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,
rudder and
sails. Seakindliness isn't only a function of
hull shape and position of the center of gravity.
Alain