Nowaekt and Sharma 
DISCUSSION 
Carl-Anders Johnsson 
Statens Skeppsprovntngsanstalt 
Goteborg, Sweden 
I should like to emphasise Professor Telfer's plea for taking 
the relative rotative efficiency seriously and draw the authors' attent- 
ion to an earlier work by Yamazaki in 1966 which contains some in- 
teresting calculations of the relative rotative efficiency. I should also 
like to ask the authors why they use wheels for measuring the wake 
and not pitot tubes. Some years ago we used wheels at the Swedish 
tank but we had difficulties in getting consistent results. 
DISCUSSION 
Gilbert Dyne 
Statens Skeppsprovntngsanstalt 
GOteborg, Sweden 
The investigation presented in this paper is a valuable con- 
tribution to the understanding of the important hull propeller interact- 
ion problem. The paper illustrates clearly how fruitful a combination 
of theory and experiment can be when treating complicated flow phe- 
nomena, 
The strength, o , of the sinks representing the propeller is 
directly related to the propeller induced mean axial velocities at the 
disk. Following the definitions used by the authors, o , is given by 
ie bead 
u 1 Al] We 
o(R,8) = - ENC ee I: | <a Bee: dsc (1) 
An 4 Uy 
= mx(l + = ) 
A 
for a moderately loaded propeller, see [1]. In Eq.(l1) ua, and Ue. 
1950 
