Fig 9 28 Mockup for second JOHNSON SEA LINK acrylic sphere. 



ample — during operations and the suitability 

 of this arrangement in terms of sustained 

 comfort. 



The only reported attempt at producing 

 order out of this chaos is related by Blair in a 

 paper describing some of the "manned" con- 

 siderations that went into the design of the 

 DSRV and the Deep Submergence Search 

 Vehicles (DSSV). 



Blair discusses DSRV^s human considera- 

 tions in terms of problems peculiar to the 

 rescue vehicle's mission of the loading, seat- 

 ing, restraining and disembarking of able 

 and disabled rescuees. His discussion of the 

 DSSV's considerations, however, has applica- 

 tion to all submersibles engaging in search, 

 survey or inspection missions. 



In order to assess the search efficiency of a 

 four-man crew in a 9-foot 5-inch-diameter 

 sphere, a DSSV mockup was constructed and 



manned for a typical 34-hour mission. Ar- 

 rangements were made to simulate varia- 

 tions in pitch, speed and altitude while a 

 video, TV image of the ocean floor, on which 

 two small targets (mines and telebuoys) were 

 superimposed, was continuously presented 

 at a central viewport. 



The results of this simulation are quite 

 interesting. To obtain a goal of 80 percent 

 detection accuracy, a 1-hour watch at the 

 viewport was found to be too long and 2 

 consecutive hours of sleep between watches 

 were too short. A minimum volume of 400 

 cubic feet for four crewmen was adequate, 

 and this allowed for inclusion of a fifth crew- 

 man who was found to be necessary in order 

 to realize the desired detection accuracy. 



Historical data presented by Blair is also 

 germane. Based on performance studies of 

 radar and asdic (sonar) operators in the late 

 1940's, a V2-hour watch increment was thor- 

 oughly documented (19) and showed that the 

 percentage of targets missed increased by 

 some 15 percent at the end of a '/2-hour 

 watch while the total missed targets in- 

 creased by 20 percent at the end of 2 hours. 



The implications of Blair's results are 

 quite compelling: Under the best designed 

 viewing position the observers still missed a 

 significant portion of targets during a 1-hour 

 watch. One can only speculate, but in the 

 viewing position shown in Figure 9.26, it 

 would seem that an incredibly high percent- 

 age of targets would be missed on a 6- to 8- 

 hour dive in this position. In view of the fact 

 that many current vehicles are performing 

 pipeline and cable inspections, which require 

 several hours at the viewport, such degrada- 

 tion in the observer's performance must be 

 taken into account. 



At this point it seems appropriate to dis- 

 cuss viewport location as it pertains to habit- 

 ability, not only because the greatest degree 

 of discomfort is found in submersibles' view- 

 ing arrangements, but also because direct 

 viewing of the environment is the raison 

 d 'etre of manned submersibles. For this 

 reason it is difficult to separate habitability 

 from efficiency and impossible to speak of 

 either without discussing viewport location. 



452 



