chapter 11 

 THE DESIGN, CONSTRUCTION, AND OUTFITTING OF SEALAB II 



Malcolm MacKinnon III 



San Francisco Bay Naval Shipyard 



San Francisco, California 



DESIGN PHILOSOPHY 



In the middle of January 1965, Hunters Point Division of the San Francisco Bay Naval 

 Shipyard was approached with an interesting proposal. Could it undertake the design, construc- 

 tion, and outfitting of an underwater habitat to be called Sealab E? Acceptance was given even 

 though it was apparent that this was a marked departure from normal. The normal tasks of a 

 shipyard are the construction, conversion, and repair of Naval Ships. There would be none of 

 the clean-cut, detailed specifications and contract plans a shipyard normally receives when 

 embarking on the construction of a prototype design. 



This project was in the realm of applied research and involved a large number of activities 

 and people. Extensive studies in many areas for equipment selection and arrangement were 

 precluded by time and economic reasons, and empirical results of precious tests were relied 

 on and used. Naturally, the most significant of these prior tests was Sealab I. 



With the initial proposal came several parameters. Sealab II was to be a habitat capable 

 of housing 10 men at a depth of 250 ft for a period of 30 days. Thus, complement, working 

 depth, and duration were established directly from the basic goals of the project. 



In addition, much experience in the hitherto nonexistent field of underwater habitat design 

 and construction was obtained by the Navy's Mine Defense Laboratory through its efforts in 

 support of Sealab I. The assistance and guidance provided by MDL in early design phases were 

 invaluable. Many equipment and installation specifications came directly from MDL. 



A great deal of the equipment utilized in Sealab I was "off-the-shelf" and of the mail-order- 

 house variety. The fact that it functioned well in Sealab I, and a tight budget and schedule for 

 Sealab n, influenced selection in many instances. 



The effect of feedback from Sealab I on basic design was considerable, and the following 

 major design parameters were obtained, most resi^lting from operational difficulties experi- 

 enced in Sealab I. 



1. Sealab II was to be a pressure vessel capable of being pressurized prior to submergence 

 to bottom pressure. 



Reason : Sealab I was a nonpressure vessel and was flooded more than once while being 

 lowered while keeping internal gas pressure higher than hydrostatic. 



2. Submergence and bottom emplacement were to be done with Sealab n in an unoccupied 

 condition. 



Reason : There would be less danger of personnel casualty if anything went wrong during 

 pressurization and lowering. The importance of personnel safety was held paramount. 



3. The pressure vessel was to be cylindrical, approximately 50 ft long and 12 ft in diameter. 



Reason : The size of Sealab I and the already fixed complement of Sealab n indicated that 

 this should be close to an optimum size and shape. 



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