Performance comparison of two similar pontoons as floating breakwater using a spectral approach based on an experiment in regular waves

This study focuses on the formulation of a spectral approach to obtain the transmission coefficient (C-t) of floating breakwaters (FB) in irregular waves based on C-t in regular waves. Additionally, it provides a performance comparison of two quite similar rectangular and circular pontoons as FB. It starts with the comparison of C-t and extends to motions in regular waves by experiment. Overall, the rectangular section showed better performance for both C-t and motions. The spectral approach is formulated and validated. A parametric study on the performance of rectangular and circular FBs has been conducted by applying large scale physical modelling. The study shows that the rectangular section has considerably better performance than the circular section in almost all irregular waves. It is concluded that the spectral approach for irregular waves is a comprehensive method. It is also easy for implementation having FB performances in a limited number of regular waves.