The difficulties due to slamming experienced in ballast condition have been 

 emphasized by several writers; Akita has pointed out at the detrimental influence of a 

 flat stern in this case [53]. 



Heavily raked stems appear advantageous only if the wedge angle of the sec- 

 tions at the centre plane is not too high. 



The proper design of superstructures, hatches, wave breakers etc. in the forebody 

 must be kept in mind. 



To investigate impact properties of the hull above the waterline at high sustained 

 sea speeds, especially in unfavorable phase conditions, it is suggested to develop a 

 model, the lines and superstructures of which are designed primarily from impact 

 considerations, and to compare such a model with a normal form. A similar proposal 

 intended to reduce the excessive air resistance of ship superstructures have been made 

 some thirty years ago. All big "roughnesses" were stripped off the deck and the super- 

 structures "streamlined". This exaggerated simplification inspired the designer of the 

 "Bremen" to try a new look which was successful. The grave error committed by 

 dropping the forecastle has not been suggested by the designer. 



5. Conclusions 



Since considerable efforts are being made at present (contrary to the earlier 

 state) to elucidate our problems, it is appropriate to try to answer in a summary way 

 the question: what will come out of present and future scientific endeavors in our 

 field for shipbuilding and shipping practice? 



1. It can be claimed that an understanding of general phenomena has been 

 reached already by the applications of the extended Froude-Krylov theory. The over- 

 whelming importance of the ratio A* = X/L is established. 



2. The influence of principal variations of hull (dimensions, proportions and 

 form), and of mass distribution on motions in regular waves can be investigated to a 

 first approximation by such elementary means. A lot of actual work remains to be 

 done. 



3. The introduction of the modern irregular seaway concept has an important 

 bearing on application in practice. Because of the presence of long waves in a fully 

 developed heavy irregular seaway the appraisal of the length dimension undergoes some 

 changes. Earlier suggestions to increase the length of our largest ships in such a way 



that the ratio A max * = remains noticeably smaller than unity are superseded. 



In general, the advantage of long ships as compared with shorter ones established by 

 the regular seaway concept may be slightly reduced; however, this problem can be 

 settled only when a satisfactory standard representation of irregular seaways will have 

 been reached. There is no need, however, to prove the truism than on the average 

 larger ships are more seaworthy than smaller ones and that from our present point of 

 view lengthening constitutes an important means to improve motions and speed qualities. 



4. Conditions are similar to those in ship resistance research. By trial and 

 error good or reasonable solutions to numerous problems have been found. It is, 

 therefore, probable that work directed to improve normal ship types will yield slow 

 progress. It should be different when new solutions which depart from the established 

 routine are sought for, as shown by E. Lewis when investigating effects of lengthening 

 ships. 



5. The Froude-Krylov theory is an inadequate tool to reconsider the problem 

 of ship behavior from principle, with the purpose to develop ship types possessing 

 optimum qualities, though its possibilities as a guide for design were not exhausted as 

 shown recently by the discussion on the supercritical range of ship operation. 



The present state of knowledge admits, however, the definite hope that the 

 problem of optimization may become reasonable within the near future and may yield 

 new basic results for design, though a damped optimism is the appropriate attitude when 



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