Operational Characteristics of Scuba.

CHAPTER 6 — Operational Planning Change A 6-25 niques highlights the significant differences between the methods and outlines the effect these differences will have on planning. 6-7.2 Operational Characteristics of Scuba. The term scuba refers to open-circuit air scuba unless otherwise noted. The main advantages of scuba are mobility, depth flexibility and control, portability, and reduced requirement for surface support. The main disadvantages are limited depth, limited duration, lack of voice commu- nications (unless equipped with a through-water communications system), limited environmental protection, remoteness from surface assistance, and the negative psychological and physiological problems associated with isolation and direct exposure to the underwater environment. 6-7.2.1 Mobility. The scuba diver is not hindered by bulky or heavy equipment and can cover a considerable distance, with an even greater range through the use of diver propulsion vehicles (DPVs), moving freely in any direction. However, the scuba diver shall be able to ascend directly to the surface in case of emergency. WARNING Scuba equipment is not authorized for use in enclosed space diving. Figure 6-13. Air Diving Techniques. A choice of three air diving techniques are available: open circuit scuba, surface-supplied gear (MK 20 MOD 0), surface-supplied deep-sea gear (MK 21 MOD 1), and surface-supplied deep sea gear (EXO BR MS). OPEN-CIRCUIT SCUBA Normal working limit: 130 fsw Operational necessity: 190 fsw SURFACE-SUPPLIED DEEP-SEA GEAR (MK 21 MOD 1) Normal working limit with EGS: 190 fsw SURFACE-SUPPLIED GEAR (MK 20 MOD 0) Normal working limit with EGS: 60 fsw SURFACE-SUPPLIED GEAR (EXO BR MS) Normal working limit: 190 fsw