oil-filled system to assure that leakage will be from, not into, the system. 
The seawater system, when developed, will be simpler in that only one line 
will be needed, and the discharged water may be used in jet pumps at the 
work point. What appears to be the simplest system might be one in which 
filtered seawater is pumped under pressure from the power source on the 
ocean surface to the bottom and then is used in a simple open circuit and 
discharged at the work point. This approach appears particularly desirable 
for moderate depths; collapse of the hose would pose no threat, as discussed 
in the previous section. Suitable hoses are available (Knechtel, 1967); these 
are sometimes referred to as flexible pipes and are quite rigid and strong in 
tension. The system needs only the satisfactory development of high-pressure 
pumps and motors capable of working on filtered seawater, a development 
well underway and with a high probability of early success. 
Power Conversion 
Hydraulic systems have seen increasingly wider applications in mobile 
equipment for the operation of auxiliary equipment, due to their flexibility 
and compactness (Bowers, 1967). In the ocean, the advantages of hydraulic 
systems become more pronounced due to their freedom from the hazard of 
electrical shock and from the unwanted effects of buoyancy and compress- 
ibility. However, the problem of contamination due to leakage does exist. 
The contamination may involve the typical working fluid, hydraulic oil, by 
seawater and result in rusting of metal parts (Evans, 1964) and degradation 
of the performance of the hydraulic oil (Anderson and Brown, 1965); or it 
may involve the atmosphere of saturated diving chambers if the hydrocarbons 
contained in hydraulic oil are volatilized when hydraulic tools are brought 
into the chambers for maintenance or storage (SEALAB II! Atmospheric 
Contamination Bill, 1967). 
One promising solution to this problem is the use of seawater as a 
hydraulic fluid. In addition to eliminating the contamination problem, 
several other benefits would accrue. Principal among these would be the 
use of the ocean as a reservoir allowing the use of an open-cycle hydraulic 
circuit. The open-cycle circuit eliminates the need of a reservoir other than 
the ocean for fluid storage and cooling. Also eliminated is the return hose, 
thereby cutting piping friction losses approximately in half. This is especially 
advantageous if a long hose is used as is the case when power is to be trans- 
mitted from a pump on the surface. Schematics of a closed-cycle seawater 
hydraulic circuit and an open-cycle hydraulic circuit are shown in Figures 
11 and 12. 
28 
