a FAR oe 2 ae 
© pola SINE c 
k 
ary (C) 
D 
dF, (C) 
i] 
rR 
gg 
Q 
19) 
Z 
The variable, C, is the longitudinal position of the section. B 
is the beam and S is the transverse submerged area. The coefficients 
supplied by Grim are C, A,, and are dependent on the wave frequency, 
section fullness and beam to draft ratio. k is the wave number of the 
incident wave (i. e., 2m/\, where \} is the wave length) and a is the 
wave amplitude. C, is an additional correction to the wave making re- 
sistance due to the three-dimensionality of the problem, rather than 
two-dimensional as assumed by Grim. 
The total added mass, damping, and wave forces are obtained by 
integrating these expressions over the length of the structure. In order 
to carry out the integrations for the multi-legged elevated platform it 
is assumed that R/A<<1, where R is the radius of a supporting leg. Also, 
the coefficients C and A, are not really available for the shape con- 
sidered, hence average valules are taken. This is not too serious an 
approximation, since the effect of the coefficients are only predominant 
near resonance. _It does mean, however, that a variety of different 
values of C and A, should be used for each problem. It will then be 
readily apparent €or what range of frequencies the results are reliable. 
For this reason, program HEAVE, superimposes the graphical output from 
multiple cases. 
