Navigation aid towers fixed onto the seabed have been constructed by Japan Coast Guard to indicate their
positions and avoid collisions of ships with offshore facilities such as manmade islands. These kind of structures,
composed of a column and gravity base,are often installed on reefs close to shore.While an impulsive wave pressure
is said to act on the circular column above sea surface,the large wave force also acts on the box shaped base.Though
the wave force on the column has been evaluated by a conventional formula, there is no appropriate formula
applicable to the base.Therefore,in order to develop an evaluation method,we conducted a series of model tests to
measure wave forces on a pipe and a box shaped base,together with pressures induced in the pipe.Furthermore,we
conducted numerical analyses by using the potential theory and Navier Stokes theory to simulate the measured wave
forces and wave transformations run-up on 1/30slope. The paper describes a comparison of experimental and
analytical results together with the evaluation of the wave force calculation method developed.