Single-point mooring systems

摘要

A permanent single-point mooring arrangement for a floating unit comprises a buoy anchored to the seabed with anchor points and catenary shaped anchor lines, which are connected to a central shaft located in the buoy around which the buoy-and the floating unit moored to the buoy-can rotate in a horizontal plane, a yoke for attaching the floating unit to the buoy being such that the floating unit may also move in a vertical plane so as to accommodate the relative motion between the buoy and the floating unit caused by wave action and loading conditions of the floating unit, the attachment for the floating unit being formed of a rigid connecting yoke which is attached at one end to the buoy and at the other to the floating unit and the attachment also comprising flexible joints associated with the rigid yoke, two radial and one axial flexible joint permitting a horizontal hinge motion between the buoy and the yoke at one side and between the yoke and the floating unit at the other, and is characterized in that the buoy is of rectangular shape the length of which is considerably greater than its width and that the catenary shaped anchor chains are connected to a central shaft the diameter of which is small with respect to the width of the buoy.