Project Mohole Drilling Platform 



5 



♦ ' t 



■ -2 -10 FEET 



10 9 8 76 5 



TO 



24 



-20 



Fig. 10 - Positioning 

 maneuvers in to 33 

 knot step increase in 

 wind from abeann 



Fig. 11 - Positioning 

 maneuvers in 3-knot 

 current and 33-knot 

 wind, both from ahead 



In the event that conditions are more severe than the design conditions, it is in- 

 tended that the vessel would be under manual control. Under manual control the 

 main shafts can be rotated at different speeds or in different directions to apply 

 thrust and torque as required. Additional power may be obtained by reassigning 

 generator capacity from drilling functions to the main propulsion motors. The 

 power plant is designed so the entire 13,000-kw generating capacity of the DC 

 electric power system can be applied to the positioning units and main propel- 

 lers. 



TRANSIT 



Self-propelled transit from site to site was not initially a basic requirement 

 for the platform. A large main propulsion system was found to be needed to in- 

 sure that the platform could remain on -station through storm conditions which 

 might occur frequently and with little warning. It was advantageous to design 

 for utilization of this propulsion system for moving to and from drill sites 

 rather than having to rely upon auxiliary vessels. More important is the added 

 freedom and safety afforded the platform. In the event of a severe storm forc- 

 ing it to leave the site, it can be moved into sheltered waters, into the open sea, 

 or possibly out of the storm track entirely. It is desirable to know the speed- 

 power characteristics of the platform at shallow draft although precise deter- 

 mination is not necessary. 



It is most essential to insure that sufficient directional stability is built 

 into the design so it can be steered with ease and precision. Principal reliance 



427 



