For hollow buoyancy type of systems, a rather large number of 

 hollow objects are packed into a container. Perhaps the hollow objects 

 could be commercially available glass spheres 10 inches in diameter. The 

 latter are receiving much attention in the industry and are proving to be 

 fairly reliable sources of buoyancy. It is easy to foresee vast and unavoidable 

 handling problems for this type of system due to the inherent brittle property 

 of glass. 



Low-density organic liquids in containers have been used as buoyant 

 materials. Gasoline, kerosene, and some other petroleum derivatives have 

 been and are being put into compartmentalized, collapsible bags to provide 

 buoyancy. This system has proven to be awkward, since some objects of 

 rather large volume must be manipulated. In addition, complex rigging gear 

 is necessary to harness the buoyancy. 



Spherical or cylindrical metal alloy, external pressure vessels such as 

 submarine hulls are another source of buoyancy. Steel, aluminum, and 

 titanium are the prevalent competing materials for this type of structure. 

 For now and the foreseeable future, high-strength steel represents the best 

 choice as far as cost/effectiveness is concerned. A study of steel pressure 

 vessels is included in Reference 9. In general, steel pressure vessels satisfying 

 the requirements of this project are well within present manufacturing 

 capabilities. They would be resistant to shipboard abuse and, as is true with 

 all buoyancy systems, require much cargo space while in transit. 



The consensus of the authors and knowledgeable outside personnel 

 is that the nonvariable buoyancy systems discussed are operationally 

 awkward. During the development of the operational procedures required 

 for these systems (both cable and free ascent/descent), it became apparent 

 that, of all the pertinent functional areas, the problem of what to do with 

 the buoy after the load is released at the bottom was the most damaging 

 factor to the feasibility of the concept. Since the load-buoy combination is 

 nearly neutral, the release of the downward force of the load requires that 

 the upward force of the buoy be opposed by some outside force, perhaps a 

 dummy load. Many schemes were proposed and analyzed in the quest for a 

 satisfactory solution to this problem. It was determined that some form of 

 variable buoyancy system is the only realistic solution. 



Variable Buoyancy. Two types of variable buoyancy sources are 

 investigated in this study; (1 ) gas generators and (2) floodable metal alloy 

 buoys. 



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