Analysis of Ship-Side Wave Profiles 



DISCUSSION 



Klaus W. Eggers 



Institut' fur Sehiffbau der Universitat Hamburg 

 Hamburg j Germany 



I feel that this paper deserves a very careful evaluation as 

 well as comparison with concurrent approaches. I shall restrict my 

 discussion to one remark only and two minor questions. 



The authors deliberately do not display any physical assumpt- 

 ions regarding the effect covered by their correction, it may result 

 from higher order effects of wave making theory for an ideal fluid or 

 from viscousity or even from wave breaking. As far as the first 

 method, called (J. correction, is concerned, it retains the anti- sym- 

 metry of a source distribution for a symmetric ship and thus will not 

 take account of viscous effects. 



Now my questions : on Figure 12, I observe that the actual 

 source density found from wave pattern survey deviates from this 

 anti -symmetry, as could have been expected, but the deviation is 

 smaller with the larger beam/length ratio. How can this be explained ? 



Second, on Figure 25 there are represented different curves 

 of wave resistance : from total drag, from wave pattern and from 

 calculation using the method proposed. I would like to know from which 

 Froude number measurement the underlying source distribution for 

 the latter curve was taken and if there was any sensitive dependence 

 found of wave resistance upon the Froude number selected for deter- 

 mining the source strength. 



745 



