1/2 

 Method 2 : Assume U = 0(e) and u) = 0(1). 



The boundary condition at the free surface in near field is 



3< f ) 1 u 2 3 2 <b 



37T*l + n wT = ° at z = (300) 



dz 



The source density is determined from the two-dimensional solution of a 

 heaving cylinder. A consistent approximation for the added resistance is 

 obtained by the three-dimensional formula, Equation (266) . 



Method 3 : Assume U = 0(1) or 0(e 1 ' 2 ) and to = 0(e~ 1/ ' 2 ) . 



The boundary condition at the free surface is the same as for Equation 

 (300) in Method 2. The source density is determined from the two- 

 dimensional solution of a heaving cylinder with the hull boundary condition 

 of Equation (296) which includes the effect of the forward speed. The 

 added resistance is calculated by the simplified formula of Equation (272), 

 but the solution is inconsistent in the order of approximation. 



Results of computations of the added resistance of the Series 60 

 model by means of various methods at several Froude numbers are illustrated 

 in Figures 11 through 13. Results of experiments are also shown for 

 comparison. It is observed that the best agreement between computations 

 and measurements is obtained by the calculation by means of the simplest 

 formula, Method 3, while more consistent methods can provide only less 

 accurate predictions. 



CONCLUDING REMARKS 



Readers may already have recognized that the four topics discussed in 

 this report have been arranged in the order of simplicity of their physical 

 phenomena. However, what is beyond our expectation for us to find out is 

 the fact that the seemingly simplest problem such as the wave resistance in 

 the uniform motion presents the greatest difficulty in attaining satis- 

 factory agreement between theoretical computations and measured results, 

 while theoretical predictions for much more complex phenomena, such as the 



102 



