Once the predive procedures have been completed, the divers are ready to enter
the water. There are several ways to enter the water, with the choice usually determined
by the nature of the diving platform. Regardless of the method of entry, the
divers should look before entering the water. Three methods for entering the water
are the:
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Ladder method
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Stage method
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Step-in method
In the water and prior to descending to operating
depth, the diver makes a final equipment check.
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The diver immediately checks for leaks in the suit or air connections.
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If two divers are being employed, both divers perform as many checks as possible
on their own rigs and then check their dive partner’s rig. The tender or
another diver can be of assistance by looking for any telltale bubbles.
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A communications check is made and malfunctions or deficiencies not previously
noted are reported at this time.
When satisfied that the divers are ready in all respects to begin the dive, they
notify the Diving Supervisor and the tenders move the divers to the descent line.
When in position for descent, the diver adjusts for negative buoyancy and signals
readiness to the Diving Supervisor.
Descent may be accomplished with the aid of a descent line or stage.
Topside personnel must ensure that air is being supplied to the diver in sufficient
quantity and at a pressure sufficient to offset the effect of the steadily increasing
water pressure. The air pressure must also include an overbottom pressure allowance
to protect the diver against a serious squeeze if he or she falls.
While descending, the diver adjusts the air supply so that breathing is easy and
comfortable. The diver continues to equalize the pressure in the ears as necessary
during descent and must be on guard for any pain in the ears or sinuses, or any
other warning signals of possible danger. If any such indications are noted, the
descent is halted. The difficulty may be resolved by ascending a few feet to regain
a pressure balance; if this is not effective, the diver is returned to the surface.
Some specific guidelines for descent are as follows:
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With a descent line, the diver locks the legs around the line and holds on to the
line with one hand.
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In a current or tideway, the diver descends with back to the flow in order to be
held against the line and not be pulled away. If the current measures more than 1.5 knots, the diver wears additional weights or descends on a weighted stage,
so that descent is as nearly vertical as possible.
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When the stage is used for descent, it is lowered with the aid of a winch and
guided to the site by a shackle around the descent line. The diver stands in the
center of the stage, maintaining balance by holding on to the side bails. Upon
reaching the bottom, the diver exits the stage as directed by the Diving
Supervisor.
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The maximum allowable rate of descent, by any method, shall not exceed 75
feet per minute (fpm), although such factors as the diver’s ability to clear the
ears, currents and visibility and the need to approach an unknown bottom with
caution may render the actual rate of descent considerably less.
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The diver signals arrival on the bottom and quickly checks bottom conditions.
Conditions that are radically different than expected are reported to the Diving
Supervisor. If there is any doubt about the safety of the diver or the diver’s
readiness to operate under the changed conditions, the dive is aborted.
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A diver should thoroughly ventilate when reaching the bottom, at subsequent
intervals as the diver feels necessary and as directed from the surface. On
dives deeper than 100 fsw, the diver may not notice the CO2 warning symptoms
because of nitrogen narcosis. It is imperative that the Diving Supervisor
monitors his or her divers’ ventilation.
