6-24 Change A
U.S. Navy Diving ManualVolume 2
and take the precautions required to ensure that these vessels remain clear of the
diving area. Hazards associated with vessel traffic are intensified under conditions
of reduced visibility.
When small civilian boats are in the area, use the civilian Sport Diver flag
(red with white diagonal stripe) as well as Code Alpha.
Territorial Waters. Diving operations conducted in the territorial waters of other
nations shall be properly coordinated prior to diving. Diving units must be alert to
the presence of foreign intelligence-collection ships and the potential for hostile
action when diving in disputed territorial waters or combat zones.
SELECT DIVING TECHNIQUE
The four main types of air diving equipment used in U.S. Navy diving operations
are (Figure 6-13):
MK 20 MOD 0 surface-supplied gear
MK 21 MOD 1 surface-supplied gear
EXO BR MS Full Face Mask surface-supplied or open-circuit scuba
Factors to Consider when Selecting the Diving Technique. When selecting the
technique to be used for a dive, the following factors must be considered:
Duration and depth of the dive
Type of work to be performed
A dive of extended length, even in shallow water, may require an air supply
exceeding that which could be provided by scuba. Specific depth limits have been
established for each type of diving gear and shall not be exceeded without specific
approval of the Chief of Naval Operations in accordance with the OPNAVINST
3150.27 series (see Figure 6-14).
The increase of air consumption with depth limits open-circuit scuba to 130 fsw
for reasonable working dives. The hazards of nitrogen narcosis and decompression
further limit open-circuit scuba to 190 fsw even for short duration dives. Surface-
supplied equipment is generally preferred between 130 and 190 fsw, although
open-circuit scuba may be used under some circumstances. Decompression scuba
dives and scuba dives deeper than 130 fsw may be conducted when dictated by
operational necessity and with the specific approval of the Commanding Officer.
All open-circuit scuba dives beyond 100 fsw shall employ twin cylinders, with
each having a capacity at least equal to a steel 72 cylinder (64.7 cubic feet).
In some operations there may be no clear-cut choice of which diving technique to
use. Selecting a diving technique may depend upon availability of equipment or
trained personnel. The following comparison of scuba and surface-supplied tech-