Demand of good seakeeping performance is increasing for sea going vessels such as cruisers, naval ships and container ships. Especially roll motion is one of major concerns in evaluation of seakeeping performance because of its large resonance motion. Since large roll resonance motion is mainly arisen from inherent small damping, use of additional mechanism to provide roll damping can significantly reduce the roll motion. In this paper, a performance evaluation method of fin stabilizer, which is very useful for stabilizing roll motion of mid- and high-speed vessels, is described. Model test and time domain simulation methods are adopted for performance evaluation in which real operating situation of fin stabilizer can be modeled more realistically. It was found that model test and simulation results show good correlation.
Sometimes large roll motion may cause unwanted dangerous situation to sea going vessels even under not so harsh environment because roll motion is very sensitive to resonant frequency. Very large resonant roll motion is mainly due to its very small inherent damping comparing to other motions such as heave and pitch, of which radiation damping is sufficiently large to suppress high resonant response. This property of roll motion gives an idea that roll motion can be controlled providing additional damping force. Anti-rolling tanks and fin-stabilizers are typical examples of roll stabilizing devices. Amongst them the fin stabilizer is most effective when a ship has relatively high speed by help of its active control. Fin stabilizers are widely used for naval ships, cruisers and container ships which require high seakeeping performance in waves. Since the fin stabilizer is an active system, it is necessary to analyze its sensitivity to design parameters such as operating range and rotating rate of fins as well as fin area, sectional shape and control gains.