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Windsurfing is a surface water sport using a windsurf board, also commonly called a sailboard, usually two to five meters long and powered by a single sail. The rig is connected to the board by a free-rotating flexible joint called the Universal Joint (U-Joint). Unlike a rudder-steered sailboat, a windsurfer is steered by the tilting and rotating of the mast and sail as well as tilting and carving the board. (wikipedia)