Active roll stabilisation system for vessels

An active roll stabilization system for a vessel, comprising:

• at least one stabilization element configured to extend from a hull of a vessel, below the water line, on a side of the vessel;
• a sensor configured to sense vessel motion and deliver control signals based on the sensed vessel motion;
• and
• a hydraulic drive assembly for moving the at least one stabilization element relative to the hull in dependence on at least the delivered control signals, wherein the hydraulic drive assembly is configured to impart at least pivoting movement in a direction of the stern of the vessel or in a direction from the stem of the vessel to the at least one stabilization element;
• wherein the hydraulic drive assembly comprises at least one auxiliary hydraulic cylinder configured to move the at least one stabilization element relative to the hull, and a main hydraulic cylinder configured to drive the at least one auxiliary hydraulic cylinder, wherein the auxiliary hydraulic cylinder and the main hydraulic cylinder are in direct fluid connection with each other.