The Influence of Freeboard on Wetness 

 METHOD OF ANALYSIS 



A number of gross assumptions have been made in the analysis as follows: 



(a) It has been assumed that for the extreme motions the conditions remain 

 linear. The model experiments were carried out for a constant height-ship length 

 ratio of 1/50. 



(b) It has been assumed that the motion is regular about the mean still 

 water draught of the ship. 



(c) The head sea case only has been considered with no spreading of the 

 wave spectra. 



(d) For comparative purposes it has been assumed that the ships are in the 

 head sea condition 100% of the time. 



Other assumptions made in the analysis will be stated later. 



By combining the response curves such as in Fig. 1 with the sea spectra 

 given in Fig. 3, the response spectra are obtained and by integration of these 

 spectra, the mean square response is derived 



Ed 



[r(M] 



The derived curves of root mean square response amplitude S^^ for a range 

 of Beaufort numbers are shown in Fig. 4 for 0.70 Cg ships of 200, 400 and 600 ft 

 lengths. 



4 6 



BEAUFORT NUMBER, 



10 



Fig. 4 - Root mean square response for 

 constant ship lengths 0.70 Cg 



601 



