SELECT EQUIPMENT AND SUPPLIES

CHAPTER 6 — Operational Planning Change A 6-27 6-7.2.2 Buoyancy. Scuba equipment is designed to have nearly neutral buoyancy when in use, permitting the diver to change or maintain depth with ease. This allows the scuba diver to work at any level in the water column. 6-7.2.3 Portability. The portability and ease with which scuba can be employed are distinct advantages. Scuba equipment can be transported easily and put into opera- tion with minimum delay. Scuba offers a flexible and economical method for accomplishing a range of tasks. 6-7.2.4 Operational Limitations. Divers shall adhere to the operational limitations contained in Figure 6-14. Bottom time is limited by the scuba’s fixed air supply, which is depleted more rapidly when diving deep or working hard. 6-7.2.5 Environmental Protection. The scuba diver is not as well protected from cold or from contact with marine plants and animals as a diver in surface-supplied gear, and is more easily swept along by current. 6-7.3 Operational Characteristics of SSDS. Surface-supplied diving systems can be divided into two major categories: lightweight full face mask (MK 20), and deep- sea (MK 21) gear. 6-7.3.1 Mobility. Surface-supplied gear allows the diver almost as much mobility as scuba. The primary use for deep-sea gear is bottom work in depths up to 190 fsw. 6-7.3.2 Buoyancy. The buoyancy associated with SSDS varies with the diving dress selected. Variable Volume Dry Suit (VVDS) provides the greatest buoyancy control (see paragraph 7-3.1.2), making it a desirable technique for working on muddy bottoms, conducting jetting or tunneling, or working where the reaction forces of tools are high. 6-7.3.3 Operational Limitations. Divers using surface supplied gear are restricted to the operational limitations described in Figure 6-14. Additional limitations of using surface-supplied gear includes additional topside support personnel and lengthy predive and postdive procedures. 6-7.3.4 Environmental Protection. Surface-supplied diving systems can offer the diver increased thermal protection when used with a Hot Water or VVDS. The MK 21 helmet can increase protection of the diver’s head. Because the diver’s negative buoyancy is easily controlled, an SSDS allows diving in areas with strong currents. 6-8 SELECT EQUIPMENT AND SUPPLIES 6-8.1 Equipment Authorized for Navy Use. Equipment procured for use in the U.S. Navy has been tested under laboratory and field conditions to ensure that it will perform according to design specifications. A vast array of equipment and tools is available for use in diving operations. The NAVSEA/00C Diving Equipment Authorized for U.S. Navy Use (ANU) list identifies much of this equipment and categorizes diving equipment authorized for U.S. Navy use.