The divers are now ready to enter the water, where their scuba shall be given
another brief inspection by their dive partners or tenders prior to descent.
There are several ways to enter the water, with the choice usually
determined by the nature of the diving platform (Figure 7-8a and Figure 7-8b).
Whenever possible, entry should be made by ladder, especially in unfamiliar
waters. Several basic rules apply to all methods of entry:
-
Look before jumping or pushing off from the platform or ladder.
-
Tuck chin into chest and hold the
cylinders with one hand to
prevent the manifold from hitting
the back of the head.
-
Hold the mask in place with the
fingers and the mouthpiece in
place with the heel of the hand.
Figure 7-8a. Scuba Entry Techniques
|
Figure 7-8b. The diver steps backward pushing himself away with his feet.
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The step-in method
is the most frequently used, and is
best used from a stable platform or
vessel. The divers should simply take
a large step out from the platform,
keeping legs in an open stride. They
should try to enter the water with a
slightly forward tilt of the upper body
so that the force of entry will not
cause the cylinder to hit the back of
the head.
-
Look before jumping or pushing off from the platform or ladder.
-
Tuck chin into chest and hold the
cylinders with one hand to
prevent the manifold from hitting
the back of the head.
-
Hold the mask in place with the
fingers and the mouthpiece in
place with the heel of the hand.
The rear roll is the
preferred method for entering the
water from a small boat. A fully
outfitted diver standing on the edge of
a boat would upset the stability of the craft and would be in danger of falling either
into the boat or into the water. To execute a rear roll, the diver sits on the gunwale
of the boat, facing inboard. With chin tucked in and one hand holding the mask
and mouthpiece in place, the diver rolls backward, basically moving through a full
backward somersault.
Divers working from the beach choose their
method of entry according to the condition of the surf and the slope of the bottom.
If the water is calm and the slope gradual, the divers can walk out, carrying their
swim fins until they reach water deep enough for swimming. In a moderate to high
surf, the divers, wearing swim fins, should walk backwards into the waves until
they have enough depth for swimming. They should gradually settle into the
waves as the waves break around them.
Once in the water, and before descending to operating
depth, the divers make a final check of their equipment. They must:
-
Make a breathing check of the scuba. Breathing should be easy, with no
resistance and no evidence of water leaks.
-
Visually check dive partner’s equipment for leaks, especially at all connection
points (i.e., cylinder valve, hoses at regulator and mouthpiece).
-
Check partner for loose or entangled straps.
Check face mask seal. A small amount of water may enter the mask upon the
diver’s entry into the water. The mask may be cleared through normal methods
(see paragraph 7-7.2).
-
Check buoyancy. Scuba divers should strive for neutral buoyancy. When carrying
extra equipment or heavy tools, the divers might easily be negatively
buoyant unless the weights are adjusted accordingly.
-
If wearing a dry suit, check for leaks. Adjust suit inflation for proper buoyancy.
-
Orient position with the compass or other fixed reference points.
When satisfied that all equipment checks out properly, the divers report their
readiness to the Diving Supervisor. The Diving Supervisor directs the divers to
zero their watches and bottom time begins. The Diving Supervisor gives a signal
to descend and the divers descend below the surface.
The diving boat should be moored as near to the dive site as
possible. While swimming, dive partners must keep visual contact with each other
and other divers in the group. They should be oriented to their surroundings to
avoid swimming off course. The most important factor in surface swimming with
scuba is to maintain a relaxed pace to conserve energy. The divers should keep
their masks on and breathe through the snorkel. When surface swimming with a
scuba regulator, hold the mouthpiece so that air does not free-flow from the
system.
Divers should use only their legs for propulsion and employ an easy kick from the
hips without lifting the swim fins from the water. Divers can rest on their backs
and still make headway by kicking. Swimming assistance can be gained by
partially inflating the life preserver or buoyancy compensator. However, the
preserver must be deflated again before the dive begins.
The divers may swim down or they may use a descending line to pull
themselves down. The rate of descent will generally be governed by the ease with
which the divers will be able to equalize the pressure in their ears and sinuses, but
it should never exceed 75 feet per minute. If either diver experiences difficulty in
clearing, both divers must stop and ascend until the situation is resolved. If the
problem persists after several attempts to equalize, the dive shall be aborted and
both divers shall return to the surface. When visibility is poor, the divers should
extend an arm to ward off any obstructions.
Upon reaching the operating depth, the divers must orient themselves to their
surroundings, verify the site, and check the underwater conditions. If conditions
appear to be radically different from those anticipated and seem to pose a hazard,
the dive should be aborted and the conditions reported to the Diving Supervisor.
The dive should be aborted if the observed conditions call for any major change in
the dive plan. The divers should surface, discuss the situation with the Diving
Supervisor, and modify the dive plan.
