Lazyjack Rigging Design [Master Thread]

[Christian Williams]

I'm guessing 1/4", but I'll be able to measure tomorrow.

 

[Nick J]

Maxibraid - Yale Cordage

Maxibraid is a 12-strand single-braid rope constructed from High Modulus Polyethylene (HMPE) fiber. HMPE has the highest strength-to-weight ratio of any synthetic or natural fiber, and it floats. The integral Maxijacket High Performance coating firms the construction, increases wear life and...

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I used this stuff in 3/16". Defender was clearing it out a few years ago. It's bee great so far. Lazy Jacks don't need to be supper strong, just good abrasion and UV resistance, slippery, and easy to splice. Any 12 strand single braid UHMWPE line should work well and you don't need the super expensive heat treated stuff.

 

[peaman]

and easy to splice

Need for ease of splicing depends on how the lines are rigged. I have a pair of "uppers" attached to the mast and which terminate with a low friction eye several feet above the boom. Each end could be made with either a splice or knot. The "lowers" have no splices and is a single line which runs through the eye of the upper on one side, then down and under the boom, then up and through the eye of the upper on the other side, and finally back to a small pad eye on the boom, where it is anchored with a knot. I have de-rigged the lower for the winter to reduce wear, and will re-rig it after inspection in spring.

 

[Nick J]

On my previous boat, I temped in the lazy jacks with knots and sailed for a few weeks before taking them down and splicing in eyes. It was certainly doable, but the knots caught the sail more frequently than the eye splice with thimbles. I did use eye splice that screwed in to the boom, but you could use a knot at the bottom or soft shackles like the one in my pic above to make removal easier.

 

[Christian Williams]

I'm guessing 1/4" Spectra for my lazyjacks

No, it measures 5 mm, which is approx 3/16th. Anyhow, less than 1/4" works fine.

(Measuring rigged line diameter with a plastic micrometer is not very satisfying. I measured under tension, which I read somewhere is the way to do it.)

 

[Second Star]

On our system, which is very similar to the original post pictures, we have taken the end of the hoist and brought it back to the thimble of the second V. This allows us to pull the jacks back to the stowed position in comfort at the mast and hook them in the reefing horns as stated in one of the posts. Some experimentation showed that the jacks don't have to be fully pulled back to prevent the full length battens from catching on the jacks during hoisting. This method allowed partially deployed jacks to be tensioned up (tension of the hoist part and on the part attached to the thimble) and so stopped the bulk of the sail from falling off the boom. We eventually added a stack pack cover system that eliminated the need for partial deployment of the jacks for the above purpose but they still need them to be retracted to hoist the main.

 

[HerbertFriedman]

I am confused, with the stack pack, the lazy jacks hold up the stack pack, so if you retract the lazy jacks back to the mast, the stack pack flops down. Is not that a problem?

 

[Dave G.]

so if you retract the lazy jacks back to the mast, the stack pack flops down

On my boat which has a Doyle stack pack you cannot retract the lazy jacks without the "bag" collapsing. My sail and pack are sewn together and is designed to pull the sides of the stack pack up against the sail when you hoist. Not real happy with it from a performance point of view but it's sure nice to drop the sail and just zip it up. I have another main with a cover that is cut out for lazy jacks, so I'm going to try that sail this year and hopefully I can adapt the current LJ system to it. I'll need to extend the LJ legs(3/16 spectra) a few feet, mount eye straps on the side of the boom, and would like the ability to retract them to the mast. I know Doyle makes a stack pack system that is not attached to the sail but you need a loose footed main which I currently don't have.

 

[Second Star]

In the practical sense, with the jacks retracted, the stack pack more or less retains shape and doesn't fall over until the sail is hoisted. The attachment of the bag to the mast for about 2 ft does this. When you lower the sail of course the jacks are tightened up and the bag resumes it's shape.

 

[HerbertFriedman]

OK, worth a try but right now my lazy jacks are fixed to a fitting on the mast. I would have to change that fitting to a ring and lengthen the lazy jacks so that I could retract them before hoisting the main. Maybe at the next haul out.

 

[Nick J]

OK, worth a try but right now my lazy jacks are fixed to a fitting on the mast. I would have to change that fitting to a ring and lengthen the lazy jacks so that I could retract them before hoisting the main. Maybe at the next haul out.

I had the system on my 25+ rigged through cheek blocks on the mast which made the top section the adjustable one. Our 35+ is equipped with a Doyle stack pack and top section is fixed to the mast and the section on the stack pack closest to the mast ("second v" in Christians photo above) is adjustable. I think it works better and requires less line. I don't fully retract mine since I have the stack pack, but I do adjust it depending on the point of sail. It would be an easy change for your setup since the top section is already fixed.

 

[David Grimm]

Christian, Trying not to make a pest of myself here. Would you happen to know the spacing between the saddles on the boom for the lazy jack attachments location on your boat? I'm trying to construct these myself.

 

[Christian Williams]

I’m out of town, but I think if you look at the first picture in post #2 you can see the proportions. Looks like one point bisects the boom. The outer location depends on compromise between fouling full length battens and letting some sail be unsecured. I don’t think any of it is critical but a temp location of the outer point is good idea, just to see how the hoist works.

 

[David Grimm]

I’m out of town, but I think if you look at the first picture in post #2 you can see the proportions. Looks like one point bisects the boom. The outer location depends on compromise between fouling full length battens and letting some sail be unsecured. I don’t think any of it is critical but a temp location of the outer point is good idea, just to see

 

[David Grimm]

What would be the pros and cons of attaching under the boom as opposed to the sides of the boom? You state preference but there may be more to it?

 

[kiwisailor]

My new boat has lazy jacks and I'm already thinking about converting to a dutchman system next season. Dutchman system is just so easy to use.

 

[David Grimm]

My new boat has lazy jacks and I'm already thinking about converting to a dutchman system next season. Dutchman system is just so easy to use.

For day sailing they're ok. Make sure the topping lift will adjust enough to get the boom off the bimini. After 3 days out in the Atlantic my Dutchman lines chafed through both to and from Bermuda. Lazy jacks seem more robust to me.

 

[Christian Williams]

pros and cons of attaching under the boom

I really can't remember. I think the rigger preferred one attachment point for both sides (that is, put one eye stap on bottom of boom for each "V"), but I thought it would look better if the lazyjacks were fixed to the sides. Less line rubbing on the boom, maybe looked neater. Either way is probably fine.

 

[Nick J]

I think mounting the lines to the bottom proved a little more support for the sail by allowing it to fold over the boom slightly. It also allows you to use a single eye for both sides, reducing the holes in the boom by half. Mounting the eyes on the side of the boom looks better, but doesn't support as well. I mounted my jacks on the bottom of the boom on my 25+ and I still had some issues with the sail falling off with the jacks retracted. If you intend to leave them up 100% of the time, I don't think it matters and the marginal improvement may not be worth the aesthetics to some. Stack height of the stowed sail will also be higher if mounted on the side of the boom.

For spacing, there's a lot of factors. I found it best to temporarily lash connection points to the boom, rig the jacks with inexpensive lines and bowlines, and test dropping the sail a few times. If your current main is not loose footed, run a line down the bottom of the boom and put the attachment point on there (horrible picture, but hopefully it makes sense):


If you have more than one main, try it with each sail. What worked for my old main was not optimal for the new one (partial battens on the old vs half full on the new sail). Look for points on the boom the sail wants to fall out of the lazy jacks, battens catching on the way up and down, natural folds in the sail catching when stowed, boom fittings, and even aesthetics. Once you're satisfied with the configuration, start drilling and use the temp jacks as templates for the final material. If using dyneema (highly recomended due to how slippery it is), a simple brummel eye splice with a thimble provides a very low profile connection that minimized the chance the sail will catch it.

 

[Christian Williams]

I imagine it does depend on weight and maybe age and crispness of sails. Mine are stiff Dacron, flake high, and don't droop over the boom at all.