diffraction waves

Ships, buoys, barges, floating docks, breakwaters, submersibles supporting
oil drilling rigs, and so on, are all structures whose safety and performance
depend on their response to waves. In a calm sea, the body weight, the
buoyancy force, and possible forces from external constraints such as ten-
sion legs, keep the body in static equilibrium. In waves, the presence of
a sufficiently large body causes diffraction (scattering) of waves. The body
must absorb some of the incident wave momentum and therefore must
suffer a dynamic force. If the constraints, such as the mooring lines, are not
sufficiently rigid, the body oscillates, hence further radiates waves, and ex-
periences reacting forces from the surrounding fluid and from the constraint.
Since the reacting forces depend on the motion of the body itself, the body,
the constraint, and the surrounding water are dynamically coupled in the
presence of incoming waves.

from:
THEORY AND APPLICATIONS OF OCEAN SURFACE WAVES
in chapter 8 :
Floating Body Dynamics: Diffraction and Radiation by Large Bodies


and another book

THE DYNAMICS OF MARINE CRAFT : Maneuvering and Seakeeping