Entirely new hydraulic equipment designs are 
needed for deep submergence. Pumps, motors, 
actuators, and such power conversion equipment 
as fluid speed reduction gears that use corrosive, 
nonlubricating seawater as the working fluid 
would be a real breakthrough. Entirely new 
concepts for pump and motor construction and 
new working fluids may prove a very fruitful 
alternative. 
2. Electrical Distribution 
a. Current Situation Electrical power must be 
distributed within and outside the pressure hull of 
undersea systems. Signals to control external 
machinery must be transmitted through the pres- 
sure hull, and outside information must enter for 
processing, interpretation, and storage. On a rela- 
tively simple vehicle, a thousand or more wires 
may pass through the hull. The Deep Submergence 
Rescue Vehicle will require more than 1,400 such 
penetrations. A large bottom habitat may require 
thousands of such penetrations. 
Electrical distribution systems within the pres- 
sure hull are similar to those for atmospheric 
applications, but external distribution systems 
encounter entirely different problems. Each wire 
and component is subjected to both pressure and 
adverse chemical effects. Deficiencies in the state- 
of-the-art exist in insulation, circuit interruption 
techniques, and automatic system monitoring 
equipment. 
Electrical hull penetrators contain contacts 
which complete circuits through the hull. Their 
selection is important, as number and size deter- 
mine hull reinforcement requirements and may 
affect internal and external equipment arrange- 
ment. 
Penetrators must be reliable barriers to hydro- 
static pressure to avoid electrical shorting or hull 
flooding. Although various configurations contain- 
ing relatively few contacts have had some success, 
none is yet satisfactory for extended operations 
requiring many signals at great depths. 
Underwater cables and connectors are a signifi- 
cant problem. Each must resist the high pressure 
seawater environment and form a reliable pressure 
resistant connection at the connector-cable and 
connector-connector interfaces. 
Underwater cable must be resistant to mechan- 
ical stresses from pressure cycling, vibration, ther- 
mal variations, abrasion, and chemical, electro- 
lytic, and biological attack. Extreme pressure 
changes cause cable insulation to squeeze and 
withdraw from between conductor strands and to 
be pinched and chafed. Voids formed in cable 
during manufacture can result in air bubble accum- 
ulation under pressure, subsequently causing rup- 
ture due to gas expansion during ascent. 
Molded distribution boxes and oil-filled junc- 
tion boxes have been utilized to distribute electri- 
cal power. In a molded distribution box, cable, 
connectors and wiring are mated in solid rubber or 
plastic. Inaccessible connecting points are fully 
protected from the outside environment. 
Oil-filled junction boxes, although heavy and 
bulky, are reliable in undersea systems. Pressure is 
compensated by an electrically insulating fluid 
(usually silicone oil) and a flexible diaphragm. 
When pressure increases, the diaphragm transmits 
pressure to the fluid in the box, thereby support- 
ing the box’s walls. The diaphragm may be 
spring-loaded to ensure a positive pressure to keep 
seawater out. Most remotely operated external 
contactors and relays are placed in oil-filled boxes. 
b. Future Needs Reliable, multiconductor hull 
penetrators, cables, and connectors are essential to 
systems development. Available components have 
only marginal capability. 
Insulations capable of withstanding many pres- 
sure cycles must be developed. New techniques of 
circuit interruption are needed. Reliable automatic 
system monitoring equipment must be developed. 
Because undersea maintenance is difficult if not 
impossible, equipment must be provided to detect, 
evaluate, and correct equipment faults automati- 
cally. Pressure and water resistant switch gear, 
preferably electronic rather than electro-mechan- 
ical, must be developed to avoid bulky protective 
enclosures and to improve reliability. New meth- 
ods of hull penetration, using radio or visible light 
frequencies now being developed for glass hulls, 
show promise and warrant increased effort. 
3. Buoyancy and Trim Control 
a. Current Situation Maintaining neutral buoy- 
ancy reliably is important because uncontrolled 
descent or ascent could be disastrous. A vehicle’s 
weight generally must be controlled through a 
range as much as +5 per cent of total weight. 
VI-39 
