overhead and causes a reduction in the breadth of the
free surface.
To understand how pocketing of the free surface
reduces the free surface effect, study figure 12-29.
View A of figure 12-29 shows a compartment in
which the free surface effect is NOT influenced by the
depth of the loose water. The compartment shown in
view B, however, contains only a small amount of
water. When the ship heels sufficiently to reduce the
waterline in the compartment from w1 to W1l1, the
breadth of the free surface is reduced and the free
surface effect is thereby reduced. A similar reduction
in free surface effect occurs in the almost full
compartment shown in view C, again because of the
reduction in the breadth of the free surface. As figure
12-29 shows, the beneficial effect of pocketing is
greater at larger angles of heel.