Dock Lines: Different Techniques

September 11, 2007
By David Bryant

Securing your boat to a dock or pier , thankfully, isn't a tricky science.This article will discuss the different techniques and hardware used in securing your boat to a dock.

What Type of Rope?

Your dock line must be nylon rope. Polypropylene degrades quickly in the sun, doesn't have the level of stretch needed, and has a low breaking strength so it is generally a bad choice. Whether you pick 3 strand twisted or braided line is up to you.

What Size?

So what size of rope should you use? The general rule is 1/8" of line for every 9' of boat. So using this rule:

Selecting dock line, however, is a lot like selecting an anchor: you can never pick dock line that is too big. Remember one other thing, every knot in your line can reduce the holding strength of the line up to 50%. Only use them when necessary. The only necessary places should mean around the cleats at the each end of the line.

What Length?

Your bow and stern lines should be about 2/3 the length of your boat. So, a 30' boat means 10' bow lines and 10' stern lines. Your spring lines should be the legnth of your boat. A spring line helps keep your boat snugly to the dock while allowing the boat to rise and fall in accordance with the dock.

Ideally, you should have two stern lines, two bow lines, and two spring lines on board. As the diagram at the end of this article shows, you don't always need to use two bow/stern lines, but you should have them on board regardless, because there will likely be a time when you do need them. When your expecting heavy/stormy conditions, consider doubling up your lines. Remember, more is always good!

How to Secure Your Boat

The diagram below illustrates three of the most common ways to secure your boat to a dock.