chapter 10 

 UMBILICAL CORD FOR THE SEALAB II HABITAT 



W. B. Culpepper and R. B. Porter 



U. S. Navy Mine Defense Laboratory 



Panama City, Florida 



INTRODUCTION 



The purpose of the umbilical cord is to provide utilities to the Sealab II habitat from the 

 support vessel. The power and communication cables were permanently attached to the Sealab 

 and penetrated the hull through pressure-proof stuffing tubes. The hose components were con- 

 nected to piping installed on the exterior of the hull with two-way shut-off quick-disconnect type 

 connectors. The short lead time available precluded the design and testing of suitable under- 

 water connectors for the power and communication cables which would have permitted the um- 

 bilical cord to be completely disconnected from the Sealab. Also, time did not permit the de- 

 sign of a special communication cable with the proper number and type of conductors required. 

 In this case, the best commerical item available was specified. The umbilical-cord require- 

 ments specified are outlined in the following paragraphs. 



REQUIREMENTS FOR THE UMBILICAL CORD 



General 



The umbilical cord from the support vessel to the Sealab will contain hoses for compressed 

 air, gas supply, and gas sampling, and cables for power and communications. The compressed- 

 air hose will provide 400 psig air for pneumatic tools. The gas-supply hose will supply, at 400 

 psig, the initial helium charge, make-up helium, and breathing air. The gas-sampling hose will 

 be used to obtain Sealab atmosphere samples and to supply emergency oxygen. The power cable 

 will supply 450-volt, 3-phase power from the support vessel. The communication cable will pro- 

 vide communication, closed-circuit television, and environment data circuits from Sealab to the 

 communication command center on the support vessel. The power and communication cables 

 will be permanently connected to the Sealab. Each hose component will have a quick-disconnect 

 type connection on each end. All hose connections on the Sealab end will be made in a central 

 location near the top entrance trunk. The connections at the support-vessel end will also be 

 made at at central location on the vessel. 



Design 



The umbilical cord shall have a nominal length of 350 ft. All components shall be compactly 

 arranged (Fig. 32) to form a compact, easily handled bundle. The bundle shall be covered over- 

 all with a woven cotton or nylon braid, a hand-sewed canvas jacket, or bound at sufficient in- 

 tervals to insure that a compact bundle is maintained. The method of binding shall be such that 

 the individual components are not damaged and a relatively smooth surface is maintained. A 

 Kellems stainless steel single-weave grip, or equal, shall be installed on each end to prevent 

 strain on the connections. A double wrap of cotton canvas shall be placed under each grip to 

 prevent damage to the components. The eye of the grip on the Sealab end of the umbilical cord 

 shall be eight feet from the end. A six foot, 7/16-in stainless steel wire rope pendant shall be 

 provided to connect the grip to the Sealab. A suitable staple or pad eye shall be installed on the 

 top entrance trunk near the umbilical connections. The cable grip on the upper end shall be a 

 Kellems stainless steel Rod Closing Grip, or equal, and shall be placed on the cord near the end 

 for shipping purposes only. Naval Ordnance Test Station (NOTS), Pasadena, will position the 

 grip at the time of lowering. Floats will be attached to cable by NOTS, Pasadena, to obtain a 

 slight positive buoyancy. 



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