gluing a wooden boom

Challenger949L · Post by **Challenger949L** » Tue Apr 29, 2008 12:43 pm

My wooden boom has some splits along the seams. They do not run the entire length of the boom. I plan to glue the cracks, and clamp them with some tie-down straps. What would be the best glue for this application? Epoxy, thickened epoxy, Gorilla glue, or something else?
Jimmy Small
Triton 662
Challenger 949L

Post by **Tim** » Tue Apr 29, 2008 1:12 pm

I'd use thickened (with silica) epoxy--thick enough to stay in place and gap-fill, but not so thick that it's a hindrance. Ketchup+, I'd call it.

David · Post by **David** » Tue Apr 29, 2008 1:27 pm

Is your boom bright or painted?

David · Post by **David** » Tue Apr 29, 2008 1:38 pm

It sounds like the glue failed in those seams. To repair it properly you need to remove the old glue on either side of the joint so you are gluing together clean wood. If you can't take the boom apart to reglue the whole spar, if painted, I would use a router to route out the seam, wet everything out with unthickened epoxy, then lay in a beveled wood spline in thickened epoxy.

Hirilondë · Post by **Hirilondë** » Tue Apr 29, 2008 7:34 pm

You can certainly try to glue up the splits. You may find however that it doesn't hold. You can never really get to the spot where the split ends and undisturbed wood or joint begin. Then it can act like the zipper that has started to come apart at one end. It may be more prudent to route out a channel slightly longer than the split and glue in a spline.

Challenger949L · Post by **Challenger949L** » Tue Apr 29, 2008 9:40 pm

Here is a picture of the boom showing the cracks.

Jimmy Small
Triton 662
Challenger 949L

Triton 185 · Post by **Triton 185** » Wed Apr 30, 2008 1:07 am

From the picture it seems that the boom is laminated from staves....and is perhaps hollow.....or am I not seeing this correct.

For any long term repair, you are best to remove the old glue and ensure a clean cut wood surface in the internal joint. This will allow increased adhesion and filamenting that will result in a stronger bond.

If the boom is staved, or even if it is a solid boom with checking, I would go the router and fillet approach.

Quetzalsailor · Post by **Quetzalsailor** » Wed Apr 30, 2008 8:49 am

Jim,

What percentage of your 14' +/- boom has failed joints? Can you see whether the joints are T & G or splined? Maybe something other than straight through?

I had failed joints on my Flying Dutchman mast. Wall thickness is about 3/8". Failure was only about 2' long in a couple places of a 26' mast. I used one of the dandy, reversible fine-bladed saws sold for dovetails and sawed the joint open. It really did not remove much wood but should have cleaned the crumbly urea resin out. I then worked WEST into the join and clamped. About 18 years, but only a few hours service, no further deterioration.

I scrounged a discarded Hinckley B40 mast for the spruce in it. Joints were maybe 30% failed. Given judicious force, another 30% let go. I sawed the remainder but the problem was that the sides were glued into rabbets on the fore and aft C sections (you can't put both glue faces into tension at the same time).

Presuming simple joints and, say, 1/3 failure, I'd cut that boom apart and reassemble with the best, clean joints that I could, using epoxy. And particularly because of the way the wood looks like it's warped so that the joints are more open. Given that the interior faces of hollow spars are not usually varnished or sealed, there's opportunity for water collecting and rot. Another excuse for opening it up and coating it.

If you want a painted spruce B 40 boom, come and get it.