US NAVY DIVE MANUAL CHAPTER 6 OPERATIONAL PLANNING AND RISK MANAGEMENT

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.

• Sunburn and windburn
• Hypothermia and frostbiten
• Heat exhaustion

MK 21 SSDS can usually work in currents up to 1.5 knots without undue difficulty,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.

88° F.

• Weight losses up to 15 lbs (or 6­8% of body weight) due to fluid loss may
• Divers should hydrate fully (approximately 500 ml or 17 oz) two hours before diving.
• Approximately 500 ml should be replaced for each hour of diving.
• Exposure limits represent maximum cumulative exposure over a 12 hour period-

• 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.

• 1. Conduct diving operations at night, dusk, or dawn.
• 2. Avoid wearing a hood with a dive skin to allow evaporative cooling.
• 3. When possible avoid wearing dive skin or anti­chafing dress.
• 4. Reduce the intensity of the diving for five days immediately prior to the diving operation.
• 5. Ensure divers maintain physical conditioning
• 6. Methods of cooling the diver should be employed whenever possible.

• GFIs are required when line voltage is above 7.5 VAC or 30 VDC
• GFIs shall be capable of tripping within 20 milliseconds (ms) after detecting a maximum leakage current of 30 milliamps (ma)
• GFIs or equipment containing built-in GFIs should not be plugged into an existing GFI circuit.

• The GFI must fail. 
• The electrical equipment which the diver is operating must experience a ground fault.
• The diver must place himself in the path between the fault and earth ground.

A U.S. Navy certified recompression chamber close enough to the dive site to support surface decompression with a surface interval of 5 minutes. 

• Note 1. Based on space constraints at the site, the Commanding Officer may authorize extension of the surface interval to a maximum of 7 minutes in accordance with Paragraphs 9-12.6 and 14-4.14.
• Note 2. A non‑Navy chamber may be used to satisfy this requirement if approved in writing by the CNO.

Level II A U.S. Navy certified recompression chamber accessible within one hour of the casualty. 

Note 2. A non‑Navy chamber may be used to satisfy this requirement if approved in writing by the CNO

A U.S. Navy certified recompression chamber accessible within six hours of the casualty

• Note 3. A non‑Navy chamber may be used to satisfy this requirement if approved in writing by the Commanding Officer.
• Note 4. During extreme circumstances when a chamber cannot be reached within 6 hours the Commanding Officer can give authorization to use the nearest approved recompression facility

• MK 21 MOD 1, KM‑37 NS diving equipment, maximum working limit without Emergency Gas Supply (EGS)
• MK 20 MOD 0 equipment surface-supplied
• Maximum depth for standby SCUBA/DP‑1 diver using a single cylinder with less than 100 SCF capacity

Open-circuit SCUBA/DP-1 with less than 100 SCF cylinder capacity

Open‑circuit SCUBA/DP‑1, normal working limit

• Open‑circuit SCUBA, maximum working limit with Commanding Officer’s or Officer-in-Charge’s permission
• MK 21 MOD 1, KM-37 NS and EXO BR MS (air) diving equipment with EGS, normal working limit

MK 21 MOD 1, KM-37 NS and EXO BR MS (air) diving equipment with EGS, maximum working limit, exceptional exposure with authorization from the Chief of Naval Operations (N873)

• Duration and depth of the dive
• Type of work to be performed
• Environmental conditions
• Time constraints

tactical and work situations that cannot be effectively accomplished by the use of underwater breathing apparatus

Is not

• 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

4

During mission essential open circuit  SCUBA operations, minimum-manning level may be reduced to three qualified divers at the Diving Supervisor’s discretion.

5

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.

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

• Surface-supplied
• No-decompression dive
• 60 fsw or less
• Same job/location
• Standby diver shall remain on deck ready for deployment when salvage operations diving is being done.

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

• To depths deeper than 130 fsw.
• To depths deeper than 100 fsw or outside no-decompression limits unless a recompression chamber is available within 5 minutes of the dive location. 
• All SCUBA cylinder manifolds shall be equipped with a manual reserve (J valve), or an independent reserve cylinder gas supply with a separate regulator. 
• A SCUBA cylinder submersible pressure gauge shall be worn by each diver.

• To depths deeper than 190 fsw if bottom time is 30 minutes or greater
• To depths deeper than 220 fsw regardless of bottom time
• To depths deeper than 100 fsw or outside no-decompression limits unless a recompression chamber is available within 5 minutes of the dive location. 
• The diver shall be equipped with an emergency gas supply (come-home bottle) for all planned decompression dives regardless of depth

• To depths deeper than 220 fsw, unless a bell diving system is used
• With a total in­ water decompression time greater than 120 minutes.
• A recompression chamber shall be available within 5 minutes of the dive location for all mixed gas dives.

Civilian divers shall remain at the location of the recompression chamber for 1 hour after surfacing for all dives that require a recompression chamber to be available within 5 minutes of the dive location

• The diver will probably be overtired and emotionally exhausted
• The diver may be suffering from or approaching hypothermia
• The diver may have a physical injury
• A SCUBA diver may be suffering from asphyxia. If a free ascent has been made, gas embolism may have developed
• Significant decompression time may have been missed.

• 1. Use line-pull signals at once. Depth, current, bottom or work site conditions may interfere.
• 2. Check the rising bubbles of air. A cessation or marked decrease of bubbles could be a sign of trouble.
• 3. Listen for sounds from the diving helmet. If no sound is heard, the circuit is probably out of order. If the flow of bubbles seems normal, the diver may be all right.
• 4. If sounds are heard and the diver does not respond to signals, assume the diver is in trouble.
• 5. Have divers already on the bottom investigate, or send down the standby diver to do so.

• 1. Rapid deployment
• 2. Portability
• 3. Minimum support requirements
• 4. Excellent horizontal and vertical mobility
• 5. Minimum bottom disturbances

• 1. Limited endurance (depth and duration)
• 2. Limited physical protection
• 3. Influenced by current
• 4. Lack of voice communication (unless equipped with a through‑water communications system or full face mask)

• 1. Unlimited by air supply
• 2. Good horizontal mobility
• 3. Voice and/or line-pull signal capabilities

1. Limited physical protection

• 1. Unlimited by air supply
• 2. Head protection
• 3. Good horizontal mobility
• 4. Voice and/or line pull signal capabilities
• 5. Fast deployment

1. Limited mobility

• 1. Unlimited by air supply
• 2. Good horizontal mobility
• 3. Voice and/or line pull signal capabilities
• 4. Fast deployment

1. Limited physical protection

• 1. Rapid deployment
• 2. Portability
• 3. Minimum support requirements
• 4. Excellent horizontal and vertical mobility
• 5. Minimum bottom disturbances
• 6. Greater endurance, air supply not limited to man carried cylinders

• 1. Limited physical protection
• 2. Influenced by current
• 3. Lack of voice communication (unless equipped with a through‑water communications system or light weight wire system

• 1. Standby diver required. Standby diver may be supplied from the DP‑1 surface box or a stand‑alone SCUBA diver. Standby must be tended. In either case the designated Standby diver must wear minimum of 100 scf capacity cylinder(s).
• 2. Small craft mandatory for diver recovery during open‑ocean diving
• 3. Moderate to good visibility preferred
• 4. Enclosed space diving prohibited

for both divers will be lost. Both divers’ air supplies will shift to EGS. In the DP-1 configuration, if you have an umbilical casualty and the second DP-1 diver is sitting as Standby Diver it must be stressed that his EGS tanks must have a minimum of 100 scf