Towing, Motion and Stability of Platfornns 



Fig, 10 - Platform on colunnns stabilized for a 

 175-foot water depth (Kerr-McGee, Rig 54) 



square in plan. These hulls have extremely poor resistance and maneuvering 

 characteristics, and it is usually necessary to have one or two tugs ahead as 

 well as a tug astern to control yaw. 



Recent developments in column stabilized platforms have used catamaran 

 hulls, such as the Mohole platform described in the preceding paper. It is pos- 

 sible also to use three or four parallel hulls without any cross connection in 

 the water, all connections being made at a considerable elevation above the sur- 

 face. An example of this is the Ocean Queen shown in Fig. 9. Such parallel 

 hulls permit very high towing speeds and yet permit the platform to be of opti- 

 mum proportions. A nonparallel catamaran has some structural advantage, and 

 the increase in resistance (Fig. 17) is tolerable. 



The Sedco 135, Fig. 8, is a column stabilized platform with elliptical foot- 

 ings at the bottom of each column. However, the speed-to-length ratio is very 

 unfavorable due to the short length of each footing. On the contrary the 



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