Epoxy for cap rail repair

[SeaSloth]

A few spots on my stern caprail are in need of repair. One spot is where a chock should be. It appears that water infiltrated the screw holes and the wood around them rot. Another place is where the dingy hoist attaches. The screw holes there appear to have stripped from one too many retightenings. The wood also appears to have some rot. It appears that the rot is localized to these two small areas.

Rather than replace the entire caprail I was considering using g flex epoxy to patch the questionable areas. Based on my research it appears that this stuff can be drilled and screwed without cracking.

Does anyone have any thoughts or advice about this?

[casual]

Don't know about Flex but have tried thickened epoxy in the past to repair screw holes.I did not have good luck. After this I began over sizing the holes and filling with an epoxied in teak plug never had one I could not tighten that way.

[s/v Jedi]

What you need is a special wood repair epoxy, or make your own.

G-flex is a good start. You need to find sawdust from the same wood that you are repairing, and use that to thicken the mixed epoxy to a paste-like consistency.

I would use a hole-saw to partially drill into the cap rail (followed by hand tools to dig it out) so that the repair looks like a plug. Make sure you get all the affected wood out.

Epoxy can't stand UV, not even for a couple of days (will change color) so keep it covered until you're ready to varnish it. If the cap rail isn't varnished, you need to make a plug of the same wood that goes in instead of the epoxy. I would prefer to do that anyway.

[capt-couillon]

If possible (depending on cap-rail configuration) we should be using through bolts rather than screws. Difference in expansion rates between metallic threaded fasteners and wood will eventually hog out the hole regardless of strain. If unable to through bolt, might think about epoxying in a threaded bronze or ss insert.

[s/v Jedi]

Originally Posted by capt-couillon

If possible (depending on cap-rail configuration) we should be using through bolts rather than screws. Difference in expansion rates between metallic threaded fasteners and wood will eventually hog out the hole regardless of strain. If unable to through bolt, might think about epoxying in a threaded bronze or ss insert.

Indeed. You can even drill through oversize, then fill with epoxy that is thickened with a high density filler, let it cure and then drill for through bolting. It'll be the last time that fasteners ruined the cap rail

[Suijin]

Depending on the size of the holes, you can drill them out and fill them with teak bungs the same diameter as the drill bit, seating them with a bit of epoxy. It will make a better and stronger (and better looking) repair than simply cramming a bunch of epoxy in them. If you have other damage that you can't fix with bungs or shims of wood, then I suppose epoxy is better than nothing, if you're not willing to cut out a section and replace.

I second the observation that the screws might not have been the appropriate fastener if they have failed and caused the rot. Otherwise it might just be poor/non-existant bedding that was to blame.

[SeaSloth]

None of the chocks are thru-bolted...something I may fix on a future project, but I may start with this one. I need to investigate the area to see how easily I can get to the backside of the deck/hull joint.

I like the idea of a threaded bronze insert for the dingy hoist. It won't get nearly the same amount of force applied to it as a chock. But the way the hoist is rigged the connection should only get shear force applied to it and not twisting or pulling which screws should be able to handle (assuming the don't rot out again). If the hoist were to get caught on a pylon or something I have to decide what I want to break. I think I'd rather it rip out some screws than pull the cap rail off.

Y'all have given me the info I need to think this through. Thanks.

[JusDreaming]

Originally Posted by s/v Jedi

What you need is a special wood repair epoxy, or make your own.


I would use a hole-saw to partially drill into the cap rail (followed by hand tools to dig it out) so that the repair looks like a plug. Make sure you get all the affected wood out.

Epoxy can't stand UV, not even for a couple of days (will change color) so keep it covered until you're ready to varnish it. If the cap rail isn't varnished, you need to make a plug of the same wood that goes in instead of the epoxy. I would prefer to do that anyway.

A forstner bit makes this a bit easier