Lazyjacks, Slab Reefing and Mainsail Covers

If you've got a slab-reefing mainsail on your sailboat, you need lazyjacks. OK, they're not absolutely essential but they'll definitely make for an easier time when pulling a slab in, or stowing the sail along the boom at the end of a day's sailing.

Without lazy jacks you'd need to find some other method of controlling the redundant area of sail that's created when a slab is pulled in.

Traditionally, the solution was to use reef cringles and pennants. The cringles were the rows of holes along the sail at each of the reefing points and the pennants were the short lengths of line secured through them.

These are tied under the foot of the sail - but never below the boom - leaving the sail tamed and bundled along the top of the boom. Neat and tidy, but creating point loads in an unreinforced section of the sail panel.

Many a sail has been damaged in this way, particularly if a reef is pulled out with the pennants still tied in.


Components of a Set of Lazy Jacks

Slab reefing mainsail with lazyjacksLazyjacks retain the sail on the boom when a slab is pulled in.

There's nothing high-tech about lazy jacks; just a couple of fittings on each side of the mast, several lengths of 10mm (3/8") line, a few thimbles and some padeyes for the boom.

The blocks are fitted around a half to three-quarters of the distance between the gooseneck and the top of the mast and the cleats at a convenient point near the gooseneck.

The 'cats-cradle' part of the lazy jacks will depend on the length of the boom, and the padeyes located accordingly - unless you chose to incorporate a mainsail cover as shown here.

Although you don't have to use swivel blocks at the intersections of the lines - hard eyes using plastic thimbles will do at a pinch for small mainsails - the lower friction of swivel blocks make the system more efficient.

So why bother with complex, expensive in-mast furling or in-boom furling systems?

You just can't beat slab reefing and lazy jacks for simplicity, reliability and value for money. 


Combining Lazyjacks with a Mainsail Cover

Lazy jacks attached to mainsail coverOften called a 'Stack Pack'

A very nifty canvas sail cover can be combined with lazyjacks.

Not only will the flappy bit of the reefed sail be contained, with one of these 'stack-packs' the sail can be dropped, the cover zipped and the gin and tonics dispensed in half the time it takes to drag a conventional mainsail cover out of its locker.

I use a similar system on Alacazam with all controls at the mast and it works very well, although it would be quite simple to lead everything back to the cockpit. But I've got enough string there already...

Artwork by Andrew Simpson


Hoisting the Mainsail

Whilst lazyjacks efficiently collect the main and guide it onto the boom as it's dropped, they are equally efficient at trapping the ends of the battens as the sail is raised.

The solution is simple - slacken them off, pull them forward and secure them on the mast. The reefing hooks, if you have them as part of your slab reefing system, are ideally placed for this.


Lazyjacks: A Few FAQs...

How do I rig lazyjacks on my sailboat?

There are different ways to rig lazyjacks, depending on your preference and your sailboat's configuration. One common method is to attach a small block on the mast where the lazyjack control line will turn and come down to deck level. Then add a cleat on the mast where you'll cleat off the lazyjack control line. The control line will run through the block and split into two, three or four legs that will attach to the boom or a stack pack. You can use snap hooks, eye straps, or pad eyes to secure the legs to the boom.

How do I hoist a mainsail with lazyjacks?

To retract lazyjacks when not in use, you need to release each lazyjack where it's cleated on the mast, pull the two lines that are attached to the boom forward, and hook them on the reef hooks or the cleats that the lazyjacks are on. Then tighten up the lazyjack lines. The lazyjacks now form a reverse "L" going along the boom and up the mast. This way, they will not chafe on the main or interfere with the sail cover.

How do I reef the mainsail with lazyjacks?

To reef the mainsail with lazyjacks, you need to follow these steps:

  • Head up into the wind and ease the mainsheet and vang;
  • Release the halyard and lower the sail until it reaches the desired reef point;
  • Secure the tack reef line to either a hook or a cleat at the gooseneck;
  • Pull in the clew reef line until it is tight and cleat it off;
  • Tension the halyard and trim the mainsheet and vang;
  • Adjust your course and sail trim for your new sail area.

The lazyjacks will help to hold the lowered part of the sail on the boom or stack pack. You may not need any additional securing, depending on the conditions.

How many legs should I have for my lazyjack system?

The number of legs for your lazyjack system depends on your boat size and boom length. Generally, smaller boats or shorter booms can get away with two-leg systems, while larger boats or longer booms may need threeor four-leg systems. The more legs you have, the better your sail will be contained when lowered.

What are some drawbacks of lazyjacks?

Lazyjacks are not without their drawbacks. Some of them are:

  • They can snag your battens or headboard when raising or lowering your sail, especially in windy conditions or if you are not pointing directly into the wind;
  • They can chafe your sail if left in place while sailing, especially on long passages or in strong winds;
  • They can interfere with your sail cover if not rigged properly or retracted when not needed;
  • They can add windage and weight aloft, which may affect your boat's performance.

What are some alternatives to lazyjacks?

Some alternatives to lazyjacks are:

  • A Dutchman system, which consists of thin monofilament lines that run through grommets in your sail and guide it into neat folds when lowered. This system requires retrofitting your sail and may be more expensive than lazyjacks;
  • A Lazybag system, which combines a sail cover and lazyjacks into one package. This system offers convenience and protection for your sail, but may also be more costly and bulky than lazyjacks;
  • A furling system, which allows you to roll up your sail inside the boom or the mast. This system eliminates the need for lazyjacks, but also changes the shape and performance of your sail. It may also require a new sail and a lot of modifications to your rig.

How do I maintain my lazyjack system?

To maintain your lazyjack system, you should:

  • Check the condition of the lines, blocks, cleats, and attachments regularly and replace them if they are worn or damaged;
  • Keep the lines clean and free of dirt, salt, and UV damage. You can wash them with freshwater and mild soap if needed;
  • Lubricate the blocks and cleats occasionally to ensure smooth operation;
  • Retract the lazyjacks when not in use to prevent chafe and windage.

How do I adjust my lazyjack system?

To adjust your lazyjack system, you can:

  • Change the length of the control line or the legs to suit your sail size and shape. You can use knots, splices, or shackles to adjust the length;
  • Change the position of the attachments on the boom or stack pack to create more or less space for your sail. You can use different holes, eye straps, or pad eyes to change the position;
  • Change the angle of the risers or the legs to create more or less tension on your sail. You can use different blocks, fairleads, or pad eyes to change the angle.

The above answers were drafted by sailboat-cruising.com using GPT-4 (OpenAI’s large-scale language-generation model) as a research assistant to develop source material; to the best of our knowledge, we believe them to be accurate.


Read more about Rigging and Sail Handling...

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