SEA GRANT COLLEGES 



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After surface cities, habitations floating under the water, the next step 

 toward widespread structures on the bottom of the sea necessitates some ocean 

 bottom engineering surveys. We'll need to develop bottom vehicles to travel be- 

 tween the ocean cities. But even before this, we'll have to develop a whole body 

 of knowledge on submarine soil mechanics. How will the ocean sediments sup- 

 port foundations and crawling vehicles? How stable will be the natural slopes or 

 the embankments we construct on the ocean bottom? How does the bottom erode? 

 And how well will it hold moorings? We need an expedition across the bottom of 

 the Atlantic and the Pacific in crawling vehicles containing men to survey the 

 terrain- -a Lewis and Clark transocean bottom expedition. Until then we will not 

 know how currents, erosion, and sediments will affect our engineering works. We 

 do know from broken submarine cables that there are catastrophic phenomena 

 much stronger than our concept of the "quiet in the deeps" would lead us to be- 

 lieve. 



Also in advance of the widespreaduse of bottom structures we need to study 

 the properties of materials at very high pressures. Materials suffer effects at 

 these pressures which are quite outside the domain of ordinary land engineering. 

 Glass apparently becomes less brittle. The analytical mechanics of thick shell 

 structures must be tackled without the simplifications which are satisfactory for 

 the thin shells we use on land. 



Already, thanks to the work of the physiologists, divers can live and work a 

 few hundred feet down. There seems every prospect that a thousand feet is now 

 not out of the question. This refers to living at the ambient pressures. In the 

 greater depths the structure to which we have referred, which will withstand the 

 pressures, will be necessary. Once people can work and live at a thousand feet, 

 the whole of the continental shelf, an area of 10 million square miles, larger 

 than North America, is opened up as a new continent for our use. Oil drilling, 

 mining, salvage, and even fish farming can be done by people down there and not, 

 as now, on the end of the string from a wobbly surface. 



So far I haven't mentioned power. And we are becoming accustomed to think 

 that the potential of nuclear power is so great that we can dismiss other sources 

 of power. The ocean is such a source, but it is termed a low-grade source be- 

 cause you need to imprison, or otherwise use, a great deal of sea water to get a 

 usable quantity of power. So that in general the power of the sea has been re- 

 garded as a nuisance rather than a potential to be tapped. Usually when people 

 think about the ocean's power, they think of tidal power and, indeed, there are 

 several tidal powerplants operating; in fact, tidal power was used to mill grain 

 a century ago in places like Maine. 



But many times the tidal power potential exists in the difference in tem- 

 perature between the top and the bottom of the ocean- -the thermal gradient power. 

 There are many places in the sea where differences of 10° occur over very short 

 horizontical or vertical distances. So far, there is only one small thermal gra- 

 dient plant in operation. With huge structures at sea, wave power becomes a 

 possibility. It's not easy to harness the up-and-down motion of the waves in any 

 practical or efficient way when we have small objects bobbing on the surface 

 even though the wave energy withstood by a ship's hull may be many times that 

 required to propel the ship. But with the size structure we envision- -huge arti- 

 ficial harbors, and stable platforms, wave power becomes a possibility. 



The ocean engineering in support of what we may call conventional fishing 

 is already here. The behaviorial scientists have a wealth of information on the 

 response of fish to sonic, chemical, and electronic stimuli that may take the 

 place of ordinary bait. And floating chemical engineering factories can take the 

 whole catch, sort the fish automatically- -trash fish for meal, more valuable 

 fish for canning or freezing, and more importantly, count the species to keep a 

 check on what is the renewable harvest. 



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