28 



SURFACE -SUBSURFACE COMPLEX 



Fig. 21. Aquanaut Sonne nburg replaces lithiura 

 hydroxide canisters in the Sealab II air condi- 

 tioning system. The canisters remove carbon 

 dioxide from the atmosphere. 



An emergency, 24-hour life-support system, providing breathing gas and CO2 removal was 

 self-contained. However, normal operation included an umbilical from the surface- support 

 vessel which provided breathing gas, a communication link, and power for CO2 removal. 



The DDC is another cylindrical structure 23 ft long and 10 ft in diameter. It contains 

 berthing for ten men, an entrance lock, a medical lock, a CO 2 scrubber, a mating hatch for the 

 PTC, and an exhaust manifold with constant-flow regulators. 



In normal operations, with the PTC on the ocean floor, the saturated divers enter and 

 close the hatch, sealing themselves at bottom pressure. The PTC is then hoisted aboard the 

 support vessel, where the capsule is removed from the stand and base and placed on the mat- 

 ing hatch of the DDC. After the mated hatches are sealed, the pressures in the PTC and DDC 

 are equalized and the divers enter the DDC from the PTC. The DDC and PTC hatches are then 

 closed and the divers start decompression as the PTC is returned to the ocean floor to serve 

 as the emergency capsule for the next team. 



SURFACE -SUPPORT VESSEL 



The support vessel (Chapter 18) as configured for the project is made from two 110 x 34 ft 

 YC barges spaced 22 ft apart and connected at one end by a covered structure. This structure 



