Savitsky, Roper 3 and Benen 



in a body axis system having its origin at the center -of -gravity. 



The straight course tests were made at port yaw angles up 

 to 12° and at port roll angles up to 20°. Also, at zero yaw and roll 

 the effects due to rudder deflection up to 35° were measured. 



The rotating arm tests were made at port yaw angles up to 

 12°, port roll angles up to 20° with the boat making port turns at 

 radii corresponding to 2. 5 and 5. boat lengths. 



The model was tested at a displacement of 120, 000 lbs. at 

 an LCG = 34 ft. and at speeds corresponding to 14 and 45 knots. 

 The data obtained during the tests were processed on a digital com- 

 puter and tables of drag, side force, yaw moment, roll moment, trim 

 and heave were produced as a function of yaw angle and roll angle for 

 each of the radii and speeds investigated. The reduced data were plott- 

 ed and cross -faired as a function of yaw angle and radius for each of 

 the speeds and roll angles. From these plots, which are not reproduc- 

 ed here, the coefficients needed for stability analysis were determined 

 and are tabulated below. These include the rates of change of side 

 force and yaw moment with yaw angle and radius at zero roll angle. 



Hydrodynamic and Inertia Coefficients 



where 



n* + T = 2 I / p B 

 z z z 



m 1 = m 1 = 2 W/p gB" 



N 1 



N/qB" 



Y 1 = Y/qB' 



q = PU /2 



B = beam = 15.7 ft. 



N = yaw moment, ft -lbs. 



Y = side force, lbs. 

 W = 120, 000 lbs. 



440 



