Denying any possibility of the sacrificium intellecti in our profession the author 

 admits that in the light of present requirements of shipbuilding and shipping practice 

 the importance of some scientific investigations and results may somewhat shrink. The 

 situation becomes completely different, however, when we accept the author's contention 

 that a considerable development of the ship is to be expected in the future. 



It is already a truism that a strong incentive for further research is to increase 

 the sustained ship speed in heavy seas. Numerous problems which at low speeds of 

 advance could be treated hopefully by hydrostatic methods require more detailed hydro- 

 dynamic consideration at higher Froude numbers. 



Several years ago we used to paraphrase Hilbert's well known remark on physics 

 by stating that ship theory is becoming too difficult for naval architects. On the other 

 side, because of the complex character of problems, it may be too complicated for 

 mathematicians and physicists. The best approach may attempt to establish a fruitful 

 cooperation between different directions of research. 



The last five or six years have seen a tremendous increase of interest in our field, 

 and considering the current rapid rate of progress, the author wishes to point out that 

 the picture sketched by him refers to a transitory condition only, and even so is 

 essentially incomplete. 



I. The Investigation of Ship Behavior in a Seaway 



Giving full credit to experimental research in the model and full scale range, 

 we find it nonetheless advantageous to describe the present state of knowledge prima- 

 rily in terms of analytic methods. 



1. The Seaway Concept 



Times are bygone, fortunately, when an amateur-oceanographer like the author 

 could gain an easy reputation by measuring big waves. In what follows we confine 

 ourselves to some remarks on the subject from a naval architect's point of view, since 

 problems of oceanography have been dealt with by Professor W. Munk. 



One of the most important recent achievements was the detection of long wave 

 components by measuring ship motions [8]. An impressive development of the theory 

 of the irregular seaway has taken place especially in this country and in Great Britain; 

 apparently, parallel important work has been done by the Russian School although from 

 the meager information available [9] it seems that the results reached are less definite. 



Successes in oceanography have an important bearing on naval architecture. 

 Obviously, no rational theory of seaworthiness of ships can be developed without a 

 thorough knowledge of actual seaway phenomena; in fact, the lack of the latter was 

 one of the reasons why the study of ship behavior remained somewhat academic and 

 failed to find a wider response in practice. 



Design procedures require the knowledge of safety limits and of average per- 

 formance of a ship in a seaway. 



Let us remember by what crude assumptions experienced model investigators 

 attempted to cope with the latter problem: an "equivalent" regular wave was arbi- 

 trarily substituted for the actual seaway. 



Under these circumstances, the work by St. Denis, Pierson and Neumann 

 proved to be extremely successful after the first shock over the unfamiliar mathe- 

 matical formulation had faded away [10]. The link with reality appears to be estab- 

 lished, although from a hydrodynamic viewpoint Neumann's seaway formula may be 



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