A forward spring line is placed from the stern of the sailboat to the dock. In reverse gear, the sailboat is slowly backed. The spring line prevents the backward motion of the boat and swings the bow away from the dock. One may also use the rudder to vary the direction of boat thrust, to aid in holding the boat to or in swinging the boat away from the pier. Once clear, the line is released and the boat is placed in forward gear and steered away from the dock. This video shows a US SAILING Basic Cruising Class learning to use a forward spring line.