Beck and Tuck 
and the pitch moment is 
a ii se (4.5) 
Thus the restoring force coefficients due to this mooring are 
Ci = k (4. 6) 
and ap mT, bets 
C SES MENT OS Ca. ae gay Coe = Bete (4. 7) 
all other C;, being zero, The total restoring force coefficient Cij 
for use in equation (2.2) is the sum of the hydrostatic contributions 
given in equations (2.4) and the mooring contributions given in (4. 6), 
(4.7) above. 
Equation (4.7) show that there is a small additional contribu- 
tion to the restoring forces in heave and pitch from the equilibrium 
tension in the mooring line, independent of its elasticity. Since these 
modes already possess very large hydrostatic restoring forces, itis 
very difficult to conceive of equilibrium cable tensions sufficient to 
produce significant effects on heave and pitch. 
For example, if we use T = 37 tons and R= 100 feet, the 
former being computed from Taylor's air resistance formula 
Z 
LZ ot= 440, 00Z218..B8 v" (4. 8) 
where B is beamand V wind speed (assumed 40 knots) , we obtain 
less than one tenth of a percent change in the computed heave and 
pitch motions of a 200000 ton ship, For this type of mooring or any 
combination of such moorings, the equilibrium tension would have to 
be quite unrealistically large™ for any significant change to occur in 
the heave and pitch motions. 
* For a single cable the figure of 37 tons is of course already in 
this category! 
1558 
