Method and apparatus for mounting lift crane on offshore structures

摘要

A method and apparatus for the mounting of lift cranes on jackup rigs, offshore platforms, and like offshore structures provides a first static bearing race portion which is mounted upon the jacking structure, for example, of a jackup rig surrounding the telescoping leg associated therewith. On offshore platforms, a vertical leg portion of the jacket can be extended vertically with the static bearing race portion being affixed to the extended vertical jacket leg. A second movable bearing race portion is attached to the static race portion with a plurality of bearings therebetween allowing the first and second bearing race portions to rotate with respect to one another. The crane is then supported on the upper bearing race portion with the telescoping leg of the jackup rig or offshore jacket structure passing through both bearing race portions, the crane structure unencumbering vertical movement of the leg in the case of a jackup rig.