A bottom crawling vehicle with integral power supply will have 

 serious limitations on its ability to perform heavy and/or prolonged tasks. 

 Integral power will be provided by storage cells, lead/acid or silver/zinc, and 

 the maximum amount of storable energy available will be several hundreds of 

 kilowatt hours. Crawlers dependent on external power sources, either surface 

 based or bottom based, lack the mobility of self-contained vehicles. Higher 

 density integral power sources such as fuel cells and nuclear generators with 

 power output in the range required are currently beyond the state-of-the-art. 



The attachment of telechiric devices or other vehicle appendages to 

 heavy pendulous loads could prove disastrous from another standpoint. The 

 relatively low mass and tractive force of the crawler in comparison with the 

 mass of the suspended load means that the crawler would be subject to 

 unplanned displacements of the load caused by movem.ent of the surface 

 support system. This could be an especially unfortunate situation if the load 

 were to begin to swing toward the crawler prior to attachment of the vehicle 

 appendages. 



Although not considered in the current study, the development of 

 bottom crawling vehicles with clearly defined missions in ocean floor 

 exploration, bottom mapping, and soil property testing may prove to be 

 feasible and useful deep ocean construction work systems. If so, a secondary 

 mission for this vehicle could be that of load guidance and placement monitor. 

 Observers aboard the crawler could relay alignment and position corrections 

 to the surface load support system. However, a bottom crawling vehicle, the 

 prime mission of which is to actively guide and position heavy, suspended 

 loads, is not considered to be a desirable or even feasible concept. 



Submersibles 



Currently operational deep diving submersibles, as well as those 

 planned for completion in the near future, are discussed elsewhere. ^^-^^ 

 Two guidance and positioning roles were initially considered for submersibles: 

 (1 ) physical displacement of suspended loads using the thrust of the vehicle 

 propulsion system and (2) relaying of load position corrections to the load 

 surface support system (ship or platform). 



The first role disregards the thrust capabilities of all existing and 

 projected, battery powered submersibles. Available thrust levels rarely 

 exceed 200 pounds, which is all that is required to propel small underwater 

 vehicles at speeds of 1 to 2 knots. A 200-pound horizontal force (typical of 

 the thrust available on a conventional submersible) will displace a 100-ton 

 suspended load about 4.5 feet from the vertical and a 600-ton load less 

 than 1 foot. Significant displacement, say 100 feet, requires about 



60 



