在多數工程的應用中，對於海上浮體耐海性之評估，於設計階段中皆停留於規則波對浮體性能的評估，而在大多數的設計過程中，並沒有考慮多重方向波對浮體所形成之效應。對於多向波思考上之缺乏，皆被廣泛的體認到，因為浮體對波浪的方向的反應，有著深切的影響，因此在本研究中，將考慮浮體對波浪的方向性的效應。在多重方向波中，浮體的運動預估則利用於頻率域中所建立的三維模擬浮體運動程式，此程式建立所用的觀念及方法是根據Fang 及Chen(1998)所發展出於規則波中之三維浮體運動程式延伸發展出來的。其後之數值解，則利用Series 60 船型之資料求得，從數值解之結果中，得知浮體之運動振幅在波之主方向較小，而其他方向則較大。
In most engineering applications, the assessment of seakeeping performance of a floating body at the design stage still stayed in regular waves. Most of design process does not consider the effect of the multi-directional wave. The shortcomings of lacking thought for multi-directional wave effects were widely recognized. Since the directionality of waves may have a profound effect on the response of a floating body, hence in this paper, the effects of wave directionality on the behavior of a floating body will be considered. A simulation program will be developed in the frequency domain for the estimation of motion in milti-directional waves, based on the well-developed methods of dealing with seakeeping problems of a ship in regular waves by the 3D method have been developed by Fang and Chen (1998). The numerical solution is obtained by applying the present method to Series 60 ship model. From the numerical results, we find that in the multi-directional waves, the amplitudes of the motions in the principal direction of wave propagation are smaller, and the amplitude of the motions in other directions is larger than in the multi-directional waves.
