CHAPTER 8 Surface-Supplied Air Diving Operations
Change A 8-27
WATER ENTRY AND DESCENT
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 deter-
mined 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
Predescent Surface Check. In the water and prior to descending to operating
depth, the diver makes a final equipment check.
The diver immediately checks for leaks in the suit or air connections.
If two divers are being employed, both divers perform as many checks as pos-
sible on their own rigs and then check their dive partners rig. The tender or
another diver can be of assistance by looking for any telltale bubbles.
A communications check is made and malfunctions or deficiencies not previ-
ously 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. 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 allow-
ance 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:
With a descent line, the diver locks the legs around the line and holds on to the
line with one hand.
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