(see Figure 10 and Appendix A). These calculations were made for Condi- 
tion 1 in Table 3 using the wake measured in the plane of the propeller 
both with and without the downstream dynamometer boat in place (Figure 10 
and Appendix A), and with the mean velocity through the propeller deter- 
mined from thrust identity used as the reference velocity. 
The use of the speed of advance based on thrust effective wake, 
V,=V(1-w,) as the reference speed in these calculations is consistent 
with the use of this velocity to correct the time-average loads for the 
effect of the dynamometer boat as discussed in the section on experimental 
results. Tsakonas et Bae recommend using the ship speed as the refer- 
ence velocity, which is equivalent to using (1-w,,)=1.05 however, this 
recommendation was not followed here because the flow does not pass through 
the propeller at the ship speed. To evaluate the sensitivity of the pro- 
2 : 
252) to the reference speed, calculations were 
cedure of Tsaknoas et al, 
performed for the first harmonic using the thrust effective wake (1-w,p) 
and the volume mean wake determined from the wake surveys (1-wy)) + These 
calculations showed the following: 
Wake without dynamometer boat 
M (using (1-w,,) = 1.02) 
OPS rene oie sal = 0.99 
HO-3e (using (1-w,,,) = 1.06) 
O04 by *yo.3, Ou = -0.3 degrees 
Wake with dynamometer boat 
M (using (1-w,,) = 0.97) 
si ie = 1.02 
HO. 34 (using (1-w,) = 0.93) 
SMOuse nT a *yo.3, uw? = 0.5 degrees 
Therefore, the calculated unsteady loads using the method of Tsakonas et 
25,34 
Allain are not sensitive to the reference speed over the range of con- 
cern in the present case. 
44 
