Table 1 1 . Comparison of Candidate 20-Ton-Lift Submersibles 



Vetnicle 



Approximate 



Dimensions 



(ft) 



Dry Weight 

 (lb) 



1. Deballasting witli 

 hydrazine 



2. Deballasting with 

 high-pressure 

 helium 



3. Lift provided by 

 buoyant, rigid 

 chambers 



30 X 1 8 X 8 

 40 X 18x8 



45 X 20 X 8 



50,043 

 91,003 



117,470 

 (46,720 lb w/o 

 ballast weight) 



A vehicle employing buoyant, rigid lift tanks is the simplest in 

 concept although it does have one detracting feature: the need for a heavy 

 ballast weight (also large in size if made from concrete) which must be 

 jettisoned after load attachment. Also, the dry weight of the rigid-chamber 

 vehicle is the greatest of the three candidates. 



A detailed design of the three heavy-lift vehicles was not attempted, 

 so it is questionable whether each candidate has equal demands on a struc- 

 tural frame to support vehicle subsystems (each conceptual design assumes 

 a 4,000-pound framework). The hydrazine vehicle is seemingly the most 

 compact and lightest in weight. Its gas generator system, however, demands 

 performance capabilities which are not now achievable even in the laboratory. 

 Presumably, an urgent requirement for such a vehicle — with appropriate 

 funds in support — would go far toward eliminating current shortcomings 

 in performance. 



Based on their limited review of the subject, the authors are convinced 

 that a 20-ton-lift submersible operable to a 6,000 foot depth is a possibility, 

 but will require considerable investment in resources — both in time and 

 money. The rigid chamber vehicle and the vehicle using high-pressure helium 

 for water deballasting are considered to be somewhat inferior in potential to 

 the hydrazine vehicle. A considerably more detailed study is needed, however, 

 to confirm this suspicion. Future studies might also explore the possibility of 

 using the candidate vehicle concepts for lifting much lighter loads in both 

 deeper and shallow water. 



80 



