Advanced Composite Materials (ACM), such as Carbon Fiber Reinforced Plastics (CFRP), have a big potential for achieving a light-weight marine structure. However material design, structural design and fabrication technology should closely be entangled in achieving a significant weight saving. The present paper aims at developing a computer aided design and manufacturing system for advanced composite marine structures. The term “marine structure” is defined here as a shell structure in which stiffness and strength for out-plane pressure and light-weight are required such as in the case of high speed boats and America's cup challenging yachts. First, this paper reports on design, manufacturing and evaluation of an ultra light-weight sailing dinghy with the use of ACM. Honeycomb sandwich structure, whose skin and core materials are angle-plied unidirectional carbon fiber reinforced epoxy and Nomex honeycomb, respectively, is adopted as the hull and deck structure. A successful application of CAD/CAE/CAM technology leads to remarkable weight reduction as large as 70 perecent of the conventional GFRP dinghy. The stiffness and strain distribution of the actual ship structure was measured and compared with the computational values and structural performance was confirmed. Second, a concept was proposed on the application of CAD/CAE/CAM technology to advanced composite marine structures. For example, definition of orientation angles, structural analysis of sandwich shells and material data base should be included in this system.