On the design of anti-roll tanks

Traditionally, the procedure to design anti-roll tanks is limited to the assessment of the reaction moment due to a regular roll motion. Although this procedure may seem adequate for a badly rolling ship, the neglect of the sway motion is by no means trivial for a well stabilized ship, which is the very purpose of the stabilizing tank. Moreover, older literature and previous studies showed that the response of the tank is nonlinearly dependent on the amplitude and frequency of this complex excitation. The present work summarizes how the complex performance of the tank can be understood and what the consequences of this understanding are for the use of frequency domain methods to predict the motion response of a stabilized ship.