Towing, Motion and Stability of Platforms 



c n TD 



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SHIP 

 WITH CENTER WELL 



CATAMARAN 



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NARROW BARGE WITH 

 OVERHANG & BALLAST SPONSON 



AW OLE CATAMARAN 



WIDE BARGE 

 WITH SLOT 



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XD 



CtX 



XD 



QUADRAMARAN 

 CZZD 



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OUTRIGGER 



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Fig. 16 - Platform hull types 



Nearly all of the forms shown in Fig. 16 have a tendency to yaw, with the 

 exception of the forms which have single or multiple parallel hulls. 



STABILITY 



It is necessary to discuss stability in this paper due to the fact that it is 

 very closely associated with considerations of motion. The stability of floating 

 vessels or barges is in all respects similar to that of ordinary ships and re- 

 quires no special comment here. The only problems of a special nature are the 

 substantial wind heel moment due to the high structures required on the decks 

 including the drilling derrick itself. Also if drilling is done on a cantilever ex- 

 tension over one side, compensating water ballast is usually needed on the op- 

 posite side with pumps of very high capacity to control the compensating moment. 

 The load hanging from the drilling derrick can be as high as one million pounds, 



459 



