For the Frank close-fit method, we have the potential as follows 



(1) = {oG^^dl (100) 



where O is the complex source density at the ship's contour and G for the twin-hull 

 body is given by Wehausen and Laitone 



Sd = ^' 2¥ 



log (y+iz-n-i?) - log (y+iz-n+iC) + 2PV 



_^-ik(y+iz-ri+i?) 



dk 



- iRe [e-^^(y+--r^+-0^ 



+ Re 



27T 



r -ik(y+iz+ri+i^) 

 log (y+iz+n-iC) - log (y+iz+n+i?) + 2PV | :^-^ — dk 



- iRe ^,-^^(y+^-+r^+iO^ 



(101) 



where (y,z) is the point where the potential is sought and (ri,^) is a source point 

 (Figure 3) 



I 2 



(-r?. f ) 



(y,z) 



Figure 3 - Sectional Coordinate System 



26 



