314 ENGINEERING EVALUATION 



3. Atmosphere gas supply 



4. Atmosphere gas sampling 



5. Compressed air for pneumatic tools (external use only). 



The umbilical cord was permanently attached to Sealab II near the top of the "conning 

 tower." The power and communication cables penetrated the hull through pressure -proof 

 stuffing tubes. The hose components of the umbilical cord were connected to piping installed 

 on the exterior of the hull with two-way shut-off, quick-disconnect type connectors. The piping 

 for the atmospheric gas supply and atmospheric gas -sampling systems penetrated the hull 

 through welded hull fittings. The compressed air piping terminated in four valved hose con- 

 nections located on exterior corners of the hull. These connections provided for the operation 

 of pneumatic tools in the sea. 



The alternate power cable was of Navy type THOF-42 (three conductor 42MCM). The 

 communication cable was a neoprene -jacketed 33 -conductor TV cable, Boston Insulated Wire 

 Company No. TV-33N. The short lead time allowed did not permit the design of a special 

 communications cable. 



During checkout at Long Beach, California, it was found that the hose components had been 

 kinked, causing the hose liners to separate from their jackets when subjected to test pressure. 

 The rubber fabric hose originally in the umbilical cord was replaced by high-pressure hose 

 with a seamless nylon core, a flexible braided nylon reinforcement, and a polyurethane jacket. 

 The gas supply and compressed-air hoses were 3/4 in. I.D. and the gas-sampling hose 1/4 in. 

 I.D. 



In the course of replacement of the hose components, two additional power cables for un- 

 derwater photographic lights and a cable for remote camera control were added to the umbili- 

 cal cord. In lieu of the original canvas jacket on the umbilical cord, the components on the 

 modified cord were married together at 8-ft intervals. The umbilical cord was stowed on the 

 platform on top of Sealab II when it was towed or transported on a barge. A circular protective 

 enclosure on top of the "conning tower" was provided for stowing the umbilical cord; however, 

 it was not adequate for stowing the enlarged cord. 



The upper end of the umbilical cord terminated at a central point on the stern of the sup- 

 port vessel and connected to the various supplies of gas, air, and power, and to the communi- 

 cation circuits. 



SYSTEMS 



Ballast System 



The ballast system was designed with sufficient compartmented liquid ballast to permit 

 adjustment of weight and of center of gravity for several conditions. First, sufficient positive 

 buoyancy and stability were required for towing Sealab II to its site. Second, positive buoy- 

 ancy, stability, and freeboard were required when the vessel was moored on the surface at the 

 site with the upper hatch open. During lowering of the vessel, a negative buoyancy was re- 

 quired, but such as not to cause undue strain on the lowering gear. In place on the bottom, the 

 vessel requires sufficient negative buoyancy to overcome that added by blowing water from the 

 entry skirt, and enough negative buoyancy with its center of gravity well between the legs to be 

 stable on the bottom in the prevailing current. The above conditions were to be satisfied with 

 inside ballast tanks, with soft boundaries between the tank space and the pressurized habitation 

 space, together with limited external ballast. This habitation space was to be pressurized be- 

 fore lowering, so provision had to be made to prevent damage to the tank boundaries. These 

 conditions were satisfied with an internal ballast tank in the upper portion of the main cylinder, 

 extending its entire length and subdivided into three compartments, and a conning tower of 

 sufficient size to double as tank and provide on-surface entry. 



