Riveting a cleat onto mast

LouisBrowne

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I want to rivet two horn cleats to the mast of my boat for securing the falls of the stack-pack lazy jacks.
I have never tried riveting before and I'd be grateful for advice on the following questions:
1. How do I decide the length of the rivet?
2. What type of rivet should I use (stainless, monel, aluminium?)?
3. I have a lazy tongs riveter: is this the right gadget?
4. If the best advice is to use monel or stainless steel how do I prevent corrosion of the mast (aluminium)?
Any other advice?
In case it's relevant, the boat is an MG335, mainsail area 30 sq.m. ; the weight on the lazy jacks is quite substantial.
Many thanks
 

ctva

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On our Jeanneau 342, we have a simple plastic 4" cleat with 5mm cord for the lazy jack. Not a lot of force on them. If you are using the Barton system, it is massively oversized with 10mm (I think) rope. Keep it small and simple with plastic cleat and monel rivets.
 

SailingDog

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A number of manufacturers rivet fittings to mast, a straight forward approach would be Monel rivets and some Harken Tef gel to ward off any corrosion. As for size it needs to fit the cleat, small enough to go through the hole with a big enough head to hang on, it doesn't need to be massively long.
 

thinwater

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a. Make sure nothing else can snag on the horns.
b. Rivnuts are not flush (about 0.065 above for 1/4-inch). The cleat may wobble. You will need a gasket/shim to make up the thickness.
c. Rivnuts leave a bigger hole and are hard to remove.

I would only use a Rivnut if I thought it highly likely that I would remove the hardware and then reinstall it, like a wind instrument or something that might need removed for maintanance. That is what they are for.

Nearly all manufacturers use 3/16" SS or monel rivets. A little Tefgel an get on with life. The corrosion will take 20 years to matter. If you want to remove it, they are easy to drill out.

Bolts and tapping are another option.
 

dunedin

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There shouldn't be much load, but there's always that time when you're tired and a bit stressed, and you forget to take up the topping lift when you drop the sail.
Or the masses of boat nowadays with rod kicker and no topping lift.

In my experience you can get a fair strain on the lazy jacks if anything goes imperfectly, particularly if sail catches slightly most way down then the wind fills it. Shouldn't happen regularly, but if drop sail a few hundred times it will sometimes - and I don’t want my lazy jacks to break in that event
 

Poignard

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There shouldn't be much load, but there's always that time when you're tired and a bit stressed, and you forget to take up the topping lift when you drop the sail.
Yes, it's easily done :rolleyes:

The downhauls for my lazy jacks are made off on nylon cleats fixed to the mast with self-tapping screws and I thought they would pull free when I forgot the topping lift but they didn't and showed no sign of strain. Of course the load is lengthwise, so not tending to pull the cleat away from the mast, so provided the screws are tight, it's not too bad. But I have been careful since then. In any case, my wife doesn't take kindly to having the boom dropped on her!
 

alahol2

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28ft boat, Boomstrut, no topping lift. I have never had the need to adjust the stackpack lazyjacks which are 5-6mm braid.
The fall of the lazyjack is adjusted and made off to the inboard suspension point of the stackpack at the start of the season. Less rope, no cleats to fit or catch other ropes.

Stackpack.JPG
 

LouisBrowne

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Thanks very much for the helpful comments.
I'm still unsure about the length of the rivet: I assume it needs to be the height of the cleat plus the thickness of the mast plus a bit to make the fixing on the inside of the boom: what should the 'plus a bit' element be? Is 5mm enough, 10mm?
With regard to the weight taken by the lazy jacks, the boat has a solid vang without a spring and it allows the boom to drop rather too low. As a result when I drop the main the weight of the boom is taken by the lazy jacks for a few minutes until I have shackled the main halyard to the end of the boom and have taken up on it.
 

Poignard

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28ft boat, Boomstrut, no topping lift. I have never had the need to adjust the stackpack lazyjacks which are 5-6mm braid.
The fall of the lazyjack is adjusted and made off to the inboard suspension point of the stackpack at the start of the season. Less rope, no cleats to fit or catch other ropes.

View attachment 129374
It's very much a matter for the individual to decide, but I like to be able to pull the lazyjacks forward to the mast when they are not needed however I can quite see that having a stackpack makes that impossible.

There are two reasons:

1. it avoids chafe between the lazyjacks and the sail; and

2. they don't get in the way when I am hoisting the mainsail.
 
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Daverw

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So what stops the rivnut from simply spinning when trying to tighten the bolt - particularly as would want TefJel to separate nut from mast?
The rivet nut is compressed into the hole with a rivet nut setting tool and then grips, use an Ali rivet nut and no issues
 

BabaYaga

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Thanks very much for the helpful comments.
I'm still unsure about the length of the rivet: I assume it needs to be the height of the cleat plus the thickness of the mast plus a bit to make the fixing on the inside of the boom: what should the 'plus a bit' element be? Is 5mm enough, 10mm?

My understanding is that the length of the rivet should be one third longer than the combined thickness of fitting + mast wall. Example fitting 6mm + mast wall 3mm = rivet 12mm.
 

ctva

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Thanks very much for the helpful comments.
I'm still unsure about the length of the rivet: I assume it needs to be the height of the cleat plus the thickness of the mast plus a bit to make the fixing on the inside of the boom: what should the 'plus a bit' element be? Is 5mm enough, 10mm?
With regard to the weight taken by the lazy jacks, the boat has a solid vang without a spring and it allows the boom to drop rather too low. As a result when I drop the main the weight of the boom is taken by the lazy jacks for a few minutes until I have shackled the main halyard to the end of the boom and have taken up on it.
Your vang needs adjusting as not fitted correctly. Sort that and the lazy jacks become simple.
 

Neeves

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I might suggest you add a topping lift. We did not have one (we don't have a vang either :) ). I installed one - not difficult. But you will need another horn cleat.

Get up to the top of you mast and check if there is a spare sheave or room for a sheave. Use the spare or add one - it makes reefing easier.

Jonathan
 

LouisBrowne

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My understanding is that the length of the rivet should be one third longer than the combined thickness of fitting + mast wall. Example fitting 6mm + mast wall 3mm = rivet 12mm.
Thanks very much; that's very helpful.
I might suggest you add a topping lift. We did not have one (we don't have a vang either :) ). I installed one - not difficult. But you will need another horn cleat.
Unfortunately there is no spare sheave nor space for one; a new vang is the only option. Cleats for the falls of the lazy jacks will tidy things up at the bottom of the mast so it's a worthwhile project even if I do change the vang for one that holds the boom up at the correct height.
Many thanks to everyone who has offered advice.
 
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