Responses of Roll Damping on Anti-rolling Tank Devices

This paper shows a study on roll damping of anti-rolling tank (ART). A flexible passive ART that consists of two fixed reservoirs, a set of three connected ducts and a set of five connected air pipes is designed for carrying out experiments. Experiments were conducted in regular sinusoidal waves of small amplitude. A view of the effect of designed ART on roll damping is shown in this research. To estimate roll damping coefficients of the model ship, several serials of experiments have been conducted. Experiments had been conducted with various diameters of the ducts and various numbers of opened valves of the connected air pipes. By changing the diameter of the ducts and controlling the number of opened valves of the connected air pipes, the volumes of moving water and air flows between two reservoirs will be changed. Consequently, the roll damping coefficients and the stabilizing moments of the ART are changed, too. Some graphs that show the responses of roll damping of the ART are drawn. The influence of the ART on roll damping of the model ship is compared in theory and in experiments. Both theoretical and experimental results show that when the model ship using ART, a stabilizing moment is created. This stabilizing moment will make the magnitude of roll motion of the model ship reduced. It is recognized that the highest effect of ART to roll motion of the model ship is obtained when the model ship is experimented with a wave frequency near its natural frequency.