10 20 30 40 50 60 70 80 



PERCENT OF OCEAN LESS THAN INDICATED DEPTH 



90 



100 



Fig. 5.2 Percent of ocean bottom at various depth levels. 



riving at an operating depth is not quite as 

 easy as it may appear, especially if the vehi- 

 cle is intended to be leased or used by a 

 variety of customers. While this problem has 

 somew^hat diminished owing to a lack of in- 

 terest (funds) on the part of potential deep- 

 diving customers, it still persists owing to 

 varying depths of interest among scientific 

 and commercial users, the relatively un- 

 known location and quantity of potential ma- 

 rine resources and the increasing vehicle 

 cost with increasing depth capability. 



The owner must weigh all of the above 

 factors to arrive at a useful, economic depth 

 of operation. Unfortunately, the ocean bot- 

 tom does not provide much assistance. Fig- 

 ure 5.2 presents the percent of the ocean 

 bottom vs. depth, as well as the number of 



submersibles within various depth ranges. 

 Approximately 8 percent of the ocean bottom 

 is located at continental shelf depths (0-600 

 feet). From this depth downward the per- 

 centage of bottom attainable increases 

 slowly at the cost of greatly increased depth 

 capability. For example, the 1,200-ft STAR II 

 can reach 10 percent of the ocean bottom, 

 while the far more complex and expensive 

 8,000-ft DEEP QUEST does not quite double 

 this percentage. Unquestionably, the least 

 gain in percentage of accessible bottom is 

 from 20,000 feet to 36,000 feet, where the 

 percentage of increase is from 98 to 100, 

 respectively. The depth decision was particu- 

 larly difficult in the early sixties when the 

 incipient field offered few clues to depth of 

 interests; from the late sixties on a trend 



246 



