Useful, inexpensive, and 
simple static buoyancy systems 
appear easily achievable for the 
short-term development of a low- 
ground-pressure or buoyed chassis 
for bottom drilling and excavation. 
_ For the long-term development 
program for depths to 20,000 feet, 
added complications in the form of 
adjustable buoyancy appear to be 
justified if it can be developed. One 
possible approach is described in a 
proposal (Beck, 1964), in which the 
goal would be the development of 
an active system capable of keeping 
a massive system at a predetermined 
level, constantly adjusting buoyancy 
to achieve this. Some formidable 
obstacles can be anticipated, not 
Figure 45. Top view of expanded the least of which is the continuous 
sphere core structure prior power drain. Small submersibles 
to tests. represent a compromise in the com- 
bination of vertical propellers, 
deballasting and ballasting (compressing a ballast tank partially filled with 
gas by pumping in seawater), and use of forward motion reacting against 
horizontal hydrodynamic surfaces. For the massive earthmoving systems 
envisioned here, the problems appear to be less awesome. Vertical accelera- 
tions would be less, both because of mass and extended horizontal surfaces. 
Power intrinsic to the operation of the machinery would always be available 
in large quantity, unlike the situation in small submersibles and in the Buoy- 
ancy Transport Vehicle developed by the Navy Undersea Research and 
Development Center, Hawaii. Both of these applications use batteries for 
power and extensive use of power for ballast control will limit their range. 
A final vertical stabilizing influence arises from the proposed vehicle's 
purpose—bottom work. The forceful contact with the bottom suggests that 
flotation trim will not be critical so long as some portion of the vertical force 
is taken in the tool contacting the bottom. 
It may well prove that for many bottoms, shear strength will be so low 
as to negate the effectiveness of wheels, tracks, belts, etc.; in those cases, a 
barge ‘floating’ at the water—bottom interface and reacting through a pro- 
peller in the water above would afford the necessary lateral movement (Figure 
46). 
57 
