High-Speed Planing Hull for Rough Water 



Hydrodynamic Impact in a Seaway 



In Reference 3 , Fridsma presents the results of a syste- 

 matic study of the effects of deadrise, trim, loading, length-beam 

 ratio, bow section shape, speed, and sea state on the performance of 

 a series of prismatic planing models operating in irregular waves. A 

 statistical analysis of the measurements of added resistance, heave 

 motions, pitch motions and impact accelerations resulted in quanti- 

 tative relations between these measured quantities and hull dimensions 

 and operating conditions. The results of those parametric studies are 

 summarized in design charts which enable full-scale performance 

 predictions for planing craft. Using the procedures described by 

 Fridsma, the average center of gravity acceleration is computed for 

 a range of combinations of beam, length-beam ratio, deadrise and 

 trim angle for a maximum speed of 45 knots in a state 3 head sea. 

 To enter the design charts of Reference 3 , the following coefficients 

 are evaluated : 



= Beam loading = 



„3 



wB 



V /vL = Speed-length ratio 

 L./B = Length-beam ratio 



H 1 J /B - Significant wave height/beam = H , /B 



C = Speed coefficient = V'/V'gB 



where 



A = displacement = 150, 000 lbs. 



V = maximum speed = 45 knots 



V = maximum speed = 76 ft/sec. 



L = length between perpendiculars, ft. 



B = average beam over aft 80% of hull, ft. 



H / = significant wave in state 3 sea = 4. 6 ft. 



w = weight density of water = 64 lbs/ft 3 



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