Realistically many boats are at the dock 5 or 6 days per week. Often times you are too far away to monitor it closely during a storm. For these reasons you should always chose quality docklines and moor your boat properly. It’s an important, if not glamorous, investment.

An appropriate dockline has two qualities strength and elasticity. This rules out sheet lines, ski ropes, clotheslines and other assorted cordage which lack these qualities.

The best type of dockline is referred to as 3-strand. This is made of three strands of twisted nylon. Along with good strength nylon is sufficiently elastic for a dockline. A 3-strand nylon dockline 30 feet in length can be expected to have up to 3 feet of stretch in it. This allows the docklines to move with the boat.

Once you have the proper material we can move onto sizing. A rule is 1/8″ per 9 feet of boat. This equates to 3/8″ for a 20 footer, 1/2″ for a 35 footer, 5/8″ for a 50 footer and so on. Assuming the line will fit on your mooring cleats, a size bigger can’t hurt and may get you through a storm.

After you have sized your dock lines, you need to buy the proper length. An easy way to get a set of lines with great utility is to buy them all roughly the length of your boat. This allows each line to be a bow, stern or spring line.

A more precise standard for length is 2/3 the length of your boat for bow and stern lines, and equal to the length for spring lines.

Once on board start by attaching the dockline to a cleat in a proper way. At the boat end take the eye splice and put it through the eye of the mooring cleat and then around the horns. At the dock end use a proper cleat hitch with a round turn, loop and a locking half hitch.

Additionally the lines should be coiled and ready to be thrown or passed ashore. A line coiled to be thrown will be split in two, with a small coil being thrown first and then a larger coil being released once the first coil is in the air.

Your boat should have a minimum of 2 bow and 2 stern lines. Bow and stern lines run diagonally from bow and stern mooring cleats. Think of them as your four corner lines. They keep the boat away from the dock and cut down side to side motion.

Bow and stern lines ideally leave the boat at about 45 degrees. This, depending on the length of the boat and slip, is seldom attainable. The bow and stern lines primary function is to keep the boat from moving too far sideways.

Spring lines keep fore and aft motion down. Ideally you will have a spring line running from the forward part of the boat aft to a dock or a post. Your other spring line will run from the aft part of the boat forward to the dock.

Spring lines can keep a boat from pushing forward towards the dock or aft out of the slip. They can also help steady a boat with a wind over the bow.

They should be as long as possible and as close to parallel to the boat as possible. The spring lines should be trying to turn the boat into predictable waves. If those waves are expected to impinge on the boat’s port bow, for example, the spring line from the back of the boat to the dock at the front of the boat should be on the starboard side.

Line chafe should be considered. The further away from a wear point, such as a fair lead, the attaching point (cleat) is, the greater the wear at that point because of the stretch between. Chafe gear can be installed and secured to the lines at the wear points. Wear points and cleats should be a smooth as possible to reduce line damage.

Another dock line accessory is a rubber line snubber. These are installed between the boat and dock. They are a rubber piece which the line wraps around to reduce the load and stretch on the line.

With the right type of line, properly attached to boat and dock, in the right positions on your boat you will take good care of the boat the majority of the time- when tied to the dock.

Links: Samson 3 Strand http://www.samsonrope.com/home/general/all3-3s-proset-nylon.cfm?ProdNum=137

This article from Torresen Marine’s SailBase

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