Study of a rudder with anode protections for the fishing vessel (1st report)

price of fuel, in order to keep and improve the management of fishing. As for the balance of income from fishing, the technology of the saving energy should be achieved by low cost and it is desirable to be adopted not only new vessels but also existing vessels.There are usually anode protections on a ship hull, bilge keels and a rudder to protect them from electric reactions from a propeller and seawater. The rudder is behind the propeller, and the inflow velocity of rudder becomes large. On a rudder, small objects like anode protections would increase resistance and reduce the lift force. The authors researched the situation of anode protections on approximately twenty Japanese fishing vessels. It is clear that the arrangement is various and there is no single confirmed way though the front positions on a rudder would be effective for the prevention from electric reactions. This study reports the hydrodynamic characteristics of a rudder with anode protections and the influence to the propulsion and the maneuvering performance of a ship. And appropriate positions of anode protections on a rudder for the energy saving are considered.This first paper reports the drag and lift characteristics of a rudder with anode protections at different cord length from leading edge and at different directions against the flow having different thickness or conditions. By model experiments in the uniformed flow and in the flow behind a propeller, this paper concludes that anode protections become resistance and reduce the lift force. And the front positions, the positions against the flow and large thickness increase the drag force and reduce the lift force. In the next paper, the detail influence to the propulsion and maneuvering performance of a ship will be reported.