Nowaekt and Sharma 
and further for ah) : 
4 
Cw = ey Bn : (10) 
Then Cy/Cy = fil 2 i aly SP (ee /Cy) (11) 
so the constants (l+k) and c,, may be determined from a linear fit 
to the plot of Cr/Cr versus F,{/Cr for low Froude numbers. 
Figure 4 shows that the linear relation implied by Equation (11) applies 
reasonably well to our model up to Froude numbers upto 0.2. The 
numerical values of the viscous form factor (l+k) and the coefficient 
Cy, were found to be 
(1+) =") OZ5 Cig ee (12) 
The coefficient of wavemaking resistance thus indirectly derived 
Cw Sear ( 1+k ) Cr (13) 
has been plotted in Figure 5 against the appropriate speed-length 
parameter Y, and compared with the corresponding calculations based 
on linearized thin ship theory (see Appendix B, especially Eq. (B28)). 
Although there is a remarkable semblance between theory and ex- 
periment (e.g. the second, third and fourth humps can be clearly iden- 
tified in the measured curve), it is disappointing to observe that even 
for our relatively thin ship (L/B = 10) reasonable quantitative agree- 
ment between theoretical predictions and experimental reality could 
be established only over a limited speed range of 2.5 <¥,< 4.5. At 
higher Y, (i. e. lower Froude numbers) the experimental curve ex- 
hibits much less pronounced humps and hollows and its general level 
is only half as high as the theoretical curve. This suggests that the 
viscous boundary layer and separation probably made the stern quite 
ineffective in wavemaking. 
In any case, the two speeds corresponding to Y, = 4(F,, =0. 354) 
and Y, = 7(F,,=0.267) were singled out from Fig. 5 as the most pro- 
mising for further investigation. At these speeds the wavemaking re- 
sistance was evaluated directly from measured wave profiles by the 
longitudinal cut method described in Appendix B.8. The result, as 
indicated by the two isolated spots in Fig. 5, showed that the wave- 
making resistance associated with the wave pattern actually generated 
by the model was about 30 to 40 percent less than the theoretical pre- 
diction or the empirical estimate of Eq. (13). Further discussion of 
the results of wave profile analysis will follow in Section 3, 5. 
The next step in hull analysis was the evaluation of nominal 
wake, i.e. the flow perturbation created by the hull in the propeller 
plane in the absence of the propeller. In order to avoid the compli- 
1854 
