A gyrostabiliser having a vacuum chamber assembly is disclosed. The gyrostabilizer can have a flywheel enclosed within a vacuum chamber formed by a housing. The flywheel shaft can be fixed to or integral with the flywheel and located relative to the housing by upper and lower spin bearings which permit rotation of the flywheel about the spin axis.

A gyrostabiliser assembly for a marine vessel comprising: a housing defining a chamber for supporting at least a partial vacuum; a flywheel mounted within the chamber for rotation about a spin axis at the partial vacuum; a flywheel shaft upon which the flywheel is supported and mounted in the housing for rotation of the flywheel about the spin axis, the flywheel shaft being rotatably supported by a first spin bearing located at one end region of the shaft and a second spin bearing located at an opposite end region of the shaft; and a lubrication system configured to circulate lubricant to the spin bearings from a lubricant reservoir. The reservoir is arranged in or on the housing to collect lubricant from the spin bearings under gravity and the first and second spin bearings are arranged in the housing for operation under the partial vacuum.

A gyrostabiliser assembly for a marine vessel comprising: a housing defining a chamber for supporting at least a partial vacuum; a flywheel mounted within the chamber for rotation about a spin axis at the partial vacuum; a flywheel shaft upon which the flywheel is supported and mounted in the housing for rotation of the flywheel about the spin axis, the flywheel shaft being rotatably supported by a first spin bearing located at one end region of the shaft and a second spin bearing located at an opposite end region of the shaft; and a lubrication system configured to circulate lubricant to the spin bearings from a lubricant reservoir. The reservoir is arranged in or on the housing to collect lubricant from the spin bearings under gravity and the first and second spin bearings are arranged in the housing for operation under the partial vacuum.