Schmitke and Jones 



DISCUSSION 



Reuven Leopold 



U.S. Navy Naval Ship Engineering Center 

 Hyattsville, Maryland, U.S.A. 



I have some comments and questions. Could a marginally 

 stable configuration be predictable to be stable by not accounting for 

 surge and thus lead to a bad foil configuration design choice ? The 

 Paper states on page 16 : 



". . . surge was neglected in this simulation in order to sim- 

 plify the problem and also because it was felt that neglect- 

 ing surge should give conservative results. " 



In a paper titled "The effect of surge, added mass and un- 

 steady lift on the motion of a hydrofoil boat in a seaway", which I 

 wrote about 10 years ago, I showed that foil configurations which were 

 stable became unstable once the surge was taken into account. 



REPLY TO DISCUSSION 



Rodney T. Schmitke 



Defence Research Establishment Atlantic 

 Dartmouth, Nova Scotia, Canada 



In answer to the question, the surge was taken into account 

 in doing stability analysis and the configuration was found to be stable 

 (Figure 12). Furthermore, in all my work on this type of configura- 

 tion I find that the only contribution of surge is a very slow subsidence 

 and it does not seem to couple into the pitch and heave motions signi- 

 ficantly. 



340 



