Lazy Jacks for Your Sailboat: Tips & Tricks


Our boat is complex. There are lots of moving parts, standing parts, parts work pretty well or parts that could use improvement. While circumnavigating, we’ve learned so much about our boat, but one of our very early lessons was on lazy jacks.

What are Lazy Jacks?

Our boat, Starry Horizons, a Fountaine Pajot Helia 44, has a stack pack for the mainsail. This stack pack attaches to the boom through a track. It closes around the sail with a zipper to keep the sail in a bundle. The lazy jacks keep the stack pack upright. The stack pack has a batten down the length of either side and integrated into the stack pack (and around the battens) are four loops on either side.

The lazy jacks tie to those loops. The part of the lazy jacks connected to the stack pack are the legs. Each leg is tied to the stack pack loop on either end, so you have four lines that make up your legs, all eight ends of the legs tied to the stack pack.

The next part of the lazy jacks is the risers. The risers run from the legs up to a pulley on the mast and then down to the base of the mast. There, they usually have their own cleats on either side where you secure the lines.

A pulley connects the risers and to the middle of the legs – or at least it should be! We were discussing lazy jacks with one FP owner. While we investigated his problem, we discovered that he didn’t have pulleys, the installers had simply tied the risers to the legs via a bowling knot. This is going to cause chafing issues with the lines so he replaced the bowlines with pulleys.

It is important that the lazy jacks never take the full weight of the sail and the boom. They are just to keep the sail and stack pack centered. The topping lift raises the boom up and takes a majority of the weight of the sail.

Why Do Boats Have Them?

Lazy jacks serve a couple of purposes. Aside from keeping the stack pack on top of the boom, they also help guide the mainsail down when you drop it. Ideally, your mainsail will naturally flake as you lower it down inside the stack pack.

When Should You Adjust Your Lazy Jacks?

We do not adjust ours at all. When you raise the mainsail, the boom lifts higher than it does when the weight is on the topping lift. This creates slack in the lines when raising the mainsail. When we drop the mainsail, we first ease our main halyard down until the topping lift is tight. This brings the lazy jacks back to their usual tightness, and then we finish dropping the sail.

If we adjust the topping lift for any reason, we adjust the topping lift. We have a line marked on our topping lift that aligns with the topping lift clutch in the cockpit. This ensures we get the boom to the same height every time.

Our Biggest Problem

Very early in cruising, we discovered that when raising your mainsail, the lazy jacks get in the way. Our mainsail has full battens, and the leech (the aft part of the sail which flogs) end of the battens often get caught on the upsidedown Y shape in the legs.

Original lazy jacks.

We complained about this problem to our friend Spike, who was the skipper of the Gunboat Tribe. He pointed out an easy solution: add a second pulley (or low-friction ring) out from the mast. David and Spike got to work and lashed a low-friction ring on our diamond stays using thin Dyneema. This angles the lazy jacks away from the mast and makes it less likely that they will catch the battens while raising the mainsail.

Newly installed low-friction ring.
New lazy jack set up.
New lazy jacks set-up viewed from above.

The Boat Galley offers a way to loosen your lazy jacks and move them forward just before raising the mainsail, but that’s two trips to the mast that you may not have to take.

Replacing Lazy Jacks

Once set up properly, they are very easy to replace. I’ve replaced ours once. All you need is the replacement line and your knowledge of the most important knots for sailors – the bowline! The legs of the lazy jack attach to the stack pack loops with a simple bowline knot. Use a hot knife with the rope cutter attachment to trim your rope and use our tricks to replace running rigging to remove the old lazy jack and replace it with the newer one.


  1. Great idea…but how do you attach the extra pulley? With lashings you say…but doesn t it slide down? Thanks

        1. No, it doesn’t interfere with the boom swing. The lazy jacks are still even and they have no problem going to one side or the other. We often move the boom at anchor when we are using the lounge deck. Under sail, of course, your lazy jacks are loose as the main is holding the boom up.

  2. Thanks, we are still searching for a solution… we’ve been using Cat Impi’s solution which is just free the main sheet an let the boom out to follow the wind, and this works well in stable seas and constant wind, but not so much if the seas are rough… talked to one guy who ran the lazy Jack’s to blocks on the end of the spreader and then to the mast and down; never got a clear answer as to how he controlled the extra tension in the lines when down wind and the boom was well out…

    Pulling the lazy jack’s forward and down is appealing, but wonder if the sail would fall out a bit over the boom… might try it and see… I don’t think I need to do anything but connect a line to the top block on each side and pull it down once I loosen the lazy jack’s…

    Your way maybe simpler, but a couple of questions:
    1) any concern about extra tension on your rigging.
    2) was there issue with extra tension on the jack lines when the boom swings out downwind.

    Getting used to life on the hard?


    1. Hey Rick! We haven’t had any issues with additional tension anywhere. Let us know which route you decide to go with!

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