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Walking Barge

At the request of McDermott Caspian Contractors, Inc, JMS conducted a feasibility study and concept design of designing, building, and installing a shallow water pipe laying barge with a walking spud positioning system. This unique system is capable of moving the barge 13 meters in one minute and change heading as needed to match the pipe lay route. The system also has to overcome 40 tons of force from pipe tensions and environmental loads.

The concept design consists of a forward and an aft pontoon barges which are to be constructed independently of the 130-meter pipe laying barge and attached to the barge in the Caspian Sea. The forward pontoon barge is 36.3 meters long and 32 meters in breadth and 6.4 meters in depth. It includes three individual spud positioning units mounted within the forward pontoon hull, two mounted fore and aft and one to be mounted athwartships. The aft pontoon barge is slightly smaller and houses two individual spud positioning units housed within the aft pontoon hull, both to be mounted fore and aft.

The legs are cylindrical spuds measuring 1.7 meters in diameter, 38 meters long with a wall thickness of 6 cm and weighing approximately 94 tons apiece. The spuds are supported by a lower and an upper guide fixed within the spud carrier. The spuds are raised by a pair of hydraulic rams which grip the spuds via a clamping collar, allowing the hydraulic rams to extend and lift each spud 5 meters in a single cycle. Once in the raised position, a second fixed clamping collar on the carrier grabs the spud and holds it in place while the ram mounted clamping collar releases its “grip” and retracts to the lowered position to repeat the cycle if necessary. The spud carrier travels on heavy bearings in slotted guides set into the sides of the spud well, providing a travel of 13 meters. The spud carrier is moved within the spud well by a traction winch, which provides pulling force to both ends of the carrier via a two part purchase on each end of the carrier. One drum of the winch is attached to each end, and spools in and out to achieve the desired motion.