516 O. Grim 
W/A 
0.002 
0.001 }— 
My 
075 1.00 1.25 1.50 (75 2.00 
Fig. 31. Resistance arising from reflexion made 
nondimensional by the weight of the ship for waves of 
2h/A = 1/40 
Figure 30 deals with the amplitude of the relative motion between the deformed wave 
and the ship body. This amplitude is not made nondimensional with the amplitude of the 
wave but with the length of the ship. The ratio of the wave height to the wavelength is 
taken 1/40. This representation has been selected because the envelope of the plotted 
curves shows to which maximal degree the water surface can move relative to the ship body 
for all waves of the ratio chosen. 
Figure 31 shows the ratio of the resistance to the weight of the ship for a constant 
ratio of wave height to wavelength of 1/40. The first part of the resistance only arising 
from reflexion is represented. 
Calculations for this example were previously carried out for a subdivision of the ship 
body in 8 sections and applying a quite different program for the computor. The results of 
both the computations closely coincide for both U and G, i.e., for the deformation of the free 
water surface in consequence of the heaving and pitching motion and for the deformation of 
the wave in the case of a restrained ship body. In the case of the heaving and particularly 
of the pitching motion somewhat greater values have been obtained with a subdivision into 
10 sections. These deviations, as checking computations have shown, are mainly caused by 
the different subdivision of the ship body. It can be stated on the basis of this BOERS OL 
that the accuracy of the calculation is sufficient. 
ACKNOWLEDGMENT 
This paper has been spensored both by the Deutsche Forschungsgemeinschaft and the 
Office of Naval Research. 
