Twin-Rudder-System Configurations’ Impact on Ferry Ships’ Course- Keeping Ability under Windy Conditions

Ship course-keeping plays a vital role in navigation safety, especially when a ship is
operating under windy conditions. A method to control ship movements through rudder-system
configuration is necessary to stabilize a ship’s course. This paper describes the twin-rudder-system

configuration design’s impact on a ship’s course-keeping ability under windy conditions. A time-
domain simulation using the MATLAB-Simulink program was developed for this purpose. A

proportional integral derivative (PID) controller was used to adjust the ship‘s heading angle
according to the desired path. Several parameters—such as relative wind velocity and directions—
were accounted for in the simulation. The result shows that, at a wind direction of 88o, the ship’s
course-keeping speed decreased; however, increasing wind velocity caused a large deviation in the
ship’s heading angle. Meanwhile, the ship‘s course-keeping speed increased with rising windspeed
directions of 219o. The ship’s course-keeping time, at around 219o under the simulation’s wind
direction, was 11.84% lower than during a previous sea-trial. A possible reason for this difference
is that the simulation excluded waves and currents.