:i6 



UVDKODVNAMK.s IN Mill' DllSlCN 



Src. 52.6 



for h/L, of about 0.0195. From Table 48.d the 

 length Lw of a Irochokirtl wiivo having a velocity 

 equal to Uie ship speotl of 20.5 kt is 231.3 ft. 

 Then, for the estimated height of the stern wave, 



h = O.OI95/.,r = 0.0195(231.3) = 1.57 ft. 



If this height is reckoned above the undisturbed 

 water level, the height above the 20-ft DWL is 

 •1.57 ft plus the sinkage (about 0.75 ft), or 5.32 ft. 



Although Ilarvald's data arc not intcndcfi to 

 take care of Iraiisoni-slcrn ships, the hciglit of tlic 

 obs»»rved stern-wave crest just forward of the 

 transom, as measured from the profiles on TMB 

 model 4505, reproduced in Fig. 66.11, is about 

 4.1 ft. reckoned above the 2(>-ft DWL. 



52.6 Prediction of the Surface-Wave Profile. 



There Is a definite lack of accurate, comprehensive, 

 and rcliiible information in Sees. 52.2 and 52.3, 

 and in the literature in general, upon which to 

 develop a wave-profile prediction method by the 

 analysis of systematic dala. This applies not only 

 to elevations in the wave profile but to the exact 

 speeds corresponding to the profiles, and to the 

 shapes and proportions of the ships making the 

 waves. Nevertheless, it is possible to sketch an 

 approximation of the surface-wave profile for a 

 ship design by using the empirical data of Sees. 

 52.2 and 52.3, plus some additional experimental 

 data relative to the number of wave lengths to be 

 expected between the bow-wave crest and the 

 stern. 

 The latter data are based preferablj' upon the 



19 10 17 16 15 14 IS 12 II 10 9 S 7 6 3 4 J 



Fio. 62.1 Wavb Profiles for TMB Sbrieb 67, Modbi, 4200W, at VARioita Spbeds 



