Nowaekt and Sharma 
C.3. Applications 
It should be obvious from the foregoing that as far as the dee- 
ply submerged open water condition is concerned , our computer pro- 
gram as described above did not really predict propeller performance 
analytically but rather simulated the known measured performance by 
means of a lifting line model . This was perfectly acceptable because 
our primary aim here was not to predict propeller performance , but 
to determine the equivalent lifting line for use in calculating thrust 
deduction and free-surface effects . However , in two subsequent ap- 
plications this program was indeed used to obtain certain genuine pre- 
dictions of propeller performance. 
First , for estimating the effect of free-surface on propeller 
performance at shallow submergence the program was run with the 
calculated self-induced wake wf (R) of the propeller as an additional 
input (see Section B.6) without any attempt to manipulate the foil 
characteristics fixed once for all on the basis of the deeply submerged 
condition , see Equation (C17) . Hence , the thrust and torque calcu- 
lated for shallow submergence as plotted in Fig. 13 and reproduced 
in the following table are , in a certain sense , true predictions of the 
free-surface effect 
h/Ry, = 3.47 h/Rp= 1.00 h/Rp= 1.00 
Measured Measured Calculated 
It may be noted that the wake w;(R) input to the program was here 
calculated for the lifting line corresponding to the deeply submerged 
propeller . In principle, it would be possible to run a second iteration 
with the wake w,(R) recomputed for the new lifting line determined 
1910 
