At Waku fishing port, facing to Japan Sea, in Yamaguchi prefecture, people are troubled with heavy water spray caused by sever waves and strong winds in winter at a vertical type breakwater constructed in front of the mouth of the port to protect the inside against incoming waves. To reduce the generation of and the damage from the water spray, three different types of countermeasures were proposed: 1) the construction of an artificial reef some distance ahead of the breakwater, 2) the construction of an offshore breakwater some distance ahead of the breakwater, and 3) the covering of the breakwater with wave dissipating blocks. Experiments using a wave flume with a wind tunnel were conducted to study the effects of suppressing the water spray generation. It was found that the countermeasure No. 3 is the most effective means and it can reduce the water spray drastically.
