Lazy jacks for gaff rig

[Jfitzger]

I'm putting together a lazy jack system for a gaff Sunday Cat and was looking for advise. My experience with lazy jacks has been exclusively on large Marconi rigged boats that have also had a stack pack.

The Sunday Cat is sailed on a small lake and is used mostly for socializing and day sailing. Lot's of stops and starts for docking, swimming, etc. I use a trolling motor two or three times a year but everything is done primarily under sail. I figured out how to trim the gaff reasonably quickly but the gaff itself drives me nuts. Dropping the sail quickly without having to worry about the gaff swinging wildly around would be helpful.

My plan is to use 1/8" dyneema and low friction rings which run to two cheek blocks on the mast. These will run a few feet down the mast and be connected to a 1/4" line of double braid. This runs down to a cleat on the mast. This setup will allow enough slack that the lazy jacks can be brought down and run along the boom to mast. This will allow the sail cover to go on without modification as well as to clear the gaff when reefed. It also means the jacks can be used as a topping lift.

I did a quick 1/3 scale mockup to check how the lines hang under tension and transferred that info into CAD. I based the basic setup on guides I found online. I moved the second leg closer to the mast to better capture the gaff. The one concern I have is the whole setup is far less vertical than is ideal. I was wondering what others have experienced and if anyone had opinions on my proposed layout.

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[David W Pratt]

Looks nice!
Since the topmost point of attachment to the mast is above the gaff jaws, you could move that up. I would suspect that with only a 13' boom, you could live with only two, the aft most, and the forward. If the after ends are led forward, via cheek blocks on the boom, and connected, a single line running under the boom, forward to where it can be reached even with the boom fully swung out, there will be little difficulty in snugging them up, and dropping the sail, even on a run.

[stromborg]

This has worked for me. The lazyjacks meet the mast at the same height as the throat halyard, you need to have some room between the "legs" for the boom and jaws as they go up the mast. Mine are arranged so they work in conjunction with a topping lift, as the peak and throat come down the boom drops a bit until it gets "caught" by the jacks/topping lift lines.

One trick is to make sure to drop the throat and peak together. If only the peak comes down it is possible for the yard to pop outside the lazyjacks, not something you want to have to sort out in any kind of seaway.

[John B]

The top line in the drawing, the one all bent by the modern style lazy jack look, is usually a topping lift. One on either side.
Just splice in droppers off that and tie them under the boom to get optimum length . The trick with the topping lifts is to make them land on the boom at a point further in than the gaff head lands when stowed, so its always captured.

[wizbang 13]

Make sure that when all is said and done, the lines get looser as they get closer to the mast.

[Jfitzger]

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Thanks for the responses. It's been very helpful.

I would suspect that with only a 13' boom, you could live with only two, the aft most, and the forward.

I think that would work on a Marconi but I can't see how that would capture the gaff. Perhaps if the forward leg was inbetween the forward two legs in the drawing.

Since the topmost point of attachment to the mast is above the gaff jaws, you could move that up.

This has worked for me. The lazyjacks meet the mast at the same height as the throat halyard, you need to have some room between the "legs" for the boom and jaws as they go up the mast.

I will try a mock up attached higher up the mast. It's a bit easier since there's no gaff jaws. It's attached with a slug. I want to experiment to see if I can get away with easing the lazy jacks without taking them down when reefed. I don't know if this will lead to a fouled gaff or tangled jacks.

The top line in the drawing, the one all bent by the modern style lazy jack look, is usually a topping lift. One on either side.
Just splice in droppers off that and tie them under the boom to get optimum length . The trick with the topping lifts is to make them land on the boom at a point further in than the gaff head lands when stowed, so its always captured.

By using the arraignment as drawn it brings the top line in at steep angle. I'm hoping that keeps it further from the gaff when reefed.

The top line is essentially a topping lift. It's two lines go through cheek blocks on the mast, run about halfway down and are spliced to one. It gives plenty of slack without having to worry about operating both sides independently.

I'm wondering what the advantage is of doing drops from the topping lift. My experience has only been with modern lazy jack systems. I like how all the legs automatically have even tension. I wouldn't consider using blocks but splicing in low friction rings is easy and cheap.

Make sure that when all is said and done, the lines get looser as they get closer to the mast.

Not sure how I would do this, at least not when the lazy jacks are under tension. Unless I'm misunderstanding, which is entirely possible, lazy jacks spread the tension automatically.

Thanks again for all the advise. The advantage of the Sunday Cat is mast can swing down with little effort in less than a minute. I can easily do a few mockups on the boat and figure out the setup.

[wizbang 13]

If the lazy jacks tension up the same as the topping lift, the boom will be harder to lift . Geometry. Imagine if the topping lifts only reached three or four feet back .

[Mike1902]

Reading this thread prompted me to rig up some ideas I've had about lazy jacks for the dinghy, some of these ideas may be of use to you.
The dinghy gaff sail dimensions are not huge 9' luff, 7' head, 15' leech and a 9'4" foot which equates to about 83 sq feet.
It all goes something like this...
IMG-9369.jpgIMG-9370.jpg
The line on the outer right represents the leech.
The topping lift shown just inside of that will have two rings sewn onto it.
The lazy jack line will be fixed at an outer point along the boom. This point is where the lower ring will touch the boom when the topping lift is laid along it, same again with the top ring.
This line goes up through the rings then down through a hole in the cleat under the boom and repeats on the other side, the line is one piece.

IMG-9373.jpgIMG-9380.jpg

When reefing, the lazy jacks can be tensioned, which pulls the topping lift forward and raises the boom.
The sail can be reefed and then the topping lift released, the tensioned lazy jacks keeping it forward and out of the way of the gaff. If the topping lift has the potential to be in the way of the gaff ,as you mentioned in your post, then tensioning the lazy jacks again and easing the topping lift will bring it all forward a little more.

IMG-9379.jpg
The topping lift can also be brought right forward to the mast and any slack in the lazy jacks taken up, coiled and belayed on the boom cleat.
All in all this small set up seemed to work quite well.
Hope you get something out of it.
I plan to take it one step further and place big game fishing swivels in line on the topping lift above the top lazy jack to take out any halyard twist that may foul things up.
I have done this (swivels) on my yacht Janet and it works well.

[rbgarr]

If the issue for you is the gaff swinging about and knocking your head run a topping lift from the masthead to the end of the boom on ech side. Cleat them about midway along the boom toward the gooseneck. Loosen them when sailing, tighten before dropping the gaff. The topping lifts will keep the boom up and gaff between.

[Jfitzger]

Reading this thread prompted me to rig up some ideas I've had about lazy jacks for the dinghy, some of these ideas may be of use to you..

Your response is super helpful. I still have my mock up setup so I will goof around with your approach.

IMG_4363.jpg

If the lazy jacks tension up the same as the topping lift, the boom will be harder to lift . Geometry. Imagine if the topping lifts only reached three or four feet back .

Makes sense. Thanks for the clarification.

I think I got my head wrapped around what I need to do. I'm going to try a few more things with the scale mock up and than move on to mocking up on the full size boat.