Vanguard Spruce Boom

[Bill Vanguard 281]

Hello folks - I am working on repairing some rot in the center of my spruce boom. Have been able to cut out in between the top and bottom lamination and remove the punky material - (it is amazing how strong this wood is after 40 years) What would be the best joint design and repair method to install a new section about 18" long in between the top and bottom "laminations" I was thinking a scarf with opposite angles on either end.
Set in an epoxy paste the screwed and clamped togethor until it dries.

I also want to fill all the old screw holes for the sail foot track as half of them were pulling out - then reverse the track and miss the old holes. What would be a good product for this.

Any thoughts would be appreciated. Thanks Bill

[Tim]

A scarf joint like you describe will be strong; still, what will really hold the boom together and join it with the repair is the epoxy you use to install it. Without seeing what you have going there, it sounds like a good approach, though.

I would also use thickened epoxy to fill your old screw holes.

[Quetzalsailor]

A scarph will work fine. If you're putting a wedge-shaped dutchman in from the end (or did I misread?) the only difficulty is making a lovely fit where it shows. Harder to work where you can't get your tools. Where hidden, inside, I think the fit can be a little sloppy. The stress is mostly compression.

I did two dutchmen on my mid'50's Flying Dutchman's wood mast. These were on each side of the mast at the hounds, where a fractional rig's shrouds are through-bolted. Lots of stress in bending so I cut a long scallop out of the mast and took care to not scallop into the hollow interior. I could judge thinness as I approached by sound and color; the inside of the mast is unfinished and thus a bit browner than the rest of the wood. That kept the epoxy from gluing the halyards. The slope at the ends of the scallop was kept to about 12:1. 12 years but only two seasons of use, they look fine.

[Hirilondë]

The 2 primary reasons for a scarf joint are added gluing surface and a graduation in the joint such that there is always some of each layer (or the one layer like in a toe rail) of wood at any given point (a butt joint leaves a complete void of that layer at the joint).

If I understand your situation you are replacing part of the middle layer of a 3 layer solid laminated boom? Does the rot go all the way through or just a spot on one side? If all the way through the hardest part of the repair will be getting a well fit piece into the space between the other 2 layers, and doing so without losing most of the epoxy you spread on the pieces and thus leave voids in the glue joint. If this is a box spar (hollow) then it is a different repair all together. I think we need pictures and/or more description to better understand your situation and be able to offer accurate advice, I do at least. Will the rest of the boom, excluding the partial middle lamination be left intact during the repair?

As for the screws: I never use any repairing spars. Spruce glues very well.

I like to bung old holes for repairing them, even if they won't be redrilled. A drilled out and bunged hole is never quite as good at holding fasteners as the original wood, but quite good. I never glue bungs in when they cover fasteners that I might want to ever remove (I use old varnish or shellac), but for repairs like yours I would use epoxy to glue them in.

[CharlieJ]

Totally agree on the "No screws" part also. I wouldn't put any in the repair.

End for ending the sail track is a workable idea I would think, and as Tim said, I'd use thickened epoxy in the holes OR a glued in peg. Depends on just how wallowed out the holes have become. Since the plugs would be under the sail track they don't have to be particularly pretty. One trick I've used to fill old screw holes is glued in wooden golf tees. Tap them in and once the glue cures, cut 'em flush with a chisel.

[Bill Vanguard 281]

Folks thanks for the comments. The rot went all the way through. I have excavated the rot and have mitered all 4 sides of the hole towards the center of the boom. (the boom is not hollow) After looking at this more I was thinking of doing a two piece insert.
Fairing and shaping a replacement piece to fit the mitered ends epoxying the first piece in place letting that cure and then fitting the opposite side in.

I have pictures but am not quite savy enough to get them posted.

Bill

[Hirilondë]

I have excavated the rot and have mitered all 4 sides of the hole towards the center of the boom. (the boom is not hollow) After looking at this more I was thinking of doing a two piece insert.

That is exactly where I was going if my assumptions were correct. This way you can assure a good epoxy coating and that is stays on during the fitting together for a good bond. You might try dry fitting both piece simultaneously and see if you want to try gluing both at once. The epoxy squeeze out and runs from the first piece may make more work for fitting the second one after. The last thing I would add would be to make your repair pieces a little proud when they fit in. Then dress them down to flush with a hand plane and/or sander to flush after you glue.

Seems like you have a plan. Now for my favorite phrase: All you gotta do is......

[CharlieJ]

In that case a two part insert would be what I would do also. Let them stand proud, then hand plane as Hirilond? suggests.

I see no problem with fitting and gluing one side, then the other. Just don't let the epoxy get totally cured after the first one- while it's still green you can easily chisel or scrape out any drips or ooze, then lay in the second side. If you catch it while it's green it'll come out like soft plastic.