Project Mohole Drilling Platform 



1200 



biooo 



s 



a 800 



"300 



u 100 



50 100 



WIND VELOCITY. KNOTS 



5 10 



TRIM ANGLE-DEGREES 



Fig, 5 - Wind force lift, 

 moment (7 ft draft) 



Fig. 6 - Variation of wind forces 

 with trim angle (70 ft draft) 



Aerodynamic Resistance and Moment 



The effects of wind on the platform were measured in the David Taylor 

 Basin low-speed wind tunnel using a 1:60 scale model (4). The tests encom- 

 passed not only heading angles of degrees, 45 degrees, 90 degrees, and 135 

 degrees, but also several angles of trim and heel. Superstructure and major 

 items of deck equipment were included in the model. Faired test results are 

 given in Figs, 5 and 6. It will be noted that although drag force increases 

 slightly with trim angle or heel angle, the lift force increases rapidly with trim 

 or list angle. The lift force, usually neglected in wind heeling calculations, is 

 seen to contribute substantially to the heeling moment. Its relative effect de- 

 creases at large angle of heel as the center of pressure moves inboard. 



Propeller Performance 



A great deal of published information exists concerning propellers in open 

 water and in various wake patterns. Selection of the main propellers was aided 

 by the work of Nordstrom (5) which gives thrust and torque coefficients for 



421 



