In connection with the significance of the cross coupling, the work of Prof. Fay 

 brings out the fact that heaving motion is strongly affected by pitching, while pitching 

 is relatively little affected by heaving. This explains why in the publications in which 

 the pitching only is considered, as Cartwright and Rydill (1956) for example, the 

 effect of cross coupling does not appear to be pronounced. This effect becomes 

 immediately evident when the heaving is considered, and in particular it leads to a 

 large increase of heaving motions. This is important in practice because large heaving 

 motion of a ship leads to the occurrence of slamming. 



G. P. Weinblum 



As expected, the discussers have succeeded in supplementing my sketchy 

 expose in such a way that a more adequate representation of the ample subject has 

 been reached. May I express my sincere thanks for their contributions. Obviously, 

 it was a hard task for them to prepare their remarks without knowledge of my manu- 

 script which I was able to make available in a very rudimentary state only to Prof. 

 Korvin and Prof. Lewis. As mentioned at the beginning of the lecture, my wish to 

 dwell at some length on foreign work less known to the audience and to assume other 

 basic publications as familiar, has distorted the oral representation of the subject. 



Dr. P. Kaplan is to be congratulated on behalf of his theory on non-steady 

 hydrofoil performance. The present writer had earlier underestimated these effects. 

 It is interesting to note, however, that Mr. Eames is supporting the rudimentary quasi- 

 steady approach. I concur with him that it should not be wholly discarded for the 

 time being. In fact, work is going on following these lines under the present writer's 

 guidance dealing with the general case of hydrofoil motions on arbitrary courses in 

 regular waves. 



Mr. Golovato's contributions have clarified important problems and promise to 

 promote knowledge in our field in the future. His success is especially gratifying to 

 me after I was afraid to lose my reputation completely because of my responsibility 

 for suggesting the oscillator used by him. There appears to exist a slight contradiction 

 between point 1. and 6. of the discussion with respect to nonlinear effects. 



Thanks to Dr. Szebehely for his competent remarks on a subject which he has 

 successfully developed for several years. With respect to point 6. I wish to emphasize 

 that in my opinion Bagnold's ideas on hydrodynamic impacts may lead to a better 

 understanding of some pertinent effects but by no means can take over Wagner's 

 theory. 



In his oral reply Dr. Gawn has justly pointed out an understatement with 

 respect to Froude's work on roll. I agree wholeheartedly with Dr. Gawn that theory 

 has drawn a blank by neglecting severely the freeboard problem. The condensed 

 experience contained in the figure presented by him should be used when freeboard 

 regulation will be reconsiderd. Theory may contribute useful results to the determina- 

 tion of freeboard, sheer and size of superstructure especially as a guide to experimental 

 work, provided extensive numerical evaluations will have been performed. The lack 

 of the latter precludes at present to discuss the figures communicated by Dr. Gawn. 



Dr. Allan refers to Kent's work to whom the profession should feel deeply 

 indebted as well as to Kempf. Dr. Allan's remarks on damping and especially on 

 controlled damping are highly appreciated as those of a pioneer in the latter field. 

 The postulate "reliability is of paramount importance" is to the point especially at a 

 meeting of the present character. Some doubts expressed as to the effectiveness of 

 varying proportions lead to the discussion by Professor E. Lewis, the protagonist of 

 the problem at stake. 



To avoid any apparent disagreement with him, I have somewhat mitigated in 

 my final text the slightly nebulous statement concerning revolutionary improvements 

 within normal limits of ship form and proportions. It has been my aim for many 

 years to emphasize an almost trivial fact — the importance of the ratio A* = \/L 



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