MARK VI MIXED-GAS BREATHING APPARATUS 419 



SUPPORT VESSEL DIVING LOCKER 



The Mk-VI and open-circuit diving locker were combined in the former Support vessel 

 electrical shop on the main deck, amidships, aft. The working area was 200 ft, which included 

 three work benches, a deep sink, a rack for the two PPI pumps, and sufficient stowage space 

 under the work benches for Mk-VI gear. Baralyme was stowed in a separate compartment. 

 Utilities to the locker included hot and cold fresh water, 440-volt ac, 220-volt ac, and 110-volt 

 ac. General lighting was excellent with the installation of work-bench lights. 



Ventilation was supplied with two standard vent-type blowers and ducts. Ventilation was 

 considered adequate for the La Jolla area, but not for tropical areas. 



Accessibility to the locker was adequate, and in general it was utilized 12 hours daily by 

 two to four men with no major problems. 



Breathing-gas supply to the diving locker is discussed in Chapter 18. 



During the stay of Teams 1 and 2 in Sealab, all Mk-VI cylinders were recharged in the top- 

 side diving locker. The minimum of 1500 psig which was set for excursion diving from Sealab 

 resulted in many partially filled cylinders being sent to the surface for charging. Handling dur- 

 ing the cylinder transfer was unavoidably rough, resulting in many repairs. All diving-gear re- 

 pairs made in the topside diving locker are listed in Table 48. 



Team 3 employed a charging line from topside to the inside of Sealab, allowing the empty 

 cylinders to be charged on the bottom. This method not only saved transfer time, but reduced 

 repairs by 90 percent. 



Rigid sterilizing procedures according to Navships 250-538 were scheduled by the master 

 diver and maintained by the personnel in the diving locker. There were no infections or virus 

 from the diving equipment, even though all diving gear was interchanged between the individual 

 team members several times daily. 



Drying of diving gear was accomplished in plywood drying boxes which contained a blower 

 and 3000-watt heat lamp. Six vests could be dried completely in 24 hours. 



OPERATIONAL DIVING 



Diving equipment for the Sealab divers was the same for each team. Three types of diving 

 apparatus were used: 



1. Mk-VT scuba. This was the standard semi-closed-circuit Mk-VI with a "K" valve in- 

 stalled in the safety plug access via a double "O" ring brass block. It was used for approxi- 

 mately 210 hours of diving during the 45 days. 



2. Arawak hookah Rig. This system utilized the Sealab atmosphere through a pressure 

 and vacuum pump arrangement. It was used approximately 84 hours. 



3. Open-circuit scuba. Standard scuba using an Aqua Master DA Regulator. It was used 

 approximately 21 hours. 



In general, for deep-excursion diving to 300 ft, the Mk-VI was considered outstanding. All 

 men agreed that the Mk-VI was superior to the open-circuit scuba. In general the men liked the 

 Arawak, but preferred free diving with the Mk-VI. 



With the Mk-VI, using 85% He, 15% O2, gas-supply duration was, in many cases, lower 

 than the expected 70 minutes at 205 ft. Table 49 gives the gas-supply durations for several, 

 but not all, of the dives made by Team 3. 



