Prediction of Ship Slamming at Sea 



20 30 40 



Relative Velocity In Ft./Sec. 



Threshold Velocity 

 t=l2.0 Ft/Sec. 



Fig. 6 - Comparison between sample 

 histogram and the truncated Rayleigh 

 distribution for relative velocity (se- 

 vere Sea State 7, ship speed 10 knots, 

 light draft) 



probability distribution of the relative velocity follows a truncated Rayleigh dis- 

 tribution. From these two conditions, the probability density function of the im- 

 pact pressure can be derived. 



Let the impact pressure associated with slamming, p, be expressed by 



P = 2Cf2 (14) 



where 



C = constant dependent upon the ship section shape, 



f - relative velocity. 



From Eqs. (11) and (14) and with the aid of the transformation theorem on 

 random variables, the following truncated exponential probability density func- 

 tion can be derived for the impact pressure associated with slamming 



559 



