For the four$-$legged structure shown in two dimentions in Fig. P$\mathrm{.}18,$ determine the maximum horizontal force, and associated time $t,$ arising

rig. r$.\mathrm{.}10$

from Airy waves of height $15$ ft and length $225$ ft $.$ The water depth is $60$ ft $.$ Assume that $C_D=1,C_{\text{I}}=2.$ All four faces of the structure are identical. The outside diameter of each leg is $3$ ft $.$

Ans. $,F=27\mathrm{.}2$kips,$t=5\mathrm{.}8.$