A gyroscopic stabiliser comprising: a support; a gimbal rotatable around a first axis relative to the support; a flywheel rotatable around a second axis relative to the gimbal, the second axis being orthogonal to the first axis; and a rotary damper for damping rotation of the gimbal around the first axis relative to the support; wherein the rotary damper comprises: a chamber containing a damping fluid; a vane that is rotatable within the chamber and that is coupled to the gimbal; and a flow passage allowing flow of the damping fluid from the chamber on one side of the vane to the chamber on the other side of the vane when the vane is rotated, wherein the flow passage comprises a flow valve configured to provide substantially the same flow rate of fluid through the flow passage for different torques applied to rotate the vane.