It is a matter of concern on environmental problems all over the world to reduce exhaust of carbon dioxide gas (CO2) assumed to be one of causes of global warming. We consider that it is one of the important points to decrease the ship's exhaust as the contribution of reduction of CO2. Some sail-equipped motor ships were constructed in Japan from the viewpoint of reduction on fuel consumption of a ship when the fuel price soared about 20 years ago (Ishihara, 1980; Matsumoto, 1982). In this time, the development of the high performance sail-equipped motor ship that uses clean energy as thrust of the ship is expected to reduce exhaust of CO2 in environmental problems. In our research institute, the investigation of aerodynamic characteristics on a hybrid-sail consisted of the rigid wing sail, which plays the role of a mast, a slat and a square soft sail was carried out at the wind tunnel in order to know performances and advantages of a sail-equipped motor ship. As a result the hybrid-sail presented in this paper is very useful compared with the previous sails and equipped on the deck of a motor ship actually. The performance of aerodynamic characteristics is also confirmed by calculation results of CFD.
The environmental destruction according to global warming in the entire earth is worried because a large amount of use of the fossil fuel increases CO2 in the atmosphere. In case of a ship, it will be effective to develop new technology of marine engines in order to reduce the exhaust gas. The thrust system using natural energy that might not make atmosphere dirty is also expected instead of the diesel engines. For instance, the use of the wind, the waves and the solar energy can be enumerated as promotion means.