A Study on Wave Sheltering of Single-mooring Spar Buoy Fences

The purpose of this paper is to estimate the wave sheltering of single-mooring spar buoy fences for the sandy coast protection. The spar buoy was constructed by a semi-closed pipe, which was designed by Liang(2000),Huang(2002) proposed a theoretical solution for the transmission coefficient of a one-layer fixed cylinder fence. Following Huang’s equation, a modified one for a one-layer spar buoy fence is deduced. The porosity ,which is the ratio of the gap and buoy spacing As the porosity increases, the transmission coefficient will increase. Experimental results agree well with the modified equation. The transmission coefficient also decreases as the wave steepness increases and the relative depth decreases. For multi-layer spar buoy system, the transmission coefficient won`t be a function of relative layer spacing when layer spacing changes, and porosity will also effect transmission coefficient, with porosity increases and transmission coefficient will be increase, Furthermore,a multi-layer spar buoy has a little better sheltering affect than a single-layer one. For the economical reason, one-layer spar buoy with small porosity is recommended.