Savitsky s Roper and Benen 



These combinations of length and beam are superposed on 

 the plots of Figure 4. This results in a substantial reduction in length- 

 beam combinations for further study. 



Smooth Water Planing (45 knots) 



A computational procedure for predicting the smooth water 

 equilibrium conditions of a planing hull is given by Savitsky 1 . This 

 procedure has been programmed for high-speed computers and is ge- 

 nerally available to the small boat naval architect. In Reference 2 , 

 Hadler extends this work to include the effects of propellers and ap- 

 pendages. Unfortunately, a computer program for this extended com- 

 putation is not yet generally available to the small boat naval architect. 



For the present study, which is intended to define the prin- 

 cipal hull dimensions for preliminary design, the simplified computa- 

 tional procedure developed by Savitsky is considered adequate. A 20° 

 deadrise hull is initially assumed and the equilibrium trim and wetted 

 keel length are computed for values of beam between 13 ft. and 18 ft; 

 for longitudinal center-of-gravity positions between 22 ft. and 44 ft. 

 forward of the transom, for a planing speed of 45 knots and a dis- 

 placement of 150, 000 lbs. The results of this computation are plot- 

 ted in Figure 5. For each value of beam, the trim angle required to 

 achieve ("H qq) =0.4 is also indicated. 



Using the results of Figure 5, the following relation between 

 beam, LCG , wetted keel length and suggested L (load waterline 

 length) is obtained. These values are also plotted in Figure 6. 



42 8 



