Figure 42. A movable continental shelf station 
which completed successful trials in late 1968. 
(Oceanic Foundation photo) 
only small pressure differentials—indeed, it may be 
made of fabric or rubber. Providing the men in a 
station with electric power, food, water, sanita- 
tion, and supplies can be formidable, especially in 
foul weather. For a very large work force active 
over acres of the sea floor, one can envision several 
stations arranged about the worksite. The equiv- 
alent of a fence, fixed lights, storage, implement 
sheds, and the foreman’s office would complete 
the resemblance to a job site on land. 
c. Variable Depth Habitat The variable depth 
habitat is anchored on the ocean floor but can be 
floated to intermediate depths. The habitat serves 
as a work station, transport vehicle, and living 
quarters. If the worksite extends vertically to the 
level of one or more decompression stages, divers 
can continue useful work during each decom- 
pression stop. This system typically is confined to 
a small-scale operation, involving two or three 
divers under rather special site and task conditions. 
d. Composite Chamber This sytem is virtually a 
variable depth habitation suspended from a ship- 
mounted crane (Figure 43). The diving compart- 
ment is nearly always a pressure hull, making it 
possible to decompress divers on the surface. An 
observation compartment (usually spherical) is 
mounted atop the diving compartment and con- 
nected with it via a pressure-tight hatch; it 
performs several functions: 
—With the hatch closed, it can carry one or two 
scientists or engineers in a shirt-sleeve environment 
to view the underwater job site. 
Figure 43. Artist’s concept of a composite 
chamber suspended from a shipmounted crane. 
(Navy photo) 
—With the hatch open, it can serve as an ante- 
chamber to the diving compartment or as a lock to 
enter or leave the diving compartment when the 
chamber is on deck. 
—If a major fault should make the diving compart- 
ment unusable during a dive, the divers can enter 
the observation compartment under pressure. 
(Normally, divers would work from the lower 
compartment, while observers would stay in the 
observation compartment throughout the dive. 
The observers, not being subjected to high pres- 
sures, can leave the compartment as soon as it is 
hoisted on deck). 
The composite chamber is quite versatile, is 
relatively easy to transport, and is more suited to 
the smaller, short-term missions than to major 
diving projects. Without the ability to mate with a 
larger chamber, the composite chamber compels 
divers to remain inside until fully decompressed; 
this puts a definite limit on the total time under 
pressure. 
e. Decompression Staging System This is a series 
of underwater stations located at principal decom- 
pression stop levels. Personnel working at a 
bottom site may decompress by entering the next 
higher habitat, spending a night, then swimming to 
VI-I11 
