Wave control functions of various types of pile-supported floating breakwaters are investigated through the model tests. Effective types of floating unit to reduce wave transmission are first shown existence of the optimum initial constriction forces is also indicated in terms of wave transmission, floating body motion and mooring forces. The model tests are extended to irregular waves and compared with those in regular waves.
Floating breakwaters have been used in coastal regions taking advantage of their sea water exchange function. The floating breakwaters are considered as structures that control waves by making use of interaction between incident waves and generated waves by floating body motions. In Japan, the demand for multi-purpose utilization of coastal structures have recently been proposed and then the floating breakwaters are sometimes suggested bema used as fishing decks under moderate sea conditions. In that case, the floating body motion should be minimized for safety, which could in return worsen the performance of floating breakwaters or increase the mooring loads. The main purpose of this study is to investigate the probability of the development of such multi-purpose floating breakwaters. The floating breakwaters treated in this study are rectangular floating units supported by four vertical piles at the corners which are frequently seen as floating piers for small crafts. The movements in some modes of motion of such floating bodies are fully or partially restricted by the plies. The behaviors of such semi-constricted floating breakwaters are first investigated by using numerical models based on the linear potential theory. The characteristics of wave transmission, wave reflection, floating body motion, and loads on piles are next examined the experiments. Many types of floats are tested changing their dimensions or mooring conditions. The optimum configuration of a floating units is selected in the experiments and the possibility of the existence of the optimum initial constriction forces that do not worsen the performance of the breakwaters are indicated.
