Strip Theory- 

 According to the KK method instead (as well as those of Haskind and Wata- 

 nabe) all listed factors are taken into account, and therefore such a method may 

 be considered adequate for practical purpose. 



Many authors have compared theoretical results based on KK theory with 

 the experimental data and have achieved in every case an acceptable agreement. 

 For this reason, it has been deemed acceptable to adopt the KK method as a 

 basis for this study, assuming that the results obtained from its application be 

 satisfactorily in accordance with the real behavior, and the influence of the dif- 

 ferent parameters has been investigated, systematically applying this method. 



As is known, the KK method allows one to know at any time, and for what- 

 ever station along the hull, the value of the wave bending moment when the ship 

 is sailing at constant speed in regular waves. Therefore solving the equation 

 that provides the bending moment values in regular waves corresponding to dif- 

 ferent stations along the hull at different times, the envelope of the peak values 

 along the hull could be determined and the peak value of the envelope curve 

 then selected. 



The bending moment value that would be obtained in this way, however, is 

 not the most dangerous obtainable, even though, as a basis for the calculation, 

 the regular wave of the highest value that the ship may encounter during its life 

 is assumed with an acceptable probability. It can easily be demonstrated, in fact, 

 with energetic considerations, that the most probable peak value of the bending 

 moment that can be obtained as a response to a confused sea spectrum is, as 

 absolute value, greater than the peak value that can be obtained in regular waves. 



Therefore in this study the most probable peak value of the bending moment 

 over 10 '^ cycles has been taken into account, when the ship is sailing against a 

 long-crested confused sea induced by a 60-knot wind, choosing for any ship the 

 transverse section where the bending moment also reaches its peak value along 

 the hull. 



The main parameters that may affect the bending moment are: length, 

 breadth, draft, speed, weight distribution along the hull, hull volumes distribu- 

 tion along the hull, waterline shape, and sea spectrum. 



While the first four parameters are uniquely determined, for the rest it 

 was necessary to carry out preliminary investigation with the aim of detecting 

 which quantities are suitable for providing a quantitative as well as qualitative 

 definition of the exposed concepts. 



To the purpose of characterizing the weight distribution, different param- 

 eters have been considered (for instance, area, moment of inertia, and ab- 

 scissa of the center of gravity of the weight curve, adequately reduced to cer- 

 tain formulas). 



After some investigation, (see Sec. 2.4), a strict correlation was discovered 

 between the wave bending moment and the quantity 



817 



