SURFACE-SUBSURFACE COMPLEX 



27 



Fig. 20. Aquanaut Carpenter checks the breathing-gas control panel 



In the three forward spaces, the overhead was insulated with one-inch cork, the sidewalls 

 with two-inch cork, and the deck was made of solid concrete, which was part of the fixed bal- 

 last. The overhead of the living spaces was fitted with three ballast tanks, which were used 

 as variable ballast during raising and lowering operations. 



The atmosphere in the living compartment contained approximately 85 percent helium, 

 11 percent nitrogen and 4 percent oxygen, at approximately 103 psia. The gas in the atmo- 

 sphere was replinshed from spare bottles of helium and oxygen outside the hull. Also, replen- 

 ishment gas was available via the umbilical from the surface -support vessel. The umbilical 

 also contained a communication cable, a gas-sampling hose, a compressed-air hose, and an 

 alternate electrical power cable, while primary electrical power and fresh water were supplied 

 via power cable and vinyl pipe from shore. 



THE DECOMPRESSION COMPLEX 



The at-sea decompression of ten divers saturated at a depth of approximately 200 ft pre- 

 sented a new problem for the U.S. Navy (Chapter 17). First, the men would have to be lifted 

 from the ocean floor in a personnel transfer capsule (PTC), maintaining the ocean-floor pres- 

 sure, to the surface-support vessel; second, they must be transferred to a larger, more com- 

 fortable deck decompression chamber (DDC), where they undergo a lengthy decompression. 



The PTC is basically a cylinder 10 ft long and 6 ft in diameter, with a 27-in. entrance hatch 

 on one end. The cylindrical portion sits on a removable stand which provides five feet of clear- 

 ance for gaining entrance through the hatch. Ballast to provide negative buoyancy is incorpo- 

 rated into the base of the stand and in a lower ballast tray clamped to the stand base. The 

 lower tray can be released from the stand to serve as an anchor in the event that aquanauts in 

 the PTC must make a controlled ascent to the surface, using an escapement mechanism in the 

 stand, rather than being lifted aboard the surface-support vessel by crane. 



