Computatton of Shallow Water Shtp Mottons 
With appendages like bilge keels, it will certainly be important in 
such terms as the roll damping. As for the problem of the boundary 
layer under the ship, I do not know how important it would be for zero 
forward speed. 
DISCUSSION 
Cheung-Hun C. Kim 
Stevens Institute of Technology 
Hoboken, New-Jersey, U.S.A. 
. 
I recently calculated the motion of the same model ship moving 
in head seas. Perhaps Dr. Tuck and Dr. Beck have made a compari- 
son with these results in forward zero speed: for h/T, the depth 
draft ratio = 2.5 and 1.5. If so have you found any difference bet- 
ween your calculation and my own ? 
REPLY TO DISCUSSION 
Robert F. Beck 
Untverstty of Michtgan 
Ann Arbor, Mtchtgan, U.S.A. 
Dr. Kim has computed the results of finite depth ship motions 
using a strip theory as opposed toa slender body theory. We compar- 
ed our computed results with his in the Melbourne paper which we 
have referenced. It may be a good idea to repeat this comparison at 
this time. 
In Figures 1 and 2 the results for heave and pitch are shown. 
These results are for head seas only, for a Series 60 ship with a block 
coefficient of .70. In Figures 1 and 2 the dashed line is the first- 
order theory mentioned in the present paper. The chain dotted line is 
for a so-called ''second order" theory ; it is the first-order theory 
with, in addition, just the mass of the ship taken into account, and is 
not, in fact, a consistant approach, since there is no added mass or 
b563 
