CHAPTER 8 — Surface-Supplied Air Diving Operations
Change A 8-35
a direct reading, without the need to add air. If the diver descends, the hose
must be cleared and a new reading made.
Tender Actions. Feel the pull of the umbilical.
Additional Personnel Actions. Monitor the gauges on the supply systems for
any powered equipment. For example, the ammeter on an electric welding unit
indicates a power drain when the arc is in use; the gas pressure gauges for a
gas torch registers the flow of fuel. Additionally, the pop made by a gas torch
being lighted will probably be audible over the intercom and bubbles from the
torch will break on the surface, giving off small quantities of smoke.
8-12
ASCENT PROCEDURES
Follow these ascent procedures when it is time for the divers to return to the
surface:
1.
To prepare for a normal ascent, the diver clears the job site of tools and
equipment. These can be returned to the surface by special messenger lines
sent down the descent line. If the diver cannot find the descent line and needs a
special line, this can be bent onto his umbilical and pulled down by the diver.
The diver must be careful not to foul the line as it is laid down. The tender then
pulls up the slack. This technique is useful in shallow water, but not practical
in deep dives.
2.
If possible, the diving stage is positioned on the bottom. If some malfunction
such as fouling of the descent line prevents lowering the stage to the bottom,
the stage should be positioned below the first decompression stop if possible.
Readings from the pneumofathometer are the primary depth measurements.
3.
If ascent is being made using the descent line or the stage has been positioned
below the first decompression stop, the tender signals the diver “Standby to
come up” when all tools and extra lines have been cleared away. The diver
acknowledges the signal. The diver, however, does not pull up. The tender lifts
the diver off the bottom when the diver signals “Ready to come up,” and the
tender signals “Coming up. Report when you leave the bottom.” The diver so
reports.
4.
If, during the ascent, while using a descent line, the diver becomes too buoyant
and rises too quickly, the diver checks the ascent by clamping his legs on the
descent line.
5.
The rate of ascent is a critical factor in decompressing the diver. Ascent must
be carefully controlled at 30 feet per minute by the tender. The ascent is
monitored with the pneumofathometer. As the diver reaches the stage and
climbs aboard, topside is notified of arrival. The stage is then brought up to the
first decompression stop. Refer to Chapter 9 for decompression procedures,
including an explanation of the tables.
