SELECT DIVING TECHNIQUE

6-24 Change A U.S. Navy Diving Manual—Volume 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. NOTE When small civilian boats are in the area, use the civilian Sport Diver flag (red with white diagonal stripe) as well as “Code Alpha.” 6-6.15 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. 6-7 SELECT DIVING TECHNIQUE The four main types of air diving equipment used in U.S. Navy diving operations are (Figure 6-13): 1. Open-circuit scuba 2. MK 20 MOD 0 surface-supplied gear 3. MK 21 MOD 1 surface-supplied gear 4. EXO BR MS Full Face Mask surface-supplied or open-circuit scuba 6-7.1 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 Environmental conditions Time constraints 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-