Under conditions where the piping will 

 serve vibrating or rotating devices, such as 

 manipulators, flexible hosing is sometimes 

 used to transport the hydraulic fluid. Several 

 varieties of wire-braided plastic hosing are 

 available to serve this function. 



EXTERNAL STRUCTURES 



External to the pressure hull are two ma- 

 jor structural components: 1) An exostruc- 

 ture consisting of a supporting framework to 

 carry the pressure hull and operational de- 

 vices; and 2) a fairing enclosing the exostruc- 

 ture and, in some cases, streamlining the hull to 

 reduce both hydrodynamic drag and the po- 

 tential for fouling with underwater objects. 



EXOSTRUCTURE 



Penzias and Goodman (28) aptly describe a 



submersible's exostructure as ". . . the 

 framework on which everything else hangs; 

 the pressure hull being merely one of the 

 'cargo units' suspended within or beneath 

 it." The exostructure of DEEPSTAR 4000 in 

 Figure 5.17 demonstrates their analogy. 



In several of the large, cylindrical vehicles, 

 e.g., ALUMINAVT, BEN FRANKLIN, AU- 

 GUSTE PICCARD, much of the equipment 

 that would be external to a smaller spherical 

 pressure-hulled vehicle is carried inside be- 

 cause of the availability of greater interior 

 volume. Consequently the need for an exo- 

 structure is limited to propulsion mountings, 

 rudders, diving planes and control sensors 

 such as sonar and echo sounders. The major- 

 ity of spherically hulled submersibles, how- 

 ever, require an exostructure. 



Having decided on the shape, penetrations 

 and materials for the pressure hull, design of 

 the exostructure should be completed prior 



Fig 5 17 The exostructure of DEEPSTAR 4000. (Westinghouse Corp.) 



263 



