Ochi 



Table 1 

 Threshold Velocity for Various Types of Ships 

 (Values are Converted to Those for a 520-ft Vessel) 



In connection with other proposed conditions leading to slamming (such as 

 unfavorable phase between bow and wave motion and angle between keel and 

 wave), it is mentioned that these are included in the two required conditions 

 found from the present tests. For example, the phase changes from time to 

 time in irregular waves, and it is apparent that the largest relative velocities 

 are associated with the out of phase motions. Thus, it may be concluded that 

 bow emergence and threshold velocity are the only conditions prerequisite to 

 ship slamming. 



It is noted here that the occurrence of impact pressure at Station 2 (0.1 L 

 aft of the forward perpendicular) was used as a criterion for slamming. The 

 justification of this statement is given in Ref. 4. 



Probability of Occurrence of Slamming per Cycle of 

 Wave Encounter 



Let w be the wave displacement and b the bow (forefoot) displacement from 

 their respective at rest (zero) positions (see Fig. 2). Upward displacement is 



548 



