Wereldsma 



harmonics encountered by the blades of propellers having eccentric location. Of 

 course these statements have to be verified by measurements. 



A couple of questions were also raised by Mr. J. B. Hadler of the Naval Ship 

 Research and Development Center which I will comment on. We did not make 

 measurements of the wake of the ship combined with the open-water boat. It was 

 assumed that the effect of the open-water boat on the fluctuating propeller output 

 was negligible. From the point of view of vibrations I do not expect considerable 

 differences when the design is changed to a five-bladed forward propeller and a 

 four-bladed aft propeller. Still the wake will have a dominant influence. These 

 statements of course have to be confirmed by additional investigations. 



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