It is known that ship motions in waves can be decreased by using a bow-wing. But it is not known that the bow-wing simultaneously decreases an added resistance and generates a thrust. A thrust is generated more efficiently by using the controlled bow-wings. We design a device of controlled bow-wings. We use a vertical motion at the bow as a control signal for practical point of view. And we evaluate its effect on the ship motion and added resistance.
A concept of using a wing at the bow in waves as an antipitching fin has been examined by Abkowitz, Matsui et al., Matsui, Bessho et al., and Ochi. In addition, the research on oscillating wings by Nishiyama, Wu, and Watanabe shows that wings in waves generate thrust. Terao, Bessho, Isshiki and authors have researched the generation of thrust by using the relative motion between a wing and a fluid. It has been clear from both the experiments and the theory that an added resistance in waves can be decreased and ship motions stabilized by installing a wing at the bow. Further a wing has generated a thrust due to the ship motions, forward speed and wave orbital velocity. We have examined the effects in regular and irregular head waves. It has been shown that there is a restricted sea condition that the bow-wing have the effectiveness. In a calm sea, a resistance of a bow-wing can not be neglected. In a rough sea, a bow-wing is damaged by the slamming. Therefore, it has been proposed that a bow-wing is stowed into ship hull in such sea conditions (calm and very rough sea conditions). It is advisable that a bow-wing becomes smaller for stowing itself. However, as a wing area becomes smaller, its effects become small.