8-28 Change A
U.S. Navy Diving Manual—Volume 2
1.5 knots, the diver wears additional weights or descends on a weighted stage,
so that descent is as nearly vertical as possible.
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.
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.
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.
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 symp-
toms because of nitrogen narcosis. It is imperative that the Diving Supervisor
monitors his or her divers’ ventilation.
8-11
UNDERWATER PROCEDURES
8-11.1
Adapting to Underwater Conditions. Through careful and thorough planning, the
divers can be properly prepared for the underwater conditions at the diving site.
The diver will employ the following techniques to adapt to underwater conditions:
Upon reaching the bottom and before leaving the area of the stage or descent
line, the diver adjusts buoyancy and makes certain that the air supply is
adequate.
The diver becomes oriented to the bottom and the work site using such clues
as the lead of the umbilical, natural features on the bottom, the direction of
current. However, bottom current may differ from the surface current. The
direction of current flow may change significantly during the period of the
dive. If the diver has any trouble in orientation, the tender can guide the diver
by using the line-pull searching signals.
The diver is now ready to move to the work site and begin the assignment.
8-11.2
Movement on the Bottom. Divers should follow these guidelines for movement
on the bottom areas:
