High-Speed Planing Hull for Rough Water 



weight of payload components ; sea state; tolerable "g" loadings in 

 that sea state ; restrictions on draft, length, and beam, metacentric 

 stability ; and maneuvering qualities. Certainly, special purpose craft 

 have additional restrictions but these are not included in this study. 



For the present paper, the following set of performance spe- 

 cifications are prescribed. 



1. Full Load Displacement : 150,000 lbs. 



A designer's experience is invaluable in making the first 

 engineering estimate of full load displacement. Nevertheless, design 

 studies and possible model tests are carried but at additional displa- 

 cements of approximately 80% and 120% of the initial estimate. 



2. Maximum Speed : In excess of 40 knots. 



Interception and attack missions require high speeds. For 

 the present study, a nominal speed of 45 knots is assumed. 



3. Cruise Speed : Approximately 12 knots. 



A patrol mission requires long endurance at slow search 

 speeds. A cruise speed of 12 knots is selected. 



4. Maximum Hull Draft : 3.5 ft. 



5. Operational Sea State : 3. 



It is desired that the craft operate at 45 knots in a state 3 

 head sea having a significant wave height of 4. 6 ft. 



6. Average Center-of -Gravity Impact Acceleration : (rj ) = 0. 4g 



It is specified that the average center-of-gravity impact ac- 

 celeration should not exceed 0. 4g while running in a state 3 head 

 sea at 45 knots. 



7. Metacentric Stability : GM = 3.0 ft. 



A GM of 3. ft. was selected to provide metacentric sta- 

 bility under conditions of high wind and severe super -structure icing. 



The above set of requirements do not pre -specify the length 

 or beam of the craft. There may, of course, be operations where 



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