all cases of hyperthermia shall

include cooling of the victim to reduce the core temperature. In mild to moderate
hyperthermia cooling should be started immediately by removing the victim’s
clothing, spraying him with a fine mist of lukewarm-to-cool water, and then fanning.
This causes a large increase in evaporative cooling. Avoid whole body immersion
in cold water or packing the body in ice as this will cause vasoconstriction which
will decrease skin blood flow and may slow the loss of heat. Ice packs to the neck,
armpit or groin may be used. Oral fluid replacement should begin as soon as the
victim can drink and continue until he has urinated pale to clear urine several
times. If the symptoms do not improve, the victim shall be transported to a medical
treatment facility.
Severe hyperthermia is a medical emergency. Cooling measures shall be started
and the victim shall be transported immediately to a medical treatment facility.
Intravenous fluids should be administered during transport.

3‑10.4.4

Prevention of Hyperthermia. Acclimatization, adequate hydration, experience, and

common sense all play a role in preventing hyperthermia. Shelter personnel from
the sun and keep the amount of clothing worn to a minimum. Adequate predive
hydration is essential. Alcohol or caffeine beverages should be avoided since they
can produce dehydra­tion. Medications containing antihistamines or aspirin should
not be used in warm water diving. Physically fit individuals and those with lower
levels of body fat are less likely to develop hyperthermia. Guidelines for diving in
warm water are contained in Chapter 6.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-57

Acclimatization is the process where repeated exposures to heat will reduce
(but not eliminate) the rise in core temperature. At least 5 consecutive days of
acclima­tization to warm water diving are needed to see an increased tolerance
to heat. Exercise training is essential for acclimation to heat. Where possible,
acclimatiza­tion should be completed before attempting long duration working
dives. Acclimatization should begin with short exposures and light workloads. All
support personnel should also be heat acclimatized. Fully acclimatized divers can
still develop hyperthermia, however. Benefits of acclimatization begin to disap­pear
in 3 to 5 days after stopping exposure to warm water.
3-11

SPECIAL MEDICAL PROBLEMS ASSOCIATED WITH DEEP DIVING
3-11.1

High Pressure Nervous Syndrome (HPNS). High Pressure Nervous Syndrome

(HPNS) is a derangement of central nervous system function that occurs during
deep helium-oxygen dives, particularly satura­tion dives. The cause is unknown. The
clinical manifestations include nausea, fine tremor, imbalance, incoordination, loss
of manual dexterity, and loss of alertness. Abdominal cramps and diarrhea develop
occasionally. In severe cases a diver may develop vertigo, extreme indifference to
his surroundings and marked confusion such as inability to tell the right hand from
the left hand. HPNS is first noted between 400 and 500 fsw and the severity appears
to be both depth and compres­sion rate dependent. With slow compression, depth of
1000 fsw may be achieved with relative freedom from HPNS. Beyond 1000 fsw,
some HPNS may be present regardless of the compression rate. Attempts to block
the appearance of the syndrome have included the addition of nitrogen or hydrogen
to the breathing mixture and the use of various drugs. No method appears to be
entirely satisfactory.
3-11.2

Compression Arthralgia. Most divers will experience pain in the joints during

compression on deep dives. This condition is called compression arthralgia. The
shoulders, knees, writs, and hips are the joints most commonly affected. The fingers,
lower back, neck, and ribs may also be involved. The pain may be a constant deep
ache similar to Type I decompression sickness, or a sudden, sharp, and intense
but short-lived pain brought on my movement of the joint. These pains may be
accompanied by “popping” or “cracking” of joints or a dry “gritty” feeling within
the joint.
The incidence and intensity of compression arthralgia symptoms are dependent on
the depth of the dive, the rate of compression, and individual susceptibility. While
primarily a problem of deep saturation diving, mild symptoms may occur with
rapid compression on air or helium-oxygen dives as shallow as 100 fsw. In deep
helium saturation dives with slower compression rates, symptoms of compression
arthralgia usually begins between 200 and 300 fsw, and increase in intensity as
deeper depths are attained. Deeper than 600 fsw, compression pain may occur even
with extremely slow rates of compression.

3-58

U.S. Navy Diving Manual — Volume 1

Compression joint pain may be severe enough to limit diver activity, travel rate, and
depths attainable during downward excursion dives from saturation. Improve­ment
is generally noted during the days spent at the saturation depth but, on occasion,
these pains may last well into the decompression phase of the dive until shallower
depths are reached. Compression pain can be distinguished from decompression
sickness pain because it was present before decompression was started and does
not increase in intensity with decreasing depth.
The mechanism of compression pain is unknown, but is thought to result from the
sudden increase in inert gas tension surrounding the joints causing fluid shifts that
interfere with joint lubrication.
3-12

OTHER DIVING MEDICAL PROBLEMS
3-12.1

Dehydration. Dehydration is a concern to divers, particularly in tropical zones. It is

defined as an excessive loss of water from the body tissues and is accompanied by a
distur­bance in the balance of essential electrolytes, particularly sodium, potassium,
and chloride.
3‑12.1.1

Causes of Dehydration. Dehydration usually results from inadequate fluid intake

and/or excessive perspi­ration in hot climates. Unless adequate attention is paid
to hydration, there is a significant chance the diver in a hot climate will enter the
water in a dehydrated state.
Immersion in water creates a special situation that can lead to dehydration in its
own right. The water pressure almost exactly counterbalances the hydrostatic pres­
sure gradient that exists from head to toe in the circulatory system. As a result,
blood which is normally pooled in the leg veins is translocated to the chest, causing
an increase central blood volume. The body mistakenly interprets the increase
in central blood as a fluid excess. A reflex is triggered leading to an increase in
urination, a condition called immersion diuresis. The increased urine flow leads to
steady loss of water from the body and a concomitant reduction in blood volume
during the dive. The effects of immersion diuresis are felt when the diver leaves
the water. Blood pools once again in the leg veins. Because total blood volume is
reduced, central blood volume falls dramatically. The heart may have difficulty
getting enough blood to pump. The diver may experience light­headness or faint
while attempting to climb out of the water on a ladder or while standing on the
stage. This is the result of a drop in blood pressure as the blood volume shifts to the
legs. More commonly the diver will feel fatigued, less alert, and less able to think
clearly than normal. His exercise tolerance will be reduced.
3‑12.1.2

Preventing Dehydration. Dehydration is felt to increase the risk of decompression

sickness. Divers should monitor their fluid intake and urine output during diving
operations to insure that they keep themselves well hydrated. During the dive
itself, there is nothing one can do to block the effects of immersion diuresis. Upon
surfacing they should rehydrate themselves as soon as the opportunity presents
itself.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-59

3-12.2

Immersion Pulmonary Edema. Immersion in water can cause fluid to leak out of

the circulation system and accu­mulate first in the interstitial tissues of the lungs
then in the alveoli themselves. This condition is called immersion pulmonary
edema. The exact mechanism of injury is not know, but the condition is probably
related to the increase in central blood volume that occurs during immersion (see
description above). Contributing factors include immersion in cold water, negative
pressure breathing, and overhy­dration pre-dive, all of which enhance the increase
in central blood volume with immersion. Heavy exercise is also a contributor.

Symptoms may begin on the bottom, during ascent, or shortly after surfacing and
consist primarily of cough and shortness of breath. The diver may cough up blood
tinged mucus. Chest pain is notably absent. A chest x-ray shows the classic pattern
of pulmonary edema seen in heart failure.
A diver with immersion pulmonary edema should be placed on surface oxygen and
transported immediately to a medical treatment facility. Signs and symptoms will
usually resolve spontaneously over 24 hours with just bed rest and 100% oxygen.
Immersion pulmonary edema is a relatively rare condition, but the incidence appears
to be increasing perhaps because of an over-emphasis on the need to hydrate before
a dive. Adequate pre-dive hydration is essential, but overhydration is to be avoided.
Beyond avoiding overhydration and negative pressure breathing situations, there is
nothing the diver can do to prevent immersion pulmonary edema.
3-12.3

Carotid Sinus Reflex. External pressure on the carotid artery from a tight fitting

neck dam, wet suit, or dry suit can activate receptors in the arterial wall, causing
a decrease in heart rate with possible loss of consciousness. Using an extra-tightfitting dry or wet suit or tight neck dams to decrease water leaks increase the
chances of activation of the carotid reflex and the potential for problems.
3-12.4

Middle Ear Oxygen Absorption Syndrome. Middle ear oxygen absorption
syndrome refers to the negative pressure that may develop in the middle ear
following a long oxygen dive. Gas with a very high percentage of oxygen enters
the middle ear cavity during an oxygen dive. Following the dive, the tissues of
the middle ear slowly absorb the oxygen. If the eustachian tube does not open
spontaneously, a negative pressure relative to ambient may result in the middle ear
cavity. Symptoms are often noted the morning after a long oxygen dive. Middle
ear oxygen absorption syndrome is difficult to avoid but usually does not pose a
significant problem because symp­toms are generally minor and easily eliminated.
There may also be fluid (serous otitis media) present in the middle ear as a result of
the differential pressure.

3‑12.4.1

Symptoms of Middle Ear Oxygen Absorption Syndrome. The diver may notice

mild discomfort and hearing loss in one or both ears. There may also be a sense of
pressure and a moist, cracking sensation as a result of fluid in the middle ear.

3-60

U.S. Navy Diving Manual — Volume 1

3‑12.4.2

Treating Middle Ear Oxygen Absorption Syndrome. Equalizing the pressure in the

middle ear using a normal Valsalva maneuver or the diver’s procedure of choice,
such as swallowing or yawning, will usually relieve the symptoms. Discomfort
and hearing loss resolve quickly, but the middle ear fluid is absorbed more slowly.
If symptoms persist, a Diving Medical Technician or Diving Medical Officer shall
be consulted.

3-12.5

Underwater Trauma. Underwater trauma is different from trauma that occurs at

the surface because it may be complicated by the loss of the diver’s gas supply
and by the diver’s decompression obligation. If possible, injured divers should be
surfaced immedi­ately and treated appropriately. If an injured diver is trapped, the
first priority is to ensure sufficient breathing gas is available, then to stabilize the
injury. At that point, a decision must be made as to whether surfacing is possible.
If the decom­pression obligation is great, the injury will have to be stabilized until
sufficient decompression can be accomplished. If an injured diver must be surfaced
with missed decompression, the diver must be treated as soon as possible, realizing
that the possible injury from decompression sickness may be as severe or more
severe than that from the other injuries.
3-12.6

Blast Injury. Divers frequently work with explosive material or are involved in

combat swim­ming and therefore may be subject to the hazards of underwater
explosions. An explosion is the violent expansion of a substance caused by the
gases released during rapid combustion. One effect of an explosion is a shock wave
that travels outward from the center, somewhat like the spread of ripples produced
by drop­ping a stone into a pool of water. This shock wave moving through the
surrounding medium (whether air or water) passes along some of the force of the
blast.

A shock wave moves more quickly and is more pronounced in water than in air
because of the relative incompressibility of liquids. Because the human body is
mostly water and incompressible, an underwater shock wave passes through the
body with little or no damage to the solid tissues. However, the air spaces of the
body, even though they may be in pressure balance with the ambient pressure, do
not readily transmit the overpressure of the shock wave. As a result, the tissues
that line the air spaces are subject to a violent fragmenting force at the interface
between the tissues and the gas.
The amount of damage to the body is influenced by a number of factors. These
include the size of the explosion, the distance from the site, and the type of explo­
sive (because of the difference in the way the expansion progresses in different
types of explosives). In general, larger, closer, and slower-developing explosions
are more hazardous. The depth of water and the type of bottom (which can reflect
and amplify the shock wave) may also have an effect. Under average conditions, a
shock wave of 500 psi or greater will cause injury to the lungs and intestinal tract.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-61

The extent of injury is also determined in part by the degree to which the diver’s
body is submerged. For an underwater blast, any part of the body that is out of
the water is not affected. Conversely, for an air blast, greater depth provides more
protection. The maximum shock pressure to which a diver should be exposed is 50
psi. The safest and recommended procedure is to have all divers leave the water if
an underwater explosion is planned or anticipated. A diver who anticipates a nearby
underwater explosion should try to get all or as much of his body as possible out
of the water. If in the water, the diver’s best course of action is to float face up,
presenting the thicker tissues of the back to the explosion.
3-12.7

Otitis Externa. Otitis externa (swimmer’s ear) is an infection of the ear canal caused
by repeated immersion. The water in which the dive is being performed does not
have to be contaminated with bacteria for otitis externa to occur. The first symptom
of otitis externa is an itching and/or wet feeling in the affected ear. This feeling
will progress to local pain as the external ear canal becomes swollen and inflamed.
Local lymph nodes (glands) may enlarge, making jaw movement painful. Fever
may occur in severe cases. Once otitis externa develops, the diver should discon­
tinue diving and be examined and treated by Diving Medical Personnel.

Unless preventive measures are taken, otitis externa is very likely to occur during
diving operations, causing unnecessary discomfort and restriction from diving.
External ear prophylaxis, a technique to prevent swimmer’s ear, should be done each
morning, after each wet dive, and each evening during diving operations. External
ear prophylaxis is accomplished using a 2 percent acetic acid in aluminum acetate
(e.g., Otic Domboro) solution. The head is tilted to one side and the external ear
canal gently filled with the solution, which must remain in the canal for 5 minutes.
The head is then tilted to the other side, the solution allowed to run out and the
procedure repeated for the other ear. The 5-minute duration shall be timed with a
watch. If the solution does not remain in the ear a full 5 minutes, the effectiveness
of the procedure is greatly reduced.
During prolonged diving operations, the external ear canal may become occluded
with wax (cerumen). When this happens, external ear prophylaxis is ineffective and
the occurrence of otitis externa will become more likely. The external ear canal can
be examined periodically with an otoscope to detect the presence of ear wax. If the
eardrum cannot be seen during examination, the ear canal should be flushed gently
with water, dilute hydrogen peroxide, or sodium bicarbonate solu­tions to remove
the excess cerumen. Never use swabs or other instruments to remove cerumen;
this is to be done only by trained medical personnel. Otitis externa is a particular
problem in saturation diving if divers do not adhere to prophylactic measures.

3-62

U.S. Navy Diving Manual — Volume 1

3-12.8

Hypoglycemia. Hypoglycemia is an abnormally low blood sugar (glucose) level.

Episodes of hypoglycemia are common in diabetics and pre-diabetics, but may
also occur in normal individuals. Simply missing a meal tends to reduce blood
sugar levels. A few individuals who are otherwise in good health will develop some
degree of hypoglycemia if they do not eat frequently. Severe exercise on an empty
stomach will occasionally bring on symptoms even in an individual who ordinarily
has no abnormality in this respect.
Symptoms of hypoglycemia include unusual hunger, excessive sweating, numb­
ness, chills, headache, trembling, dizziness, confusion, incoordination, anxiety,
and in severe cases, loss of consciousness.
If hypoglycemia is present, giving sugar by mouth relieves the symptoms promptly
and proves the diagnosis. If the victim is unconscious, glucose should be given
intravenously.
The possibility of hypoglycemia increases during long, drawn out diving opera­
tions. Personnel have a tendency to skip meals or eat haphazardly during the
operation. For this reason, attention to proper nutrition is required. Prior to long,
cold, arduous dives, divers should be encouraged to load up on carbohydrates. For
more information, see Naval Medical Research Institute (NMRI) Report 89-94.

CHAPTER 3­—Underwater Physiology and Diving Disorders	

3-63

PAGE LEFT BLANK INTENTIONALLY

3-64

U.S. Navy Diving Manual — Volume 1

CHAPTER 4

Dive Systems
4-1

INTRODUCTION
4-1.1

Purpose. The purpose of this chapter is to promulgate general policy for main­

taining diving equipment and systems.
4-1.2

Scope. This chapter provides general guidance applicable to maintaining all

diving equip­ment and diving systems. Detailed procedures for maintaining diving
equipment and systems are found in applicable military and manufacturer’s
operating and maintenance (O&M) manuals and Planned Maintenance System
(PMS) Mainte­nance Requirement Cards (MRC).
4-2

GENERAL INFORMATION
4-2.1

Document Precedence. If a conflict arises between the documents containing the

maintenance procedures for diving equipment and systems, the following actions
are required:
1. PMS/MRC takes precedence.
2. If PMS/MRC is inadequate or incorrect, the applicable military O&M manual

takes precedence. Report inadequate or incorrect PMS via a PMS feedback report
in accordance with current PMS instructions.

3. If PMS/MRC and applicable military O&M manual are inadequate or incorrect,

the manufacturer’s technical manual takes precedence. Report inadequate or
incorrect military technical manual information in accordance with procedures in
the affected technical manual.

Call NAVSEA or NAVFAC prior to disregarding any required maintenance
pro­ce­dures on certified diving equipment. Failure to do so may compromise
certification.
4-2.2

Equipment Authorized For Navy Use (ANU). Diving equipment used to conduct

diving operations shall be authorized for use by NAVSEA/00C Diving Equipment
Authorized For Navy Use (ANU) list or hold a current NAVSEA or NAVFAC
system safety certification certificate. Naval Sea Systems Command (Code
00C3B), Supervisor of Diving is the cognizant authority for the NAVSEA/00C
ANU list. Surface supplied diving systems, hyper­baric chamber systems, and
selected free swimming SCUBA underwater breathing apparatus shall be certified
in accordance with U.S. Navy Diving and Manned Hyperbaric System Safety
Certification Manual (SS521-AA-MAN-010).
4-2.3

System Certification Authority (SCA). Naval Sea Systems Command Code 00C4
is SCA for all afloat and portable diving and hyperbaric systems. Naval Facilities

CHAPTER 4 ­— Dive Systems	

4-1

Engineering Command Code OFP-SCA is SCA for all shore-based diving
and hyperbaric systems. Naval Sea Systems Command Code 07Q is SCA for
submarine-employed Dry Deck Shelters and one atmosphere diving systems.
4-2.4

Planned Maintenance System. Diving equipment shall be maintained in

accordance with the applicable PMS package. Failure to maintain equipment in
accordance with current PMS guidance reduces the equipment reliability and may
void the system safety certification for formally certified systems.

4-2.5

Alteration of Diving Equipment. Diving equipment shall not be modified or altered

from approved configuration unless prior written approval has been granted by the
applicable diving equipment technical program manager.

4‑2.5.1

Technical Program Managers for Shore-Based Systems. Alterations for shore-

based systems are managed by Naval Facilities Engineering Command (Code
OFP-SCA), who is the cognizant technical authority for the develop­ment and
approval of alterations to shore-based systems.
4‑2.5.2

Technical Program Managers for Other Diving Apparatus. The technical program

managers for other diving apparatus are:






4-2.6

MK 16 MOD 0 - NAVSEASYSCOM (PMS NSW)
MK 16 MOD 1 - NAVSEASYSCOM (PMS-EOD)
MK 20 - NAVSEASYSCOM (SEA 00C)
MK 21 - NAVSEASYSCOM (SEA 00C)
MK 25 - NAVSEASYSCOM (PMS NSW)
Dry Deck Shelter - NAVSEASYSCOM (PMS 399)

Operating and Emergency Procedures. Operating procedures (OPs) are detailed

check sheets for operating the diving system and for performing various systemrelated tasks. All diving and recom­pression chamber systems shall be operated in
accordance with a set of NAVSEA or NAVFAC approved operating procedures
(OPs) and Emergency Operating Procedures (EPs) and requires the Commanding
Officer’s or OIC’s signature on the cover page as final review.
4‑2.6.1

Standardized OP/EPs. Standardized diving equipment such as the Light Weight

MK 3 Surface Supplied Diving System, Transportable Recompression Chamber
System (TRCS), and class-certified equipment such as the MK 16 and MK 25
Underwater Breathing Apparatus shall be operated per a single set of standardized
OP/EPs that are included as part of the system O&M Manual.

Proposed changes/updates to OP/EPs for standardized diving equipment shall be
submitted as a formal change proposal to the respective O&M Manual in accor­
dance with directions contained therein.
4‑2.6.2

Non-standardized OP/EPs. Diving and diving support equipment such as ships,

small boats, and unique shore facility surface supplied diving and recompression
chamber systems shall be oper­ated in accordance with a single set of standard OP/

4-2

U.S. Navy Diving Manual­ — Volume 1

EPs that are developed at the command level and approved for use after validation
by NAVSEA Code 00C3 or NAVFAC Code OFP-SCA. Proposed changes/updates
to OPs/EPs for non-standard­ized diving equipment shall be submitted to the
applicable approval authority. The following addresses are provided to assist in
submitting proposed OP/EP changes and updates.
Submit proposed OP/EP changes and updates for afloat, portable diving and
recompression chamber systems, and class-certified equipment to:
COMNAVSEASYSCOM (Code 00C3)
1333 Isaac Hull Ave., SE
Washington Navy Yard, DC 20376-1070
Submit proposed OP/EP changes and updates for fixed, shore-based facilities to:
COMNAVFACENGCOM (OFP-SCA)
1322 Patterson Ave., SE
Suite 1000
Washington Navy Yard, DC 20374-5065
4‑2.6.3

OP/EP Approval Process. Submission of OPs/EPs for approval (if required) must
precede the requested on-site survey date by 90 calendar days to allow complete
review and resolution of questions. Follow these procedures when submitting OPs/
EPs for approval:

 The command shall validate in the forwarding letter that the OPs/EPs are
complete and accurate.
 The command must verify that drawings are accurate. Accurate drawings are
used as a guide for evaluating OPs/EPs. Fully verified system schematics/
drawings with components, gas consoles, manifolds, and valves clearly labeled
shall be forwarded with the OPs/EPs.
 Approved OPs/EPs shall have the revision date listed on each page and not
have any changes without written NAVSEA/NAVFAC approval.
 The command shall retain system documentation pertaining to DLSS approval,
i.e., PSOBs, supporting manufacturing documentation, and OPs/EPs.
4‑2.6.4

Format. The format for OPs/EPs is as follows:

 System: (Name or description, consistent with drawings)
 Step, Component, Description, Procedure, Location, Initials, Note (read in
seven columns)

CHAPTER 4 ­— Dive Systems	

4-3

4‑2.6.5

Example.

 System: High Pressure Air
 Step/Component/Description/Procedure/Location /Initials /Note
1. ALP-15/Reducer outlet/Open/Salvage Hold/Initials/Note
2. ALP-GA-7/Reducer outlet/Record Pressure/Salvage Hold/Initials/Note 1

The operator executing the procedure shall initial the Check column. Hazards and
items of particular concern shall be identified in the Note column.
Once NAVSEA or NAVFAC has approved the system OP/EPs, they shall not be
changed without specific written approval from NAVSEA or NAVFAC.
4-3

DIVER’S BREATHING GAS PURITY STANDARDS
4-3.1

Diver’s Breathing Air. Diver’s air compressed from ANU or certified diving system

sources shall meet the U.S. Military Diver’s Breathing Air Standards contained in
Table 4-1.

Table 4‑1. U.S. Military Diver’s Compressed Air Breathing Purity Requirements for
ANU Approved or Certified Sources.
Constituent

Specification

Oxygen (percent by volume)

20–22%

Carbon dioxide (by volume)

1,000 ppm (max)

Carbon monoxide (by volume)

20 ppm (max)

Total hydrocarbons (as CH4 by volume)

25 ppm (max)

Odor and taste

Not objectionable

Oil, mist, particulates

5 mg/m3 (max)

Diver’s breathing air may be procured from commercial sources if a source of
military diver’s air is not readily available. Diver’s air procured from commercial
sources shall be certified in writing by the vendor as meeting the purity standards
of FED SPEC BB-A-1034 Grade A Source I (pressurized container) or Source II
(compressor) air. Specifications for this standard are outlined in Table 4‑2.

4-4

U.S. Navy Diving Manual­ — Volume 1

Table 4‑2. Diver’s Compressed Air Breathing Requirements if from Commercial
Source.

Constituent

Specification
Source I
Source II

Oxygen (percent by volume)

20–22%

Carbon dioxide (by volume)

500 ppm (max)

Carbon monoxide (by volume)

10 ppm (max)

Total hydrocarbons [as Methane (CH4) by volume]

25 ppm (max)

Odor

Not objectionable

Oil, mist, particulates

.005 mg/l (max)

Separated Water

None

Total Water

0.02 mg/l (max)

Halogenated Compounds (by volume):
Solvents

0.2 ppm (max)

Reference: FED SPEC BB-A-1034 B

4-3.2

Diver’s Breathing Oxygen. Oxygen used for breathing at 100-percent concentra­

tions and for mixing of diver’s breathing gases shall meet Military Specification
MIL-PRF-27210G, Oxygen, Aviators Breathing, Liquid and Gaseous. The purity
standards are contained in Table 4-3.
Table 4‑3. Diver’s Compressed Oxygen Breathing Purity Requirements.
Specification

Constituent

General Note: Gaseous and liquid oxygen shall contain not less than 99.5% by volume. The remain­
der, except for moisture and minor constituents specified below, shall be Argon and Ni­trogen.
Type I Gaseous
Oxygen (percent by volume)

99.5%

Carbon dioxide (by volume)

10 ppm (max)

Methane (CH4 by volume)

50 ppm (max)

Acetylene (C2H2)

0.1 ppm (max)

Ethylene (C2H4)

0.4 ppm (max)

Ethane (C2H6 and other hydrocarbons)

6.0 ppm (max)

Nitrous Oxide (N2O by volume)

4.0 ppm (max)

Halogenated Compounds (by volume):
Refrigerants

2.0 ppm (max)

Solvents

0.2 ppm (max)

Moisture (water vapor measured by ppm or
measured by dew point)

7 ppm (max)
<–82°F

Odor

Odor free

CHAPTER 4 ­— Dive Systems	

4-5

Table 4‑3. Diver’s Compressed Oxygen Breathing Purity Requirements (Continued).
Specification

Constituent

Type II Liquid
Oxygen (percent by volume)

99.5%

Carbon dioxide (by volume)

5 ppm (max)

Methane (CH4 by volume)

25 ppm (max)

Acetylene (C2H2)

0.05 ppm (max)

Ethylene (C2H4)

0.2 ppm (max)

Ethane (C2H6 and other hydrocarbons)

3.0 ppm (max)

Nitrous Oxide (N2O by volume)

2.0 ppm (max)

Halogenated Compounds (by volume):
Refrigerants

1.0 ppm (max)

Solvents

0.10 ppm (max)

Moisture (water vapor measured by ppm or
measured by dew point)

7 ppm (max)
<–82°F

Odor

Odor free

Reference: Military Specification MIL-PRF-27210G

4-3.3

Diver’s Breathing Helium. Helium used for diver’s breathing gas shall meet
Military Specification, MIL-PRF-27407B Propellant Pressurizing Agent Helium,
Type I Gaseous Grade B, Respirable Helium. The purity standards are contained
in Table 4-4.

Table 4‑4. Diver’s Compressed Helium Breathing Purity Requirements.
Constituent

Specification

Helium (percent by volume)

99.997%

Moisture (water vapor)

9 ppm (max)

Dew Point (not greater than)

–78°F

Hydrocarbons (as Methane)

1 ppm (max)

Oxygen

3 ppm (max)

Nitrogen + Argon

5 ppm (max)

Neon

23 ppm (max)

Hydrogen

1 ppm (max)

Reference: Military Specification MIL-PRF-27407B

4-3.4

4-6

Diver’s Breathing Nitrogen. Nitrogen used for divers breathing gas shall meet
Federal Specification A-A-59155 Nitrogen, High Purity, Special Purpose. The
purity standards are contained in Table 4-5.

U.S. Navy Diving Manual­ — Volume 1

Table 4‑5. Diver’s Compressed Nitrogen Breathing Purity Requirements.
Class I Oil Free, Type I Gaseous & Type II Liquid
Specification/Grade
Constituent

A

B

Nitrogen

99.95%

99.50%

Oxygen

0.05%

0.50%

Moisture (water vapor)
Total Hydrocarbons
(as meth­ane by volume)
Odor

.02 mg/l

.02 mg/l

50 ppm

50 ppm

None

None

Note: Type I Nitrogen shall not contain any solid particles whose dimensions are greater than
50 microns. A 10 micron or better nominal filter at or close to the cylinder charging manifold will
be used.
Reference: Federal Specification A-A-59155

4-4

DIVER’S AIR SAMPLING PROGRAM

NAVSEA Code 00C manages the diver’s breathing air sampling program in accor­
dance with OPNAVINST 3150.27 (series). The purpose of the air sampling program
is to:
 Provide technical support for the operation and maintenance of diver’s breathing
air compressors and diving air storage systems.
 Provide general guidance concerning use of local commercial air sampling
sources, including the evaluation of commercial air sampling capabilities and
equipment.
 Perform program management for centrally funded air sampling services as
directed by CNO Code N873.
 Collaborate with other government agencies and commercial industry on gas
purity standards and sampling procedures related to diver’s breathing gases.
4-4.1

Maintenance Requirements. Taking periodic air samples is a required maintenance

action and shall be performed in accordance with the PMS card(s) applicable to
the compressor or system producing diver’s breathing air. Each diver breathingair source in service must be sampled approximately every 6 months (within
the interval between 4 and 8 months following the last accomplishment), when
contamination is suspected and after system overhaul.

Do not use a compressor that is suspected of producing contaminated air or that
has failed an air sample analysis until the cause of the problem has been corrected
and a satisfactory air sample analysis has been obtained validating the production
of acceptable air.

CHAPTER 4 ­— Dive Systems	

4-7

Diving systems that do not have a high-pressure (HP) air compressor within the
scope of certification shall only be charged with air produced by HP air compres­
sors listed on the ANU list and must have all applicable PMS completed up to date,
including air sample requirements. Examples of these types of systems include MK
3 LWDS, Roper Cart, and various diving boats. HP banks on these systems need
not be sampled unless contamination is suspected.
Air drawn from submarine HP air storage banks for use as diver’s breathing air
shall be sampled in accordance with the PMS maintenance requirement card appli­
cable to the system, i.e., dry deck shelter system, submarine escape trunk, SCUBA
charging station. See paragraph 4‑4.2 for additional information on system line-up
for sampling compressors where a sampling connection cannot be made immedi­
ately downstream from the last air filtration device.
Table 4‑1 shows the minimum purity requirements for diving air produced by
ANU-approved and certified diving air compressors. Air sampling services may
be procured locally from government or commercial air analysis facilities, or may
be acquired by utilizing analysis services coordinated via Naval Surface Warfare
Center, Panama City, Florida (NSWC-PC).
NOTE

The most recent air sample analysis report shall be maintained on file
for each air compressor (by compressor serial number) used to produce
diver’s breathing air.

4-4.2

General Air Sampling Procedures. The following general information is provided

to assist commands in managing air sample analysis programs.
Ensure all applicable PMS has been completed on the compressor and associated
filtration system prior to taking an air sample.
 When sampling from HP charging systems, separate samples should be taken
from each compressor supplying the system. Samples from the compressors
should be taken as close to the compressor as possible but down stream of the
last compressor-mounted air treatment device (moisture separator, filter, etc.).
Some systems do not have fittings that allow samples to be taken from the
system at a location other than the charging connection. In this case, the storage
flasks should be isolated from the system, the system purged with air from the
compressor to be sampled and the sample taken at the charging connection.
 When sampling from a low-pressure (LP) breathing-air system, separate air
samples shall be taken from each LP compressor connected to the system.
Samples shall be taken from each LP compressor as close to the compressor as
possible, but downstream of the last compressor installed air treatment device
(moisture separator, filter, etc.). Some systems do not have fittings that allow
samples to be taken at connections other than the diver’s manifold. In this case,
a HP source should be isolated from the LP system, the system purged with
air from the LP compressor to be sampled, and the sample obtained from the
diver’s manifold.

4-8

U.S. Navy Diving Manual­ — Volume 1

NOTE

Failure to purge the system line-up of air produced from other compressors
or storage flasks will lead to an invalid air sample for the compressor
being sampled.

 Ensure that the compressor being sampled has reached full operating status
(proper operating temperature, oil pressure, and air pressure) and is properly
lined up to deliver air to the sample kit.
 Ensure that the compressor’s intake is clear of any potential sources of
contamination (including consideration of ambient smog levels in areas where
smog is a problem).
 Follow the procedures on applicable air sample MRC card.
 Follow the instructions for operation of the air sampling kit.
4-4.3

NSWC-PC Air Sampling Services. The following applies to centrally funded air

sampling services coordinated by NSWC-PC. Due to limited funding, commands
are requested to schedule all compressors and associated samples to be taken at
the same time. NSWC-PC coordinates air sampling services with a commercial
contractor. Commands are not authorized to communicate directly with the
commercial contractor. Sampling services are provided at no cost to the command.
To request air sampling services, fill out and fax Air Sampling services request to
NSWC-PC (Attn: Air Sampling). Telephone numbers are listed in Appendix 1C.

 The user must provide the sample expiration date, the number and type (HP or
LP) of samples required, a complete mailing address, user point of contact and
phone number. Air sample kits will not be shipped until the required information
is received.
 Allow a minimum of 5 working days after submitting a properly filled out
request form for delivery of a sampling kit in CONUS. Kits will be sent via
commercial air with a prepaid return mailer. Incomplete sample requests cannot
be acted on and will result in delay of shipping of sample kit.
 Allow a minimum of 3 weeks after submitting a properly filled out request
form for delivery of a sampling kit if overseas. Kits will be sent via certified
priority mail for overseas/FPO-APO addressees with prepaid return mailing.
Incomplete sample requests cannot be acted on and will result in delay of
shipping of sample kit.
 Detailed instructions are included with each sample kit. It is imperative to
follow those instructions and the instructions on the applicable compressor air
sampling MRC card.
 Air samples shall be taken and returned to NSWC-PC within 5 working days
of receipt of the air sample kit to preclude incurring late fees.

CHAPTER 4 ­— Dive Systems	

4-9

 Air sample analysis reports for samples that meet air purity standards will be
mailed to the command. Commands will be notified by quickest means possible
of any samples that do not meet minimum purity requirements.
 The user will be contacted immediately by phone and/or message by NSWCPC if the sample fails to meet established purity standards. The user will
discontinue use of the air source until cause of contamination is corrected.
Corrective action must be taken prior to laboratory retest.
4-4.4

Local Air Sampling Services. Commands may use local government (e.g.,

shipyards, ship repair facilities, government research laboratories) or commercial
laboratories to analyze diver’s air samples. Commands are required to bear the
cost of locally procured air sample services. Local sampling facilities must be able
to analyze to U.S. Navy air purity standards.
4-5

DIVING COMPRESSORS
4-5.1

Equipment Requirements. Compressors used to supply diving air or transfer

oxygen or mixed gases shall be listed in the NAVSEA/00C Authorized for Navy
use (ANU) list or be an element of a certified diving system.
4-5.2

4-5.3

Air Filtration System. Military diving compressors shall be equipped with an air
filtration system that is listed in the NAVSEA/00C Authorized for Navy use (ANU)
list or be an element of a certified diving system. The term air filtration system
as used here is inclu­sive, referring collectively to compressed gas system filters,
moisture separators, air purification, air cooling, and dehydration equipment.
Lubrication. Compressors used to produce military diver’s breathing air are

normally of oil-lubricated, two-to-five-stage reciprocating type. Oil lubrication:
 Prevents wear between friction surfaces
 Seals close clearances
 Protects against corrosion
 Transfers heat away from heat-producing surfaces

 Transfers minute particles generated from normal system wear to the oil sump
or oil filter if so equipped
A malfunctioning oil-lubricated compressor poses a contamination risk to the
diver’s air supply. Contamination may occur due to excess oil mist being passed
out of the compressor due to excess clearances, broken parts, or overfilling the
oil sump.
Gaseous hydrocarbons and carbon monoxide may also be produced should a
compressor overheat to the point of causing combustion of the lubricating oil and/
or gaskets and other soft goods found in the compressor. Compressor overheating

4-10

U.S. Navy Diving Manual­ — Volume 1

may be caused by a number of events including, but not limited to: loss of cooling
water or air flow, low lube oil level, malfunction of stage unloader or relief valves,
friction from broken or excessively worn parts, and/or compressor operation at an
RPM above its rated capacity.
Diver’s air filtration systems are designed to work with compressors operating
under normal conditions, and cannot be relied on to filter or purify air from a
malfunctioning compressor.
WARNING

Do not use a malfunctioning compressor to pump diver’s breathing air or
charge diver’s air storage flasks as this may result in contamination of
the diver’s air supply.

Lubricants used in diver’s air compressors shall conform to MIL-PRF-17331 (2190
TEP) for normal operations, or MIL-PRF-17672 (2135TH) for cold weather opera­
tions. Where the compressor manufacturer specifically recommends the use of a
synthetic base oil in their compressor for production of breathing air, that manu­
facturer recommended synthetic base oil may be used in lieu of MIL-PRF-17331 or
MIL-PRF-17672 oil. Oil shall be changed out on compressors in strict accordance
with the PMS requirements applicable to that compressor.
4-6

DIVING GAUGES
4-6.1

Selecting Diving System Gauges. Select a gauge whose full scale reading

approximates 130 percent to 160 percent of the maximum operating pressure of
the system. Following this guideline, a gauge with a full scale reading of 4,000
or 5,000 psi would be satisfactory for installation in a system with a maximum
operating pressure of 3,000 psi.

Selecting gauge accuracy and precision should be based on the type of system and
how the gauge will be used. For example, a high level of precision is not required
on air bank pressure gauges where only relative values are necessary to determine
how much air is left in the bank or when to shut down the charging compressor.
However, considerable accuracy (¼ of 1 percent of full scale for saturation diving
operations and 1 percent of full scale for surface supplied operations) is required
for gauges that read diver depth (pneumofathometers and chamber depth gauges).
Depth gauge accuracy is critical to selecting the proper decompression or treat­
ment table.
Many gauges are provided with a case blowout plug on the rear surface. The
blowout plug protects the operator in the event of Bourdon tube failure, when case
overpressurization could otherwise result in explosion of the gauge lens. The plug
must not be obstructed by brackets or other hardware.
All diving system gauges should be provided with gauge isolation valves and cali­
bration fittings. If a gauge fails during an operation, the isolation valve closes to
prevent loss of system pressure.

CHAPTER 4 ­— Dive Systems	

4-11

4-6.2

Calibrating and Maintaining Gauges. All installed gauges and portable gauges

(tank pressure gauges, submersible tank pressure gauges, and gauges in small
portable test sets) in use must be calibrated or compared in accordance with the
Planned Maintenance System schedule unless a malfunction requires repair and
calibration sooner. Programs such as the Ship­board Gauge Calibration Program
as outlined in the NAVSEA Instruction 4734.1 (series) provide authority for a
command to calibrate its own gauges. Calibrated gauges not in use should be kept
in a clean, dry, vibration-free environment.
Calibration and comparison data must include the date of the last satisfactory check,
the date the next calibration is due, and the activity accomplishing the cali­bration.
Gauges are delicate instruments and can be damaged by vibration, shock, or impact.
They should be mounted in locations that minimize these factors and should always
be mounted to gauge boards, panels, or brackets. The piping connection should
not be the sole support for the gauge. A gauge can be severely damaged by rapid
pulsations of the system when the fluid pressure is being measured. When this
condition exists, a gauge snubber should be installed between the isolation valve
and the gauge to protect the instrument. Most gauges are not waterproof and are
not designed for use in a marine environment. Enclo­sures of transparent acrylic
plastic, such as lucite, can be used to protect the gauges from water and salt spray.
However, the enclosure must have vent passages to allow the atmospheric pressure
to act on the gauge sensing element.
4-6.3

Helical Bourdon Tube Gauges. Manufacturers make two basic types of helical

Bourdon tube gauges for use on recompression chambers and for surface-supplied
diving systems. One is a caisson gauge with two ports on the back. The reference
port, which is capped, is sealed with ambient air pressure or is piped to the exterior
of the pressure chamber. The sensing port is left open to interior pressure. The
other gauge is the standard exte­rior gauge.
Both are direct-drive instruments employing a helical Bourdon tube as the sensing
element. The gauges are accurate to ¼ of 1 percent of full scale pressure at all dial
points. With no gears or linkages, the movement is unaffected by wear, and accu­
racy and initial calibration remains permanent.
A comparative check in lieu of recalibration should be made in accordance with
the Planned Maintenance System. A dial adjustment screw on the front face of the
gauge provides for zero-point adjustment and special set pressure. Dial readout
units of measure can be in pounds per square inch (psi) and/or feet of seawater
(fsw).

4-12

U.S. Navy Diving Manual­ — Volume 1

4-7

COMPRESSED GAS HANDLING AND STORAGE

Handling and storing compressed gas are inherent parts of virtually all diving
activities, whether conducted with SCUBA or surface supplied diving equipment. It
is imperative that divers be familiar with the safety aspects of handling compressed
gas. Diver’s compressed gas shall be stored in military standard (MIL-STD) or
DOT approved cylinders or ASME flasks applicable to the type and pressure levels
of the compressed gas being stored.
Compressed gas shall be transported in cylinders meeting Department of Trans­
portation (DOT) regulations applicable to the compressed gas being handled. DOT
approved cylinders bear a serial number, DOT inspection stamp, a pressure rating,
the date of last hydrostatic test, are equipped with applicable cylinder valve, and
are appropriately color coded.
Refer to the following references for more detailed information on compressed gas
handling and storage:
 Industrial Gases, Generating, Handling and Storage, NAVSEA Technical
Manual S9086-SX-STM-000/CH-550.
 American and Canadian Standard Compressed-Gas Cylinder Valve Outlet and
Inlet Connections (ANSI-B57.1 and CSA-B96).
 American National Standard Method of Marking Portable Compressed-Gas
Containers to Identify the Material Contained (Z48.1).
 Guide to the Preparation of Precautionary Labeling and Marking of Compressed
Gas Cylinders (CGA Pamphlet C-7).

CHAPTER 4 ­— Dive Systems	

4-13

PAGE LEFT BLANK INTENTIONALLY

4-14

U.S. Navy Diving Manual­ — Volume 1

CHAPTER 5

Dive Program Administration
5-1

INTRODUCTION
5-1.1

Purpose. The purpose of this chapter is to promulgate general policy for main­

taining and retaining command smooth diving logs, personal diving logs, per­sonal
diving records, diving mishap reports, and failure analysis reports.
5-1.2

Scope. The record keeping and reporting instructions outlined in this chapter

pertain to command smooth diving logs, individual diving logs, personal diving
records, diving mishap reports, and failure analysis reports.
5-2

OBJECTIVES OF THE RECORD KEEPING AND REPORTING SYSTEM

There are five objectives in the diving record keeping and reporting system.
1. Establish a comprehensive operational record for each diving command. The

Command Smooth Diving Log is a standardized operational record prepared in
accordance with established military practice. This record establishes the diving
history for each diving command and constitutes the basic operational record
requirement under normal, uneventful circumstances.

2. Gather data for safety and trend analysis. Information about current diving opera­

tions conducted in the Navy, the incidence of Hyperbaric Treatments, and diving
mishaps is provided to the Naval Safety Center through the Diving Reporting System
and by message as required in OPNAVINST 5102.1 (series) via the Web Enabled
Safety System (WESS). This information enables the Safety Center to identify
safety-related problems associated with operating procedures and training.
3. Provide data for a personal record. OPNAVINST 3150.27 (series) requires each

diver to maintain a personal diving log/history.

4. Report information about diving mishaps and casualties in accordance with

the requirements of OPNAVINST 5102.1 (series) via WESS. Complete and
accurate information enables the command to take appropriate action and prevent
reoccurrence.

5. Report information about equipment deficiencies to the responsible technical

agencies through the Failure Analysis Report (FAR) system.

5-3

RECORD KEEPING AND REPORTING DOCUMENTS

The documents established to meet the objectives of the record keeping and
reporting system are:
 Command Smooth Diving Log (Figure 5‑1)

CHAPTER 5 ­— Dive Program Administration	

5-1

 Dive/Jump Reporting System (DJRS)
 Diver’s Personal Dive Record (diskette or hard copy)
 Diving Mishap/Hyperbaric Treatment/Death Report, Symbol OPNAV 5102/5
(via WESS)
 Diving Mishaps reported in accordance with OPNAVINST 5102.1 (series) via
WESS
 Equipment Accident/Incident Information Sheet (Figure 5‑2)
 Diving Life Support Equipment Failure Analysis Report (FAR) for surfacesupplied diving systems, and open-circuit SCUBA (NAVSEA Form 10560/4)
(Figure 5‑3). FARS may be reported via the on-line reporting system at www.
supsalv.org.
 Failure Analysis Report (NAVSEA Form 10560/1) (Figure 5‑4) or Failure
Analysis or Inadequacy Report. FARS maybe reported via the on-line reporting
system at www.supsalv.org.
5-4

COMMAND SMOOTH DIVING LOG

The Command Smooth Diving Log is a chronological record of all dives conducted
at that facility or command. It contains information on dives by personnel attached
to the reporting command and dives by personnel temporarily attached to the
command, such as personnel on TAD/TDY.
Dives conducted while temporarily assigned to another diving command shall be
recorded in the host command’s Smooth Diving Log. Additionally, record the dive
in the Dive/Jump Reporting System (DJRS) of the host command.
The OPNAVINST 3150.27 (series) requires commands to retain the official diving log
for 3 years. The minimum data items in the Command Smooth Diving Log include:
 Date of dive
 Purpose of the dive
 Identification of divers and standby divers
 Times left and reached surface, bottom time
 Depth
 Decompression time
 Air and water temperature
 Signatures of Diving Supervisor or Diving Officer/Master Diver

5-2

U.S. Navy Diving Manual — Volume 1

U.S. Navy Command Smooth Diving Log

Start Date_________________________________________________________________________________________________
End Date__________________________________________________________________________________________________
This log must be maintained in accordance with the U.S. Navy
Diving Manual, Volume 1, (NAVSEA).

Figure 5-1. U.S. Navy Diving Log (sheet 1 of 2).

CHAPTER 5 ­— Dive Program Administration	

5-3

COMMAND SMOOTH DIVING LOG
Date

Geographic Location

Air Temp (°F)

Equipment Used

Dress

Wave Height (ft)

Breathing Medium

Platform

Water Temp (°F)

Breathing Medium Source

Current (kts.)

Depth of Dive (fsw)
Diver

LS

Bottom Type
RB

LB

Purpose of Dive, Tools Used, etc.

Bottom Vis (ft)
RS

TBT

TDT

TTD

Sched Used

Repet Group

Surface Interval

New Repet Group

RNT

Dive Comments

Signature (Diving Supervisor)

Signature (Diving Officer/Master Diver)

Figure 5-1. U.S. Navy Diving Log (sheet 2 of 2).

5-4

U.S. Navy Diving Manual — Volume 1

EQUIPMENT ACCIDENT/INCIDENT INFORMATION SHEET
GENERAL
Unit point of contact_________________________________ Position__________________________
Command UIC__________________ Date_______________ Time of occurrence_________________
__________________________________________________________________________________
EQUIPMENT (indicate type of all equipment worn/used)    Contributing factor________________________
UBA:

SCUBA_________________ MK21__________________ MK20__________________
MK 16_________________ LAR V_________________ KM37__________________
Other (specify)________________________________________________________

Suit type:

Dry________________ Wet________________ Hot water______________________

Other dress:

Gloves_____________ Booties______________ Fins__________________________
Mask______________ Snorkel_____________ Knife__________________________
Weight belt (indicate weight)_____________________________________________
Depth gauge___________________ Last calibration date_______________________

Buoyancy compensator/life preserver:_________________________________________________
Inflated at scene:______________ Partially______________ Operational ____________________
Inflation mode: Oral____________ CO2 __________________ Independent supply______________
Cylinders:

Number worn_________ Size (cu ft)__________ Valve type_____________________
Gas mix______________ Aluminum__________ Steel_________________________
Surface pressure:    Before____________________ After______________________

Regulator:__________________ Last PMS date____________ Functional at scene?_______________
Submersible pressure gauge:___________________________ Functional at scene?_______________
CONDITIONS

Location_____________________________________________________________

__________________________________________________________________________________
Depth__________fsw Visibility__________ft. Current__________Knots
Air temp______________°F

sea state____________(0-9)

Water temp: at surface_______________°F at depth______________°F

Bottom type (mud, sand, coral, etc.)______________________________________________________
DIVE TIME
Bottom________________ Decompression_________________ Total dive time_________________
Was equipment operating and maintenance procedure a contributing factor?
(Explain):________________________________________________________________________
Is there contributory error in O&M Manual or 3M System?
(Explain):________________________________________________________________________
OTHER CONTRIBUTING FACTORS________________________________________________________

Figure 5-2. Equipment Accident/Incident Information Sheet. (sheet 1 of 2).

CHAPTER 5 ­— Dive Program Administration	

5-5

EQUIPMENT ACCIDENT/INCIDENT INFORMATION SHEET
Pertaining to UBA involved, fill in blanks with data required by items 1 through 9.
KM 37


MK 21


MK 20
MOD 0


SCUBA


MK 16


MK 25


N/A

N/A

OTHER


1. Number of turns to secure topside gas umbilical supply:
N/A

2. Number of turns to secure valve on emergency gas supply (EGS):
Reserve
Up/Down

N/A

N/A

N/A

Mouthpiece
Valve:
Surface
________
Dive
________

Mouthpiece
Valve:
Surface
________
Dive
_________

3. Number of turns to secure gas supply at mask/helmet:

4. Number of turns to secure gas bottle:
N/A

N/A

N/A

Air
Bottle
________

O2
________
Diluent
________

O2
Bottle
________

EGS
_____ psig

EGS
_____ psig

_____ psig

O2
_____ psig
Diluent
_____ psig

_____ psig

N/A

Diluent

N/A

5. Bottle Pressure:
EGS
_____ psig

6. Gas Mixture:
Primary

Primary

% ______

% ______

EGS

EGS

N2O2 _____

% ______

% ______

HeO2 _____

7. Data/color of electronic display:
N/A

N/A

N/A

N/A

Primary

N/A

________
Secondary
__________
__________
__________
8. Battery voltage level:
N/A

N/A

N/A

N/A

Primary

N/A

________
Secondary
________
9. Condition of canister:
N/A

N/A

N/A

N/A

Note:  If UBA involved is not listed above, provide information on separate sheet.

Figure 5‑2. Equipment Accident/Incident Information Sheet. (sheet 2 of 2).

5-6

U.S. Navy Diving Manual — Volume 1

5-5

RECOMPRESSION CHAMBER LOG

The Recompression Chamber Log is the official chronological record of proce­dures
and events for an entire dive. It is mandatory that all U.S. Navy diving activities
maintain a Recompression Chamber Log. The log shall be legibly main­tained in
a narrative style. The Diving Officer, Master Diver, and Diving Supervisor shall
review and sign the log daily or at the end of their watches. The Recompression
Chamber Log must be retained for 3 years after the date of the dive. The minimum
data items in the Recompression Chamber Log include:
 Date of dive
 Purpose of the dive
 Identification of diver(s)/patients(s)
 Identification of tender(s)
 Time left surface
 Time reached treatment depth
 Time reached stop
 Time left stop
 Depth/time of relief
 Change in symptoms
 Recompression chamber air temperature (if available)
 Oxygen and Carbon Dioxide % (if available)
 Medicine given
 Fluid administered
 Fluid void
 Signatures of Diving Officer, Master Diver, or Diving Supervisor

CHAPTER 5 ­— Dive Program Administration	

5-7

Figure 5-3. Failure Analysis Report (NAVSEA Form 10560/4).

5-8

U.S. Navy Diving Manual — Volume 1

Figure 5‑4. Failure Analysis Report. (NAVSEA Form 10560/1).

CHAPTER 5 ­— Dive Program Administration	

5-9

5-6

DIVER’S PERSONAL DIVE LOG

Although specific Navy Divers Personal Logbooks are no longer required, each
Navy trained diver is still required to maintain a record of his dives in accordance
with the OPNAVINST 3150.27 (series). The best way for each diver to accomplish
this is to keep a copy of each Diving Log Form in a binder or folder. The Diving
Log Form is generated by the Diver Reporting System (DRS) software. These
forms, when signed by the Diving Supervisor and Diving Officer, are an acceptable
record of dives that may be required to justify special payments made to you as a
diver and may help substantiate claims made for diving-related illness or injury. If
an individual desires a hard copy of the dives, the diver’s command can generate
a report using the DRS or by submitting a written request to the Naval Safety
Center.
5-7

DIVING MISHAP/CASUALTY REPORTING

Specific instructions for diving mishap, casualty, and hyperbaric treatment are
provided in OPNAVINST 5102.1 (series). The Judge Advocate General (JAG)
Manual provides instructions for investigation and reporting procedures required
in instances when the mishap may have occurred as a result of procedural or
personnel error. Diving equipment status reporting instructions related to diving
accidents/incidents are specified in this chapter.
5-8

EQUIPMENT FAILURE OR DEFICIENCY REPORTING

The Failure Analysis Report (FAR) system provides the means for reporting,
tracking and resolving material failures or deficiencies in diving life-support
equipment (DLSE). The FAR was developed to provide a rapid response to DLSE
failures or deficiencies. It is sent directly to the configuration manager, engineers,
and technicians who are qualified to resolve the deficiency. FAR Form 10560/4
(stock number 0116-LF-105-6020) covers all DLSE not already addressed by other
FARs or reporting systems. For example, the MK 21 MOD 1, MK 20 MOD 0 mask,
and all open-circuit SCUBA are reportable on this FAR form; the UBAs MK 16 and
MK 25 are reportable on a FAR or a Failure Analysis or Inadequacy Report (FAR)
in accordance with their respective technical manuals. When an equipment failure
or deficiency is discovered, the Diving Supervisor or other responsible person shall
ensure that the FAR is properly prepared and distributed. Refer to paragraph 5‑10
for additional reporting requirements for an equipment failure suspected as the
cause of a diving accident.
An electronic version of the FAR form is also available on-line at http://www.
supsalv.org. Click on Diving or 00C3 Diving. When the next screen appears, click
on Failure Analysis Reporting. Follow the instructions and submit the form.

5-10

U.S. Navy Diving Manual — Volume 1

5-9

U.S. NAVY DIVE REPORTING SYSTEM (DRS)

The Dive Reporting System (DRS) is a computer-based method of recording
and reporting dives required by the OPNAVINST 3150.27 (series), and replaces
reporting on DD Form 2544. The computer software provides all diving commands
with a computerized record of dives.
The DRS makes it easy for commands to submit diving data to the Naval Safety
Center. The computer software allows users to enter dive data, transfer data to
the Naval Safety Center, and to generate individual diver and command reports.
The DRS was designed for all branches of the U.S. Armed Services and can be
obtained through:
Commander, Naval Safety Center
Attention: Code 37
375 A Street
Norfolk, VA 23511-4399
5-10

ACCIDENT/INCIDENT EQUIPMENT INVESTIGATION REQUIREMENTS

An accident is an unexpected event that culminates in loss of or serious damage to
equipment or loss of consciousness, injury, or death to personnel. An incident is an
unexpected event that degrades safety and increases the probability of an accident.
The number of diving accidents/incidents involving U.S. Navy divers is small when
compared to the total number of dives conducted each year. The mishaps that do
occur, however, must receive a thorough review to identify the cause and determine
corrective measures to prevent further diving mishaps.
This section expands on the OPNAVINST 5102.1 (series) that requires expedi­
tious reporting and investigation of diving related mishaps. The accident/incident
equipment status reporting procedures in this chapter apply, in general, to all diving
mishaps when malfunction or inadequate equipment performance, or unsound
equipment operating and maintenance procedures are a factor.
In many instances a Diving Life Support Equipment Failure Analysis Report
(FAR) may also be required. The primary purpose of this requirement is to identify
any material deficiency that may have contributed to the mishap. Any suspected
malfunction or deficiency of life support equipment will be thoroughly investi­
gated by controlled testing at the Navy Experimental Diving Unit (NEDU). NEDU
has the capability to perform engineering investigations and full unmanned testing
of all Navy diving equipment under all types of pressure and environmental condi­
tions. Depth, water turbidity, and temperature can be duplicated for all conceivable
U.S. Navy dive scenarios.
Contact NAVSEA/00C3 to assist diving units with investigations and data collec­
tion following a diving mishap. 00C3 will assign a representative to inspect the
initial condition of equipment and to pick up or ship all pertinent records and

CHAPTER 5 ­— Dive Program Administration	

5-11

equipment to NEDU for full unmanned testing. Upon receiving the defective
equipment, NEDU will conduct unmanned tests as rapidly as possible and will
then return the equipment to the appropriate activity.
NOTE
5-11

Do not tamper with equipment without first contacting NAVSEA/00C3
for guidance.

REPORTING CRITERIA

The diving and diving related accident/incident equipment status requirements set
forth in this chapter are mandatory for all U.S. Navy diving units in each of the
following circumstances:
 In all cases when an accident/incident results in a fatality or serious injury.
 When an accident/incident occurs and a malfunction or inadequate perfor­
mance of the equipment may have contributed to the accident/incident.
5-12

ACTIONS REQUIRED

U.S. Navy diving units shall perform the following procedure when a diving
­accident/incident or related mishap meets the criteria stated in paragraph 5‑11.
1. Immediately secure and safeguard from tampering all diver-worn and ancillary/

support equipment that may have contributed to the mishap. This equipment
should also include, but is not limited to, the compressor, regulator, depth gauge,
submersible pressure gauge, diver dress, buoyancy compensator/life preserver,
weight belt, and gas supply (SCUBA, emergency gas supply, etc.).
2. Expeditiously report circumstances of the accident/incident via WESS. Commands

without WESS access should report by message (see OPNAVINST 5102.1 (series)
for format requirements) to:

 NAVSAFECEN NORFOLK VA//JJJ// with information copies to
CNO WASHINGTON DC//N773//
COMNAVSEASYSCOM WASHINGTON DC//00C// and
NAVXDIVINGU PANAMA CITY FL//JJJ//.
 If the accident/incident is MK 16 MOD 1 related, also send information
copies to PEO LMW WASHINGTON DC//PMS-EOD// and
NAVEODTECHDIV INDIAN HEAD MD//70//.
 If the accident/incident is MK 16 MOD 0 related, also send information
copies to PEO LMW WASHINGTON DC//PMS-NSW//.
 If the accident/incident occurs at a shore-based facility, contact NAVFAC
SCA, also send information copies to NFESC EAST COAST DET
WASHINGTON DC//55//.

5-12

U.S. Navy Diving Manual — Volume 1

3. Expeditiously prepare a separate, written report of the accident/incident. The

report shall include:

 A completed Equipment Accident/Incident Information Sheet (Figure 5‑2)
 A sequential narrative of the mishap including relevant details that might
not be apparent in the data sheets
4. The data sheets and the written narrative shall be mailed by traceable registered

mail to:

Commanding Officer
Navy Experimental Diving Unit
321 Bullfinch Road
Panama City, Florida 32407-7015
Attn: Code 03, Test & Evaluation
5. Package a certified copy of all pertinent 3M records and deliver to NAVSEA/00C3

on-scene representative.

NOTE

5-12.1

5-12.2

Call NAVSEA/NEDU/NAVFAC with details of the mishap or incident when­
ever possible. Personal contact may prevent loss of evidence vital to the
evaluation of the equipment.
Technical Manual Deficiency/Evaluation Report. If the accident/incident is
believed to be solely attributable to unsound operating and maintenance procedures,
including publications, submit a NAVSEA (user) Technical Manual Deficiency/
Evaluation Report (TMDER) and request guidance from NEDU to ascertain if
shipment of all or part of the equipment is necessary.
Shipment of Equipment. To expedite delivery, SCUBA, MK 16 and EGS bottles
shall be shipped separately in accordance with current DOT directives and
command procedures for shipment of compressed gas cylinders. Cylinders shall
be forwarded in their exact condition of recovery (e.g., empty, partially filled,
fully charged). If the equipment that is believed to be contributory to the accident/
incident is too large to ship economi­cally, contact NEDU to determine alternate
procedures.

CHAPTER 5 ­— Dive Program Administration	

5-13

PAGE LEFT BLANK INTENTIONALLY

5-14

U.S. Navy Diving Manual — Volume 1

APPENDIX 1A

Safe Diving Distances from
Transmitting Sonar
1A-1

INTRODUCTION

The purpose of this appendix is to provide guidance regarding safe diving distances
and exposure times for divers operating in the vicinity of ships transmit­ting with
sonar. Table 1A‑1 provides guidance for selecting Permissible Exposure Limits
Tables; Table 1A‑2 provides additional guidance for helmeted divers. Tables 1A‑3
through 1A‑5 provide specific procedures for diving operations involving AN/
SQS-23, -26, -53, -56; AN/BSY-1, -2; and AN/BQQ-5 sonars. Table 1A‑6 provides
procedures for diving operations involving AN/SQQ-14, -30, and -32. Section 1A‑5
provides guidance and precautions concerning diver exposure to low-frequency
sonar (160-320Hz). Contact NAVSEA Supervisor of Diving (00C3B) for guidance
on other sonars. This appendix has been substantially revised from Safe Diving
Distances from Transmitting Sonar (NAVSEAINST 3150.2 Series) and should be
read in its entirety.
1A-2

BACKGROUND

Chapter 18 of OPNAVINST 5100.23 Series is the basic instruction governing
hearing conservation and noise abatement, but it does not address exposure to
waterborne sound. Tables 1A‑3 through 1A‑6 are derived from experimental and
theoretical research conducted at the Naval Submarine Medical Research Labora­
tory (NSMRL) and Naval Experimental Diving Unit (NEDU). This instruction
provides field guidance for determining safe diving distances from transmitting
sonar. This instruction supplements OPNAVINST 5100.23 Series, and should be
implemented in conjunction with OPNAVINST 5100.23 Series by commands that
employ divers.
The Sound Pressure Level (SPL), not distance, is the determining factor for estab­
lishing a Permissible Exposure Limit (PEL). The exposure SPLs in Tables 1A‑3
through 1A‑6 are based upon the sonar equation and assume omni-directional sonar
and inverse square law spreading. Any established means may be used to estimate
the SPL at a dive site, and that SPL may be used to determine a PEL. When the
exposure level is overestimated, little damage, except to working sched­ules, will
result. Any complaints of excessive loudness or ear pain for divers require that
corrective action be taken. Section 1A‑5 provides guidance for diver exposure to
low-frequency active sonar (LFA), which should be consulted if expo­sure to LFA
is either suspected or anticipated.
This appendix does not preclude the operation of any sonar in conjunction with
diving operations, especially under operationally compelling conditions. It is based
upon occupational safety and health considerations that should be imple­mented for

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-1

routine diving operations. It should be applied judiciously under special operational
circumstances. The guidance in Tables 1A‑3 through 1A‑6 is intended to facilitate
the successful integration of operations.
1A-3

ACTION

Commanding Officers or Senior Officers Present Afloat are to ensure that diving
and sonar operations are integrated using the guidance given by this appendix.
Appropriate procedures are to be established within each command to effect coor­
dination among units, implement safety considerations, and provide efficient
operations using the guidance in Tables 1A‑3 though 1A‑6.
1A-4

SONAR DIVING DISTANCES WORKSHEETS WITH DIRECTIONS FOR USE
1A-4.1

General Information/Introduction. Permissible Exposure Limits (PEL) in minutes

for exposure of divers to sonar transmissions are given in Tables 1A-3 through
1A-6.

1A‑4.1.1

1A‑4.1.2

Effects of Exposure. Tables 1A‑3 through 1A‑5 are divided by horizontal double
lines. Exposure conditions above the double lines should be avoided for routine
operations. As Sound Pressure Level (SPL) increases above 215 dB for hooded
divers, slight visual-field shifts (probably due to direct stimulation of the semi­
circular canals), fogging of the face plate, spraying of any water within the mask,
and other effects may occur. In the presence of long sonar pulses (one second or
longer), depth gauges may become erratic and regulators may tend to free-flow.
Divers at Naval Submarine Medical Research Laboratory experienc­ing these
phenomena during controlled research report that while these effects are unpleasant,
they are tolerable. Similar data are not available for un-hooded divers but visualfield shifts may occur for these divers at lower levels. If divers need to be exposed
to such conditions, they must be carefully briefed and, if feasible, given short
training exposures under carefully controlled conditions. Because the probability
of physiological damage increases markedly as sound pressures increase beyond
200 dB at any frequency, exposure of divers above 200 dB is prohibited unless
full wet suits and hoods are worn. Fully protected divers (full wet suits and hoods)
must not be exposed to SPLs in excess of 215 dB at any frequency for any reason.
Suit and Hood Characteristics. There is some variation in nomenclature and

characteristics of suits and hoods used by divers. The subjects who partici­pated
in the Naval Submarine Medical Research Laboratory experiments used 3/8-inch
nylon-lined neoprene wet suits and hoods. Subsequent research has shown that
3/16-inch wet suit hoods provide about the same attenuation as 3/8-inch hoods.
Hoods should be well fitted and cover the skull completely includ­ing cheek and
chin areas. The use of wet-suit hoods as underwater ear protec­tion is strongly
recommended.
1A‑4.1.3

In­-Water Hearing vs. In-Gas Hearing. A distinction is made between in-water

hearing and in-gas hearing. In-water hearing occurs when the skull is directly in
contact with the water, as when the head is bare or covered with a wet-suit hood.
In-gas hearing occurs when the skull is surrounded by gas as in the MK 21 diving

1A-2

U.S. Navy Diving Manual — Volume 1

helmet. In-water hearing occurs by bone conduction—sound incident anywhere
on the skull is transmitted to the inner ear, bypassing the external and middle ear.
In-gas hearing occurs in the normal way—sound enters the external ear canal and
stimulates the inner ear through the middle ear.
1A-4.2

Directions for Completing the Sonar Diving Distances Worksheet. Follow the
steps listed below to determine Permissible Exposure Limits (PELs) for the case
when the actual dB Sound Pressure Level (SPL) at the dive site is unknown. Figure
1A-1 is a worksheet for computing the safe diving distance/exposure time. Figures
1A-2 through 1A-5 are completed worksheets using example problems. Work
through these example problems before applying the work­sheet to your particular
situation.

Step 1.

Diver Dress. Identify the type of diving equipment—wet-suit un-hooded; wet-suit
hooded; helmeted. Check the appropriate entry on step 1 of the worksheet.

Step 2.

Sonar Type(s). Identify from the ship’s Commanding Officer or representative the

type(s) of sonar that will be transmitting during the period of time the diver is
planned to be in the water. Enter the sonar type(s) in step 2 of the worksheet.
Step 3.

PEL Table Selection. Use the Table 1A‑1 to determine which PEL table you will

use for your calculations. For swimsuit diving use wet suit un-hooded tables.
Check the table used in step 3 of the worksheet.
Table 1A‑1. PEL Selection Table.
SONAR

DIVER DRESS:

All except
AN/SQQ
-14, - 30, -32

AN/SQQ
-14, -30, -32

Unknown
Sonar

Wet suit - Un-hooded

Table 1A‑3

Table 1A‑6

Start at 1000 yards and move in to
diver comfort

Wet suit - Hooded

Table 1A‑4

Table 1A‑6

Start at 600 yards and move in to
diver comfort

Helmeted

Table 1A‑5

No restriction

Start at 3000 yards and move in to
diver comfort

For guidance for sonars not addressed by this instruction, contact NAVSEA
(00C32).
NOTE

If the type of sonar is unknown, start diving at 600–3,000 yards, depending
on diving equipment (use greater distance if helmeted), and move in to
limits of diver comfort.

Step 4.

Distance to Sonar. Determine the distance (yards) to the transmitting sonar from

place of diver’s work. Enter the range in yards in step 4 of the worksheet.

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-3

SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET
1.  Diver dress:

Wet Suit - Un-hooded             
Wet Suit - Hooded            
Helmeted              

2.  Type(s) of sonar:                                          
3.  PEL Table 1A-3       ; 1A-4           ; 1A-5        ; 1A-6      
4.  Range(s) to sonar (yards):                                            
5.  Estimated SPL at range(s) in step 3 (from table/column in step 3):                                     
Reminder: If range is between two values in the table, use the shorter range. 
If the SPL is measured at the dive site, use the measured value.
6.  Depth Reduction             dB
Reminder:  0 if not helmeted, see table in instructions if helmeted.
7.  Corrected SPL (Step 5 minus Step 6)                                                                        
8.  Estimated PEL at SPL (from table/column in step 3 of the appendix):                                                         
9.  Duty Cycle Known: Yes                 (do step 9); No             (stop)
Adjusted PEL for actual duty cycle
Actual DC % = 100 ×          sec. (pulse length /        sec. (pulse repetition period)
Actual DC % =        
Adjusted PEL = PEL (from step 8)          min. × 20 / actual duty cycle (%)        =          min.
PEL1 =            minutes; PEL2 =            minutes
Reminder: Do not adjust the PEL if duty cycle is unknown.
10. Multiple Sonars: Yes              (do step 10); No           (stop)
Sonar 1:

DT1 =              (Desired dive duration)
PEL1 =                (from Step 8 or 9, as applicable)
DT1/PEL1 =                          .

Sonar 2:

DT1 =              (Desired dive duration)
PEL1 =                 (from Step 8 or 9, as applicable)
DT1/PEL1 =                          .

ND =             +               =                 (This is less than 1.0, so dive is acceptable and may proceed.)
Reminder: The Noise Dose must not exceed a value of 1.0.

Figure 1A-1. Sonar Safe Diving Distance/Exposure Time Worksheet.
1A-4

U.S. Navy Diving Manual — Volume 1

NOTE

If range is between two values in the table, use the shorter range.
This will insure that the SPL is not underestimated and that the PEL is
conservative.

Step 5.

Estimated SPL. In the PEL selection table (Table 1A‑1) determined in step 3 of

Step 6.

the worksheet (Figure 1A‑1), locate the diving distance (range) in the appropriate
sonar equipment column. Read across to the leftmost column to find the SPL in
dB. For ranges intermediate to those shown use the shorter range. Enter this SPL
value in step 5 of the worksheet. If the SPL value in dB can be determined at the
dive site, enter the measured SPL value in step 5.
Helmeted Dive Depth Reduction.

If the diver dress is not helmeted, enter 0 in step 6 of the worksheet and go to step
7 of these instructions.
Helmeted divers experience reduced sensitivity to sound pressure as depth increases.
The reductions listed in Table 1A‑2 may be subtracted from the SPLs for helmeted
divers in Table 1A‑5. Enter the reduction in step 6 of the worksheet. If the depth
is between two values in the table, use the lesser reduction since that value will
produce a conservative PEL.
Table 1A‑2. Depth Reduction Table.
Depth (FSW)

Step 7.

Reduction (dB)

Depth (FSW)

Reduction (dB)

9

1

98

6

19

2

132

7

33

3

175

8

50

4

229

9

71

5

297

10

Corrected SPL. The corrected SPL equals the Estimated SPL from step 5 minus the

reduction in dB from step 6. Enter the corrected SPL in step 7 of the worksheet.

Step 8.

PEL Determination. Go to the SPL in the appropriate table and read one column

Step 9.

Duty Cycle/Adjusted PEL Calculation. Tables 1A‑3 through 1A‑6 assume a

right to find the PEL for the SPL shown in step 7 of the worksheet. Enter in step 8
of the worksheet.
transmit duty cycle of 20 percent. Duty cycle (DC) is the percentage of time in a
given period that the water is being insonified (sonar transmitting). Sonar operators
may use various means of computing DC that are valid for the purpose of this
instruction. If the actual duty cycle is different from 20 percent, PELs may be
extended or shortened proportionally. Use step 9 of the worksheet to calculate and
enter the corrected PEL.

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-5

The formula for duty cycle is:
DC = 100 × Pulse length (sec.) / Pulse Repetition Period (sec.)
The formula for the adjusted PEL is:
Adjusted PEL = PEL × 20 / actual duty cycle; Equation 1
Example Problem. An un-hooded wet suited diver is 16 yards from an AN/SQQ-14

sonar transmitting a 500 msec pulse (.5 seconds) every 10 seconds.
Solution. The actual duty cycle (DC) % is:

Actual DC % = 100 × .5 / 10 = 5 percent.
Locate the PEL from the table (which is for a 20% duty cycle). Compute the
adjusted PEL as:
Using worksheet step 9, Adjusted PEL = PEL (from step 8) 170 × 20/5=680
minutes.
If variable duty cycles are to be used, select the greatest percent value.
Step 10.

Multiple Sonar/Noise Dose Calculation. When two or more sonars are operating

simultaneously, or two or more periods of noise exposure of different values occur,
the combined effects must be considered. In the following formula, ND is the
daily noise dose and must not exceed a value of 1.0, DT is the dive (exposure)
time (left surface to reach surface), and PEL is the PEL for each noise exposure
condition computed as described above:
ND = DT1/PEL1 + DT2/PEL2 + .... DTn/PELn; Equation 2
Note: DT1/PEL1 is for the first sonar, DT2/PEL2 is for the second sonar, up to the
total number of sonars in use.
To use the worksheet, go through the steps 1-9 for each sonar, entering the appro­
priate values in each step of the worksheet. Enter the PELs into the worksheet step
10. There is room for two sonars in the worksheet. If more than two are being used,
follow the same format and continue the calculations in the white space at the end
of the worksheet.
Example Problem. A hooded wet suited diver is 100 yards from a transmitting AN/
SQS-53A sonar and a transmitting AN/SQS-23 sonar for fifteen minutes.
Solution.

DT1 = 15 minutes
PEL1 (for SQS-53A) = 50 minutes
DT1/PEL1 = 15/50 = .3

1A-6

U.S. Navy Diving Manual — Volume 1

DT2 = 15 minutes
PEL2 (for SQS-23) = 285 minutes
DT2/PEL2 = 15/285 = .05
ND = .3 + .05 = .35
This is less than 1.0 and therefore is acceptable.

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-7

Example 1: You are planning a routine dive for 160 minutes using wet-suited divers without hoods at a
dive site 17 yards from an AN/SQQ-14 sonar. The duty cycle for the AN/SQQ-14 sonar is unknown. Is
this dive permitted? Provide justification for your decision.

SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET
1.  Diver dress:

Wet Suit - Un-hooded       X      
Wet Suit - Hooded            
Helmeted  ______

2.  Type(s) of sonar: AN/SQQ-14
3.  PEL Table 1A-3 __; 1A-4     ; 1A-5 __; 1A-6   X  
4.  Range(s) to sonar (yards): 17
5.  Estimated SPL at range(s) in step 3 (from table/column in step 3): SPL =  198  dB
Reminder: If range is between two values in the table, use the shorter range. 
If the SPL is measured at the dive site, use the measured value.
6.  Depth Reduction      0       dB
Reminder:  0 if not helmeted, see table in instructions if helmeted.
7.  Corrected SPL (Step 5 minus Step 6)    SPL1 198 – 0 = 198 dB      
8.  Estimated PEL at SPL (from table/column in step 3 of the appendix):  PEL1 = 170 minutes
9.  Duty Cycle Known: Yes ______ (do step 9); No      X      (stop)
Adjusted PEL for actual duty cycle
Actual DC % = 100 × _____ sec. (pulse length / _____ sec. (pulse repetition period)
Actual DC % = ______
Adjusted PEL = PEL (from step 8) ___ min. × 20 / actual duty cycle (%) ___ = ___ min.
Reminder: Do not adjust the PEL if duty cycle is unknown.
10. Multiple Sonars: Yes _____ (do step 10); No    X      (stop)
Sonar 1:

DT1 =          (Desired dive duration)
PEL1 =          (from Step 8 or 9, as applicable)
DT1/PEL1 =               .

Sonar 2:

DT1 =          (Desired dive duration)
PEL1 =          (from Step 8 or 9, as applicable)
DT1/PEL1 =               .

ND = ____ + _____ = ____  (This is less than 1.0, so dive is acceptable and may proceed.)
Reminder: The Noise Dose must not exceed a value of 1.0.
The dive time of 160 minutes is permitted because the PEL is 171 minutes.

Figure 1A‑2. Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example).

1A-8

U.S. Navy Diving Manual — Volume 1

Example 2: You are planning a routine dive for 75 minutes using wet-suited divers without hoods at a dive
site which is 1000 yards from an AN/SQQ-23 sonar. The SPL was measures at 185 dB. The duty cycle
for the AN/SQS-23 sonar is unknown. Is this dive permitted? Provide justification for your decision.

SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET
1.  Diver dress:

Wet Suit - Un-hooded       X      
Wet Suit - Hooded            
Helmeted  ______

2.  Type(s) of sonar: AN/SQS-23
3.  PEL Table 1A-3    X   ; 1A-4     ; 1A-5 __; 1A-6      
4.  Range(s) to sonar (yards): 1000
5.  Estimated SPL at range(s) in step 3 (from table/column in step 3): SPL =  185  dB
Reminder: If range is between two values in the table, use the shorter range. 
If the SPL is measured at the dive site, use the measured value.
6.  Depth Reduction      0       dB
Reminder:  0 if not helmeted, see table in instructions if helmeted.
7.  Corrected SPL (Step 5 minus Step 6)    SPL1 185 – 0 = 185 dB      
8.  Estimated PEL at SPL (from table/column in step 3 of the appendix):  PEL1 = 170 minutes
9.  Duty Cycle Known: Yes ______ (do step 9); No      X      (stop)
Adjusted PEL for actual duty cycle
Actual DC % = 100 × _____ sec. (pulse length / _____ sec. (pulse repetition period)
Actual DC % = ______
Adjusted PEL = PEL (from step 8) ___ min. × 20 / actual duty cycle (%) ___ = ___ min.
Reminder: Do not adjust the PEL if duty cycle is unknown.
10. Multiple Sonars: Yes _____ (do step 10); No    X      (stop)
Sonar 1:

DT1 =          (Desired dive duration)
PEL1 =          (from Step 8 or 9, as applicable)
DT1/PEL1 =               .

Sonar 2:

DT1 =          (Desired dive duration)
PEL1 =          (from Step 8 or 9, as applicable)
DT1/PEL1 =               .

ND = ____ + _____ = ____  (This is less than 1.0, so dive is acceptable and may proceed.)
Reminder: The Noise Dose must not exceed a value of 1.0.. 
The dive time of 75 minutes is permitted because the PEL is 170 minutes.

Figure 1A-3. Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example).

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-9

Example 3: You are planning a 98 fsw dive for 35 minutes using the MK 21 at a dive site which is 3000
yards from an AN/SQS-53C sonar. The duty cycle for the AN/SQS-53C sonar is unknown. Is this dive
permitted? Provide justification for your decision.

SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET
1.  Diver dress:

Wet Suit - Un-hooded             
Wet Suit - Hooded            
Helmeted       X       

2.  Type(s) of sonar: AN/SQS-53C
3.  PEL Table 1A-3       ; 1A-4     ; 1A-5   X   ; 1A-6      
4.  Range(s) to sonar (yards): 3000
5.  Estimated SPL at range(s) in step 3 (from table/column in step 3): SPL1 =  181  dB
Reminder: If range is between two values in the table, use the shorter range.
If the SPL is measured at the dive site, use the measured value.
6.  Depth Reduction      6       dB
Reminder:  0 if not helmeted, see table in instructions if helmeted.
7.  Corrected SPL (Step 5 minus Step 6)    SPL1 181 – 6 = 175 dB      
8.  Estimated PEL at SPL (from table/column in step 3 of the appendix):  PEL1 = 50 minutes
9.  Duty Cycle Known: Yes ______ (do step 9); No      X      (stop)
Adjusted PEL for actual duty cycle
Actual DC % = 100 × _____ sec. (pulse length / _____ sec. (pulse repetition period)
Actual DC % = ______
Adjusted PEL = PEL (from step 8) ___ min. × 20 / actual duty cycle (%) ___ = ___ min.
Reminder: Do not adjust the PEL if duty cycle is unknown.
10. Multiple Sonars: Yes _____ (do step 10); No    X      (stop)
Sonar 1:

DT1 =          (Desired dive duration)
PEL1 =          (from Step 8 or 9, as applicable)
DT1/PEL1 =               .

Sonar 2:

DT1 =          (Desired dive duration)
PEL1 =          (from Step 8 or 9, as applicable)
DT1/PEL1 =               .

ND = ____ + _____ = ____  (This is less than 1.0, so dive is acceptable and may proceed.)
Reminder: The Noise Dose must not exceed a value of 1.0.
The dive time of 35 minutes is permitted because the PEL is 50 minutes.

Figure 1A‑4. Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example).
1A-10

U.S. Navy Diving Manual — Volume 1

Example 4: You are planning a routine dive for 120 minutes using wet-suited divers with hoods at a dive
site which is 200 yards from an AN/SQS-53A sonar and 120 yards from an AN/SQS-23 sonar. The AN/
SQS-53A sonar is transmitting an 800 msec pulse (0.8 sec) every 20 seconds. The duty cycle for the
AN/SQS-23 sonar is unknown. Is this dive permitted? Provide justification for your decision.

SONAR SAFE DIVING DISTANCE/EXPOSURE TIME WORKSHEET
1.  Diver dress:

Wet Suit - Un-hooded             
Wet Suit - Hooded       X     
Helmeted            

2.  Type(s) of sonar: AN/SQS-53A and AN/SQS-23
3.  PEL Table 1A-3       ; 1A-4   X  ; 1A-5        ; 1A-6      
4.  Range(s) to sonar (yards): 200 (from SQS-53A); 120 (from SQS-23)
5.  Estimated SPL at range(s) in step 3 (from table/column in step 3): SPL1 = 201; SPL2 = 196
(per reminder, use SPL for 112 yard range)
Reminder: If range is between two values in the table, use the shorter range.
If the SPL is measured at the dive site, use the measured value.
6.  Depth Reduction      0       dB
Reminder: 0 if not helmeted, see table in instructions if helmeted.
7.  Corrected SPL (Step 5 minus Step 6)    SPL1 201 – 0 = 201 dB; SPL2 196 – 0 = 196 dB;  
8.  Estimated PEL at SPL (from table/column in step 3 of the appendix):  PEL1 = 143 min; PEL 2 = 339 min
9.  Duty Cycle Known: Yes        X         (do step 9); No             (stop)
Adjusted PEL for actual duty cycle
Actual DC % = 100 ×     0.8     sec. (pulse length /    20    sec. (pulse repetition period)
Actual DC % =    4    
Adjusted PEL = PEL (from step 8) 143 min. × 20 / actual duty cycle (%) 4 = 715 min.
PEL1 =   715   minutes; PEL2 =   339   minutes
Reminder: Do not adjust the PEL if duty cycle is unknown.
10. Multiple Sonars: Yes       X       (do step 10); No           (stop)
Sonar 1:

Sonar 2:

DT1 = 120 (Desired dive duration)
PEL1 = 715 (from Step 8 or 9, as applicable)
DT1/PEL1 = 120/715 = 0.17 .
DT1 =   120 (Desired dive duration)
PEL1 = 339 (from Step 8 or 9, as applicable)
DT1/PEL1 = 120/339 = .35  .

ND = 0.17 + 0.35   = 0.52   (This is less than 1.0, so dive is acceptable and may proceed.)
Reminder: The Noise Dose must not exceed a value of 1.0.
The dive time of 120 minutes is permitted because the ND is less than 1.0.

Figure 1A‑5. Sonar Safe Diving Distance/Exposure Time Worksheet (Completed Example).
APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-11

Table 1A‑3. Wet Suit Un-Hooded.

Permissible Exposure Limit (PEL) within a 24-hour period for exposure to AN/SQS-23, -26, -53, -56,
AN/BSY-1, -2 and AN/BQQ-5 sonars, including versions and upgrades. Exposure conditions shown
above the double line should be avoided except in cases of compelling operational necessity.
Estimated Ranges in yards for given SPL and PEL for sonar.

BQQ-5
BSY-2
SQS-26CX(U)
SQS-53A, SQS-53B
SQS-56(U)

SQS-23
SQS-26AX
SQS-26BX, SQS-26CX
SQS-56

SPL

PEL

(dB)

(MIN)

BSY-1
SQS-53C

200
199
198
197
196
195
194
193
192
191

13
15
18
21
25
30
36
42
50
60

316
355
398
447
501
562
631
708
794
891

224
251
282
316
355
398
447
501
562
631

71
79
89
100
112
126
141
158
178
200

190
189
188
187
186
185
184
183
182
181
180
179
178
177
176
175

71
85
101
120
143
170
202
240
285
339
404
480
571
679
807
960

1,000
1,122
1,259
1,413
1,585
1,778
1,995
2,239
2,512
2,818
3,162
3,548
3,981
4,467
5,012
5,623

708
794
891
1,000
1,122
1,259
1,413
1,585
1,778
1,995
2,239
2,512
2,818
3,162
3,548
3,981

224
251
282
316
355
398
447
501
562
631
708
794
891
1,000
1,122
1,259

A
V E
O	X
I P
D O
		 S
T U
H R
I E
S

All ranges and SPLs are nominal.
*SPL is measured in dB/1 µPA at the dive site. To convert SPL for sound levels referenced to mbar,
subtract 100 dB from tabled levels.
(U) = upgrade

1A-12

U.S. Navy Diving Manual — Volume 1

Table 1A‑4. Wet Suit Hooded.

Permissible Exposure Limit (PEL) within a 24-hour period for exposure to AN/SQS-23, -26, -53, -56,
AN/BSY-1, -2, and AN/BQQ-5 sonar, including versions and upgrades. Exposure conditions shown
above the double line should be avoided except in cases of compelling operational necessity.
Estimated Ranges in yards for given SPL and PEL for sonar.

BQQ-5
BSY-2
SQS-26CX(U)
SQS-53A, SQS-53B
SQS-56(U)

SQS-23
SQS-26AX
SQS-26BX, SQS-26CX
SQS-56

SPL

PEL

(dB)

(MIN)

215
214
213
212
211
210
209
208
207
206

13
15
18
21
25
30
36
42
50
60

56
63
71
79
89
100
112
126
141
158

40
45
50
56
63
71
79
89
100
112

13
14
16
18
20
22
25
28
32
35

205
204
203
202
201
200
199
198
197
196
195
194
193
192
191
190

71
85
101
120
143
170
202
240
285
339
404
480
571
679
807
960

178
200
224
251
282
316
355
398
447
501
562
631
708
794
891
1,000

126
141
158
178
200
224
251
282
316
355
398
447
501
562
631
708

40
45
50
56
63
71
79
89
100
112
126
141
158
178
200
224

BSY-1
SQS-53C

A
V E
O	X
I P
D O
		 S
T U
H R
I E
S

All ranges and SPLs are nominal.
*SPL is measured in dB/1 µPA at the dive site. To convert SPL for sound levels referenced to mbar,
subtract 100 dB from tabled levels.
(U) = upgrade

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-13

Table 1A‑5. Helmeted.

Permissible Exposure Limit (PEL) within a 24-hour period for exposure to AN/SQS-23, -26, -53, -56,
AN/BSY-1, -2, and AN/BQQ-5 sonar, including versions and upgrades. Exposure conditions shown
above the double line should be avoided except in cases of compelling operational necessity.
Estimated Ranges in yards for given SPL and PEL for sonar.

BQQ-5
BSY-2
SQS-26CX(U)
SQS-53A, SQS-53B
SQS-56(U)

SQS-23
SQS-26AX
SQS-26BX, SQS-26CX
SQS-56

SPL

PEL

(dB)

(MIN)

183
182
181
180
179
178
177
176
175
174

13
15
18
21
25
30
36
42
50
60

2,239
2,512
2,818
3,162
3,548
3,981
4,467
5,012
5,623
6,310

1,585
1,778
1,995
2,239
2,512
2,818
3,162
3,548
3,981
4,467

501
562
631
708
794
891
1,000
1,122
1,259
1,413

173
172
171
170
169
168
167
166
165
164
163
162
161
160
159
158

71
85
101
120
143
170
202
240
285
339
404
480
571
679
807
960

7,079
7,943
8,913
10,000
11,220
12,589
14,125
15,849
17,783
19,953
22,387
25,119
28,184
31,623
35,481
39,811

5,012
5,623
6,310
7,079
7,943
8,913
10,000
11,220
12,589
14,125
15,849
17,783
19,953
22,387
25,119
28,184

1,585
1,778
1,995
2,239
2,512
2,818
3,162
3,548
3,981
4,467
5,012
5,623
6,310
7,079
7,943
8,913

BSY-1
SQS-53C

A
V E
O	X
I P
D O
		 S
T U
H R
I E
S

All ranges and SPLs are nominal.
*SPL is measured in dB/1 µPA at the dive site. To convert SPL for sound levels referenced to mbar,
subtract 100 dB from tabled levels.
(U) = upgrade

1A-14

U.S. Navy Diving Manual — Volume 1

Table 1A‑6. Permissible Exposure Limit (PEL) Within a 24-hour Period for Exposure to AN/SQQ-14, -30,
‑32 Sonars.

Estimated Ranges in yards for given SPL and PEL for sonar.

WET SUIT UN-HOODED
SPL
(dB)

PEL
(MIN)

Range
(yards)

200
199
198
197
196
195
194
193
192
191
190
189
188

120
143
170
202
240
285
339
404
480
571
679
807
960

13
14
16
18
20
22
25
28
32
35
40
45
50

WET SUIT HOODED
SPL
(dB)

PEL
(MIN)

Range
(yards)

215
214
213
212
211
210
209
208
207
206
205
204
203

120
143
170
202
240
285
339
404
480
571
679
807
960

2
3
3
3
4
4
4
5
6
6
7
8
9

Dry suit helmeted divers: no restriction for these sonars. All ranges and SPLs are nominal.
*SPL is measured in dB/1 µPA at the dive site. To convert SPL for sound levels referenced to mbar,
subtract 100 dB from tabled levels.

APPENDIX 1A – Safe Diving Distances from Transmitting Sonar	

1A-15

1A-5

GUIDANCE FOR DIVER EXPOSURE TO LOW-FREQUENCY SONAR (160–320 Hz)

If possible, you should avoid diving in the vicinity of low-frequency sonar (LFS).
LFS generates a dense, high-energy pulse of sound that can be harmful at higher
power levels. Because a variety of sensations may result from exposure to LFS, it
is necessary to inform divers when exposure is likely and to brief them regarding
possible effects; specifically, that they can expect to hear and feel it. Sensations
may include mild dizziness or vertigo, skin tingling, vibratory sensations in the
throat and abdominal fullness. Divers should also be briefed that voice communi­
cations are likely to be affected by the underwater sound to the extent that line pulls
or other forms of communication may become necessary. Annoyance and effects
on communication are less likely when divers are wearing a hard helmet (MK
21) diving rig. For safe distance guidance, contact NAVSEA (00C3). Tele­phone
numbers are listed in Volume 1, Appendix C.
1A-6

GUIDANCE FOR DIVER EXPOSURE TO ULTRASONIC SONAR (250 KHz AND
GREATER)

The frequencies used in ultrasonic sonars are above the human hearing threshold.
The primary effect of ultrasonic sonar is heating. Because the power of ultrasonic
sonar rapidly falls off with distance, a safe operating distance is 10 yards or greater.
Dive operations may be conducted around this type of sonar provided that the
diver does not stay within the sonar’s focus beam. The diver may finger touch
the transducer’s head momentarily to verify its operation as long as the sonar is
approached from the side.

1A-16

U.S. Navy Diving Manual — Volume 1

APPENDIX 1B

References
References

Subject

BUMEDINST 6200.15

Suspension of Diving During Pregnancy

BUMEDINST 6320.38

Clinical Use of Recompression Chambers for Non-Diving
Illnesses: Policy for

Manual of the Medical Department, Article 15-66

Medical Examinations

MILPERSMAN Article 1220

Military Personnel Manual

NAVEDTRA 10669-C

Hospital Corpsman 3 & 2

NAVFAC P-990

UCT Conventional Inspection and Repair Techniques

NAVFAC P-991

Expedient Underwater Repair Techniques

NAVFAC P-992

UCT Arctic Operations Manual

NAVMED P-5010

Manual of Naval Preventive Medicine

NAVSEA 10560 ltr, Ser 00C34/3160 of 27 Sept 01

UBA Canister Duration

NAVSEA/00C ANU,
www.navsea.navy.mil/sea00c/doc/anu_disc.html

Authorized for Navy Use

NAVSEA (SS521-AA-MAN-010)

U.S. Navy Diving and Manned Hyperbaric System Safety
Certification Manual

NAVSEA Technical Manual (S0600-AA-PRO-010)

Underwater Ship Husbandry Manual

NAVSEA Technical Manual (SS500-HK-MMO-010)

MK 3 MOD 0 Light Weight Diving System Operating and
Maintenance

NAVSEA Technical Manual (SS500-AW-MMM-010)

MK 6 MOD 0 Transportable Recompression Chamber System
Operating and Maintenance

NAVSEA Technical Manual (SS600-AA-MMA-010)

MK 16 MOD 0 Operating and Maintenance

NAVSEA Technical Manual (SS600-AQ-MMO-010)

MK 16 MOD 1 Operating and Maintenance

NAVSEA Technical Manual (SS-600-A3-MMO-010)

MK 25 MOD 2 UBA Operating and Maintenance

NAVSEA Technical Manual (S9592-B1-MMO-010)

Fly Away Dive System (FADS) III Air System Operating and
Maintenance

NAVSEA Technical Manual (SS9592-B2-MMO-010)

Fly Away Dive System (FADS) III Mixed Gas System (FMGS)
Operating and Maintenance

NAVSEA Technical Manual (S9592-AN-MMO-010)

Emergency Breathing System Type I Operating and
Maintenance

NAVSEA Technical Manual (0938-LP-011-4010)

Nuclear Powered Submarine Atmosphere Control Manual

NAVSEA Technical Manual (S9592-AY-MMO-020)

MK 5 MOD 0 Flyaway Recompression Chamber (FARCC)

NAVSEA Technical Manual (SS500-B1-MMO-010)

Standard Navy Double-Lock Recompression Chamber System

NAVSEA Technical Manual (SH700-A2-MMC-010)

Emergency Hyperbaric Stretcher Operations and Maintenance

NAVSEA Technical Manual (SS521-AJ-PRO-010)

Guidance for Diving in Contaminated Waters

APPENDIX 1B — References	

1B-1

Naval Ships Technical Manual, Chapter 74, Vol. 1  (S9086-CHSTM-010)

Welding and Allied Processes

Naval Ships Technical Manual, Chapter 74, Vol. 3 (S9086-CHSTM-030)

Gas Free Engineering

Naval Ships Technical Manual, Chapter 262 (S9086-H7-STM010)

Lubricating Oils, Greases, Specialty Lubricants, and
Lubrication Systems

Naval Ships Technical Manual, Chapter 550 (S9086-SX-STM010)

Industrial Gases, Generating, Handling, and Storage

NAVSEA Operation & Maintenance Instruction (0910-LP-0016300)

Fly Away Diving System Filter/Console

NAVSEA Operation & Maintenance Instruction (0910-LP-0011500)

Fly Away Diving System Diesel Driven Compressor Unit EX 32
MOD 0, PN 5020559

Naval Safety Center Technical Manual

Guide to Extreme Cold Weather

NAVSEA Technical Manual (S0300-A5-MAN-010)

Polar Operations Manual

Office of Naval Research Technical Manual

Guide to Polar Diving

ASTM G-88-90

Standard Guide for Designing Systems for Oxygen Service

ASTM G-63-92

Standard Guide for Evaluating Nonmetallic Materials for
Oxygen Service

ASTM G-94-92

Standard Guide for Evaluating Metals for Oxygen Service

FED SPEC BB-A-1034 B

Diver’s Compressed Air Breathing Standard

FED SPEC A-A-59503

Compressed Nitrogen Standard

MIL-D -16791

Detergents, General Purpose (Liquid, Nonionic)

MIL-PRF-27210G

Oxygen, Aviators Breathing, Liquid and Gaseous

MIL-PRF-27407B

Propellant Pressurizing Agent Helium, Type I Gaseous
Grade B

MIL-STD-438

Schedule of Piping, Valves and Fittings, and Associated Piping
Components for Submarine Service

MIL-STD-777

Schedule of Piping, Valves and Fittings, and Associated Piping
Components for Naval Surface Ships

MIL-STD-1330

Cleaning and Testing of Shipboard Oxygen, and Nitrogen
Systems Helium, Helium - Oxygen

OPNAVINST 3120.32C CH-1

Equipment Tag-Out Bill

OPNAVINST 3150.27 Series

Navy Diving Program

OPNAVINST 5100.19C, Appendix A-6

Navy Occupational Safety and Health (NAVOSH) Program
Manual for Forces Afloat

OPNAVINST 5100.23

Navy Occupational Safety and Health (NAVOSH) Afloat
Program Manual

OPNAVINST 5102.1C CH-1

Mishap Investigation and Reporting

OPNAVINST 8023.2C CH-1

U.S. Navy Explosives Safety Policies, Requirements, and
Procedures (Department of the Navy Explosives Safety Policy
Manual)

OSHA 29 CFR Part 1910 Subpart T, PG 6-36

Commercial Diving Operations

MIL-PRF-17331

Lubricant (2190 TEP)

1B-2

U.S. Navy Diving Manual — Volume 1

MIL-PRF-17672

Lubricant (2135 TH)

ANSI-B57.1 and CSA-B96

American and Canadian Standard Compressed-Gas Cylinder
Valve Outlet and Inlet Connections

Z48.1

American National Standard Method of Marking Portable
Compressed-Gas Containers to Identify the Material Contained

CGA Pamphlet C-7

Guide to the Preparation of Precautionary Labeling and
Marking of Compressed Gas Cylinders

APPENDIX 1B — References	

1B-3

PAGE LEFT BLANK INTENTIONALLY

1B-4

U.S. Navy Diving Manual — Volume 1

APPENDIX 1C

Telephone Numbers
Command

Department

Telephone

Fax

Naval Surface Warfare Center -

Diver Life Support (Fleet Support

(850) 234-4482  

(850) 234-4775

& Air Sampling

DSN: 436-4482

Panama City, Florida (NSWCPC)
BUMED M3B42
National Oceanic and Atmospheric

(202) 762-3444
HAZMAT

(206) 526-6317

(206) 526-6329

Naval Sea Systems Command

(202) 781-XXXX

(202) 781-4588

(COMNAVSEASYSCOM)

DSN: 326-XXXX

Administration (NOAA)

00C

Director

(202) 781-0731

00C1

Finance

(202) 781-0648

00C2

Salvage

(202) 781-2736

00C3

Diving

(202) 781-0934

00C4

Certification

(202) 781-0927

00C5

Husbandry

(202) 781-3453

Deep Submergence Systems

(202) 781-1467

Certification

(202) 781-1336

(Code OFP)

(202) 433-5596

Naval Sea Systems Command Code
07Q
NAVFAC Ocean Facilities Program

(202) 433-2280

DSN 288-5596.

Appendix 1C — Telephone Numbers	

1C-1

PAGE LEFT BLANK INTENTIONALLY

1C-2

U.S. Navy Diving Manual — Volume 1

APPENDIX 1D

List of Acronyms
ABS

Acrylonitrile Butadiene Styrene

ACF

Actual Cubic Feet

ACFM

Actual Cubic Feet per Minute

ACGIH

American Conference of Governmental Industrial Hygienists

ACLS

Advanced Cardiac Life Support

ADS

Advance Diving System

AGE

Arterial Gas Embolism

ALSS

Auxiliary Life-Support System

AM

Amplitude Modulated

ANU

Authorized for Navy Use List

AQD

Additional Qualification Designator

ARD

Audible Recall Device

AS

Submarine Tender

ASDS

Advanced SEAL Delivery System

ASRA

Air Supply Rack Assembly

ASME

American Society of Mechanical Engineers

ATA

Atmosphere Absolute

ATP

Ambient Temperature and Pressure

ATS

Active Thermal System

BC

Buoyancy Compensator

BCLS

Basic Cardiac Life Support

BIBS

Built-In Breathing System

BPM

Breaths per Minute

APPENDIX 1D — List of Acronyms	

1D-1

1D-2

BTPS

Body Temperature, Ambient Pressure

BTU

British Thermal Unit

CDO

Command Duty Officer

CCTV

Closed-Circuit Television

CGA

Compressed Gas Association

CNO

Chief of Naval Operations

CNS

Central Nervous System

CONUS

Continental United States

COSAL

Coordinated Shipboard Allowance List

CPR

Cardiopulmonary Resuscitation

CRS

Chamber Reducing Station

CSMD

Combat Swimmer Multilevel Dive

CUMA

Canadian Underwater Minecountermeasures Apparatus

CWDS

Contaminated Water Diving System

DATPS

Divers Active Thermal Protection System

DC

Duty Cycle

DCS

Decompression Sickness

DDC

Deck Decompression Chamber

DDS

Deep Diving System

DDS

Dry Deck Shelter

DHMLS

Divers Helmet Mounted Lighting System

DLSE

Diving Life-Support Equipment

DLSS

Divers Life Support System

DMO

Diving Medical Officer

DMS

Dive Monitoring System

DMT

Diving Medical Technician

U.S. Navy Diving Manual — Volume 1

DOT

Department of Transportation

DRS

Dive Reporting System

DSI

Diving Systems International

DSM

Diving System Module

DSRG

Deep Submergence Review Group

DSRV

Deep Submergence Rescue Vehicle

DSSP

Deep Submergence System Project

DT

Dive Time or Descent Time

DT/DG

Dive Timer/Depth Gauge

DUCTS

Divers Underwater Color Television System

DV

Diver

DPV

Diver Propulsion Vehicle

EAD

Equivalent Air Depth

EBA

Emergency Breathing Apparatus

EBS I

Emergency Breathing System I

EDWS

Enhanced Diver Warning System

EEHS

Emergency Evacuation Hyperbaric Stretcher

EGS

Emergency Gas Supply

ENT

Ear, Nose, and Throat

EOD

Explosive Ordnance Disposal

EPs

Emergency Procedures

ESDS

Enclosed Space Diving System

ESDT

Equivalent Single Dive Time

ESSM

Emergency Ship Salvage Material

FADS III

Flyaway Air Dive System III

FAR

Failure Analysis Report

APPENDIX 1D — List of Acronyms	

1D-3

1D-4

FARCC

Flyaway Recompression Chamber

FED SPEC

Federal Specifications

FFM

Full Face Mask

FFW

Feet of Fresh Water

FMGS

Flyaway Mixed-Gas System

FPM

Feet per Minute

FSW

Feet of Sea Water

FV

Floodable Volume

GFI

Ground Fault Interrupter

GPM

Gallons per Minute

HBO2

Hyperbaric Oxygen

HOSRA

Helium-Oxygen Supply Rack Assembly

HP

High Pressure

HPNS

High Pressure Nervous Syndrome

HSU

Helium Speech Unscrambler

ICCP

Impressed-Current Cathodic Protection

IDV

Integrated Divers Vest

IL

Inner Lock

ILS

Integrated Logistics Support

ISIC

Immediate Senior in Command

JAG

Judge Advocate General

J/L

Joules per Liter, Unit of Measure for Work of Breathing

KwHr

Kilowatt Hour

LB

Left Bottom

LCM

Landing Craft, Medium

LFA

Low Frequency Acoustic
U.S. Navy Diving Manual — Volume 1

LFS

Low Frequency Sonar

LP

Low Pressure

LPM

Liters per Minute

LS

Left Surface

LSS

Life Support System or Life Support Skid

LWDS

Light Weight Diving System

MBC

Maximal Breathing Capacity

MCC

Main Control Console

MD

Maximum Depth

MDSU

Mobile Diving and Salvage Unit

MDV

Master Diver

MEFR

Maximum Expiratory Flow Rate

MEV

Manual Exhaust Valve

MFP

Minimum Flask Pressure

MGCCA

Mixed-Gas Control Console Assembly

MIFR

Maximum Inspiratory Flow Rate

MIL-STD

Military Standard

MMP

Minimum Manifold Pressure

MP

Medium Pressure

MRC

Maintenance Requirement Card

MSW

Meters of Sea Water

MVV

Maximum Ventilatory Volume

NAVEDTRA

Naval Education Training

NAVFAC

Naval Facilities Engineering Command

NAVMED

Naval Medical Command

NAVSEA

Naval Sea Systems Command

APPENDIX 1D — List of Acronyms	

1D-5

1D-6

ND

Noise Dose

NDSTC

Naval Diving and Salvage Training Center

NEC

Navy Enlisted Classification

NEDU

Navy Experimental Diving Unit

NEURO

Neurological Examination

NID

Non-Ionic Detergent

NITROX

Nitrogen-Oxygen

NMRI

Navy Medical Research Institute

NOAA

National Oceanic and Atmospheric Administration

NO-D

No Decompression

NPC

Naval Personnel Command

NRV

Non Return Valve

NSMRL

Navy Submarine Medical Research Laboratory

NSN

National Stock Number

NSTM

Naval Ships Technical Manual or NAVSEA Technical Manual

NSWC-PC

Naval Surface Warfare Center - Panama City

O&M

Operating and Maintenance

OBP

Over Bottom Pressure

OCEI

Ocean Construction Equipment Inventory

OIC

Officer in Charge

OJT

On the Job Training

OL

Outer Lock

OOD

Officer of the Deck

OPs

Operating Procedures

OSF

Ocean Simulation Facility

OSHA

Occupational Safety and Health Administration
U.S. Navy Diving Manual — Volume 1

PEL

Permissible Exposure Limit

PMS

Planned Maintenance System

PNS

Peripheral Nervous System

PP

Partial Pressure

PPCO2

Partial Pressure Carbon Dioxide

PPM

Parts per Million

PPO2

Partial Pressure Oxygen

PSI

Pounds per Square Inch

PSIA

Pounds per Square Inch Absolute

PSIG

Pounds per Square Inch Gauge

PSOB

Pre-Survey Outline Booklet

PTC

Personnel Transfer Capsule

PTS

Passive Thermal System

QA

Quality Assurance

RB

Reached Bottom

RCC

Recompression Chamber

REC

Re-Entry Control

RMV

Respiratory Minute Ventilation

RNT

Residual Nitrogen Time

ROV

Remotely Operated Vehicle

RQ

Respiratory Quotient

RS

Reached Surface

RSP

Render Safe Procedure

SAD

Safe Ascent Depth

SCA

System Certification Authority

SCF

Standard Cubic Feet

APPENDIX 1D — List of Acronyms	

1D-7

1D-8

SCFM

Standard Cubic Feet per Minute

SCFR

Standard Cubic Feet Required

SCSCs

System Certification Survey Cards

SCUBA

Self Contained Underwater Breathing Apparatus

SDRW

Sonar Dome Rubber Window

SDS

Saturation Diving System

SDV

SEAL Delivery Vehicle

SEAL

Sea, Air, and Land

SET

Surface Equivalent Table

SEV

Surface Equivalent (percent or pressure)

SI

Surface Interval or System International

SLED

Sea Level Equivalent Depth

SLM

Standard Liters per Minute (short version used in formulas)

SLPM

Standard Liters per Minute

SNDB

Standard Navy Dive Boat

SOC

Scope of Certifications

SPL

Sound Pressure Level

SRDRS

Submarine Rescue and Diver Recompression System

SSB

Single Side Band

SSDS

Surface Supplied Diving System

STEL

Safe Thermal Exposure Limits

STP

Standard Temperature and Pressure

STPD

Standard Temperature and Pressure, Dry Gas

SUR D

Surface Decompression

SUR D AIR

Surface Decompression Using Air

SUR D O2

Surface Decompression Using Oxygen
U.S. Navy Diving Manual — Volume 1

T-ARS

Auxiliary Rescue/Salvage Ship

T-ATF

Fleet Ocean Tug

TBT

Total Bottom Time

TDCS

Tethered Diver Communication System

TDT

Total Decompression Time

TL

Transfer Lock

TLC

Total Lung Capacity

TLD

Thermal Luminescence Dosimeter

TLV

Threshold Limit Values

TM

Technical Manual

TMDER

Technical Manual Deficiency Evaluation Report

TRC

Transportable Recompression Chamber

TRCS

Transportable Recompression Chamber System

TTD

Total Time of Dive

UBA

Underwater Breathing Apparatus

UCT

Underwater Construction Team

UDM

Underwater Decompression Monitor

UQC

Underwater Sound Communications

UWSH

Underwater Ship Husbandry

VENTIDC

Vision Ear Nausea Twitching Irritability Dizziness
Convulsions

VTA

Volume Tank Assembly

VVDS

Variable Volume Dry Suit

WOB

Work of Breathing

YDT

Diving Tender

APPENDIX 1D — List of Acronyms	

1D-9

PAGE LEFT BLANK INTENTIONALLY

1D-10

U.S. Navy Diving Manual — Volume 1

VOLUME 2

Air Diving
Operations

6

Operational Planning
and Risk Management

7

Scuba Air Diving
Operations

8

Surface Supplied Air
Diving Operations

9

Air Decompression

10

Nitrogen Oxygen
Diving Operations

11

Ice and Cold Water
Diving Operations

Appendix 2A

Optional Shallow Water
Diving Tables

U.S. Navy Diving Manual

PAGE LEFT BLANK INTENTIONALLY

Volume 2 - �Table of Contents
Chap/Para

Page

6

Operational Planning and Risk Management

6-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1

6-2

6-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1

6-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1

MISSION OBJECTIVE AND OPERATIONAL TASKS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1
6-2.1

Underwater Ship Husbandry (UWSH). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-1
6‑2.1.1
6‑2.1.2
6‑2.1.3
6‑2.1.4
6-2.1.5

6-2.2

Salvage/Object Recovery. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.3

Search Missions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.4

Explosive Ordnance Disposal. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.5

Security Swims. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

6-2.6

Underwater Construction . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-4
6‑2.6.1
6‑2.6.2
6‑2.6.3

6-3

6-4

Objective of UWSH Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2
Repair Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2
Diver Training and Qualification Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2
Training Program Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3
Ascent Training and Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-3

Diver Training and Qualification Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5
Equipment Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5
Underwater Construction Planning Resources . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6-2.7

Demolition Missions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6-2.8

Combat Swimmer Missions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6-2.9

Enclosed Space Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

GENERAL PLANNING AND ORM PROCESS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-6
6-3.1

Concept of ORM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-6

6-3.2

Risk Management Terms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-6

6-3.3

ORM Process. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-7

COLLECT and ANALYZE DATA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8
6-4.1

Information Gathering. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8

6-4.2

Planning Data. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8

6-4.3

Object Recovery. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8
6‑4.3.1

6-4.4

Searching for Objects or Underwater Sites . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-8

Data Required for All Diving Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-9
6‑4.4.1
6‑4.4.2
6‑4.4.3
6‑4.4.4

Table of Contents­—Volume 2	

Surface Conditions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-9
Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-13
Type of Bottom. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-13
Tides and Currents. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-13

2–i

Chap/Para
6-5

Page
IDENTIFY OPERATIONAL HAZARDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-15
6-5.1

Underwater Visibility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-16

6-5.2

Temperature . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-16

6-5.3

Warm Water Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-17
6‑5.3.1
6‑5.3.2

6-5.4

Contaminated Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-19

6-5.5

Chemical Contamination. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20

6-5.6

Biological Contamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

6-5.7

Altitude Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20

6-5.8

Underwater Obstacles. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20

6-5.9

Electrical Shock Hazards . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-20
6‑5.9.1
6‑5.9.2

6-6

Explosions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.11

Sonar. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.12

Nuclear Radiation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.13

Marine Life . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.14

Vessels and Small Boat Traffic. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-22

6-5.15

Territorial Waters. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24

6-5.16

Emergency Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24

SELECT DIVING TECHNIQUE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24
6-6.1

Factors to Consider when Selecting the Diving Technique. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-24

6-6.2

Breathhold Diving Restrictions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27

6-6.3

Operational Characteristics of SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27

6-6.4

Mobility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
Buoyancy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
Portability. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-27
Operational Limitations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27
Environmental Protection . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

Operational Characteristics of SSDS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
6‑6.4.1
6‑6.4.2
6‑6.4.3
6‑6.4.4

2–ii

Reducing Electrical Shock Hazards. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-21
Securing Electrical Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-21

6-5.10

6‑6.3.1
6‑6.3.2
6‑6.3.3
6‑6.3.4
6‑6.3.5

6-7

Operational Guidelines and Safety Precautions. . . . . . . . . . . . . . . . . . . . . . 6-17
Mission Planning Factors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-19

Mobility. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
Buoyancy. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
Operational Limitations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28
Environmental Protection. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

SELECT EQUIPMENT AND SUPPLIES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28
6-7.1

Equipment Authorized for Navy Use. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

6-7.2

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-28

6-7.3

Diving Craft and Platforms . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-29

6-7.4

Deep-Sea Salvage/Rescue Diving Platforms. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-29

6-7.5

Small Craft . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-29

U.S. Navy Diving Manual—Volume 2

Chap/Para
6-8

Page
SELECT AND ASSEMBLE THE DIVING TEAM . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-30
6-8.1

Manning Levels. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-30

6-8.2

Commanding Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6-8.3

Command Diving Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6-8.4

Watchstation Diving Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6-8.5

Master Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32
6‑8.5.1
6‑8.5.2

6-8.6

Diving Supervisor . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
6‑8.6.1
6‑8.6.2
6‑8.6.3
6‑8.6.4

Pre-dive Responsibilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
Responsibilities While Operation is Underway. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
Post-dive Responsibilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33
Diving Supervisor Qualifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34

6-8.7

Diving Medical Officer. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-34

6-8.8

Diving Personnel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-34
6‑8.8.1
6‑8.8.2
6‑8.8.3
6‑8.8.4
6‑8.8.5
6‑8.8.6
6‑8.8.7
6‑8.8.8
6‑8.8.9
6‑8.8.10
6‑8.8.11
6‑8.8.12
6‑8.8.13

6-8.9

Diving Personnel Responsibilities . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diving Personnel Qualifications. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Standby Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Buddy Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Diver Tender. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Recorder. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Medical Personnel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Other Support Personnel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Cross-Training and Substitution. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Physical Condition. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Underwater Salvage or Construction Demolition Personnel . .  .  .  .  .  .  .  .  .  .  .
Blasting Plan . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Explosive Handlers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

6-34
6-34
6-35
6-36
6-36
6-36
6-36
6-37
6-37
6-37
6-38
6-38
6-38

OSHA Requirements for U.S. Navy Civilian Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-38
6‑8.9.1
6‑8.9.2
6‑8.9.3
6‑8.9.4

6-9

Master Diver Responsibilities. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32
Master Diver Qualifications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-33

SCUBA Diving (Air) Restriction . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Surface Supplied Air Diving Restrictions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Mixed Gas Diving Restrictions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Recompression Chamber Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

6-39
6-39
6-39
6-40

ORGANIZE AND SCHEDULE OPERATIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-40
6-9.1

Task Planning and Scheduling . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-40

6-9.2

Post-dive Tasks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-40

6-10 BRIEF THE DIVING TEAM. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41
6-10.1

Establish Mission Objective . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.2

Identify Tasks and Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.3

Review Diving Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.4

Assignment of Personnel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-41

6-10.5

Assistance and Emergencies. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-42

6-10.6

Notification of Ship’s Personnel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-42

6-10.7

Fouling and Entrapment.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-42

Table of Contents­—Volume 2	

2–iii

Chap/Para

Page
6-10.8

Equipment Failure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-43
6‑10.8.1 Loss of Gas Supply . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-43
6‑10.8.2 Loss of Communications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-43

6-10.9

Lost Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-54

6-10.10 Debriefing the Diving Team. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-54
6-11

AIR DIVING EQUIPMENT REFERENCE DATA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-54

7

SCUBA Air Diving Operations

7-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1

7-2

7-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1

7-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1

REQUIRED EQUIPMENT FOR SCUBA OPERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-1
7-2.1

Equipment Authorized for Navy Use. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-2

7-2.2

Open-Circuit SCUBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-2
7‑2.2.1
7‑2.2.2
7‑2.2.3
7‑2.2.4

7-2.3

Minimum Equipment. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-7
7‑2.3.1
7‑2.3.2
7‑2.3.3
7‑2.3.4
7‑2.3.5
7‑2.3.6
7‑2.3.7
7‑2.3.8

7-3

Protective Clothing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-11
7‑3.1.1
7‑3.1.2
7‑3.1.3
7‑3.1.4
7‑3.1.5
7‑3.1.6
7‑3.1.7
7‑3.1.8
7‑3.1.9
7‑3.1.10

2–iv

Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-7
Life Preserver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-8
Buoyancy Compensator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-8
Weight Belt. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-9
Knife. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-9
Swim Fins. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10
Wrist Watch . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10
Depth Gauge . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10

OPTIONAL EQUIPMENT FOR SCUBA OPERATIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-10
7-3.1

7-4

Demand Regulator Assembly. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-2
Cylinders . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-4
Cylinder Valves and Manifold Assemblies. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-6
Backpack or Harness. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-7

Wet Suits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-11
Dry Suits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-11
Gloves . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12
Writing Slate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12
Signal Flare . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12
Acoustic Beacons. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Lines and Floats. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Snorkel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Compass . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-13
Submersible Cylinder Pressure Gauge . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-14

AIR SUPPLY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-14
7-4.1

Duration of Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-14

7-4.2

Compressed Air from Commercial Sources . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-16

7-4.3

Methods for Charging SCUBA Cylinders . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-16

U.S. Navy Diving Manual—Volume 2

Chap/Para

Page
7-4.4

Operating Procedures for Charging SCUBA Tanks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-17
7‑4.4.1

7-4.5
7-5

Safety Precautions for Charging and Handling Cylinders. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-19

PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-20
7-5.1

Equipment Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-20
7‑5.1.1
7‑5.1.2
7‑5.1.3
7‑5.1.4
7‑5.1.5
7‑5.1.6
7‑5.1.7
7‑5.1.8
7‑5.1.9
7‑5.1.10
7‑5.1.11
7‑5.1.12
7‑5.1.13

7-6

Air Cylinders. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Harness Straps and Backpack. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Breathing Hoses. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Regulator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Life Preserver/Buoyancy Compensator (BC). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Swim Fins. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Dive Knife. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Snorkel. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Weight Belt. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Submersible Wrist Watch. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Depth Gauge and Compass. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Miscellaneous Equipment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

7-21
7-21
7-21
7-21
7-22
7-22
7-22
7-23
7-23
7-23
7-23
7-23
7-23

7-5.2

Diver Preparation and Brief. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-23

7-5.3

Donning Gear. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-24

7-5.4

Predive Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-25

WATER ENTRY AND DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
7-6.1

Water Entry. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
7‑6.1.1
7‑6.1.2
7‑6.1.3

7-7

Topping off the SCUBA Cylinder . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-19

Step-In Method. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
Rear Roll Method. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-26
Entering the Water from the Beach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-28

7-6.2

Pre-descent Surface Check . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-28

7-6.3

Surface Swimming . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29

7-6.4

Descent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29

UNDERWATER PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29
7-7.1

Breathing Technique. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-29

7-7.2

Mask Clearing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-30

7-7.3

Hose and Mouthpiece Clearing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-30

7-7.4

Swimming Technique . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-30

7-7.5

Diver Communications . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31
7‑7.5.1
7‑7.5.2

Through-Water Communication Systems . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31
Hand and Line-Pull Signals . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31

7-7.6

Buddy Diver Responsibilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-32

7-7.7

Buddy Breathing Procedure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-32

7-7.8

Tending. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-36
7‑7.8.1
7‑7.8.2

Table of Contents­—Volume 2	

Tending with a Surface or Buddy Line.. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-36
Tending with No Surface Line. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-36

2–v

Chap/Para

7-8

Page
7-7.9

Working with Tools . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-36

7-7.10

Adapting to Underwater Conditions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-37

ASCENT PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-37
7-8.1

Emergency Free-Ascent Procedures . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-38

7-8.2

Ascent From Under a Vessel . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-38

7-8.3

Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-39

7-8.4

Surfacing and Leaving the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-40

7-9

POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-40

8

Surface Supplied Air Diving Operations

8-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-2

8-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

MK 21 MOD 1, KM-37. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1
8-2.1

Operation and Maintenance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-2.2

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-2
8‑2.2.1
8‑2.2.2
8‑2.2.3

8-3

MK 20 MOD 0. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7
8-3.1

Operation and Maintenance. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7

8-3.2

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7
8‑3.2.1
8‑3.2.2
8‑3.2.3

8-4

8-5

EGS Requirements for MK 20 MOD 0 Enclosed-Space Diving. .  .  .  .  .  .  .  .  .  .  . 8-7
EGS Requirements for MK 20 MOD 0 Open Water Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8
Flow Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

EXO BR MS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8
8-4.1

EXO BR MS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.2

Operations and Maintenance . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.3

Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.4

EGS Requirements for EXO BR MS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-8

8-4.5

Flow and Pressure Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9

PORTABLE SURFACE-SUPPLIED DIVING SYSTEMS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9
8-5.1

MK 3 MOD 0 Lightweight Dive System (LWDS). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9
8‑5.1.1
8‑5.1.2
8‑5.1.3

2–vi

Emergency Gas Supply Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-2
Flow Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-3
Pressure Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-4

MK 3 MOD 0 Configuration 1. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-9
MK 3 MOD 0 Configuration 2. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10
MK 3 MOD 0 Configuration 3. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-5.2

MK 3 MOD 1 Lightweight Dive System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-5.3

ROPER Diving Cart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

U.S. Navy Diving Manual—Volume 2

Chap/Para

Page
8-5.4

Flyaway Dive System (FADS) III. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-13

8-5.5

Oxygen Regulator Console Assembly (ORCA). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-13

8-6

ACCESSORY EQUIPMENT FOR SURFACE-SUPPLIED DIVING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-15

8-7

SURFACE AIR SUPPLY SYSTEMS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-16
8-7.1

Requirements for Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-16
8‑7.1.1
8‑7.1.2
8‑7.1.3
8‑7.1.4
8‑7.1.5

8-7.2

8-9

8-16
8-16
8-16
8-17
8-17

Primary and Secondary Air Supply. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-17
8‑7.2.1
8‑7.2.2
8‑7.2.3

8-8

Air Purity Standards. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Air Supply Flow Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Supply Pressure Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Water Vapor Control. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Standby Diver Air Requirements . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

Requirements for Operating Procedures and Emergency Procedures . .  .  . 8-18
Air Compressors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-18
High-Pressure Air Cylinders and Flasks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-21

DIVER COMMUNICATIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-22
8-8.1

Diver Intercommunication Systems. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-22

8-8.2

Line-Pull Signals. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-23

PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-24
8-9.1

Predive Checklist . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-24

8-9.2

Diving Station Preparation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.3

Air Supply Preparation . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.4

Line Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.5

Recompression Chamber Inspection and Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.6

Predive Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-25

8-9.7

Donning Gear. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-9.8

Diving Supervisor Predive Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-10 WATER ENTRY AND DESCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-25

8-11

8-10.1

Predescent Surface Check. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-26

8-10.2

Descent. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-26

UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-27
8-11.1

Adapting to Underwater Conditions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-27

8-11.2

Movement on the Bottom . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-27

8-11.3

Searching on the Bottom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-28

8-11.4

Enclosed Space Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29
8‑11.4.1
8‑11.4.2

Enclosed Space Hazards. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29
Enclosed Space Safety Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29

8-11.5

Working Around Corners. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-29

8-11.6

Working Inside a Wreck . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30

8-11.7

Working With or Near Lines or Moorings . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30

Table of Contents­—Volume 2	

2–vii

Chap/Para

Page
8-11.8

Bottom Checks. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30

8-11.9

Job Site Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-30
8‑11.9.1
8‑11.9.2

Underwater Ship Husbandry Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-31
Working with Tools. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-31

8-11.10 Safety Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-31
8‑11.10.1
8‑11.10.2
8‑11.10.3
8‑11.10.4

Fouled Umbilical Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32
Fouled Descent Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-32
Falling. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32
Damage to Helmet and Diving Dress. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32

8-11.11 Tending the Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-32
8-11.12 Monitoring the Diver’s Movements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-33
8-12 ASCENT PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-34
8-13 SURFACE DECOMPRESSION . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35
8-13.1

Disadvantages of In-Water Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

8-13.2

Transferring a Diver to the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

8-14 POSTDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

2–viii

8-14.1

Personnel and Reporting . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

8-14.2

Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-36

9

Air Decompression

9-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1
9-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1

9-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1

9-2

THEORY OF DECOMPRESSION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-1

9-3

AIR DECOMPRESSION DEFINITIONS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2
9-3.1

Descent Time . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.2

Bottom Time . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.3

Total Decompression Time. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.4

Total Time of Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.5

Deepest Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.6

Maximum Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.7

Stage Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-2

9-3.8

Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.9

Decompression Schedule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.10

Decompression Stop. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.11

No-Decompression (No “D”) Limit. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.12

No-Decompression Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.13

Decompression Dive. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.14

Surface Interval. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

U.S. Navy Diving Manual—Volume 2

Chap/Para

Page
9-3.15

Residual Nitrogen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.16

Single Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.17

Repetitive Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.18

Repetitive Group Designator. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.19

Residual Nitrogen Time. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-3

9-3.20

Equivalent Single Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-3.21

Equivalent Single Dive Time. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-3.22

Surface Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-3.23

Exceptional Exposure Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-4

DIVE CHARTING AND RECORDING . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-4

9-5

THE AIR DECOMPRESSION TABLES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-6

9-6

GENERAL RULES FOR THE USE OF AIR DECOMPRESSION TABLES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-7

9-6.1

Selecting the Decompression Schedule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.2

Descent Rate . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.3

Ascent Rate. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.4

Decompression Stop Time . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9-6.5

Last Water Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-8

9-6.6

Eligibility for Surface Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-8

NO-DECOMPRESSION LIMITS AND REPETITIVE GROUP DESIGNATION TABLE
FOR NO-DECOMPRESSION AIR DIVES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-8
9-7.1

9-8

Optional Shallow Water No-Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-9

THE AIR DECOMPRESSION TABLE. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-9
9-8.1

In-Water Decompression on Air . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-9

9-8.2

In-Water Decompression on Air and Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-11
9-8.2.1
9-8.2.2

9-8.3

Surface Decompression on Oxygen (SurDO2). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-15
9-8.3.1
9-8.3.2

9-8.4
9-9

Procedures for Shifting to 100% Oxygen at 30 or 20 fsw. . . . . . . . . . . . . . . 9-11
Air Breaks at 30 and 20 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-13

Surface Decompression on Oxygen Procedure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-15
Surface Decompression from 30 and 20 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-17

Selection of the Mode of Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-19

REPETITIVE DIVES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-21
9-9.1

Repetitive Dive Procedure . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-21

9-9.2

RNT Exception Rule. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-25

9-9.3

Repetitive Air-MK 16 Dives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-29

9-9.4

Order of Repetitive Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-30

9-10 EXCEPTIONAL EXPOSURE DIVES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-31

Table of Contents­—Volume 2	

2–ix

Chap/Para
9-11

Page
VARIATIONS IN RATE OF ASCENT . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-31
9-11.1

Travel Rate Exceeded. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-31

9-11.2

Early Arrival at the First Decompression Stop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-31

9-11.3

Delays in Arriving at the First Decompression Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-32

9.11.4

Delays in Leaving a Stop or Between Decompression Stops. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-32

9-12 EMERGENCY PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-35
9-12.1

Bottom Time in Excess of the Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-35

9-12.2

Loss of Oxygen Supply in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-36

9-12.3

Contamination of Oxygen Supply with Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-37

9-12.4

CNS Oxygen Toxicity Symptoms (Non-convulsive) at 30 or 20 fsw Water Stop. .  .  .  .  . 9-37

9-12.5

Oxygen Convulsion at the 30- or 20-fsw Water Stop . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-38

9-12.6

Surface Interval Greater than 5 Minutes. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-39

9-12.7

Decompression Sickness During the Surface Interval . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-40

9-12.8

Loss of Oxygen Supply in the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-41

9-12.9

CNS Oxygen Toxicity in the Chamber. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-42

9-12.10 Asymptomatic Omitted Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-12.10.1 No-Decompression Stops Required. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-12.10.2 Omitted Decompression Stops at 30 and 20 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
9-12.10.3 Omitted Decompression Stops Deeper than 30 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

9-42
9-43
9-44
9-44

9-12.11 Decompression Sickness in the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-45
9-12.11.1 Diver Remaining in the Water . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-45
9-12.11.2 Diver Leaving the Water. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13 DIVING AT ALTITUDE . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13.1

Altitude Correction Procedure. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13.1.1 Correction of Dive Depth . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-46
9-13.1.2 Correction of Decompression Stop Depth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-47

9-13.2

Need for Correction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-47

9-13.3

Depth Measurement at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-47

9-13.4

Equilibration at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-49

9-13.5

Diving at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-50
9-13.5.1 Corrections for Depth of Dive at Altitude and In-Water Stops . .  .  .  .  .  .  .  .  .  . 9-50
9-13.5.2 Corrections for Equilibration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-52

9-13.6

Repetitive Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-53

9-14 ASCENT TO ALTITUDE AFTER DIVING / FLYING AFTER DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-57

10

Nitrogen-Oxygen Diving Operations

10-1 INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-1
10-1.1

Advantages and Disadvantages of NITROX Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-1

10-2 EQUIVALENT AIR DEPTH. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-1
10-2.1

2–x

Equivalent Air Depth Calculation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-2

U.S. Navy Diving Manual—Volume 2

Chap/Para

Page

10-3 OXYGEN TOXICITY. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-2
10-3.1

Selecting the Proper NITROX Mixture . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-3

10-4 NITROX DIVING PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-3
10-4.1

NITROX Diving Using Equivalent Air Depths . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-3

10-4.2

SCUBA Operations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-4.3

Special Procedures. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-4.4

Omitted Decompression. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-4.5

Dives Exceeding the Normal Working Limit . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5

10-5 NITROX REPETITIVE DIVING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5
10-6 NITROX DIVE CHARTING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-5
10-7 FLEET TRAINING FOR NITROX. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10-8 NITROX DIVING EQUIPMENT. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10-8.1

Open-Circuit SCUBA Systems . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10‑8.1.1 Regulators . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-7
10‑8.1.2 Bottles . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10-8.2

General. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10-8.3

Surface-Supplied NITROX Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10-9 EQUIPMENT CLEANLINESS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8
10-10 BREATHING GAS PURITY . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-9
10-11 NITROX MIXING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-9
10-12 NITROX MIXING, BLENDING, AND STORAGE SYSTEMS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-12

11

Ice and Cold Water Diving Operations

11-1

INTRODUCTION. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-2

11-1.1

Purpose. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-1.2

Scope . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

OPERATIONS PLANNING. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1
11-2.1

Planning Guidelines . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-2.2

Navigational Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-1

11-2.3

SCUBA Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-2

11-2.4

SCUBA Regulators. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-2
11‑2.4.1
11‑2.4.2

Special Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3
Octopus and Redundant Regulators . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3

11-2.5

Life Preserver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3

11-2.6

Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4

11-2.7

SCUBA Equipment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4

Table of Contents­—Volume 2	

2–xi

Chap/Para

Page
11-2.8

Surface-Supplied Diving System (SSDS) Considerations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4
11‑2.8.1 Advantages and Disadvantages of SSDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-4
11‑2.8.2 Effect of Ice Conditions on SSDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-5

11-2.9

Suit Selection . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-5
11‑2.9.1
11‑2.9.2
11‑2.9.3

Wet Suits . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-5
Variable Volume Dry Suits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-6
Extreme Exposure Suits/Hot Water Suits. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-6

11-2.10 Clothing. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-6
11-2.11 Ancillary Equipment . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7
11-2.12 Dive Site Shelter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7
11-3

11-4

11-5

11-6

PREDIVE PROCEDURES . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7
11-3.1

Personnel Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7

11-3.2

Dive Site Selection Considerations. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-7

11-3.3

Shelter. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.4

Entry Hole. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.5

Escape Holes . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.6

Navigation Lines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.7

Lifelines. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-8

11-3.8

Equipment Preparation. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-9

UNDERWATER PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10
11-4.1

Buddy Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

11-4.2

Tending the Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

11-4.3

Standby Diver. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

OPERATING PRECAUTIONS . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10
11-5.1

General Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-10

11-5.2

Ice Conditions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-11

11-5.3

Dressing Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-11

11-5.4

On-Surface Precautions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-11

11-5.5

In-Water Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-12

11-5.6

Postdive Precautions . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-12

EMERGENCY PROCEDURES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-13
11-6.1

Lost Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-13

11-6.2

Searching for a Lost Diver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-13

11-6.3

Hypothermia. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-14

11-7

ADDITIONAL REFERENCES. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-14

2A

Optional Shallow Water Diving Tables
2-A1.1

2–xii

Introduction. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2A-1

U.S. Navy Diving Manual—Volume 2

Volume 2 - List of Illustrations
Figure

Page

6-1

Underwater Ship Husbandry Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-2

6-2

Salvage Diving. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

6-3

Explosive Ordnance Disposal Diving. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

6-4

Underwater Construction Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-5

6‑5

Planning Data Sources. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-9

6‑6

Environmental Assessment Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-11

6-7

Sea State Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-12

6‑8

Equivalent Wind Chill Temperature Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-14

6‑9

Pneumofathometer . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-15

6‑10

Bottom Conditions and Effects Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-16

6‑11

Water Temperature Protection Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-18

6‑12

International Code Signal Flags . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-23

6‑13

Air Diving Techniques . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-25

6‑14

Normal and Maximum Limits for Air Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-26

6‑15

MK 21 Dive Requiring Two Divers. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-30

6‑16

Minimum Personnel Levels for Air Diving Stations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-31

6‑17

Master Diver Supervising Recompression Treatment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-32

6‑18

Standby Diver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-35

6-19

Diving Safety and Planning Checklist. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-44

6-20

Ship Repair Safety Checklist for Diving. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-48

6-21

Surface-Supplied Diving Operations Predive Checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-50

6‑22

Emergency Assistance Checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-53

6‑23

SCUBA General Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-55

6-24

MK 20 MOD 0 General Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-56

6-25

MK 21 MOD 1, KM-37 General Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-57

6‑26

EXO BR MS Characteristics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6-58

7-1

Schematic of Demand Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

7-2

Full Face Mask . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-4

7-3

Typical Gas Cylinder Identification Markings. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-5

7-4

Life Preserver . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-8

7-5

Protective Clothing . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-12

7-6

Cascading System for Charging SCUBA Cylinders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17

7-7

SCUBA Entry Techniques. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-27

List of Illustrations—Volume 2	

2–xiii

Figure

2–xiv

Page

7-8

Clearing a Face Mask. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-31

7-9

SCUBA Hand Signals . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-33

8-1

MK 21 MOD 1 SSDS. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-1

8-2

MK 20 MOD 0 UBA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-7

8-3

MK 3 MOD 0 Configuration 1 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-10

8-4

MK 3 MOD 0 Configuration 2 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-11

8-5

MK 3 MOD 0 Configuration 3 . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-11

8-6

Flyaway Dive System (FADS) III. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-12

8-7

ROPER Cart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-12

8-8

Oxygen Regulator Control Assembly (ORCA) II Schematic . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-14

8-9

Oxygen Regulator Control Assembly (ORCA) II. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-14

8‑10

HP Compressor Assembly (top); MP Compressor Assembly (bottom). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-19

8-11

Communicating with Line-Pull Signals . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-23

8-12

Surface Decompression . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-35

9-1

Diving Chart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-5

9‑2

Graphic View of a Dive with Abbreviations . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-6

9‑3

Completed Air Diving Chart: No-Decompression Dive . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-10

9‑4

Completed Air Diving Chart: In-water Decompression on Air . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-12

9‑5

Completed Air Diving Chart: In-water Decompression on Air and Oxygen. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-14

9‑6

Completed Air Diving Chart: Surface Decompression on Oxygen . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-18

9‑7

Decompression Mode Selection Flowchart. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-20

9‑8

Repetitive Dive Flow Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-22

9‑9

Repetitive Dive Worksheet . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-24

9‑10

Completed Air Diving Chart: First Dive of Repetitive Dive Profile. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-26

9‑11

Completed Repetitive Dive Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-27

9‑12

Completed Air Diving Chart: Second Dive of Repetitive Dive Profile . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-28

9‑13

Completed Air Diving Chart: Delay in Ascent deeper than 50 fsw. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-33

9‑14

Completed Air Diving Chart: Delay in Ascent Shallower than 50 fsw . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-34

9‑15

Diving at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-51

9‑16

Completed Diving at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-54

9‑17

Completed Air Diving Chart: Dive at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-55

9‑18

Repetitive Dive at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-56

9‑19

Completed Repetitive Dive at Altitude Worksheet. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-58

9‑20

Completed Air Diving Chart: First Dive of Repetitive Dive Profile at Altitude. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-59

9‑21

Completed Air Diving Chart: Second Dive of Repetitive Dive Profile at Altitude. .  .  .  .  .  .  .  .  .  .  .  . 9-60

U.S. Navy Diving Manual—Volume 2

Figure

Page

10‑1

NITROX Diving Chart . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-6

10‑2

NITROX SCUBA Bottle Markings . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-8

10‑3

NITROX O2 Injection System. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-10

10‑4

LP Air Supply NITROX Membrane Configuration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-12

10‑5

HP Air Supply NITROX Membrane Configuration. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-13

11‑1

Ice Diving with SCUBA . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-3

11-2

Typical Ice Diving Worksite. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11-9

List of Illustrations—Volume 2	

2–xv

PAGE LEFT BLANK INTENTIONALLY

2–xvi

U.S. Navy Diving Manual—Volume 2

Volume 2 - List of Tables
Table

Page

7‑1

Sample SCUBA Cylinder Data . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 7-6

8‑1

MK 21 MOD 1 and KM-37 Overbottom Pressure Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

8‑2

Primary Air System Requirements. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-17

8‑3

Line-Pull Signals. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8-24

9‑1

Pneumofathometer Correction Factors. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-7

9‑2

Management of Extended Surface Interval and Type I Decompression
Sickness during the Surface Interval. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-41

9‑3

Management of Asymptomatic Omitted Decompression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-43

9‑4

Sea Level Equivalent Depth (fsw). .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-48

9‑5

Repetitive Groups Associated with Initial Ascent to Altitude . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-50

9‑6

Required Surface Interval Before Ascent to Altitude After Diving . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-61

9‑7

No-Decompression Limits and Repetitive Group Designators for
No-Decompression Air Dives. . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-62

9‑8

Residual Nitrogen Time Table for Repetitive Air Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-63

9‑9

Air Decompression Table. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9-64

10‑1

Equivalent Air Depth Table . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-4

10‑2

Oil Free Air. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10-11

2A‑1

No-Decompression Limits and Repetitive Group Designators for Shallow Water
Air No-Decompression Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2A-2

2A‑2

Residual Nitrogen Time Table for Repetitive Shallow Water Air Dives . .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2A-3

List of Tables—Volume 2	

2–xvii

PAGE LEFT BLANK INTENTIONALLY

2–xviii

U.S. Navy Diving Manual—Volume 2

CHAPTER 6

Operational Planning
and Risk Management
6-1

INTRODUCTION
6-1.1

Purpose. Diving operations are inherently risky. This chapter provides a general

guide for planning diving operations. All Naval activities shall apply the Operational
Risk Management (ORM) process in planning operations and training to optimize
oper­ational capability and readiness in accordance with OPNAV INSTRUCTION
3500.39 (series). Correct application of these techniques will reduce mishaps and
associated costs resulting in more efficient use of resources. ORM is a decision
making tool used by personnel at all levels to increase operational effectiveness
by identifying, assessing, and managing risks. Proper application of ORM minimizes risks to acceptable levels, commensurate with mission accomplishment. The
amount of risk we will accept in war is much greater than that we should accept in
peace, but the ORM process remains the same.
6-1.2

Scope. This chapter outlines a comprehensive planning process to effectively

plan and execute diving operations in support of military operations. The planning
work­sheets and checklists contained in this chapter are examples of U.S. Navy
material. They may be used as provided or modified locally to suit specific needs.
6-2

MISSION OBJECTIVE AND OPERATIONAL TASKS

A clear and concise statement of the mission objective shall be established. If the
officer planning the operation is unclear about the urgency of the mission objec­
tive, he or she shall obtain clarification from the tasking authority to determine
acceptable risks.
Example: Locate, recover, and deliver lost anchor to USS SMITH at Pier A.

This section outlines the primary diving functions that may be identified in an operational task. These functions may be incorporated singly or in conjunction with
others. Each task shall be identified and placed in the context of an overall schedule or job profile. Work items that must be coordinated with other support teams
shall also be identified. The availability of outside assistance, including assistance
for possible emergencies, from a diving unit or other sources must be coordinated
in advance.
6-2.1

Underwater Ship Husbandry (UWSH). UWSH is the inspection, maintenance, and

repair of Navy hulls and hull append­ages while the hulls are waterborne. UWSH
includes tasks such as patching, plug­ging, attaching cofferdams, waterborne hull
cleaning, underwater weld repair to ship’s hulls and appendages, propeller replacement, underwater hull inspection, and nondestructive testing (Figure 6-1).

CHAPTER 6­—Operational Planning and Risk Management	

6-1

Figure 6-1. Underwater Ship Husbandry Diving.
6‑2.1.1

Objective of UWSH Operations. The objective of all UWSH operations is to

provide a permanent repair without dry-docking the ship. When a permanent repair
is not possible, temporary repairs are performed to allow the ship to operate until
its next scheduled drydocking where permanent repairs can be accomplished.
6‑2.1.2

Repair Requirements. All UWSH repairs shall follow strict Quality Assurance (QA)

procedures to en­sure underwater systems are properly repaired. Divers shall work
closely with all other repair activities to ensure procedures comply with prescribed
ship design and maintenance specifications. All relevant technical manuals shall be
made available for dive planning, and individual diver background and expertise
shall be considered when assembling dive teams. The NAVSEA Underwater Ship
Hus­bandry Manual (S0600-AA-PRO-010) provides general guidance and specific
procedures to accomplish many underwater repairs.
6‑2.1.3

Diver Training and Qualification Requirements. Many UWSH training

requirements and qualifications are task specific. General training may be
accomplished by:
n Formalized instruction as in First or Second Class Dive School
n NAVSEA-sponsored training, e.g., Sonar Dome Rubber Window (SDRW)
Repair
n On the Job Training (OJT)
n Personnel Qualification Standards (PQS)

6-2

U.S. Navy Diving Manual — Volume 2

6‑2.1.4

Training Program Requirements. A proper training program should result in per-

manent repairs meeting the same tolerances and QA requirements as if performed
in dry-dock. If there are any ques­tions as to the qualifications required for a permanent repair, divers should consult with their command repair department or
contact NAVSEA 00C5.
6-2.1.5

Ascent Training and Operations. Ascent operations are conducted by qualified

divers or combat swimmers. These operations require the supervision of an Ascent
Supervisor but operational conditions preclude the use of instructors. Ascent
training is distinctly different from ascent operations as performed by Navy Special
Warfare groups.
No ascent training may be conducted unless fully qualified instructors are present,
recompression chamber is available within 10 minutes, Diving Medical Technician
is on station, and a Diving Medical Officer is able to provide immediate response
to an accident.

6-2.2

Salvage/Object Recovery. In a salvage or object-recovery operation, divers work

to recover sunken or wrecked naval craft, submersibles, downed aircraft, human
remains, or critical items of equipment to help determine the cause of a mishap.
Salvaged items may include classified or sensitive materials (Figure 6-2).
6-2.3

Search Missions. Underwater searches are conducted to locate underwater objects

or subsurface geological formations. Searches can be performed by various
methods depending on the undersea terrain and purpose of the mission. Because
using divers for an unaided visual search over a large area is time consuming
and labor intensive, this type of search operation should incorporate the use of
sidescan sonar and other search equipment whenever possible. Remotely Operated
Vehicles (ROVs) may be used to extend searches into deep waters and areas that
are particularly dangerous for a diver. A reconnaissance dive may be conducted
prior to other scheduled dives to gather information that can save in-water time
and identify any special hazards of the dive mission.
6-2.4

Explosive Ordnance Disposal. Divers perform Explosive Ordnance Disposal tasks

including recovering, identi­fying, disarming, and disposing of explosive devices
that must be cleared from harbors, ships, and sea-lanes (Figure 6-3). Diving in
the vicinity of ordnance combines the risks of diving and the explosive hazards
of the ordnance. EOD divers shall accomplish diving to investigate, render safe,
or dispose of explosive ordnance found underwater, regardless of type or fusing.
Refer to Chapter 18 for more information on EOD operations.
6-2.5

Security Swims. Security swims are employed to search for underwater explosives
or other devices that may have been attached to ships or piers. All qualified divers
may conduct ship security swims. Once a task is identified as involving ordnance
disposal, the area shall be marked. If EOD qualified personnel are not on site
they shall be requested. Only EOD personnel may attempt to handle or dispose of
underwater explosives.

CHAPTER 6­—Operational Planning and Risk Management	

6-3

Figure 6-2. Salvage Diving. Surface-supplied divers on an aircraft recovery mission.

Figure 6-3. Explosive Ordnance Disposal Diving. An EOD diver using handheld sonar to
locate objects underwater.
6-2.6

6-4

Underwater Construction. Underwater construction is the construction, inspection,
repair, and removal of in-water facilities in support of military operations. An
in-water facility can be defined as a fixed harbor, waterfront, or ocean structure
located in or near the ocean. Pipelines, cables, sensor systems, and fixed/advancedbase structures are examples of in-water facilities (Figure 6-4).

U.S. Navy Diving Manual — Volume 2

6‑2.6.1

Diver
Training
and
Qualification
Requirements. Seabee divers are specifically

trained in the special techniques used to
accomplish underwater construction tasks.
6‑2.6.2

Equipment
Requirements.
Tools and
equipment used include common underwater
tools in addition to specialized ocean
construction equipment. Specific tools and
components for large ocean engineering
projects are maintained in the Ocean
Construction Equipment Inventory (OCEI)
located at St. Julian Creek, Norfolk, Virginia.

6‑2.6.3

Underwater Construction Planning Resources. References for underwater construction

planning can be found in:
n UCT Conventional Inspection and Repair
Techniques Manual NAVFAC P‑990
n Expedient Underwater Repair Techniques
NAVFAC P-991
n UCT Arctic Operations Manual NAVFAC
P-992
n Design and Installation of Near­shore
Ocean Cable Pro­tection Systems FPO‑178(3)

Figure 6-4. Underwater
Construction Diving.

For more information on ocean construction,
commands should consult NAVFAC Ocean Facilities Program.
6-2.7

Demolition Missions. Diving operations may include demoli­tion duties to remove

man-made structures such as barriers, sunken naval craft, and damaged piers.
Blasting, freeing, flattening, or cutting with explosives define demolition oper­
ations. Divers may also be assigned to destroy natural formations, such as reefs,
bars, and rock structures that interfere with transportation routes. All personnel
involved in handling explo­sives shall be qualified in accordance with the
OPNAVINST 8023.2 series.
6-2.8

6-2.9

Combat Swimmer Missions. Combat swimmers conduct reconnaissance and
neutralization of enemy ships, shore-based installations, and personnel. Some
missions may require an under­water approach to reach coastal installations
undetected. Reconnaissance missions and raids may expose the combat swimmers
to additional risk but may be neces­sary to advance broader warfare objectives.
Enclosed Space Diving. Divers are often required to work in enclosed or confined

spaces. Using surface-supplied Underwater Breathing Apparatus (UBA) (MK 20
MOD 0, MK 21 MOD 1, KM-37, or EXO BR MS), divers may enter submarine

CHAPTER 6­—Operational Planning and Risk Management	

6-5

ballast tanks, mud tanks, or cofferdams, which may be in either a flooded or dry
condition. Access to these spaces is normally restrictive, making it difficult for
the diver to enter and exit. Enclosed space diving shall be supported by a surfacesupplied air system. Refer to Section 8-11.4 for more information on the hazards
of enclosed space diving.
6-3

GENERAL PLANNING AND ORM PROCESS

A successful diving mission is the direct outcome of careful, thorough planning.
The nature of each operation determines the scope of the planning effort, but certain
general considerations apply to every operation.
n Bottom Time. Bottom time is always at a premium. Developing measures to
conserve bottom time or increase diver effectiveness is critical for success.
n Preplanning. An operation that is delayed due to unanticipated problems may
fail. Preplanning the use of the time available to accomplish specific objectives
is a prerequisite to success.
n Equipment. Selecting the correct equipment for the job is critical to success.
n Environmental Conditions. Diving operational planners must plan for safely
mitigating extreme environmental conditions. Personnel and support facility
safety shall be given the highest priority.
n Diver Protection. It is critical to protect divers from all anticipated hazards.
Application of the ORM process will identify hazards prior to the operation.
n Emergency Assistance. It is critical to coordinate emergency assistance from
outside sources before the operation begins.
n Weather. Because diving operations are weather dependent, dive planning shall
allow for worst-case scenarios.
6-3.1

Concept of ORM:

n ORM is a decision making tool used by people at all levels to increase
operational effectiveness by anticipating hazards and reducing the potential for
loss, thereby increasing the probability of successful mission.
n Increases our ability to make informed decisions by providing the best baseline
of knowledge and experience available.
n Minimizes risks to acceptable levels, commensurate with mission
accomplishment. The amount of risk we will take in war is much greater than
that we should be willing to take in peace, but the process is the same. Applying
the ORM process will reduce mishaps, lower costs, and provide for more
efficient use of resources.
6-3.2

Risk Management Terms:

n Hazard – A condition with potential to cause personal injury or death, property
damage, or mission degradation.
n Risk – An expression of possible loss in terms of severity and probability.

6-6

U.S. Navy Diving Manual — Volume 2

n Risk Assessment – The process of detecting hazards and assessing associated
risks.
n ORM – The process of dealing with risk associated within military operations,
which includes risk assessment, risk decision-making and implementation of
effective risk controls.
6-3.3

ORM Process. The five step process is:
1. Identify Hazards – Begin with an outline or chart of the major steps in the

operation (operational analysis). Next, conduct a Preliminary Hazard Analy­sis
by listing all of the hazards associated with each step in the operational analysis
along with possible causes for those hazards.

2. Assess Hazards – For each hazard identified, determine the associated degree

of risk in terms of probability and severity. Although not required; the use of a
matrix may be helpful in assessing hazards.

3. Make Risk Decisions – First, develop risk control options. Start with the most

serious risk first and select controls that will reduce the risk to a minimum
consistent with mission accomplishment. With selected controls in place,
decide if the benefit of the operation outweighs the risk. If risk outweighs
benefit or if assistance is required to implement controls, communicate with
higher authority in the chain of command.

4. Implement Controls – The following measures can be used to eliminate haz­

ards or reduce the degree of risk. These are listed by order of preference:
n

Administrative Controls – Controls that reduce risks through specific
administrative actions, such as:

n

Providing suitable warnings, markings, placards, signs, and notices.

n

Establishing written policies, programs, instructions and standard oper­
ating procedures (SOP).

n

Training personnel to recognize hazards and take appropriate precau­
tionary measures.

n

Limiting the exposure to hazard (either by reducing the number or per­
sonnel/assets or the length of time they are exposed).

n

Engineering Controls – Controls that use engineering methods to reduce
risks by design, material selection or substitution when technically or
economically feasible.

n

Personal Protective Equipment – Serves as a barrier between personnel
and hazard. It should be used when other controls do not reduce the haz­
ard to an acceptable level.

5. Supervise – conduct follow-up evaluations of the controls to ensure they remain

in place and have the desired effect. Monitor for changes, which may require
further ORM. Take corrective action when necessary.

CHAPTER 6­—Operational Planning and Risk Management	

6-7

6-4

COLLECT AND ANALYZE DATA

Information pertinent to the mission objective shall be collected, organized, and
analyzed to determine what may affect successful accomplishment of the objec­
tive. This process aids in:
n Planning for contingencies
n Developing the dive plan
n Selecting diving technique, equipment, and diver personnel
n Identifying potential hazards and the need for any special emergency
procedures
6-4.1

Information Gathering. The size of the operation, the diving site location, and the

prevailing environ­mental conditions influence the extent and type of information
that must be gathered when planning an operation. Some operations are of a
recurring nature; so much of the required information is readily available. An
example of a recur­ring operation is removing a propeller from a particular class
of ship. However, even for a standard operation, the ship may have been modified
or special environ­mental conditions may exist, requiring a change in procedure or
special tools. Potential changes in task requirements affecting work procedures
should not be overlooked during planning.
6-4.2

Planning Data. Many operations require that detailed information be collected in

advance. For example, when planning to salvage a sunken or stranded vessel, the
diving team needs to know the construction of the ship, the type and location of
cargo, the type and location of fuel, the cause of the sinking or stranding, and the
nature and degree of damage sustained. Such information can be obtained from
ship’s plans, cargo manifests and loading plans, interviews with witnesses and
survivors, photo­graphs, and official reports of similar accidents.
6-4.3

Object Recovery. Operations involving the recovery of an object from the bottom

require knowledge of the dimensions and weight of the object. Other useful
information includes floodable volume, established lifting points, construction
material, length of time on the bottom, probable degree of embedment in mud or
silt, and the nature and extent of damage. This data helps determine the type of lift
to be used (e.g., boom, floating crane, lifting bags, pontoons), indicates whether
high-pressure hoses are needed to jet away mud or silt, and helps determine the
disposition of the object after it is brought to the surface. Preliminary planning may
find the object too heavy to be placed on the deck of the support ship, indicating
the need for a barge and heavy lifting equipment.

6‑4.3.1

Searching for Objects or Underwater Sites. When the operation involves searching

for an object or underwater site, data gath­ered in advance helps to limit the search
area. There are numerous planning data sources available to help supervisors
collect data for the operation (see Figure 6‑5).

6-8

U.S. Navy Diving Manual — Volume 2

PLANNING DATA SOURCES
�

Aircraft Drawings

�

Light Lists

�

Ship’s Personnel

�

Cargo Manifest

�

Local Yachtsmen/Fishermen

�

�

Coastal Pilot Publications

�

LORAN Readings

Ships Drawings (including docking
plan)

�

Cognizant Command

�

Magnetometer Plots

�

Side-Scan Sonar Plots

�

Communications Logs

�

Navigation Text
(Dutton's/Bowditch)

�

SINS Records

�

SITREP

�

Construction Drawings

�

Current Tables

�

Navigational Charts

�

Sonar Readings and/or Charts

�

Diving Advisory Messages

�

NAVOCEANO Data

�

TACAN Readings

�

DRT Tracks

�

Notices to Mariners

�

Technical Reference Books

�

DSV/DSRV Observations

�

OPORDERS

�

Test Records

�

Electronic Analysis

�

Photographs

�

Tide Tables

�

Equipment Operating Procedures
(OPs)

�

Radar Range and Bearings

�

Underwater Work Techniques

�

RDF Bearings

�

USN Diving Manual Reference List

�

Equipment Operation and Maintenance Manuals

�

ROV Video and Pictures

�

USN Instructions

�

Sailing Directions

�

USN Ship Salvage Manual

�

Eyewitnesses

�

Salvage Computer Data

�

Visual Bearings

�

Flight or Ship Records

�

Ship’s Curves of Forms

�

Weather Reports

�

Flight Plan

�

Ship’s Equipment

�

Hydrographic Publications

�

Ship’s Logs and Records

Figure 6‑5. Planning Data Sources.

For example, information useful in narrowing the search area for a lost aircraft
includes the aircraft’s last known heading, altitude, and speed; radar tracks plotted
by ships and shore stations; tape recordings and radio transmissions; and eyewit­
ness accounts. Once a general area is outlined, a side scan sonar system can be
used to locate the debris field, and an ROV can identify target items located by the
side scan sonar. Once the object of the search has been found, the site should be
marked, preferably with an acoustic transponder (pinger) and/or a buoy. If time and
conditions permit, preliminary dives by senior, experienced members of the team
can be of great value in verifying, refining, and analyzing the data to improve the
dive plan. This method saves diver effort for recovering items of interest.
6-4.4

Data Required for All Diving Operations. Data involving the following general
categories shall be collected and analyzed for all diving operations:

n Surface conditions
n Underwater conditions
n Equipment and personnel resources
n Assistance in emergencies
6‑4.4.1

Surface Conditions. Surface conditions in the operating area affect both the divers

and the topside team members. Surface conditions are influenced by location, time

CHAPTER 6­—Operational Planning and Risk Management	

6-9

of year, wind, waves, tides, current, cloud cover, temperature, visibility, and the
presence of other ships. Completing the Environmental Assessment Worksheet
(Figure 6‑6) helps ensure that environmental factors are not overlooked during
planning. For an extensive dive mission, a meteorological detachment may be
requested from the local or regional meteorological support activity.
6‑4.4.1.1

Natural Factors. Normal conditions for the area of operations can be determined

from published tide and current tables, sailing directions, notices to mariners,
and special charts that show seasonal variations in temperature, wind, and ocean
currents. Weather reports and long-range weather forecasts shall be studied to
determine if condi­tions will be acceptable for diving. Weather reports shall be
continually monitored while an operation is in progress.
NOTE

6‑4.4.1.2

Diving shall be discontinued if sudden squalls, electrical storms, heavy
seas, unusual tide or any other condition exists that, in the opinion of
the Diving Supervisor, jeopardizes the safety of the divers or topside
personnel.
Sea State. A significant factor is the sea state (Figure 6‑7). Wave action can
affect everything from the stability of the moor to the vulnerability of the crew
to seasickness or injury. Unless properly moored, a ship or boat drifts or swings
around an anchor, fouling lines and dragging divers. Because of this, any vessel
being used to support surface-supplied or tended diving operations shall be secured
by at least a two-point moor. Exceptions to diving from a two-point moor may
occur when moored alongside a pier or another vessel that is properly anchored, or
when a ship is performing diving during open ocean transits and cannot moor due
to depth. A three- or four-point moor, while more difficult to set, may be preferred
depending on dive site conditions.

Divers are not particularly affected by the action of surface waves unless operating
in surf or shallow waters, or if the waves are exceptionally large. Surface waves
may become a serious problem when the diver enters or leaves the water and during
decompression stops near the surface.
6‑4.4.1.3

Tender Safety. Effective dive planning shall provide for extreme temperatures

that may be encountered on the surface. Normally, such conditions are a greater
problem for tending personnel than for a diver. Any reduction in the effectiveness
of the topside personnel may endanger the safety of a diver. Tending personnel
shall guard against:
n Sunburn and windburn
n Hypothermia and frostbite
n Heat exhaustion
6‑4.4.1.4

Windchill Factor. In cold, windy weather, the windchill factor shall be considered.

Exposure to cold winds greatly increases dangers of hypothermia and all types of
cold injury. For example, if the actual tempera­ture is 35°F and the wind velocity is

6-10

U.S. Navy Diving Manual — Volume 2

ENVIRONMENTAL CHECKLIST
Date:
Surface
Sea Surface
Sea State
Wave Action:
Height
Length
Direction
Current:
Direction
Velocity
Type
Surf. Visibility
Surf. Water Temp.
Local Characteristics

Atmosphere
Visibility
Sunrise (set)
Moonrise (set)
Temperature (air)
Humidity
Barometer
Precipitation
Cloud Description
Percent Cover
Wind Direction
Wind Force (knots)
Other:

Subsurface
Underwater & Bottom
Depth
Water Temperature:
depth
depth
depth
bottom
Thermoclines

Visibility
Underwater
ft
ft
ft
Bottom
ft
Bottom Type:

Curent:
Direction
Source
Velocity
Pattern
Tides:
High Water
Low Water
Ebb Dir.
Flood Dir.

Obstructions:

at
at
at

depth
depth
depth

at

depth

Marine Life:
Time
Time
Vel.
Vel.

Other Data:

NOTE: A meteorological detachment may be requested from the local meteorological support activity.

Figure 6‑6. Environmental Assessment Worksheet. The Environmental Assessment Worksheet indicates
­­categories of data that might be gathered for an operation. Planners may develop an assessment methodology
to suit the particular situation. The data collected is vital for effective operations planning, and is also of value
when filing Post Salvage Reports.

CHAPTER 6­—Operational Planning and Risk Management	

6-11

Sea
State

Description

Wind Force
(Beaufort)

Wind
Descrip­tion

Wind
Range
(knots)

Wind
Velocity
(knots)

Average
Wave
Height
(ft)

0

Sea like a mirror.

0

Calm

<1

0

0

Ripples with the appearance of scales are formed,
but without foam crests.

1

Light Air

5-3

2

0.05

1

Small wavelets still short but more pronounced;
crests have a glassy appearance but do not
break.

2

Light Breeze

4-6

5

0.18

2

Large wavelets, crests begin to break. Foam
of glassy appearance, perhaps scattered
whitecaps.

3

Gentle
Breeze

7-10

8.5
10

0.6
0.88

3

Small waves, becoming longer; fairly frequent
whitecaps.

4

Moderate
Breeze

15-16

12
13.5
14
16

1.4
1.8
2.0
2.9

4

Moderate waves, taking a more pronounced long
form; many whitecaps are formed. Chance of
some spray.

5

Fresh
Breeze

17-21

18
19
20

3.8
4.3
5.0

5

Large waves begin to form; white foam crests are
more extensive everywhere. Some spray.

6

Strong
Breeze

22-27

22
24
24.5
26

6.4
7.9
8.2
9.6

6

Sea heaps up and white foam from breaking waves
begins to be blown in streaks along the direction
of the wind. Spindrift begins.

7

Moderate
Gale

28-33

28
30
30.5
32

11
14
14
16

7

Moderately high waves of greater length; edges
of crests break into spindrift. The foam is blown
in well marked streaks along the direction of the
wind. Spray affects visibility.

8

Fresh Gale

34-40

34
36
37
38
40

19
21
23
25
28

8

High waves. Dense streaks of foam along the
direction of the wind. Sea begins to roll. Visibility
affected.

9

Strong Gale

45-47

42
44
46

31
36
40

9

Very high waves with long overhanging crests.
Foam is in great patches and is blown in dense
white streaks along the direction of the wind. The
surface of the sea takes on a white appearance.
The rolling of the sea becomes heavy and shocklike. Visibility is affected.

10

Whole Gale

48-55

48
50
51.5
52
54

44
49
52
54
59

Exceptionally high waves. The sea is completely
covered with long white patches of foam along
the direction of the wind. Everywhere the edges
of the wave crests are blown into froth. Visibility
seriously affected.

11

Storm

56-63

56
59.5

64
73

Air filled with foam and spray. Sea completely white
with driving spray. Visibility seriously affected.

12

Hurricane

64-71

>64

>80

Figure 6-7. Sea State Chart.

6-12

U.S. Navy Diving Manual — Volume 2

35 mph, the windchill factor is equivalent to 5°F (Figure 6‑8). For information on
ice and cold water diving operations, refer to Chapter 11.
6‑4.4.1.5

Surface Visibility. Variations in surface visibility are important. Reduced visibility

may seriously hinder or force postponement of diving operations. For operations
to be conducted in a known fog belt, the diving schedule should allow for delays
because of low visibility. Diver and support crew safety is the prime consideration
when determining whether surface visibility is adequate. For example, a surfacing
diver might not be able to find his support craft, or the diver and the craft itself
might be in danger of being hit by surface traffic. A proper radar reflector for small
craft should be considered.
6‑4.4.2

Depth. Depth is a major factor in selecting both diving personnel and apparatus

and influences the decom­pression profile for any dive. Operations in deep waters
may also call for special support equipment such as underwater lights, cameras,
ROV, etc.
Depth must be carefully measured and plotted over the general area of the operation
to get an accurate depth profile of the dive site. Soundings by a ship-mounted
fathometer are reasonably accurate but shall be verified by either a lead-line
sounding, a pneumofathometer (Figure 6‑9), or a high resolution sonar (bottom
finder or fish finder). Depth readings taken from a chart should only be used as an
indication of probable depth.
6‑4.4.3

Type of Bottom. The type of bottom may have a significant effect upon a

diver’s ability to move and work effi­ciently and safely. Advance knowledge of
bottom conditions is important in scheduling work, selecting dive technique and
equipment, and anticipating possible hazards. The type of bottom is often noted on
the chart for the area, but conditions can change within just a few feet.
Independent verification of the type of bottom should be obtained by sample or
observation. Figure 6‑10 outlines the basic types of bottoms and the characteristics
of each.
6‑4.4.4

Tides and Currents. The basic types of currents that affect diving operations are:

n River or Major Ocean Currents. The direction and velocity of normal river,
ocean, and tidal currents will vary with time of the year, phase of the tide,
con­figuration of the bottom, water depth, and weather. Tide and current tables
show the conditions at the surface only and should be used with caution when
planning diving operations. The direction and velocity of the current beneath
the surface may be quite different than that observed on the surface.
n Ebb Tides. Current produced by the ebb and flow of the tides may add to or
subtract from any existing current.
n Undertow or Rip Current. Undertow or rip currents are caused by the rush of
water returning to the sea from waves breaking along a shoreline. Rip currents
will vary with the weather, the state of the tide, and the slope of the bottom.

CHAPTER 6­—Operational Planning and Risk Management	

6-13

Wind MPH
Actual
Air
Temp
°F (°C)

5

10

15

20

25

30

35

40

Equivalent Chill Temperature °F (°C)

40

(4)

35

(2)

30 (-1)

25 (-4)

20 (-7)

15 (-9)

10 (-12)

10 (-12)

10 (-12)

35

(2)

30 (-1)

20 (-7)

15 (-9)

10 (-12)

10 (-12)

5 (-15)

5 (-15)

0 (-17)

30 (-1)

25 (-4)

15 (-9)

10 (-12)

5 (-15)

0 (-17)

0 (-17)

0 (-17)

-5 (-21)

25 (-4)

20 (-7)

10 (-12)

0 (-17)

0 (-17)

-5 (-21)

-10 (-23)

-10 (-23)

-15 (-26)

20 (-7)

15 (-9)

5 (-15)

-5 (-21)

-10 (-23)

-15 (-26)

-20 (-29)

-20 (-29)

-20 (-29)

15 (-9)

10 (-12)

0 (-17)

-10 (-23)

-15 (-26)

-20 (-29)

-25 (-32)

-25 (-32)

-30 (-34)

10 (-12)

5 (-15)

-10 (-23)

-20 (-29)

-25 (-32)

-30 (-34)

-30 (-34)

-30 (-34)

-35 (-37)

5 (-15)

0 (-17)

-15 (-26)

-25 (-32)

-30 (-34)

-35 (-37)

-40 (-40)

-40 (-40)

-45 (-43)

0 (-17)

-5 (-15)

-20 (-24)

-30 (-34)

-35 (-37)

-45 (-43)

-55 (-46)

-50 (-46)

-55 (-48)

-5 (-21)

-10 (-23)

-25 (-32)

-40 (-40)

-45 (-43)

-50 (-46)

-65 (-54)

-60 (-51)

-60 (-51)

-10 (-23)

-15 (-26)

-35 (-37)

-45 (-43)

-50 (-46)

-60 (-54)

-70 (-57)

-65 (-54)

-70 (-57)

-15 (-26)

-20 (-29)

-40 (-40)

-50 (-46)

-60 (-51)

-65 (-54)

-70 (-57)

-75 (-60)

-75 (-60)

-20 (-29)

-25 (-32)

-45 (-43)

-60 (-51)

-65 (-54)

-75 (-60)

-80 (-62)

-85 (-65)

-90 (-68)

-25 (-32)

-30 (-34)

-50 (-46)

-65 (-45)

-75 (-60)

-80 (-62)

-85 (-65)

-90 (-68)

-95 (-71)

-30 (-34)

-35 (-37)

-60 (-51)

-70 (-57)

-80 (-62)

-90 (-68)

-95 (-71)

-100 (-73)

-100 (-73)

-35 (-37)

-40 (-40)

-65 (-54)

-80 (-62)

-85 (-65)

-95 (-71)

-100 (-73)

-105 (-76)

-110		 (-79)

-40 (-40)

-45 (-43)

-70 (-57)

-85 (-65)

-95 (-71)

-105 (-76)

-110 (-79)

-115 (-82)

-115 (-82)

-45 (-43)

-50 (-46)

-75 (-60)

-90 (-68)

-100 (-73)

-110 (-79)

-115 (-82)

-120 (-85)

-125 (-87)

-50 (-46)

-55 (-48)

-80 (-62)

-100 (-73)

-110 (-79)

-120 (-85)

-125 (-87)

-130 (-90)

-130 (-90)

-55 (-48)

-60 (-51)

-90 (-68)

-105 (-76)

-115 (-82)

-125 (-87)

-130 (-90)

-135 (-93)

-140 (-96)

-60 (-51)

-70 (-57)

-95 (-71)

-110 (-79)

-120 (-85)

-135 (-93)

-140 (-96)

-145 (-98)

-150 (-101)

LITTLE DANGER
INCREASING DANGER (flesh may freeze within one minute)
GREAT DANGER (flesh may freeze within 20 seconds)

Figure 6‑8. Equivalent Wind Chill Temperature Chart.

6-14

U.S. Navy Diving Manual — Volume 2

pressure gauge (calibrated in feet of seawater)

air supply

water column

pneumofathometer
hose

Figure 6‑9. Pneumofathometer.  The pneumofathometer hose is attached to a diver or
weighted object and lowered to the depth to be measured. Water is forced out of the hose
by pressurized air until a generally constant reading is noted on the pressure gauge. The air
supply is secured, and the actual depth (equal to the height of the water column displaced
by the air) is read on the gauge.

These currents may run as fast as two knots and may extend as far as one-half
mile from shore. Rip currents, not usually identified in published tables, can
vary significantly from day to day in force and location.
n Surface Current Generated by Wind. Wind-generated surface currents are
temporary and depend on the force, duration, and fetch of the wind. If the wind
has been blowing steadily for some time, this current should be taken into
consideration especially when planning surface swims and SCUBA dives.
6‑4.4.4.1

6-5

Equipment Requirements for Working in Currents. A diver wearing a surfacesupplied outfit, such as the MK 21 SSDS with heavy weights, can usually work
in currents up to 1.5 knots without undue difficulty. A diver supplied with an
additional weighted belt may be able to accomplish useful work in currents as
strong as 2.5 knots. A SCUBA diver is severely handicapped by currents greater
than 1.0 knot. If planning an operation in an area of strong current, it may be
necessary to schedule work during periods of slack water to minimize the tidal
effect.

IDENTIFY OPERATIONAL HAZARDS

Underwater environmental conditions have a major influence on the selection of
divers, diving technique, and the equipment to be used. In addition to environ­
mental hazards, a diver may be exposed to operational hazards that are not unique
to the diving environment. This section outlines the environmental and operational
hazards that may impact an operation.

CHAPTER 6­—Operational Planning and Risk Management	

6-15

TYPE

CHARACTERISTICS

VISIBILITY

DIVER MOBILITY ON BOTTOM

Rock

Smooth or jagged,
minimum sediment

Generally unrestricted by dive
movement

Good, exercise care to prevent line
snagging and falls from ledges

Coral

Solid, sharp and jagged,
found in tropical waters
only

Generally unrestricted by diver
movement

Good, exercise care to prevent line
snagging and falls from ledges

Gravel

Relatively smooth,
granular base

Generally unrestricted by diver
movement

Good, occasional sloping bottoms
of loose gravel impair walking and
cause instability

Shell

Composed principally of
broken shells mixed with
sand or mud

Shell-sand mix does not impair
visibility when moving over
bottom. Shell-mud mix does
impair visibility. With higher
mud concentrations, visibility is
increasingly impaired.

Shell-sand mix provides good
stability. High mud content can
cause sinking and impaired
movement

Sand

Common type of bottom,
packs hard

Generally unrestricted by diver
movement

Good

Mud
and
Silt

Common type of bottom,
composed of varying
amounts of silt and clay,
commonly encountered
in river and harbor areas

Poor to zero. Work into the
current to carry silt away from
job site, minimize bottom
disturbance. Increased hazard
presented by unseen wreckage,
pilings, and other obstacles.

Poor, can readily cause diver
entrapment. Crawling may be
required to prevent excessive
penetration, fatiguing to diver.

Figure 6‑10. Bottom Conditions and Effects Chart.

6-5.1

Underwater Visibility. Underwater visibility varies with depth and turbidity.

Horizontal visibility is usually quite good in tropical waters; a diver may be able to
see more than 100 feet at a depth of 180 fsw. Horizontal visibility is almost always
less than vertical visi­bility. Visibility is poorest in harbor areas because of river
silt, sewage, and industrial wastes flowing into the harbor. Agitation of the bottom
caused by strong currents and the passage of large ships can also affect visibility.
The degree of underwater visibility influences selection of dive technique and
can greatly increase the time required for a diver to complete a given task. For
example, a diving team preparing for harbor operations should plan for extremely
limited visibility, possibly resulting in an increase in bottom time, a longer period
on station for the diving unit, and a need for additional divers on the team.
6-5.2

Temperature. Figure 6-11 illustrates how water temperature can affect a diver’s

performance, and is intended as a planning guide. A diver’s physical condition,
amount of body fat, and thermal protection equipment determine how long
exposure to extreme temperatures can be endured safely. In cold water, ability to
concentrate and work efficiently will decrease rapidly. Even in water of moderate

6-16

U.S. Navy Diving Manual — Volume 2

temperature (60–70°F, 15.5–21.5°C), the loss of body heat to the water can quickly
bring on diver exhaustion.
6-5.3

Warm Water Diving. Warm water diving is defined as those diving operations that

occur in water temperatures exceeding 88° F. During recent studies at the Navy
Experimental Diving Unit, physiological limits have been developed for diving
operations in water temperatures up to 99°F. Diving in water temperatures above
99°F should not be attempted without first contacting NAVSEA 00C.
6‑5.3.1

Operational Guidelines and Safety Precautions. These guidelines are based on
data collected from heat acclimated divers dressed in UDT swim trunks and t-shirts
who were well rested, calorically replete, well hydrated, and had no immediate
heat exposure prior to starting exercise. Exercise rate for the divers replicated a
moderate swimming effort. Conditions that contribute to thermal loading such as
heavy work rates, significant pre/post dive activities, and various diver dress (dive
skins/wetsuits/dry suits) can reduce expo­sure limits appreciably. Guidelines for
exposure limits are based on diver dress and water temperatures. The following
precautions apply to all warm water diving operations above 88°F:

n Weight losses up to 15 lbs (or 6-8% of body weight) due to fluid loss may occur
and mental and physical performance can be affected. Divers should hydrate
fully (approximately 500 ml or 17 oz) two hours before diving. Fluid loading
in excess of the recommended 500 ml may cause life-threatening pul­monary
edema and should not be attempted.
n Hydrating with water or a glucose/electrolyte beverage should occur as soon as
possible after diving. Approximately 500 ml should be replaced for each hour
of diving.
n Exposure limits represent maximum cumulative exposure over a 12 hour
period. Divers should be hydrated and calorically replete to baseline weight,
rested, and kept in a cool environment for at least 12 hours before a repeat
exposure to warm water is deemed safe.
NOTE

The following are the general guidelines for warm water diving. Specific
UBAs may have restrictions greater than the ones listed below; refer to
the appropriate UBA Operations and Maintenance manual. The maximum
warm water dive time exposure limit shall be the lesser of the approved
UBA operational limits, canister duration limits, oxygen bottle duration or
the diver physiological exposure limit.

n A diver working at a moderate rate e.g. swimming at 0.8 kts or less:
88°–94°F - limited to canister/O2 bottle duration or diver aerobic endurance
94°–97°F - limited to three hours based on physiological limits.
97°–99°F - limited to one hour based on physiological limits.

CHAPTER 6­—Operational Planning and Risk Management	

6-17

WATER TEMPERATURE PROTECTION CHART
Unprotected
Diver

Water Temp
C

32.0

Resting diver
will overheat

90
Working diver may
overheat depending
on workload

29.5
26.5

Dry Suit
Diver

(At shallow
(<20fsw) depths)

F

35.0

Wet Suit
Diver

80

Resting diver
chills in 1-2
hours

Thermal protection usually needed
below 80 F water

24.0
21.0

70
Thermal protection
usually not the limiting
factor in a wet suit

18.5
15.5

60

13.0
10.0

01.5
Freezing point
Fresh water
-01.0
Freezing point
Salt water
-04.0

Thermal protection
usually not the limiting
factor in a dry suit

3 hours

5 hours

1 hour

3 hours

50

07.0
04.5

5 hours

40

30

* Below 40 F,
hot water suit or
dry suit is reccommended
for surface-supplied
diving

This chart can be used as a guide for planning dives in cold water. The dive durations listed for
each suit are not rules or limits. Instead they represent dive times that will challenge the average
diver wearing the thermal protection listed, but will have a minimal chance of producing
significant hypothermia. Acutal dive durations may be longer or shorter than those listed, due to
operational considerations and/or individual tolerance.

Figure 6‑11. Water Temperature Protection Chart.

6-18

U.S. Navy Diving Manual — Volume 2

NOTE

In cases of SDV and DDS operations, thermal loading may change during
the course of the mission. Exposure times should be reduced and fluids
replaced during the dive when possible.

n A resting diver e.g. during decompression:
88°–94°F - limited to canister duration.
94°–97°F - limited to canister duration.
97°–99°F - limited to two hours based on physiological limits.
6‑5.3.2

Mission Planning Factors. The following mission planning factors may mitigate
thermal loading and allow greatest utilization of the exposure limits:
1. Conduct diving operations at night, dusk, or dawn to reduce heat stress incurred

from sun exposure and high air temperatures.
2. Avoid wearing a hood with a dive skin to allow evaporative cooling.
3. When possible avoid wearing dive skin or anti-chafing dress. Although the

effect of various diver dress is not known, it is expected that safe exposure
durations at temperatures above 96°F will be less.
4. Follow the guidelines in paragraph 3‑10.4 regarding acclimatization. Reduce the

intensity of the diving for five days immediately prior to the diving operation.

5. Ensure divers maintain physical conditioning during periods of warm water

diving.
6. Methods of cooling the diver should be employed whenever possible. These

include using hot water suits to supply cold water to the diver and the use of ice
vests.
Mission planning should also include recognition and management of heat stress
injuries as part of pre-dive training and briefing. The diver and topside personnel
shall be particularly alert for the symptoms of heat stress. Further guidance is
contained in paragraph 3‑10.4.4 (Excessive Heat - Hyperthermia), paragraph
3‑12.1 (Dehydration), and Figure 3‑6 (Oxygen Consumption and RMV at
Different Work Rates).
6-5.4

Contaminated Water. When planning for contaminated water diving, medical

personnel should be consulted to ensure proper pre-dive precautions are taken and
post-dive moni­toring of divers is conducted. In planning for operations in polluted
waters, protective clothing and appropriate preventative medical procedures shall
be taken. Diving equipment shall be selected that gives the diver maximum protec­
tion consistent with the threat. Resources outside the scope of this manual may
be required to deal with nuclear, biological, or chemical contaminants. Resources
and technical advice for dealing with contaminated water diving conditions are
available in the Guidance for Diving in Contaminated Waters, SS521-AJ-PRO010, or contact NAVSEA 00C3.

CHAPTER 6­—Operational Planning and Risk Management	

6-19

6-5.5

Chemical Contamination. Oil leaking from underwater wellheads or damaged

tanks can foul equipment and seriously impede a diver’s movements. Toxic
materials or volatile fuels leaking from barges or tanks can irritate the skin and
corrode equipment. Diving units should not conduct the dive until the contaminant
has been identified, the safety factors evaluated, and a process for decontamination
set up. Divers operating in waters where a chemical or chemical warfare threat is
known or suspected shall evaluate the threat and protect themselves as appropriate.
The MK 21 UBA with a double exhaust and a dry suit dress assembly affords
limited protection for diving in polluted and contaminated water. Refer to the MK
21 UBA NAVSEA Technical Manual, S6560-AG-OMP-010, for more information
on using the MK 21 UBA with a dry suit assembly.
6-5.6

Biological Contamination. A diver working near sewer outlets may be exposed

to biological hazards. SCUBA divers are especially vulnerable to ear and skin
infections when diving in waters that contain biological contamination. Divers
may also inadvertently take polluting materials into the mouth, posing both
physiological and psychological problems. External ear prophylaxis should be
provided to diving personnel to prevent ear infections.

6-5.7

Altitude Diving. Divers may be required to dive in bodies of water at higher altitudes.

Planning shall address the effects of the atmospheric pressures that may be much
lower than those at sea level. Air Decompression Tables and Surface-Supplied
Helium-Oxygen Tables are authorized for use at altitudes up to 300 feet above sea
level without corrections (see paragraphs 9-13 and 14-6). Transporting divers out
of the diving area, which may include movement into even higher elevations either
overland or by plane, requires special consideration and planning. The Diving
Supervisor shall be alert for symptoms of hypoxia and decompression sickness after
the dive due to the lower oxygen partial pressure and atmospheric pressure.

6-5.8

Underwater Obstacles. Various underwater obstacles, such as wrecks or discarded

munitions, offer serious hazards to diving. Wrecks and dumping grounds are often
noted on charts, but the actual presence of obstacles might not be discovered until
an operation begins. This is a good reason for scheduling a preliminary inspection
dive before a final work schedule and detailed dive plan is prepared.
6-5.9

Electrical Shock Hazards. Electrical shock may occur when using electric
welding or power equipment. All electrical equipment shall be in good repair
and be inspected before diving. Although equipped with test buttons, electrical
Grounds Fault Interrupters (GFI) often do not provide any indication when the
unit has experienced an internal component failure in the fault circuitry. Therefore,
GFI component failure during operation (subsequent to testing the unit) may go
unnoticed. Although this failure alone will not put the diver at risk, the GFI will
not protect the diver if he is placed in contact with a sufficiently high fault current.
The following is some general information concerning GFIs:

n GFIs are required when line voltage is above 7.5 VAC or 30 VDC.
n GFIs shall be capable of tripping within 20 milliseconds (ms) after detecting a
maximum leakage current of 30 milliamps (ma).
6-20

U.S. Navy Diving Manual — Volume 2

CAUTION

GFIs require an established reference ground in order to function
properly. Cascading GFIs could result in loss of reference ground;
therefore, GFIs or equipment containing built-in GFIs should not be
plugged into an existing GFI circuit.
In general, three independent actions must occur simultaneously to electrically
shock a diver:
n The GFI must fail.
n The electrical equipment which the diver is operating must experience a ground
fault.
n The diver must place himself in the path between the fault and earth ground.

6‑5.9.1

Reducing Electrical Shock Hazards. The only effective means of reducing

electrical shock hazards are to ensure:
n Electrical equipment is properly maintained.
n All electrical devices and umbilicals are inspected carefully before all
operations.
n Electrical umbilicals are adequately protected to reduce the risk of being
abraded or cut when pulled over rough or sharp objects.
n Personnel are offered additional protection through the use of rubber suits (wet,
dry, or hot-water) and rubber gloves.
n GFI circuits are tested at regular intervals throughout the operation using builtin test circuits.
Divers operating with remotely operated vehicles (ROVs) should take similar
precautions to ensure the ROV electrical system offers the required protection.
Many new ROVs use extremely high voltages which make these protective actions
even more critical to diver safety.
6‑5.9.2

Securing Electrical Equipment. The Ship Repair Safety Checklist for Diving

requires underwater electrical equip­ment to be secured while divers are working
over the side. While divers are in the water:
n Ship impressed current cathodic protection (ICCP) systems must be secured,
tagged out, and confirmed secured before divers may work on an ICCP device
such as an anode, dielectric shield, or reference cell.
n When divers are required to work close to an active ICCP anode and there is a
risk of contact with the anode, the system must also be secured.
n In situations other than those described above, the ICCP should remain active.

CHAPTER 6­—Operational Planning and Risk Management	

6-21

n Divers working within 15 feet of active systems must wear a full dry suit,
unisuit, or wet suit with hood and gloves.
n All other underwater electrical equipment shall be secured while divers are
working over the side.
6-5.10

Explosions. Explosions may be set off in demolition tasks intentionally,

accidentally, or as the result of enemy action. When working with or near
explosives, the procedures outlined in SWO 60-AA-MMA-010 shall be followed.
Divers should stay clear of old or damaged munitions. Divers should get out of the
water when an explosion is imminent.
WARNING

6-5.11

Welding or cutting torches may cause an explosion on penetration of
gas-filled compartments, resulting in serious injury or death.
Sonar. Appendix 1A provides guidance regarding safe diving distances and

exposure times for divers operating in the vicinity of ships transmitting with
sonar.
6-5.12

Nuclear Radiation. Radiation may be encountered as the result of an accident,

proximity to weapons or propulsion systems, weapons testing, or occasionally
natural conditions. Radia­tion exposure can cause serious injury and illness. Safe
tolerance levels have been set and shall not be exceeded. These levels may be
found in the Radiological Control Manual, NAVSEA 0389-LP-660-6542. Local
instructions may be more stringent and in such case shall be followed. Prior to
diving, all dive team members shall be thoroughly knowledgeable of the local/
command radiological control requirements. When required divers shall have a
Thermal Luminescence Dosimeter (TLD) or similar device and be apprised of the
locations of items such as the reactor compartment, discharges, etc.
6-5.13

6-5.14

6-22

Marine Life. Certain marine life, because of its aggressive or venomous nature,
may be dangerous to man. Some species of marine life are extremely dangerous,
while some are merely an uncomfortable annoyance. Most dangers from marine
life are largely overrated because most underwater animals leave man alone. All
divers should be able to identify the dangerous species that are likely to be found
in the area of operation and should know how to deal with each. Refer to Appendix
5C for specific information about dangerous marine life, including identification
factors, dangerous characteristics, injury prevention, and treatment methods.
Vessels and Small Boat Traffic. The presence of other ships is often a serious
problem. It may be necessary to close off an area or limit the movement of
other ships. A local Notice to Mariners should be issued. At any time that diving
operations are to be conducted in the vicinity of other ships, they shall be properly
notified by International Code signal flags (Figure 6-12). An operation may have
to be conducted in an area with many small boats operated by people with varied
levels of seamanship and knowledge of Nautical Rules of the Road. The diving
team should assume that these operators are not acquainted with diving signals
and take the precautions required to ensure that these vessels remain clear of the

U.S. Navy Diving Manual — Volume 2

IN: “I require a diver.”

IO: “I have no diver.”

IN1: “I require a diver to clear my propeller.”

IP: “A diver will be sent as soon as possible or at time indicated.”

IN2: “I require a diver to examine bottom.”

IQ: “Diver has been attacked by diver’s
disease and requires decompression
chamber treatment.”

IN3: “I require a diver to place collision mat.”

IR: “I am engaged in submarine survey
work (underwater operations). Keep
clear of me and go slow.”

IN4: “I require a diver to clear my anchor.”

A: “I have a diver down; keep well clear at
slow speed.”

Code Flag (Note 1)

Sport Diver (Unofficial)

General Note: Rule 27 of Navigation Rules-International-Inland of March 1999 states the lights
and shapes that must be displayed when engaged in diving operations.
Note 1: International Signal Code – All signals must be preceded by the code flag to signify that they
are international signals. (Do not use code flag in inland waters.)

Figure 6‑12. International Code Signal Flags.

CHAPTER 6­—Operational Planning and Risk Management	

6-23

diving area. Hazards associated with vessel traffic are intensified under conditions
of reduced visibility.
NOTE:

When small civilian boats are in the area, use the civilian Sport Diver flag
(red with white diagonal stripe) as well as “Code Alpha.”

6-5.15

Territorial Waters. Diving operations conducted in the territorial waters of other
nations shall be properly coordinated prior to diving. Diving units must be alert to
the presence of foreign intelligence-collection ships and the potential for hostile
action when diving in disputed territorial waters or combat zones.

6-5.16

Emergency Equipment. The Diving Safety and Planning Checklist (see Figure

6-19) lists operational steps and equipment required to safely conduct diving
operations. The following minimum emergency equipment will be available onstation for every diving operation:
n Communications equipment capable of reaching help in the event of an
emergency
n A completely stocked first aid kit
n Portable oxygen supply with sufficient capacity to reach either the recompression
chamber or the planned evacuation location listed in the Emergency Assistance
Checklist (Figure 6-22)
n Resuscitator or Bag-mask (to provide rescue breathing)
n A means of extracting and transporting an unconscious diver (e.g., litter,
stretcher, mesh stretcher, backboard)
If unable to comply due to operational restrictions (limited space, DDS operations,
saturation diving), this equipment will be as close as practical to the diving
operations and ready for immediate use.
6-6

SELECT DIVING TECHNIQUE

The four main types of air diving equipment used in U.S. Navy diving operations
are (Figure 6‑13):
1. Open-circuit SCUBA
2. MK 20 MOD 0 Full Face Mask surface-supplied or open-circuit SCUBA
3. MK 21 MOD 1, KM-37 surface-supplied gear
4. EXO BR MS Full Face Mask surface-supplied or open-circuit SCUBA
6-6.1

Factors to Consider when Selecting the Diving Technique. When selecting the

technique to be used for a dive, the following factors must be considered:
n Duration and depth of the dive
n Type of work to be performed

6-24

U.S. Navy Diving Manual — Volume 2

OPEN-CIRCUIT SCUBA
Normal working limit: 130 fsw
Operational necessity: 190 fsw

SURFACE-SUPPLIED GEAR
(MK 20 MOD 0)
Normal working limit: 60 fsw

SURFACE-SUPPLIED GEAR
(EXO BR MS)
Normal working limit with EGS:
190 fsw

SURFACE-SUPPLIED DEEP-SEA GEAR
(MK 21 MOD 1, KM-37)
Normal working limit with EGS: 190 fsw

Figure 6‑13. Air Diving Techniques. A choice of four air diving techniques are available: open circuit SCUBA,
surface-supplied gear (MK 20 MOD 0), surface-supplied deep-sea gear (MK 21 MOD 1 and KM-37), and
surface-supplied deep sea gear (EXO BR MS).

n Environmental conditions
n Time constraints
A dive of extended length, even in shallow water, may require an air supply
exceeding that which could be provided by SCUBA. Specific depth limits have been
established for each type of diving gear and shall not be exceeded without specific
approval of the Chief of Naval Operations in accordance with the OPNAVINST
3150.27 series (see Figure 6‑14).
The increase of air consumption with depth limits open-circuit SCUBA to 130 fsw
for reasonable working dives. The hazards of nitrogen narcosis and decompression
further limit open-circuit SCUBA to 190 fsw even for short duration dives. Surfacesupplied equipment is generally preferred between 130 and 190 fsw, although opencircuit SCUBA may be used under some circumstances. Decom­pression SCUBA
dives and SCUBA dives deeper than 130 fsw may be conducted when dictated by
operational necessity and with the specific approval of the Commanding Officer

CHAPTER 6­—Operational Planning and Risk Management	

6-25

NORMAL AND MAXIMUM LIMITS FOR AIR DIVING
Depth fsw
(meters)

Limit for Equipment

Notes

60 (18)

MK 21 MOD 1, KM-37 diving equipment, maximum working
limit without Emergency Gas Supply (EGS)

a

60 (18)

MK 20 MOD 0 equipment surface-supplied

a

60 (18)

Maximum depth for standby SCUBA diver using a single
cylinder with less than 100 SCF capacity

100 (30)

Open-circuit SCUBA with less than 100 SCF cylinder capacity

b

130 (40)

Open-circuit SCUBA, normal working limit

b

190 (58)

Open-circuit SCUBA, maximum working limit with
Commanding Officer’s or Officer-in-Charge’s permission

190 (58)

MK 21 MOD 1, KM-37 and EXO BR MS (air) diving equipment
with EGS, normal working limit

c, d, e

285 (87)

MK 21 MOD 1, KM-37 and EXO BR MS (air) diving equipment
with EGS, maximum working limit, exceptional exposure with
authorization from the Chief of Naval Operations (N873)

c, d, e

b, d

General Operating Notes (Apply to all):
1.

These limits are based on a practical consideration of working time versus decompression time and
oxygen-tolerance limits. These limits shall not be exceeded except by specific authorization from the
Chief of Naval Operations (N873).

2.

Do not exceed the limits for exceptional exposures for the Air Decompression Table.

3.

In an emergency, any operable recompression chamber may be used for treatment if deemed safe to
use by a DSWS qualified Chamber Supervisor.

Specific Notes:
a.

When diving in an enclosed space, EGS must be used by each diver.

b.

Under normal circumstances, do not exceed the limits of the No-Decompression Table. Dives requiring
decompression may be made if considered necessary with approval by the Commanding Officer or
Officer-in-Charge of the diving command. The total time of a SCUBA dive (including decompression)
shall not exceed the duration of the apparatus in use, disregarding any reserves.

c.

A Diving Medical Officer is required on the dive station for all air dives deeper than 190 fsw and for
exceptional exposure dives.

d.

All planned decompression dives deeper than 130 fsw require a certified recompression chamber
on site. An on-site chamber is defined as a certified and ready chamber accessible within 30
minutes of the dive site by available transportation.

e.

Exceptional exposure dives have a significantly higher probability of DCS and CNS oxygen toxicity.

Figure 6‑14. Normal and Maximum Limits for Air Diving.

6-26

U.S. Navy Diving Manual — Volume 2

or the Officer-in-Charge. All open-circuit SCUBA dives deeper than 100 fsw shall
employ cylinders having a capacity of at least 100 cubic feet.
In some operations there may be no clear-cut choice of which diving technique
to use. Selecting a diving technique may depend upon availability of equipment
or trained personnel. The following comparison of SCUBA and surface-supplied
techniques highlights the significant differences between the methods and outlines
the effect these differences will have on planning.
6-6.2

Breathhold Diving Restrictions. Breathhold diving shall be confined to tactical

and work situations that cannot be effectively accomplished by the use of
underwater breathing apparatus and appli­cable diver training situations such as
SCUBA pool phase and shallow water obstacle/ordnance clearance. Breathhold
diving includes the practice of taking two or three deep breaths prior to the dive.
The diver shall terminate the dive and surface at the first sign of the urge to
breathe. Hyperventilation (excessive rate and depth of breathing prior to a dive, as
differentiated from two or three deep breaths prior to a dive) shall not be practiced
because of the high possibility of causing unconsciousness under water.
6-6.3

Operational Characteristics of SCUBA. The term SCUBA refers to open-circuit

air SCUBA unless otherwise noted. The main advantages of SCUBA are mobility,
depth flexibility and control, portability, and reduced requirement for surface
support. The main disadvantages are limited depth, limited duration, lack of voice
communications (unless equipped with a through-water communications system),
limited environmental protection, remoteness from surface assistance, and the
negative psychological and physio­logical problems associated with isolation and
direct exposure to the underwater environment.
6‑6.3.1

Mobility. The SCUBA diver is not hindered by bulky or heavy equipment and can

cover a considerable distance, with an even greater range through the use of diver
propul­sion vehicles (DPVs), moving freely in any direction. However, the SCUBA
diver shall be able to ascend directly to the surface in case of emergency.
WARNING
6‑6.3.2

SCUBA equipment is not authorized for use in enclosed space diving.
Buoyancy. SCUBA equipment is designed to have nearly neutral buoyancy when

in use, permitting the diver to change or maintain depth with ease. This allows the
SCUBA diver to work at any level in the water column.
6‑6.3.3

Portability. The portability and ease with which SCUBA can be employed are

distinct advan­tages. SCUBA equipment can be transported easily and put into
operation with minimum delay. SCUBA offers a flexible and economical method
for accom­plishing a range of tasks.
6‑6.3.4

Operational Limitations. Divers shall adhere to the operational limitations

contained in Figure 6‑14. Bottom time is limited by the SCUBA’s fixed air supply,
which is depleted more rapidly when diving deep or working hard.

CHAPTER 6­—Operational Planning and Risk Management	

6-27

6‑6.3.5

Environmental Protection. The SCUBA diver is not as well protected from cold

or from contact with marine plants and animals as a diver in surface-supplied gear,
and is more easily swept along by current.
6-6.4

Operational Characteristics of SSDS. Surface-supplied diving systems can be

divided into two major categories: light­weight full face mask (MK 20 and EXO
26-BR), and deep-sea (MK 21 and KM-37) gear.
6‑6.4.1

Mobility. Surface-supplied gear allows the diver almost as much mobility as SCUBA.

The primary use for deep-sea gear is bottom work in depths up to 190 fsw.

6‑6.4.2

Buoyancy. The buoyancy associated with SSDS varies with the diving dress

selected. Vari­able Volume Dry Suit (VVDS) provides the greatest buoyancy
control (see paragraph 7-3.1.2), making it a desirable technique for working on
muddy bottoms, conducting jetting or tunneling, or working where the reaction
forces of tools are high.
6‑6.4.3

Operational Limitations. Divers using surface-supplied gear are restricted to the

operational limitations described in Figure 6‑14. Additional limitations of using
surface-supplied gear include additional topside support personnel and lengthy
predive and postdive procedures.

6‑6.4.4

6-7

Environmental Protection. Surface-supplied diving systems can offer the diver
increased thermal protection when used with a Hot Water or VVDS. The MK 21
helmet can increase protection of the diver’s head. Deep sea gear (MK 21 MOD
1, KM-37) should be used for jobs involving underwater rigging, heavy work, use
of certain underwater tools, and any situation where more physical protection is
desired. Because the diver’s negative buoyancy is easily controlled, an SSDS allows
diving in areas with strong currents.

SELECT EQUIPMENT AND SUPPLIES
6-7.1

6-7.2

Equipment Authorized for Navy Use. Equipment procured for use in the U.S.
Navy has been tested under laboratory and field conditions to ensure that it will
perform according to design specifications. A vast array of equipment and tools
is available for use in diving operations. The NAVSEA/00C Diving Equipment
Authorized for U.S. Navy Use (ANU) list iden­tifies much of this equipment and
categorizes diving equipment authorized for U.S. Navy use.
Air Supply. The quality of diver’s breathing air is vitally important. Air supplies
provided to the diver in tanks or through a compressor shall meet five basic
criteria.
1. Air shall conform to standards for diving air purity found in paragraph 4‑3 and

paragraph 4‑4.

2. Flow to the diver must be sufficient. Refer to the appropriate equipment oper­

ations and maintenance manual for flow requirements.

3. Adequate overbottom pressure shall be maintained at the dive station.

6-28

U.S. Navy Diving Manual — Volume 2

4. Adequate air supply shall be available to support the duration and depth of the

dive (see paragraph 7-4.1 for SCUBA; paragraph 8-2.2 for MK 21).

5. A secondary air supply shall be available for surface-supplied diving.
6-7.3

Diving Craft and Platforms. Regardless of the technique being supported, craft
used for diving operations shall:

n
n
n
n
n
n
n

Be seaworthy
Include required lifesaving and other safety gear
Have a reliable engine (unless it is a moored platform or barge)
Provide ample room for the divers to dress
Provide adequate shelter and working area for the support crew
Be able to carry safely all equipment required for the operation
Have a well-trained crew

Other support equipment—including barges, tugs, floating cranes, or vessels and
aircraft for area search—may be needed, depending on the type of operation. The
need for additional equipment should be anticipated as far in advance as possible.
6-7.4

Deep-Sea Salvage/Rescue Diving Platforms.

n Auxiliary Rescue/Salvage Ship (T-ARS) (Safeguard Class). The mission of
the T-ARS ship is to assist disabled ships, debeach stranded vessels, fight fires
alongside other ships, lift heavy objects, recover submerged objects, tow other
vessels, and perform manned diving operations. The T-ARS class ships carry a
complement of divers to perform underwater ship husbandry tasks and salvage
operations as well as underwater search and recovery. This class of vessel is
equipped for all air diving techniques. Onboard equipment allows diving with
air to a depth of 190 fsw.
n Submarine Tender (AS). U.S. submarine tenders are designed specifically
for servicing nuclear-powered submarines. Submarine tenders are fitted with
a recompression chamber used for hyperbaric treatments. Submarine tenders
support underwater ship husbandry and maintenance and security swims.
n Fleet Ocean Tug (T-ATF). T-ATFs are operated by the Military Sealift Com­
mand. Civilian crews are augmented with military communications and diving
detachments. In addition to towing, these large ocean-going tugs serve as sal­
vage and diving platforms.
n Diving Tender (YDT). These vessels are used to support shallow-water diving
operations. Additionally, a wide variety of Standard Navy Dive Boats (SNDB),
LCM-8, LCM-6, 50-foot work boats, and other yard craft have been fitted with
surface-supplied dive systems.
6-7.5

Small Craft. SCUBA operations are normally conducted from small craft. These

can range in size and style from an inflatable rubber raft with an outboard engine
to a small landing craft. If divers are operating from a large ship or diving float,
a small boat must be ready as a rescue craft in the event a surfacing diver is in

CHAPTER 6­—Operational Planning and Risk Management	

6-29

trouble some distance from the support site. A small boat used by SCUBA divers
must be able to slip its moorings quickly and move to a diver needing assistance.
6-8

SELECT AND ASSEMBLE THE DIVING TEAM

When planning diving assignments and matching the qualifications and experi­ence
of diving personnel to specific requirements of the operation, a thorough knowledge
of the duties, responsibilities, and relationships of the various members of the diving
team is essential. The diving team may include the Diving Officer, Master Diver,
Diving Supervisor, Diving Medical Officer, divers qualified in various techniques
and equipment, support personnel (tenders—qualified divers if possible), recorder,
and medical personnel, as indicated by the type of operation (Figure 6‑15). Other
members of the ship’s company, when properly instructed, provide support in
varying degrees in such roles as boat crew, winch operators, and line handlers.
6-8.1

Manning Levels. The size of the diving team may vary with the operation,
depending upon the type of equipment being used, the number of divers needed to
complete the mission, and the depth. Other factors, such as weather, planned length
of the mission, the nature of the objective, and the availability of various resources
will also influence the size of the team. The minimum number of personnel required
on station for each particular type of diving equipment is provided in Figure 616. Minimum levels as determined by ORM shall be maintained; levels must be
increased as necessary to meet anticipated operational conditions and situations.

Figure 6‑15. MK 21 Dive Requiring Two Divers. The team consists of one Diving
Supervisor, two divers, a standby diver, one tender per diver, comms and logs, console
operator, and extra personnel (as required).

6-30

U.S. Navy Diving Manual — Volume 2

MINIMUM MANNING LEVELS FOR AIR DIVING
Open circuit SCUBA Operations

Surface-Supplied Operations

Single
Diver

Buddy
Pair

Diving Supervisor

1

1

1

Comms and Logs

(a)

(a)

(a)

Console Operator

(a)

Diver

1

2

1

Standby Diver

1

1

1

Diver Tender (b, c)
Standby Diver Tender
Total

1(b)

1(b)

(c)

(c)

1

4(d)

4

5(e)

WARNING
These are the minimum personnel levels required. ORM may require these
personnel levels be increased so the diving operations can be conducted
safely. See Paragraph 6-1.1 and 6-9.1
NOTES:
(a) Diving Supervisor may perform/assign Comms/Logs or Console Operator positions as necessary or required by the
system/operations/mission.
(b) See paragraph 6-8.8.5.2 for Tender Qualifications.
(c) If the standby diver is deployed, the Diving Supervisor shall tend the standby diver.
(d) The diver will be tended or have a witness float attached, see paragraph 7-3.1.7. A tender is required when the diver does
not have free access to the surface, see paragraph 7-8.2 for further guidance. During mission essential open circuit
SCUBA operations, minimum-manning level may be reduced to three qualified divers at the Diving Supervisor’s discretion.
(e) Although five is the minimum number of personnel for the MK III and Extreme Lightweight Dive System (XLDS) operations,
six or more is highly recommended based on mission requirements and ORM.

Figure 6‑16. Minimum Personnel Levels for Air Diving Stations.

CHAPTER 6­—Operational Planning and Risk Management	

6-31

6-8.2

Commanding Officer. The ultimate responsibility for the safe and successful

conduct of all diving opera­tions rests with the Commanding Officer. The
Commanding Officer’s responsibilities for diving operations are defined and the
provisions of U.S. Navy Regulations and other fleet, force, or command regulations
confirm specific authority. To ensure diving operations are efficiently conducted,
the Commanding Officer delegates appropriate authority to selected members of
the command who, with subordinate personnel, make up the diving team.
6-8.3

Command Diving Officer. The Command Diving Officer’s primary responsibility

is the safe conduct of all diving operations within the command. The Command
Diving Officer will become thoroughly familiar with all command diving
techniques and have a detailed knowledge of all applicable regulations and is
responsible for all operational and administrative duties associated with the
command diving program. The Command Diving Officer is designated in writing
by the Commanding Officer and must be a qualified diver. In the absence of a
commissioned officer or a Master Diver, a senior enlisted diving supervisor may
be assigned as the Command Diving Officer. On submarines the senior qualified
diver may be assigned Command Diving Officer.

6-8.4

6-32

Watchstation Diving Officer. The Watchstation Diving Officer must be a qualified
diver and is responsible to the Commanding Officer for the safe and successful
conduct of the diving operation. The Watchstation Diving Officer provides overall
supervision of diving operations, ensuring strict adherence to procedures and
precautions. A qualified Diving Officer or Master Diver may be assigned this
watchstation. The Watchstation Diving
Officer must be designated in writing by
the Commanding Officer.

6-8.5

Master Diver

6‑8.5.1

Master

The
Master Diver is the most qualified person
to supervise air and mixed-gas dives
(using SCUBA and surface-supplied
diving equipment) and recompression
treatments (Figure 6-17). He is directly
responsible to the Commanding
Officer, via the Diving Officer, for the
safe conduct of all phases of diving
operations. The Master Diver manages
preventive and corrective maintenance
on diving equipment, support systems,
salvage machinery, handling systems,
and submarine rescue equipment.
The Master Diver, who also ensures
that divers are trained in emergency
procedures, conducts training and
requalification of divers attached to the
Diver

Responsibilities.

Figure 6‑17. Master Diver Supervising
Recompression Treatment.

U.S. Navy Diving Manual — Volume 2

command. The Master Diver recommends to the Commanding Officer, via the
Diving Officer, which enlisted divers are qualified to serve as Diving Supervisors.
The Master Diver oversees the efforts of the Diving Supervisor and provides advice
and technical expertise. If circumstances warrant, the Master Diver shall relieve
the Diving Supervisor and assume control of the dive station. In the absence of a
Diving Officer, the Master Diver can assume the duties and responsibilities of the
Diving Officer.
6‑8.5.2

Master Diver Qualifications. The Master Diver has completed Master Diver
evaluation course (CIN A-433-0019) successfully and is proficient in the
operation of Navy-approved underwater breathing equipment, support systems,
and recompression chambers. He is also trained in diagnosing and treating diving
injuries and illnesses. The Master Diver is thoroughly familiar with operating and
emergency procedures for diving sys­tems, and possesses a working knowledge of
gas mixing and analysis, computa­tions, salvage theory and methods, submarine
rescue procedures, towing, and underwater ship husbandry. The Master Diver
shall possess a comprehensive knowledge of the scope and application of all Naval
instructions and publications pertaining to diving, and shall ensure that logs and
reports are maintained and sub­mitted as required.

6-8.6

Diving Supervisor. While the Master Diver is in charge of the overall diving

operation, the Diving Supervisor is in charge of the actual diving operation for a
particular dive or series of dives. Diving operations shall not be conducted without
the presence of the Diving Supervisor. The Diving Supervisor has the authority
and responsibility to discontinue diving operations in the event of unsafe diving
conditions.
6‑8.6.1

Pre-dive Responsibilities. The Diving Supervisor shall be included in preparing

the operational plans. The Diving Supervisor shall consider contingencies,
determine equipment require­ments, recommend diving assignments, and establish
back-up requirements for the operation. The Diving Supervisor shall be familiar
with all divers on the team and shall evaluate the qualifications and physical fitness
of the divers selected for each particular job. The Diving Supervisor inspects all
equipment and conducts pre-dive briefings of personnel.
6‑8.6.2

Responsibilities While Operation is Underway. While the operation is underway,

the Diving Supervisor monitors progress; debriefs divers; updates instructions to
subsequent divers; and ensures that the Master Diver, Diving Officer, Commanding
Officer, and other personnel as neces­sary are advised of progress and of any
changes to the original plan. The Diving Supervisor should not hesitate to call
upon the technical advice and expertise of the Master Diver during the conduct of
the dive operation.
6‑8.6.3

Post-dive Responsibilities. When the mission has been completed, the Diving
Supervisor gathers appropriate data, analyzes the results of the mission, prepares
reports to be submitted to higher authority, and ensures that required records are
completed. These records may range from equipment logs to individual diving
records.

CHAPTER 6­—Operational Planning and Risk Management	

6-33

6‑8.6.4

Diving Supervisor Qualifications. The Diving Supervisor may be commissioned

or enlisted depending on the size of the operation and the availability of qualified
personnel. When qualifying a Diving Supervisor, selection is based on knowledge
of diving technique, experience, level of training, and the competence of the
available personnel. Regardless of rank, the Diving Supervisor shall be a qualified
diver of demonstrated ability and experi­ence. The Diving Supervisor shall be
designated in writing by the Commanding Officer. Diving Supervisors under
instruction shall stand their watches under the supervision of a qualified Diving
Supervisor.
6-8.7

Diving Medical Officer. The Diving Medical Officer recommends the proper

course of medical action during medical emergencies. The Diving Medical Officer
provides on-site medical care for divers as conditions arise and ensures that diving
personnel receive proper attention before, during, and after dives. The Diving
Medical Officer may modify recompression treatment tables, with the specific
concurrence of the Commanding Officer. A Diving Medical Officer is required
on site for all air dives deeper than 190 fsw, or for planned exceptional exposure
dives. A DMO must be consulted at some point during an actual recompression
chamber treatment prior to the release of the patient.

6-8.8

Diving Personnel

6‑8.8.1

Diving Personnel Responsibilities. While working, the diver shall keep topside

personnel informed of conditions on the bottom, progress of the task, and of any
developing problems that may indicate the need for changes to the plan or a call
for assistance from other divers. To ensure safe conduct of the dive, the diver shall
always obey a signal from the surface and repeat all commands when using voice
communications. The diver is responsible for the diving gear worn and shall ensure
that it is complete and in good repair.
6‑8.8.2

Diving Personnel Qualifications. Military divers shall be qualified and designated

in accordance with instructions issued by the Naval Personnel Command (NPC)
or as appropriate by USMC, U.S. Army, or U.S. Air Force orders. Civilian
divers under military cognizance must be qualified in accordance with OPNAV
3150.27 (Series). The diving team selected for an operation shall be qualified for
the positions manned, diving technique used, the equipment involved, and for
diving to the depth required. The DSWS NAVEDTRA 43245 Series Personnel
Qualification Standard (PQS) is required for Navy Diver, and equivalent Navy
civilian divers. All other Military Divers qualifying to operate or supervise diving
systems and equipment contained in the NAVEDTRA 43245 Series PQS, should
use the current NAVEDTRA 43245 Series PQS Watch Stations as a guide for
qualification, in an effort to standardize DOD qualifications and ensure safe conduct
of diving operations. Diving personnel assigned to Navy Experimental Diving
Unit (NEDU) and Naval Submarine Medical Research Laboratory (NSMRL) are
exempt from such requirements as they are assigned as experimental test subjects
and may be employed in experimental dive profiles as required within approved
test protocols.

6-34

U.S. Navy Diving Manual — Volume 2

Formal training is required for all designated U.S. Military and DOD civilian
employee divers. The Center for EOD and Diving (CENEODDIVE) is authorized
to designate fleet units to train personnel in specific critical diving skill sets (HEO2,
Saturation, MK-16 Mod 0 and Mod 1, and MK 25). Commands performing these
local qualifications must be designated in writing. Qualifications will be conducted
using curricula and materials provided and controlled by CENEODDIVE.
Commands conducting local qualifications must have a Master Diver qualified in
the equipment being trained and who holds NEC 9502 or an equivalent instructor
qualification as determined by CENEODDIVE.
6‑8.8.3

Standby Diver. A standby diver

with a tender is required for all
diving operations. The standby
diver need not be equipped
with the same equipment as the
primary diver (except as otherwise
specified), but shall have equivalent
depth and operational capabili­ties.
SCUBA shall not be used for the
standby diver for surface-supplied
diving operations.
6‑8.8.3.1

Standby Diver Qualifications. The

standby diver is a fully qualified
diver, assigned for back-up or to
provide emergency assistance, and
is ready to enter the water immeFigure 6‑18. Standby Diver.
diately. For surface-supplied operations, the standby diver shall be
dressed to the following points, MK 20 or MK 21 MOD 1, KM-37, with strain relief connected to the harness. Under certain conditions, the Diving Supervisor may
require that the helmet be worn. A standby SCUBA diver shall don all equipment
and be checked by the Diving Supervisor. The standby diver may then remove the
mask and fins and have them ready to don immediately for quick deployment. For
safety reasons at the discre­tion of the Diving Supervisor, the standby diver may
remove the tank. The standby diver receives the same briefings and instructions as
the working diver, monitors the progress of the dive, and is fully prepared to respond if called upon for assis­tance. The SCUBA standby diver shall be equipped
with an octopus rig.
6‑8.8.3.2

Deploying the Standby Diver as a Worker Diver. The standby diver may be

deployed as a working diver provided all of the following conditions are met:
1. Surface-supplied no-decompression dive of 60 fsw or less.
2. Same job/location, e.g., working on port and starboard propellers on the

vessel:
n

Prior to deploying the standby diver, the work area shall be determined to be
free of hazards (i.e., suctions, discharges) by the first diver on the job site.

CHAPTER 6­—Operational Planning and Risk Management	

6-35

n

NOTE

6‑8.8.4

When working in ballast tanks or confined spaces, the standby diver may
deploy as a working diver, but both divers shall be tended by a third diver
who is outside the confined space.

The standby diver shall remain on deck ready for deployment when
salvage operations diving is being done.
Buddy Diver. A buddy diver is the diver’s partner for a SCUBA operation. The
buddy divers are jointly responsible for the assigned mission. Each diver keeps
track of depth and time during the dive. Each diver shall watch out for the safety
and well-being of his buddy and shall be alert for symptoms of nitrogen narcosis,
decompression sickness, and carbon dioxide build-up. A diver shall keep his buddy
within sight and not leave his buddy alone except to obtain additional assistance in
an emer­gency. If visibility is limited, a buddy line shall be used to maintain contact
and communication. If SCUBA divers get separated and cannot locate each other,
both divers shall surface immediately.

6‑8.8.5

Diver Tender

6‑8.8.5.1

Diver Tender Responsibilities. The tender is the surface member of the diving

team who works closely with the diver on the bottom. At the start of a dive, the
tender checks the diver’s equipment and topside air supply for proper operation
and dresses the diver. Once the diver is in the water, the tender constantly tends
the lines to eliminate excess slack or tension (certain UWSH tasking may preclude
this requirement, e.g., working in submarine ballast tanks, shaft lamination, dry
habitat welding, etc.). The tender exchanges line-pull signals with the diver, keeps
the Diving Supervisor informed of the line-pull signals and amount of diving hose/
tending line over the side, and remains alert for any signs of an emergency.
6‑8.8.5.2

Diver Tender Qualifications. The tender should be a qualified diver. When

circumstances require the use of a non-diver as a tender, the Diving Supervisor
shall ensure that the tender has been thoroughly instructed in the required duties.
If a substitute tender shall be employed during an operation, the Diving Supervisor
must make certain that the substitute is adequately briefed before assuming
duties.

6‑8.8.6

6‑8.8.7

Recorder. The recorder shall be a qualified diver. The recorder maintains worksheets, fills out the diving log for the operation, and records the diver’s descent
time, depth of dive, and bottom time. The recorder reports to the Diving Supervisor the ascent time, first stop, and time required at the decompression stop. In
SCUBA opera­tions, the Diving Supervisor may assume the duties of the recorder.
The recorder is required to have on hand a copy of the U.S. Navy Decompression
Table being used. When decompression begins, the schedule selected by the Diving Supervisor is recorded o