Hydraulic Characteristics of Flaring Shaped Scawall (FSS) in deepwater were investigated experimentally. A minimum crest height on which no wave overtopping is allowed, a reflection coefficient and a wave overtopping rate were measured for two types of FSS with aquadrant circular cross section and a semicircular one. Above three factors of FSS were compared with those of a conventional vertical seawall to clarify efficiency of the proposed seawall in deepwater. The minimum crest height of FSS is smaller than that of the vertical seawall and this effectiveness becomes large with increase of offshore wave steepness. The same results were obtained for the wave overtopping. The reflection coefficient of FSS with a semicircular cross section becomes smaller than that with a quadrant circular cross section and the vertical seawall.
