Abstract: An offshore jack-up workover rig. The workover rig includes a vessel which may be self powered or powered by a tug. The vessel may be raised above the surface of a water body by extending the legs until they reach the water body bed and then continuing to extend the legs. The workover rig contains a workover floor unit which includes at least a drawworks, a drawworks motor, and a well aperture. The workover rig is detachably mounted on an extensible cantilevered frame. The frame may be extended to position the workover floor unit over an offshore platform to be serviced. The workover floor unit is also configured to mover laterally relative to the extensible frame. The vessel is also provided with a crane. The crane may be used to lift the detachable workover floor unit from the vessel and deposit it, including its equipment, on the platform.