How to fix spinning captive nuts

[EO32]

I've been stripping paint off of my teak gunwales and removed the tracks that are bolted through. 3" 1/4 stainless.

The problem I have is the 1/4" bolts are sealed in fiberglass/Gelcoat or Filler.

A couple I had to grind the filler out so I could get a grip on the nuts so I could remove the screws. Others I got lucky on and can remove, but I can't torque them back down snug.

One thought is to pour some epoxy down the holes, let it setup to lock the nut in place, then retap the threads.

Any other ideas?

[Rockter]

That might work there EO.
On the Union 36 they are self-tappers. Under high loads, they lift.... last time under storm sail tensions.

[feetup]

That is probably your only choice EO but I see a potential trap there, in that when you re-drill and tap getting the tap to just clean out the threads in the nut and not try to re-cut the threads between pitches might be a chore. IMHO you might be better off to run a well waxed, or greased screw down the hole into the nut until the epoxy cures, then run it out and run a tap down the hole to be sure you get full thread depth in the hole. Hex head would make the job of cracking it free easier but you may have difficulty locating a full thread hex head cap screw. If you have a hard time cracking the screw free, give it a sharp blow straight down with a fairly heavy hammer, better yet, smack the end of the screw driver with a soft blow hammer, or try heating it with a soldering copper or gun.
This technique would have the added benefit of having threads the full depth of the hole with the stainless nut at or near the bottom. It is quite surprising how much hold fully cured , thickened epoxy has on a coarse threaded hole, and in fact the "cast in" nut would be functioning more as a safety than a primary fastener.

Feetup

[tweitz]

Based on the title, I assumed that this thread dealt with recalcitrant crew members. What a disappointment.

[sailingdog]

it might be worth drilling out the loose captive nuts and replacing them with these:




If you leave a screw that has been well coated with mold release wax or something similar threaded into the T-nut, the epoxy won't stick to it or the threads... and you'll have a nicely threaded hole in the thickened epoxy as well.

[EO32]

SD, yeah, I pick up some of those to replace the ones I had to "Cut" into.

I also had the same thoughts about tapping and being able to hit the threads.

I'm thinking of using a 1/4 OD tube, run it to the bottom of the nut, injecting epoxy until full then insert a screw with wax on it.