Marsich and Merega 



The results of the work are reported in the first part, while in the second the 

 procedure adopted and the justification of the assumptions made are given in 

 detail. 



In the third part the formulas are given in the form used for the calculation, 

 slightly modified in respect to the original ones of KK with the purpose of simpli- 

 fying the numerical evaluation of certain quantities. 



The complete program is also reported, worked out in FORTRAN 2, together 

 with the input data formats and the output tables. 



Note that the application of a known hydrodynamic theory has permitted find- 

 ing a solution of practical utility of one of the most serious problems related to 

 the study of ship's strength, leading to results given in general form, which it 

 otherwise, given the present state of knowledge, would not have been possible to 

 achieve. 



1. DETERMINATION OF WAVE BENDING MOMENT 

 1.1 Parameters Affecting the Phenomenon 



As is known, the wave bending moment is essentially due to: 



(a) local hydrostatic pressure variations produced by: 



(1) height of wave profile in way of each hull transverse section; 



(2) vertical shift of each section owing to pitching and heaving 

 motions; 



(b) inertial forces variable from time to time and from section to section; 



(c) hydrodynamic forces variable as well during the time and along the 

 hull and which can be divided as follows: 



(1) exciting forces due to the vertical velocity of water particles; 



(2) forces due to the vertical velocity of hull sections; 



(3) exciting forces due to modifications induced by the hull presence 

 on the velocity potential. 



In the static method of wave bending moment calculation, according to which 

 the hull is considered in balance on a wave, only the factors listed under (a) are 

 taken into consideration, and therefore the calculation is referred to a position 

 where the rotation due to pitching is zero. 



Methods deriving from Froude-Krilov hypotheses lead one to neglect the fac- 

 tors listed in (2) and (3) of (c) above and therefore not to take properly into account 

 the hydrodynamic influence. 



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