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Figure 34 - Effect on Resistance of Reversal of Direction 



(Courtesy of Institution of Naval Architects) 



For variable stern shape, the results depend upon the type of hull. 

 By fining the stern of a full symmetrical vessel, only negligible or moder- 

 ate reductions in resistance were obtained up to a Froude number of F c 0.3 

 (thus "Froude 's rule" proved to be consistent), while by increasing the after- 

 body displacement of a finer ship a more pronounced increase was found. 



7. WAVE PHENOMENA DUE TO THE PROPELLER ACTION 



The interaction between ship and propeller can be successfully stud- 

 ied by the method of singularities. In particular, the mutual forces between 

 hull and propeller can be calculated by Lagally's theorem as soon as appro- 

 priate Images are known. Source and sink distributions which picture the hy- 

 drodynamic properties of a ship have been already discussed. As far as the 



