Mooring system for floating drilling vessels

摘要

A mooring system is disclosed for maintaining a ship shape drilling vessel within alignment limits and for warping it into the sea while drilling a well from the vessel in the sub-surface ground below it. The mooring system absorbs all of the forces on the vessel, such as wind, current, wave, swell, roll, pitch, heave, surge and sway. These forces are measured by sensing load on a motor, electric, hydraulic, and the like, driving the anchor chain wildcat while hauling it in, by sensing load on the brake bands for the windlass wildcats, and by sensing load on the chain stopper, which sensed loads are transmitted to a display device which provides sufficient information to maintain the drilling vessel within the alignment limits and to warp it into the sea to minimize forces and motions of the vessel and to avoid beam sea forces. Preferably, a chain counter is provided on the power wildcat which counts the links, and hence the distance, the anchor chain is payed out or hauled in, which is transmitted to the display device. The anchor chains extend from each side both fore and aft of the vessel and each anchor chain has an electric motor driven wildcat, and extends through a chain stopper and fairlead. Vessel alignment is displayed on a cathode ray tube using an acoustic position resonance system.