Recently the ship equipped scilling rudder is on increase. Generally, the scilling rudder is the fish-shape section with end-plates and provides high lift performance. This rudder can make wide range rudder angle to the maximum 70 degrees in comparison with normal one. In addition, it has a tendency not only to make high rudder thrust but also to maintain good performance on backward handling. As mentioned above, the scilling rudder displays higher handling performance than the normal one, especially in berthing controls. However, the mechanism bringing strong lift force even in large rudder angle is not entirely studied yet. To know the above mechanism will give useful suggestion and information to navigator, shipbuilder and marine engineer. In this paper, as the basic research clearing up this mechanism, we examined experimentally the relation between the shape of fishlike rudder section and hydrodynamic forces. And also in order to understand the mechanism of high lift force, we tried to carry out the visualization of fluid flow around rudder.
