nical field and to evaluate and interpret results in such a way that they can be used in 

 design. The extensive algebraic, numerical and experimental work needed to establish 

 quantitative relations and to appraise the importance of various parameters is a nec- 

 essary prerequisite for making suggestions which may lead to an increasing safety and 

 seakindliness of ships. There should be no inferiority complex about such kind of 

 endeavours. 



Lack of systematic evaluations is one reason for the wide discrepancy between 

 scientific activities and the limited amount of their application, and contributes to 

 the fact that the determination of seagoing qualities, except for roll, rested more on 

 opinion than on knowledge. 



As pointed out already, International Safety Regulations for passenger ships 

 are restricted to elementary considerations only on longitudinal and transverse stability, 

 especially in damaged condition — an insufficient approach. 



It is utterly futile to search for coherent scientific ideas underlying present 

 cargo vessel freeboard regulations, upon which the vessel's safety depends to a large 

 extent. Faute de mieux, one would expect that there exists at least proportionality 

 between freeboard / and length L of similar ships; but actually the freeboard ratio f/L 

 for smaller ships, following tables, can be lower than for bigger vessels, although the 

 former are much more imperilled by short waves which possess higher steepness ratio 

 than longer ones. 



Worse than that, safety considerations were sacrificed to arbitrary requirements 

 presented by tonnage regulations. Open spaces with tonnage openings (and in earlier 

 times scuttles) were an affront to common sense. 



Under such circumstances it becomes understandable that the distinguished 

 work of experimenters like R. E. Froude, [59] Kent, and Kempf, although aimed at 

 immediate application, did not find the deserved response in practice, especially com- 

 mercial practice. At the VII International Towing Tank Conference even a loss of 

 experience in the experimental field was stated. 



The lack of interest in theoretical findings is clearly demonstrated by the fact 

 that apparently nobody objected over a long time to the inconsistency of period formulas 

 for heave and pitch calculated without the added mass effect. 



The narrow concern with the calm water resistance once led to the development 

 of extremely U-shaped forebody sections with flat bottom parts; a design which was 

 disproved by continuous damages due to slamming. 



We have here purposely assumed an aggressive tone when dealing with the con- 

 ditions in a not too distant past, because in our opinion an appeasing attitude towards 

 irrational regulations has seriously hampered progress. 



Obviously, there are inherent difficulties in dealing with our problem from the 

 designer's point of view. It is already a task to appraise the importance of seakindly 

 performance as compared with other postulates in design. The viewpoint of enlightened 

 practice has been presented in discussions to Ref. 5. Researchers should consult a paper 

 by Kent [7] which gives an interesting aspect of the problems. 



In what follows, frequent reference will be made to work by E. Lewis [5], [60], 

 [61]. We can slightly amplify a list of topics enumerated by him, some of which may 

 be considered as criteria of danger: 



1. Shipping green water, 



2. Large displacements, especially angular displacements, due amongst other 

 reasons to loss of stability in waves, 



3. Impacts, especially slamming, 



4. Large accelerations, 



5. Conditions leading to high stresses, especially girder stresses, 



6. Resistance increase, 



7. Loss of steering properties. 



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