A method of stopping a leak at sea during the days of sail. The old practice was to fill a basket with ashes and chopped rope-yarns and cover it loosely with canvas. The basket was then fixed to the end of a long pole and plunged repeatedly into the sea as near as possible to the leak. As the rope-yarns were gradually shaken through the side of the basket or over the top, they were drawn into the leak with the water entering it, and so choked it. A more efficient method, developed later, was to draw a sail, or a piece of canvas, closely thrummed with yarns, under the bottom of the ship in the area of the leak, the pressure of water holding it close to the ship's side and thus stopping the leak. This is the same principle as that on which the collision mat works, but was used in smaller vessels in which proper collision mats were not carried.