Abstract: A bearing structure which may, for example, be used for rotatable mounting of a turret or a rig (11) on the hull (14) of a vessel comprises a first annular bearing surface which is supported by the vessel hull (14), and which may be substantially plane or cylindrical. A second annular bearing surface which is in engagement with and supported by the first bearing surface is formed on the turret or rig (11). The hull (14) of the vessel is exposed to heavy forces caused by wind and waves, and such forces may cause deformations of the hull and consequently of said first bearing surface. In order to compensate for such deformations, the first bearing surface is divided into sections, and position control means, such as mechanical, pneumatic, or hydraulic spring means, are provided for maintaining all of the bearing surface sections in abutting engagement with said second bearing surface formed on the turret or rig (11).