How to Use Jacklines

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What Is a Jackline?

Coiled Jackline
Photo © Tom Lochhaas.

A jackline is a line or strap used 0n a sailboat to help keep you on the boat. Typically a jackline is run from the stern to the bow on both sides of the boat. A sailor wearing a safety harness uses a tether to connect to the jackline when moving along the deck of the boat. Having one continuous jackline from stern to bow makes it easy and safe to stay clipped on the whole time when moving forward to the bow from the cockpit.

Shown here is a commercially available jackline coiled before use. Typically sailors stow jacklines away until needed or until taking the boat offshore, when it’s a good idea to have jacklines in place so that they’re ready when needed.

When purchasing a jackline, get one about the length of your boat. Typically a jackline runs from a strong cleat at the bow to one on the stern—one on each side.

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Jackline Secured to Bow Anchor Cleat

Jackline on Cleat
Photo © Tom Lochhaas.

This boat has a heavy cleat near the bow on each side. This photo shows the view back from the bow of a jackline running down the deck toward the stern. The line is tied to an aft cleat using a cleat hitch.

Notice that this jackline is a heavy strap, not a round line. It is important to use a flat strap rather than a round rope. If you step on a round line, the line may roll and cause you to lose your footing. If you make your own jacklines rather than purchasing them, keep in mind that the standard is at least 5000 lbs. breaking strength. This may seem excessive, but a person thrown across the deck by a big wave may strain a line with well over a thousand pounds of force.

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Safety Tether Clipped to Jackline

Tether Clipped to Jackline
Photo © Tom Lochhaas.

With the jackline in place, you simply clip onto to it with the shackle on the end of the tether hooked to your harness. As you move along the deck in either direction, the tether simply slides along the jackline.

With a well-positioned jackline, you can clip on for safety before leaving the harness and attend to any business on deck without having to unclip.

Safety Issue vs Personal Preference?

Since most tethers are 6 feet long, a sailor who is thrown overboard while tethered to a jackline will likely go into the water but not with head immersed. Sailors who have had this happen while the boat is moving very fast in a high wind have described the plight of being bashed around in the water and against the hull until the crew can stop the boat and hoist them back aboard. Some sailors, therefore, prefer to use the 3-foot length of a double tether to clip on and crawl forward along the deck—the shorter tether should prevent you from hitting the water at all. With a double tether, you can always switch to the 6-foot tether when necessary to stand up at the bow.

Read more about other Sailing Safety topics.