3 ocean surface 
reservoir 
pump 
20,000 ft 
ocean floor 
motor 
Figure 7. Two-hose closed hydraulic system. 
Comparison of Mechanical Systems 
Two mechanical approaches to power transmission were considered: 
(1) the use of a taut cable to transmit linear motion to drive a hydraulic 
pump on the ocean bottom (Figure 19) and (2) the use of a taut cable to 
transmit rotary motion to drive a hydraulic pump on the ocean bottom 
(Figure 20). In both systems, the major and only significant power loss 
was presumed to be due to skin-friction drag in the water. Either system 
will require a relatively heavy mass on the bottom. The bottom mass for 
a reciprocating cable system must exceed the maximum cable tension at 
the hydraulic pump on the bottom so that the cable can be held taut. The 
rotating cable must be constantly in tension to avoid coiling. 
11 
