We have partly presented a new type of floating breakwater, which is able to reduce reflection waves for comparatively short waves and also transmission waves for comparatively long waves as compared to the conventionalp ontoon-typef loatingb reakwater.T wo additionald evices are adaptedt o the pontoonb reakwater;s uch as vertical-barrier-typree flectiond issipatersa nd submergedh orizontalp lates. In this study, i n order to improvet he performance of a new breakwater for much longer waves, effect of the dimension of submerged horizontal plate is examinede xtensively.A fter such 2-D examinationsa, newly developedf loatingb reakwateri s applied to the 3-D wave field. By the use of 3-D wave tank, wave height distributions around the arrayed floating breakwaters are observedt o know the effectivenessin the open sea. In the test, we have used two differenta rrangemenmt ethods of the breakwater array to improve the performance.
