› west-advisor › Dock-LinesHow to Choose the Right Dock Lines | West Marine May 28, 2020 · Dock lines should be made from nylon, a synthetic fiber that has a superior combination of strength and stretch. Nylon is strong (although it shrinks and loses about 10-15% of its strength when wet), durable, and stretchy (three-strand nylon stretches up to 16% of its length when loaded to 15% of its breaking strength), so it absorbs shocks.