I'm redoing a 1974 O'Day 32' CC, and it had teak coaming boxes that had rotted out including the balsa end-core above, to the sides, and below. I've cleaned it out pretty thoroughly, and want to fill the void between the two fiberglass skins with a thichened epoxy mixture, but I have no idea how to fill these vertical voids. I've thought about taping all the open edges thoroughly, drilling some holes at the top of the voids, and sluicing a thinner epoxy mixture into these holes until it starts oozing out the top holes. But I'm not sure that the tape will hold, and keep that much liquid from from spilling everywhere. Any ideas or suggestions as to how I might do this repair? Thanks
epoxy filling void on vertical surface
- Thread starter jknappsax
- Start date
- Status
When you fill the voids, you'll probably want to use epoxy thickened with colloidial silica, to the thickness of mayonnaise. However, when you're about to do this, coat the area with regular epoxy to prevent the wood in the area from absorbing epoxy from the thickened epoxy and starving it of epoxy.
To prevent the epoxy from getting everywhere, tape over the holes and edges and then place thin plastic or wooden boards over the tape and brace them to keep their shape.
To prevent the epoxy from getting everywhere, tape over the holes and edges and then place thin plastic or wooden boards over the tape and brace them to keep their shape.
If you have clear access to the edges you can cut and fit wood between the skins when that has cured you can use new empty caulk tubes that can be purchased from Jamestown marine Sold under the boatlife brand name. mix your thickened epoxy in a freezer weight zipper bag, resin and hardener first and then add the filler, only one tube at a time fill the tube and squirt this into the holes that you had planned to drill. Drill one hole near the bottom and one near the top in each section. pump into the bottom hole when the mix comes out the top plug the bottom hole with a stick. After you have worked your way all around and the epoxy is hard drill some test holes near the top to check for complete filling.
Different approach
Why do you think you need to fill the voids? If the voids are just between the cockpit fiberglass and the inside of the coaming fiberglass, why not just dry it out and replace the wood? Do you know where the water could be coming from? The wood may not have rotted from the inside (void side) out. But if it did, then filling the void just at the front isn't going to stop water intrusion into that space. Just brainstorming.
Why do you think you need to fill the voids? If the voids are just between the cockpit fiberglass and the inside of the coaming fiberglass, why not just dry it out and replace the wood? Do you know where the water could be coming from? The wood may not have rotted from the inside (void side) out. But if it did, then filling the void just at the front isn't going to stop water intrusion into that space. Just brainstorming.
It rotted out due to the deterioration of the teak coaming boxes; they had deteriorated to the point that the bedding wasn't attached to the teak fascia, so water intruded into the core around the fascia. The rough openings are about 16 3/4" wide and 6 1/2' high; the rot extended about 2" at the top, about 10" (but uneven) at the sides, and the bottom about 2", as there was a tab along the bottom and the top. The void between the inner and outer skins of the coaming is about 1/4" wide. I might be able to fit furring strips in between, but with the the irregular shape of the void will make that difficult. Once the new ABS coaming boxes are bedded in place, I'm pretty sure that there will be no point of entry for water intrusion.
I've run into the same problem when I replaced the port to the head and I ended up filling the void with some wood then mixed up some West systems epoxy thickened to a peanut butter consistency and it worked well, I ended up with an opening that was water tight all around before installing the new port, where were the coaming boxes installed? I want to install some below my winch's
Be careful how much you mix at once
If you mix too much in one batch it can kick over very quickly and violently to the point where you will be burned if you touch it (sound like I learned this the hard way?). Keeping the materials cold will slow down the reaction and give you more time to work. It sounds like you have a large void to fill and will need quite a bit of mix to fill it. The microballoons are very light weight and I'd suggest you want a lot of that versus epoxy. Island Packet uses a mix like that for their deck cores instead of wood, you can read about it on their web site. No chance of rot, seems like a good practice, not sure how much weight penalty though.
To hold material in position I have had good luck with Saran wrap taped in place, the saran wrap can be stretched tight so it gives the epoxy a smooth finished surface when cured minimizing the finish work. Any plastic film will work but Saran wrap stretches easily and can be smoothed out. The plastic film won't stick to the epoxy so it peels right off.
If you mix too much in one batch it can kick over very quickly and violently to the point where you will be burned if you touch it (sound like I learned this the hard way?). Keeping the materials cold will slow down the reaction and give you more time to work. It sounds like you have a large void to fill and will need quite a bit of mix to fill it. The microballoons are very light weight and I'd suggest you want a lot of that versus epoxy. Island Packet uses a mix like that for their deck cores instead of wood, you can read about it on their web site. No chance of rot, seems like a good practice, not sure how much weight penalty though.
To hold material in position I have had good luck with Saran wrap taped in place, the saran wrap can be stretched tight so it gives the epoxy a smooth finished surface when cured minimizing the finish work. Any plastic film will work but Saran wrap stretches easily and can be smoothed out. The plastic film won't stick to the epoxy so it peels right off.
Has anyone here had any experience with System 3's RotFix products. I've heard that GitRot never really hardens, but I was wondering about a two-part epoxy product. Thanks.
I can't remember where i read it, but I once found something saying that runny epoxy (diluted very slightly with acetone) would penetrate wood as well as the 'rot' products, so that's what I used when doing some core repairs on our boat.
Our cockpit floor had a few core issues where moisture had entered through some cracks/holes in the thin bottom skin. There were only a few small areas of core rot. After the floor had dried out, I epoxied a new layer of glass cloth on the underside covering up the cracks, let that harden, then I drilled some holes from above and pumped in a mix of runny epoxy + microballoons with a big syringe.
Back on your original problem - if at all possible, I'd echo the other suggestions to try and replace the rotted cores with plywood (or a foam core material). It's quite OK to cut the inner fg skin away, epoxy the new core pieces in, then epoxy the inner skin back on, with strips of glass cloth over the gaps, It will be as light and strong as the original, uses less epoxy, and reduces the chance of leaving voids.
That is a good suggestion! It'll be a little tight getting to the inner skin, as it's the coaming, and access here is not good, but I'll have to think on that one a while. Thanks.
- Status