Dock Line Guide

What they do

Dock lines secure your boat to a dock, or to another boat when rafting, either temporarily or semi-permanently. These applications demand different types of dock lines. When your boat is away from its regular slip or mooring, you need to have some designated nylon lines aboard, preferably with spliced eyes, ready for use when you tie up somewhere. The eye in the end is easily passed around a cleat or piling by someone on the dock and the bitter end is adjusted on board. There are dozens of combinations of diameters and lengths.

How much do I need?

A properly outfitted boat should have at least six dock lines on hand. Two (each) bow and stern lines, and two spring lines. The length of the lines depends upon how and where you moor your boat.

Types of Dock Lines

Dock lines are often made from nylon, which has a superior combination of strength and stretch. Both three-strand and braided construction are common. Three-strand stretches more, is very abrasion- and snag-resistant and less expensive. Braided nylon is stronger, comes in colors, and has a nice feel or “hand”. Polypropylene line is great to attach a life ring or other floatation device because it usually comes in bright colors and it floats. This line is also used for skiing, wake boarding and tubing.  


For designated dock lines, the size of your line is determined by its diameter and depends on the size and weight of your boat.
The following is an approximate guide:

• Boats under 20 feet = 3/8"
• Boats 20 to 30 feet = 1/2"
• Boats 30 to 40 feet = 5/8"
• Boats 40 to 60 feet = 3/4"
• Boats over 60 feet = 1"


Dock lines should be about 2/3 of the boat’s length when used on the bow and stern. Spring lines should be equal to your boat’s length.