equipment. Wave energy can be focused by port- 
able structures to accomplish enormous work. 
Dredging is a major coastal zone activity. 
Sediment stabilization will become a greater 
problem as more complex current patterns and 
more traffic result from human activity. Present 
methods of protecting materials from corrosion, 
biological attack, erosion, waves, and currents are 
inadequate or excessively expensive for many 
missions. 
Recommendations: 
The following observational and measurement 
capabilities should be developed: 
—Methods and instrumentation for on-site meas- 
urement of the engineering properties of sedi- 
ments. 
—Methods, equipment, and instrumentation for 
rapid core sampling and automatic analysis of 
samples. 
—Methods and instrumentation for continuous 
mapping of bottom sediments. 
—Effective experimental methodology and associ- 
ated instrumentation and data processing systems. 
Research and development programs should be 
conducted to: 
—Improve modeling techniques for the study of 
coastal processes and controls. 
—Evaluate new methods and equipment for major 
shoreline modification and construction and island 
building. 
—Develop faster and less costly methods and 
materials to stabilize sediment. 
C. Shelf Installations 
In order for man to conquer the sea, he must go 
into the sea. Much has been said about the 
complexity of advancing technology to exploit, 
occupy, and manage the U.S. Continental Shelf. 
However, it is now technically possible to occupy 
the shelf by applying developments of the past 
several years. Conquest of the ocean depths must 
start on the continental shelf, for experience 
VI-110 
gained there will be the foundation for the thrust 
into the deep oceans. 
Several ambient pressure, continental shelf 
habitats have been demonstrated in recent years, 
in the United States and abroad. They have been 
temporary installations depending upon cables to 
surface ships or shore for power. 
A Fixed Continental Shelf Laboratory as de- 
scribed in Chapter 7 is designed to facilitate 
development of the technology to occupy and 
manage the shelf and to minimize logistic support. 
The laboratory will be available for joint civilian- 
academic-military use in the accomplishment of 
subsystem and component development tasks. 
1. Current Sitatuion 
a. Habitats Widely varying approaches have been 
suggested and tried for undersea habitats. Some 
are quite small; others are large, providing working 
space for six to eight divers. For a single worksite, 
a relatively immobile shelter may be planted on 
the bottom. Moving worksites for inspection of 
communication cables or pipelines may require a 
mobile habitat integral to a submersible vehicle. 
All systems have three features in common: 
—They can maintain the diver at or near the 
ambient pressure at the worksite for extended 
periods. 
—The habitat (or an elevator-like chamber inter- 
facing with it) can bring divers to the surface for 
decompression. When an elevator is used, divers 
nearly always are transferred to a separate and 
larger chamber on the surface for decompression. 
—The chamber at the underwater worksite has at 
least one bottom hatch from which divers can 
enter the water and return. 
Functionally, seven habitat types can be identi- 
fied: (1) continental shelf station, (2) variable 
depth habitat, (3) composite chamber, (4) decom- 
pression staging system, (5) personnel transfer 
capsule/deck decompression chamber, (6) vehicle 
with diver lockout, and (7) hybrids. 
b. Continental Shelf Station The most elemen- 
tary configuration provides structural simplicity 
and relative freedom for divers from the turbulent 
air-sea interface (Figure 42). If intended only for 
bottom installation, the hull need be designed for 
