When it is time to return to the surface, either diver may signal the end of the dive.
When the signal has been acknowledged, the divers shall ascend to the surface
together at a rate not to exceed 30 feet per minute. For a normal ascent, the divers
will breathe steadily and naturally. Divers must never hold their breath during
ascent, because of the danger of an air embolism. While ascending, divers must
keep an arm extended overhead to watch for obstructions and should spiral slowly
while rising to obtain a full 360 degree scan of the water column.
If a diver is suddenly without air or if the
scuba is entangled and the dive partner cannot be reached quickly, a free ascent
must be made. Guidelines for a free ascent are:
1. Drop any tools or objects being carried by hand.
2. Abandon the weight belt.
3. If the scuba has become entangled and must be abandoned, actuate the quickrelease
buckles on the waist, chest, shoulder, and crotch straps. Slip an arm out
of one shoulder strap and roll the scuba off the other arm. An alternate method
is to flip the scuba over the head and pull out from underneath. Ensure that the
hoses do not wrap around or otherwise constrict the neck. The neck straps
packed with some single-hose units can complicate the overhead procedure
and should be disconnected from the unit and not used.
4. If the reason for the emergency ascent is a loss of air, drop all tools and the
weight belt and actuate the life preserver to surface immediately. Do not drop
the scuba unless it is absolutely necessary.
5. If a diver is incapacitated or unconscious and the dive partner anticipates
difficulty in trying to swim the injured diver to the surface, the partner should
activate the life preserver or inflate the buoyancy compensator. The weight
belt may have to be released also. However, the partner should not lose direct
contact with the diver.
6. Exhale continuously during ascent to let the expanding air in the lungs escape
freely.
When underwater ship husbandry tasks are
required, surface-supplied lightweight equipment is preferred. Scuba diving is
permitted under floating hulls; however, a tending line to the scuba diver must be
provided. In the event of casualty and the lack of immediate assistance by the dive
partner, the scuba diver will be able to return to the surface using the tending line.
Ships are often moored against closed-face piers or heavy camels and care must be
exercised to ensure that the tending line permits a clear path for emergency
surfacing of the diver.
Due to the unique nature of EOD operations involving limpet search and neutralization,
the use of tending lines is not practical and is not required. During EOD
limpet mine training, the use of tending lines is required.
Scuba dive plans on deep-draft ships should restrict diving operations to one quadrant
of the hull at a time. This theoretical quartering of the ship’s hull will
minimize potential diver disorientation caused by multiple keel crossings or fore
and aft confusion.
When notified of a lost diver, a search shall be conducted by a tended diver in the
area where the lost diver was last seen.
Predive briefs must include careful instruction on life preserver use when working
under a hull to prevent panic blowup against the hull. Life preservers should not be
fully inflated until after the diver passes the turn of the bilge.
Open-circuit scuba dives are normally planned as no-decompression
dives. Open-circuit scuba dives requiring decompression may be made
only when considered absolutely necessary and authorized by the Commanding
Officer or Officer in Charge (OIC). Under this unique situation, the following
provides guidance for scuba decompression diving.
The Diving Supervisor shall determine the required bottom time for each dive.
Based upon the time and depth of the dive, the required decompression profile
from the tables presented in Chapter 9 shall be computed. The breathing supply
required to support the total time in the water must then be calculated. If the air
supply is not sufficient, a backup scuba will have to be made available to the
divers. The backup unit can be strapped to a stage or tied off on a descent line
which also has been marked to indicate the various decompression stops to be
used.
When the divers have completed the assigned task, or have reached the maximum
allowable bottom time prescribed in the dive plan, they must ascend to the stage or
the marked line and signal the surface to begin decompression. With the stage
being handled from the surface, the divers will be taken through the appropriate
stops while the timekeeper controls the progress. Before each move of the stage,
the tender will signal the divers to prepare for the lift and the divers will signal
back when prepared. When using a marked line, the tender will signal when each
stop has been completed, at which point the divers will swim up, signaling their arrival at the next stop. Stop times will always be regulated by the Dive
Supervisor.
In determining the levels for the decompression stops, the sea state on the surface
must be taken into consideration. If large swells are running, the stage or marker
line will be constantly rising and falling with the movements of the surfacesupport
craft. The depth of each decompression stop should be calculated so that
the divers’ chests will never be brought above the depths prescribed for the stops
in the decompression tables.
In the event of an accidental surfacing or an emergency, the Diving Supervisor
will have to determine if decompression should be resumed in the water or if the
services of a recompression chamber are required. The possibility of having to
make such a choice should be anticipated during the planning stages of the operation
(Chapters 1 and 5).
When approaching the surface, divers must not
come up under the support craft or any other obstruction. They should listen for
the sound of propellers and delay surfacing until satisfied that there is no obstruction.
On the surface, the diver should scan immediately in all directions and check
the location of the support craft, other divers, and any approaching surface traffic.
If they are not seen by the support craft, they should attempt to signal the support
craft with hand signals, whistle, or flare.
On the surface, the divers can rest while waiting to be picked up. For buoyancy,
life vests or buoyancy compensators can be inflated orally or the diver can use a
snorkel for breathing.
As the divers break the surface, the tender and other personnel in the support craft
must keep them in sight constantly and be alert for any signs of trouble. While one
diver is being taken aboard the support craft, attention must not be diverted from
the divers remaining in the water. The dive is completed when all divers are safely
aboard.
Usually, getting into the boat will be easier if the divers remove the weight belts
and scuba and then hand them to the tenders. If the boat has a ladder, swim fins
should also be removed. Without a ladder, the swim fins will help to give the diver
an extra push to get aboard. A small boat may be boarded over the side or over the
stern depending on the type of craft and the surface conditions. As each diver
comes aboard a small boat or a raft, other personnel in the boat should remain
seated.
In the event of an accidental surfacing or an emergency, the Diving Supervisor
will have to determine if decompression should be resumed in the water or if the
services of a recompression chamber are required. The possibility of having to
make such a choice should be anticipated during the planning stages of the operation
(Chapters 1 and 5).
