Table 9. Effectiveness of Candidate Systems 



System 



Ex 10-'* 

 (100 tn) 



Ex 10-'* 

 (600 tn) 



Hydrodynamic Winch 



1.99 



0.90 



Platform/Pipe 



1,180.00 



524.00 



Ship/Pipe 



3,720.00 



543.00 



Platform/Cable 



1,560.00 



288.00 



SInip/Cable 



587.00 



77.30 



Free Ascent/Descent 



1.24 



0.17 



Winch-Down 



5.25 



0.17 



Ship/Cable/ 

 Buoyant Assist 



39.50 



2.19 



Platform/Cable/ 

 Buoyant Assist 



60.30 



15.60 



Exercise of the model served as confirmation of the authors' findings. 

 Based on the assumptions of the model and the results of the investigations 

 and calculations, it can be confidently asserted that a surface vessel lowering 

 and raising a load via pipe string is the most realizable approach for compli- 

 ance with the requirements of the project. There is little if any question that 

 this approach offers the greatest possibility of success, yet still has high 

 degrees of safety and predictability. While there are some shortcomings to 

 a pipe string system, they are not in the realm of the unknown; no research 

 and development is required before it can be built, nor is there a need to 

 resort to untried techniques and equipment. The pipe string system is essen- 

 tially state-of-the-art in both size and methodology. 



For 100-ton loads there is the possibility of using cable as the 

 suspending medium. As discussed earlier, suspending 100-ton loads from a 

 SVa-inch diameter cable is feasible although the safety factor used would 

 probably not meet with industrywide acceptance. 



47 



