van Manen and Oosterveld 



Conventional screw 

 Kt-0186 Cq-^S^ 



Contra-rotating propellers 

 Kt.0.185 cTo-^eo 

 forward propeller aft propeller 



Fig. 13 - Cavitation patterns of conventional and 

 contrarotating propellers behind cargo liner 



synchronized the combination. By exchanging the real dynamometer and the 

 dummy dynamometer, the vibratory outputs of both propellers were determined. 



The results of the measurements of the propeller induced vibratory forces 

 are given in Figs, 14 through 17. Samples of the instantaneous torque and thrust 

 of the conventional screw and of the forward and aft propeller of the contrarotat- 

 ing propellers are shown in Figs. 14 and 15. The instantaneous thrust eccen- 

 tricity for the different propellers is given in Fig. 16, and the instantaneous 

 transverse forces are presented in Fig. 17. 



152 



