Vassilopoulos and Mandel 



51. Lee, C. M., "Heaving Forces and Pitching Moments on a Semisubmerged 

 and Restrained Prolate Spheroid Proceeding in Regular Head Waves," Inst, 

 of Engineering Research, Univ. of California, Report No. NA-64-2, Contract 

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52. Grim, O., "The Deformation of Regular Head and Following Waves by a 

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53. Spens, G. P., "Experimental Measurements of the Deformation of Regular 

 Head and Following Seas by a Ship Model," Stevens Institute of Technology, 

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54. Newman, J. N., "The Exciting Forces on Fixed Bodies in Waves," Jour, of 

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DISCUSSION 



Winnifred R. Jacobs 



Stevens Institute of Technology 



Hob ok en, New Jersey 



I am belatedly aware of your criticism of the Korvin-Kroukovsky linear 

 theory of ship motions. I wasn't at Bergen and therefore missed your presen- 

 tation and Dr. Kaplan's defense as well as the counter-attacks. 



Since I am equally responsible for what yoi^ consider erroneous in the anal- 

 ysis, I should like to discuss your paper with you, in particular two statements 

 which, I believe, epitomize your criticism. (I hope I am correct in not consid- 

 ering as criticism the paragraph which states the fact that certain added mass 

 and damping coefficients were used in one study, while different coefficients 

 were used in other studies at Davidson Laboratory. Professor Korvin and, in- 

 deed, everyone involved in this work at Davidson Laboratory have repeatedly 

 said that when more suitable hydrodynamic coefficients are available, they will 

 be used.) 



In one instance you say "Table 2 shows that the expressions for four of the 

 newly proposed coefficients do not agree with those derived by Korvin- 

 Kroukovsky. The differences in the Korvin-Kroukovsky coefficients e(co^) , 

 B(a)g), c and E(a;g) appear to be mainly due to an erroneous time differentiation 

 of a fixed body coordinate with the result that 



356 



