acrylic plastic other shallow diving vehicles 

 continued to use either flat or conically- 

 shaped viewports. Shaping the viewports 

 into a wraparound geometry naturally costs 

 more than merely cutting it out of a flat 

 sheet; this also may have accounted for a 

 reluctance to follow Martine's lead. 

 With the launching of NEMO in 1970 the 



best and most comfortable view was finally 

 provided. The spherical plastic-hulled vehicle 

 (Fig. 9.30c) allowed both occupants a view in 

 virtually any direction while seated comfort- 

 ably in padded chairs. At this point in time 

 acrylic plastic had undergone extensive de- 

 velopment and testing, and its dependability 

 and safety as a hull material was amply 



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457 



