Kim and Uevoiev 



swaying forces, [C HH ] , [ 5 HH^ and t C Hs] ' ^HS^ ' respectivel y* 

 on the individual bodies a and b. The swaying forces L^jjc J > C^HS-J 

 on a and b are equal, opposite and colinear, hence, the resultant 

 forces on the twin bodies ( a + b ) are only the heaving forces 

 2 [C HH ] a and 2 [%jj] a (see Table 11). Figure 14b represents a 

 typical force system induced by the swaying motion. This motion also 

 induces both heaving and swaying forces on each body. The sway-induc- 

 ed heaving forces [Cgtr] and [5ott] on a as well as b set up a 

 couple which contributes to the resultant rolling moments 2[Cg R ] a 

 and 2 [5g R ] (see Tables 8, 11). The sums of the swaying forces on 

 the twin bodies ( a+b ) are equal to 2[Cgg] and 2[5gg] , 

 which also contribute to the resultant rolling moments ^TCg^T] , 

 2[<5g R ] (Tables 8,11). 



Another typical force system is that induced by the rolling mo- 

 tion, as illustrated in Figure 14c. The rolling motion induces the heav- 

 ing forces [Crtt] > ^RH-3 an d the swaying forces [Crq] , L^ogJ on 

 each body. The heaving forces set up a couple and hence contribute to 

 the resultant rolling moments Crr , ^RR on * ne twin bodies ( a+b) 

 (Tables 8,11). The swaying forces on a and b are equal. Their re- 

 sultants on ( a + b ) are equal to 2[C R ] and 2[5 R o] , and also 



contribute to the rolling moments C , 8 (Tables 8, 11). 



i\t\, RR 



The non-dimensional expressions of the wave-exciting forces 

 and moments are defined in Table 9. Referring to Figure 14d, first 

 let us observe the typical wave-induced force system. The even and 

 odd wave potentials induce both sway- and heave -exciting forces. The 

 sway-exciting forces on a,b [fg J a , [fg ]u are equal, opposite 

 and colinear, while the heave-exciting forces [fg°'] a , Ph 3b se * U P 

 a couple. 



We see from the figure that the resultant roll-exciting moment 

 and the resultant sway-exciting force are due only to the odd wave po- 

 tential, whereas the resultant heave -exciting force is due only to the 

 even wave potential. (See Table 13). 



The Radiated and Diffracted Waves 



We consider at first the evaluation of the radiated and diffract- 

 ed waves generated from a rigidly connected twin-cylinder floating in 

 a regular beam wave , 



The radiated and diffracted waves generated by a monohull 

 cross section floating in a regular beam wave were evaluated in the 

 previous work [30] . The radiated or the diffracted wave is the vector 



814 



