Hydrofoil Motions in a Randonn Seaway 

 Sideslip 



y/3( F) ' C^ > ^/3( c) ^ ^^ > 



- [c[^(^/1~1l)«(L)] sin r^L^ + [cL^^^^(hR)a(Rj sin r^j,) 



Roll 



- y(L) [cL^^^/hL)a^L)] " Y^R) [^L.( r /^( R) >""( R)] 



^ ['^^(L)(''Ld.p.)''(L)(D.P.)] + [c£^^^/h^P)(D.p_))a^R)^D.P.)J 



Yaw 



- ^L) [Cl^(L)^^l)^L)] si" ^(L) + '^(R) [CL^(^/hg)^R) ]sin T^r) 



+ Cd y(L) + ^D y^R^ + (ixx-iyy^ '^^^ ^'^^^ 



^(L)(total) *-^'' ^(R)(total) ^ "^ > '"' ^^ 



Care must be exercised when applying these equations to a particular hydro- 

 foil as it is possible to overestimate some effects such as damping in roll. K 

 side forces, for example, are assumed to be derived from equivalent vertical 

 struts which in fact have an appreciable dihedral angle then the roll damping 

 may be overestimated. In some instances due to foil geometry the local velocity 

 vector 4) z may be along the foil element and not normal to the foil as is implied 

 in the above equations. 



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