Currently construction in the coastal zone is 
accomplished almost entirely by surface methods 
and equipment. Moreover, most construction tech- 
niques have remained static for the past century 
(excluding development of new power sources). 
Divers are used for preliminary surveys, inspection, 
salvage, simple installation, and assembly opera- 
tions, but the operations are basically dependent 
upon land or seasurface methods. 
It is conceivable that wave energy will be 
controlled and focused to accomplish work at the 
land-sea interface. Natural bottom contours guide 
wave fronts, concentrating wave energy at points 
along a coastline. If wave refraction and reflection 
could be controlled by the emplacement of port- 
able undersea barriers, enormous work could be 
accomplished at a great saving of time and money. 
Moving sediment along the coast from an over- 
supplied area to a denuded area is one obvious 
application; however, no investigations of the 
feasibility of harnessing wave energy for this pur- 
pose have been attempted. Controlled use of wave 
energy is at present an undeveloped technology. 
In some instances, the impetus to improve 
technology in such coastline engineering as harbor 
and port development, artificial islands, tunnels, 
and underwater transportation and distribution 
systems is coming from other sources. Examples 
are mineral exploration and exploitation, pipeline 
installation, petroleum production, etc. 
The application of underwater technology to 
coastal engineering probably will result as spinoffs 
from other developments with more immediate 
need. 
Coastal design and construction technology 
must include underwater methods and equipment 
to a greater degree. Requirements for offshore 
cities, passenger and freight terminals for ocean or 
air transportation, or recreational facilities estab- 
lish a need for application of underwater tech- 
nology as an integral part of coastal engineering. In 
the following paragraphs, some activities are con- 
sidered briefly as a means of identifying potential 
technological opportunities. 
Dredging sediments for navigation channels and 
barrier island passes, for drainage or diversion of 
currents and sediment, or for construction of 
islands, peninsulas, and beaches is a major coastal 
zone activity. In shallow and protected waters, 
surface vessels will continue to be the primary 
means of moving sediments for such projects. 
VI-108 
In deeper waters, in waters with adverse surface 
conditions, and where the bottom is coral, consoli- 
dated sediment, rock, etc., subsurface drilling, 
blasting, hydraulic jetting, and hauling may be 
necessary. The presence of equipment in the sea 
will compel the presence of men so means of 
underwater communication and observation will 
be essential for supervision and control. 
These requirements do not pose insurmount- 
able problems, although considerable development 
is needed. Primary is heavy machinery operating 
on the ocean floor to haul or handle material. In 
coastal areas, such equipment could be powered 
by cabled electric power or snorkel equipped 
engines. Work illumination will be a major 
problem to undersea operations; hence, further 
development of illumination devices—even electro- 
magnetic or acoustic—will be required. 
Sediment stabilization will become a greater 
problem as offshore installations and coastline 
modifications create more complex current 
patterns and traffic. Present methods depend upon 
mechanical stabilization—the application of such 
hard mechanical cover as shell, riprap, scrap metal, 
etc. The feasibility of chemical additives applied 
under water needs further investigation. Develop- 
ment of a fine-grained artificial material with the 
aesthetic qualities of natural sand but more prac- 
tical characteristics for beach stability (i-e., in 
terms of specific gravity, etc.) is a future possi- 
bility. 
The difficulty of men and machines working 
underwater while maintaining adequate communi- 
cations and lighting is a prime problem. This is 
especially true in areas of concentrated activity 
and where current and wave action interface. For 
some operations working from the surface may 
pose fewer problems than attempting heavy earth- 
moving or site preparation with underwater equip- 
ment and methods. Extensive tunneling under the 
bottom starting from shore appears more feasible 
than an offshore sea bottom entrance with less 
tunneling required. This entire situation could 
reverse if a simple method of making a sea bottom 
entrance could be perfected. 
Protection of materials used in coastal modifi- 
cations and structures will require technology 
advances. Present protection against corrosion, 
biological attack, erosion, waves, and currents is 
inadequate or excessively expensive for many 
missions. For example, monel metal covering at 
