This durable line is made of 100% double braid nylon that has excellent UV and abrasion resistance and comes in a variety of colors and sizes! The Gen3 Marine Dock Lines come with a professionally spliced 12" eye at one end. Secure your boat today with Gen3 Marine Dock Lines! For bow and stern lines, it is recommended that you purchase line that is 1.5-2.5 times the beam of the boat. These lines are used to help prevent the boat from moving side to side. Choose a single or double bow line depending on your dock configuration. For spring lines, it is recommended that your purchase line that is 1-1.5 times the length of the boat. These lines help reduce fore and aft movement. It is recommended to use a minimum of four dock lines per boat. If your boat is being docked in a windy or stormy area, choose the next size up in line diameter.