Moored Discus Buoy Motions in Currents, Waves and Breaking Waves

Abstract

In this paper, moored discus buoy characteristics (motions, accelerations, mooring tensions) in currents, regular waves, transient water waves, irregular waves and breaking waves are investigated in details, but winds are not included. For this study four types and 1/10, 1/20, 1/50 scale models are used, and a running mooring system is considered for generating relative current speed. Model motions are recorded by a remote measuring technique. From this study, following main points are concluded. (1) Frequency transfer functions in currents can be estimated farely well by the so called Strip Method even for such a full and flat body. (2) Effects of mooring rope on buoy motions are small like moored semi-submersible plat forms. (3) Capsizing rate and safety zone from capsizing in breaking waves could be shown, (4) Effects of type difference on infinitensimal motions are very small but on capsizing characteristics in breaking waves are farly large at large pre tensions or in small breaking wave height.