Yes, the author explains clearly the basic notions of hydrostatic stability. But, as he highlights, the subject is much wider and complex: the sea isn't always flat, the boat
is moving with 6 degrees of freedom, the position of mass in the hull
and rig has a direct influence on inertia, thence roll and pitch
response, which also depend on damping provided by the keel
. Seakindliness isn't only a function of hull
shape and position of the center of gravity.