When a ship is at rest in calm water, the forces of
buoyancy (B) and gravity (G) are equal and lie in the
same vertical line, as shown in figure 12-17. The center
of buoyancy, being the geometric center of the ship’s
underwater body, lies on the centerline and usually
near the midship section, and its vertical height is
usually a little more than half the draft. As the draft
INCREASES, B rises with respect to the keel.
Figure 12-18 shows how different drafts will create
different values of the HEIGHT OF THE CENTER OF
BUOYANCY FROM THE KEEL (KB). A series of
values for KB (the center of buoyancy from the keel) is
obtained and these values are plotted on a curve to
show KB versus draft. Figure 12-19 shows an example
of a KB curve for a warship.