JPS6237174B

PURPOSE:To enhance the effect of breaking waves by a method in which a cylindrical structure whose upper and lower ends are both opened is set in the sea where tidal waves are generating by projecting its upper end above the sea surface and also positioning its lower end below the sea surface at a depth a small distance apart from the seabed. CONSTITUTION:Sea water comes in and out of the lower end opening of a cylindrical structure 1, and vertically moves in the structure 1, whereupon the energy of the waves is dissipated and the surrounding waves of the structure 1 are reduced. The waves breaking effect, as represented by the formula D/L= 0.1-0.3, h1>=0.5H, and h2=(0.5-0.8)H+DELTAh, wherein D is diameter of the structure 1, h1 is height above the sea surface P of the structure 1, h2 is immersed height below the waterline P of the structure 1, and L is wave length of predominant period, can thus be greatly enhanced.