to final stress relief of the hull. As explained 

 above, if the exostructure is to be bolted to 

 the hull, which many are (Fig. 5.17), the 

 attachment points should be welded on be- 

 fore final stress relieving in order that no 

 residual stresses remain in the welds or 

 heat-affected zones. If the exostructure is to 

 be strapped to the hull, e.g., SDL-1, then 

 such precautions are unnecessary. 



Design of the exostructure is preceded by a 

 great deal of research into the vehicle's pro- 

 jected components and subsystems; essen- 

 tially, the submersible is virtually "sized" 

 (see Chap. 6) by the time the exostructure is 



designed. Figure 5.18 provides an idea of the 

 complexity involved in packaging the variety 

 of necessary equipment. Some of the consid- 

 erations that must be resolved before final 

 design are as follows: 



1) Location of objects as they affect trim, 

 buoyancy and their own ability to per- 

 form. 



2) Volume of objects: Are they compatible 

 with the dimensional constraints of the 

 vehicle? 



3) Weight of objects both in air and in 

 water. 



Kmsre 



Fig, 5 18 Stern view o( DEEPSTAR 4000 showing "packing" of the exostructure. (NAVOCEANO) 



264 



