The force of gravity is a resultant or composite force,
including the weights of all portions of the ship’s
structure, equipment, cargo, and personnel. The force
of gravity may be considered as a single force, which
acts downward through the ship’s center of gravity (G).
The force of buoyancy is also a composite force,
which results from the pressure of the water on the
ship’s hull. A good example of this is immersing a
container in a tank of water as shown in view A of
figure 12-16. The container must be held under the
water to keep it from rising. View B of figure 12-16
shows the position of the container when it is released.