Chapter 17 

 THE DECOMPRESSION COMPLEX 



D. C. Pauli and G. P. Clapper 



Office of Naval Research 



Washington, D.C. 



and 



W. P. Frost 



U.S. Navy Mine Defense Laboratory 



Panama City, Florida 



INTRODUCTION 



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

 sented new problems for the U.S. Navy. First, the men would have to be lifted from the ocean 

 floor in a personnel transfer capsule (PTC), maintaining the ocean-floor pressure, to the 

 surface -support vessel; second, they must be transferred to a larger, more comfortable deck 

 decompression chamber (DDC); and then they finally must undergo the lengthy decompression — 

 approximately 30 hours — at the prescribed 6 ft per hour linear decompression schedule. 



Alternate modes of decompression were possible, but in view of accompanying problems 

 and the general need of the Navy to have experience in use of mating PTC/DDC decompression 

 complex systems, these alternate solutions were not considered. Alternate solutions available 

 were: 



1. Use of the habitat as the decompression complex — This solution would require lifting 

 the habitat for each crew change or decompression of crews at depth, with later free ascent, 

 which would considerably complicate the design of the habitat. 



2. Use of the PTC as not only a transfer capsule, but also as the main decompression 

 chamber — This was done on Sealab I, where a smaller crew (four men) was involved. Reason- 

 ably comfortable space for ten men for the duration of the decompression would require a 

 much larger PTC and associated difficult at-sea handling problems. Further, the PTC, if thus 

 occupied, could not serve as a refuge or for lift of the following team should an emergency 

 arise. 



The concept of shuttling aquanauts from surface to the habitat, where they become satu- 

 rated, and then back to the surface for decompression placed certain back-up safety require- 

 ments on the system. The possibility of contamination of the atmosphere within the habitat 

 required that a refuge be available to the aquanauts that had the necessary self-contained life- 

 support systems. The possibility of the surface-support vessel losing one or more legs of its 

 moor implied that the support-vessel winches might not be readily available in an emergency 

 to lift the PTC to the surface; thus, the PTC should be equipped with a self-contained raising 

 subsystem. 



PTC -DDC SYSTEM 



PTC Functional Requirements 



The following are the functional and design requirements to which the PTC was designed. 

 The PTC was to be: 



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