Alignment tolerance ±1—3 degrees 



(rotation) 



Attitude tolerance ± 1 —3 degrees 



(vertical) 



Undoubtedly, with refinements of DOT task objectives and load configurations, 

 these criteria will be modified, but the authors feel that for the present study 

 they represent a useful starting point. 



To the above list can be added other desirable features for a feasible 

 NBTS. For example, the system should be independent, as much as possible, 

 from the lift system. For surface independence, power should be on-board; 

 however, this may prove to be impractical due to the large power demand 

 required for some systems. The NBTS should be capable of performing 

 several lifts per mission in order to economize on bottom time. Some 

 candidate systems will be launched from the surface, spend several hours on 

 the bottom, and then return to the surface support vessel where the NBTS 

 will be recycled for its next mission. 



If manned, the NBTS should have certain fail-safe features. The 

 passenger capsule, spherical or cylindrical, will be positively buoyant and 

 separable from the remainder of the vehicle in the event of an emergency. 

 Lift, whether provided by mechanical means or by vehicle buoyancy, should 

 be controllable. The NBTS must at all times be near a state of neutral 

 buoyancy, with or without a load attached, so as to prevent a sudden, 

 disastrous ascent to the surface or an uncontrollable descent to the sea floor. 



When operating near the sea floor, it is imperative that vehicles or 

 devices do not stir up bottom sediments. Pelagic sediments, once disturbed, 

 may obscure work sites for hours, weeks, or even years. Probably most work 

 sites will not be located in areas where the softest sediments predominate, 

 but the possibility of some vehicle induced turbidity is quite likely. 



Cruising speed, range, and duration of candidate NBTS vehicles will 

 depend, primarily, on available power sources. A bottom transport system 

 should have a bottom time of at least 6 hours. This minimum time period 

 will allow the NBTS to locate bottom resting loads, pick them up, and 

 transport them to the desired site. Integral power will most likely be provided 

 by batteries, lead/acid or silver/zinc, since fuel cells and nuclear sources are 

 either at an early stage of development or are too costly. A range of several 

 hundred yards and a speed of 1 to 2 knots is deemed adequate. 



Vehicle response in attitude and horizontal and vertical alignment 

 should be adequate to allow the precise positioning of loads. If manned, 

 the operation of the NBTS must have visual access in all directions provided 



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