of manned submersibles, it was, according to 

 the author, the first such application in a 

 habitat and supplied 5 kilowatts at 28 VDC 

 for a period of 48 hours and with no malfunc- 

 tions. This report's final statement rather 

 succinctly states the major problem with fuel 

 cells: "A reduction in cost is required before 

 extensive use becomes a reality." 



The latest attempt at utilizing fuel cells in 

 submersibles was conducted off Marseilles in 

 May 1970 with a hydrazine-hydrogen perox- 

 ide generator in the SP-350 (23). Several 

 tests of this fuel cell were conducted in 265 

 feet of water during a series of dives of not 

 more than 15 minutes in length. The investi- 

 gators concluded that the tests were success- 

 ful and indicated that the fuel cell is not only 

 a theoretical possibility, but a practicality in 

 submersible operations. 



For those interested in the potential and 

 technological state-of-the-art of fuel cells for 

 deep submergence application references (5), 

 (24), (25), (26), and (27) are recommended. The 

 last two of these include a discussion of 

 nuclear and other power sources, as well as 

 fuel cells. 



NUCLEAR POWER 



The U.S Navy's NR-1 is the only submers- 

 ible known to use a nuclear reactor as an 

 electric power source. Since NR-l^s details 

 are classified, one can only speculate about 

 it. On the other hand, while nuclear power 

 has revolutionized the military submarine, 

 its past, present and proximate influence on 

 submersible design is likely to be minimal. 

 The reason is quite simple; iVi?-l costs in the 

 neighborhood of $100 million; even the most 

 optimistic advocates of deep submergence 

 would find it difficult to justify such an ex- 

 penditure for a commercial venture. Again 

 the reader is referred to references (5), (26), 

 and (27) for an account of nuclear power 

 potential and application to other areas of 

 marine technology. 



CABLE-TO-SURFACE 

 (UMBILICAL) 



Three submersibles obtain electrical power 

 through a cable from the surface: KURO- 



SHIO II, GVPPY and OPSUB. The pros and 

 cons of this approach are many and will not 

 be explored in detail here. It is sufficient to 

 note that in the case oi GUPPY , the reason- 

 ing which led to an umbilical included: 

 Launch/retrieval would require no divers 

 and the projected customer (offshore oil) 

 would require more in the way of electrical 

 power than batteries or fuel cells could sup- 

 ply within the dimensional constraints of the 

 preconceived vehicle (28). An additional con- 

 sideration was based on KUROSHIO's and 

 the unmanned CURVs history of successful 

 tethered operations — i.e., they provided 

 proven techniques. 



A few submersibles, SEA RANGER in par- 

 ticular, include an umbilical option by pro- 

 viding an external electrical attachment. 

 The option has a great deal of merit if tasks 

 are required where long-term, stationary ob- 

 servations are planned, such as may happen 

 in some biological or sedimentological stud- 

 ies. The design, construction and operation 

 of a tethered power supply is discussed fully 

 in the literature. For a thorough and excel- 

 lent summary of the subject, the work of Evo 

 Giorgi (27) is recommended. 



The umbilical system is basically quite 

 simple (Fig. 7.14) and consists of a generator, 

 winch and a load-bearing, conducting cable. 

 In the GVPPY operation, the surface genera- 

 tor sends 35 kW at 440 VAC down the insu- 

 lated and strengthened cable to the vehicle. 

 Since power coming to the submersible is 

 already AC, no on-board converters are 

 needed, with consequent weight and volume 

 savings. Buoys are attached at intervals 

 along the cable to keep it from fouling the 

 vehicle and adding to the propulsion load. 

 The cable also serves as a hard line underwa- 

 ter telephone. 



The KUROSHIO II system— essentially 

 similar to that of Ct/PPy— sends 400 VAC to 

 the submersible where a transformer within 

 the pressure hull supplies 100 V to the vehi- 

 cle's instruments. Specifications for KURO- 

 SHIO II's generator and cable are presented 

 in Tables 7.6 and 7.7, respectively. The cable 

 winch is driven by a 10-hp, AC motor and 

 consists of a controller, reduction gear, reel 

 and winding drum mounted on a common 

 platform (29). 



334 



