The first approximation at low speed is given by the substitution of 

 o~(x,y,z) by a_(x,y,z) and $(x,y) by $ (x,y), where a (x,y,z) is the source 

 distribution of the double body in a uniform flow. The result of this 

 approximation is not identical with that of Equation (32) because the 

 boundary condition on the hull surface is not satisfied by the source 

 distribution a (x,y,z). 



As a numerical example, wave resistance of Wigley's parabolic model is 

 calculated. Figure 4 shows the result calculated by Equation (28) with 

 the Kochin function defined by Equations (32) or (40) and by (42). The 

 results are compared with the residuary resistance of towing tests and 

 results of wave pattern analysis of the longitudinal cut method as well as 

 the calculation by Michell's formula. A considerable improvement is 

 observed in agreement with the measured results, especially in lower speed 



U/VgL 



Figure 4 - Computed and Measured Wave-Resistance Coefficient 

 of Wigley Model 



22 



