input on repairing broken boom

[Klos2019]

Looking for some input on repairing a broken boom. 1982 Whitby42 Ketch and the main boom recently broke about 1/3 of the way out from gooseneck. I am looking to make this repair myself.


This is actually a break that had been repaired bt a previous owner with a wood and epoxy solid sleeve and the wood finally gave way.


The boom is a round tube profile at 4.5" outer diameter with 0.125 wall thickness in I am assuming 6061 aluminum. My thought is to insert a new sleeve of aluminum tube and rivet it with monel rivets.


One of the challenges is finding al tubing with the correct OD to use as a sleeve. I have found source for 4.5 OD tubing but this leaves me with a 0.125 gap all around. Fitting exactly would likely be impossible to fit into boom, but I feel that 0.125 may be too sloppy.


Questions
What would you suggest to shim or otherwise account for gap on inner sleeve?
How long should the inner sleeve be? (boom is 15 feet long)
Is a sleeve wall thickness equal to boom wall thickness sufficient?
I am not concerned about aesthetics, do I also need an outer sleeve?


Of course if Im overlooking anything, I'll welcome input.


Oh, and new (even used) boom is not likely to work as I am in the Caribbean and my current setup has all reefing hardware on the boom and rerigging for internal reefing lines, etc is beyond my goals at the moment. Not that I wouldn't jump on a used boom with similar setup, just not thinking the odds are in my favor here.


thanks


Karl

[neilpride]

There has been much discussion in CF about the aspect of the sleeve not fitting perfectly.

The problem is to bring the sleeve once put to close fit, which would be ideal, if you can bring it with rivets, perfect.

You can also make the sleeve hybrid, i.e. semi OD, with a cut at the bottom and fit it to close fit.

3X3 ft could be enough.

Boom thickness sleeve thickness equal no problem.

You don't need an outer sleeve.

If you have a boom vang it would be ideal to move it to where the future sleeve will be.

You would have to keep the sleeve from reaching where the gooseneck fits.

[Bowdrie]

Typically you get a section of tube with an OD that is as close to the ID of the boom as is practicable.
Then slit the tube lengthwise to make two halves which are independently fastened inside the boom in the 0-180 degree positions, the "seams" as it were, in the 90-270 position.
Internal constraints may cause the positions to be shifted, that's ok.
The centerline rivets are done first to lock the sleeve(s) into place, then working away from the centerline to pull the sleeve edges into conformity with the ID radius of the boom.
Sometimes only one slit is required, it depends upon how close fitting the parts are.

[Cheechako]

Originally Posted by Klos2019

Looking for some input on repairing a broken boom. 1982 Whitby42 Ketch and the main boom recently broke about 1/3 of the way out from gooseneck. I am looking to make this repair myself.


This is actually a break that had been repaired bt a previous owner with a wood and epoxy solid sleeve and the wood finally gave way.


The boom is a round tube profile at 4.5" outer diameter with 0.125 wall thickness in I am assuming 6061 aluminum. My thought is to insert a new sleeve of aluminum tube and rivet it with monel rivets.


One of the challenges is finding al tubing with the correct OD to use as a sleeve. I have found source for 4.5 OD tubing but this leaves me with a 0.125 gap all around. Fitting exactly would likely be impossible to fit into boom, but I feel that 0.125 may be too sloppy.


Questions
What would you suggest to shim or otherwise account for gap on inner sleeve?
How long should the inner sleeve be? (boom is 15 feet long)
Is a sleeve wall thickness equal to boom wall thickness sufficient?
I am not concerned about aesthetics, do I also need an outer sleeve?


Of course if Im overlooking anything, I'll welcome input.


Oh, and new (even used) boom is not likely to work as I am in the Caribbean and my current setup has all reefing hardware on the boom and rerigging for internal reefing lines, etc is beyond my goals at the moment. Not that I wouldn't jump on a used boom with similar setup, just not thinking the odds are in my favor here.


thanks


Karl

It sounds like you need a 4.25 OD tube for an inside sleeve. Right?
If you cannot find that, you should take a size that is close, but larger.
A saw cut lengthwise and you can reduce it to slip inside . If the tube you use is close, like 4.5" OD then it will fit very well if you take out about a .90 wide strip on one side. (recalc these numbers accurately with what you have) You can then squeeze the tube down to slip in.

Once you have the sleeve, consider using a structural epoxy (this is a thick paste texture) between the sleeve and the boom. Drill and rivet before the epoxy sets up.

This is what a pro rigging company who does various mast sleeves and custom racing spars did for me on a mast. They bought the identical mast extrusion piece and slotted it to get into the mast. then did the epoxy and many rivets line spaced 1.5" all over in a pattern.