Injecting epoxy in wet core - Page 2 - SailNet Community
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post #11 of 28 Old 08-03-2009
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How big is the wet area? In my opinion, if you cannot remove all the wet core easily through a single small access hole then you're better off to cut open and recore it properly. The other problem with your plan is that if it doesn't work, and I think the consensus is that it won't, you have caused whoever does the future recore job (you) a great deal of work removing the skin to do it properly. Recoring is very hard to do properly from below and very messy. Vacuum bagging will help but still not necessarily a guarantee of successful bonding. The best way to a successful job is to do it from the top. While this means repair to deck coating - painting or non skid - it will also go much faster depending on the size of the wet area to be recored.
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post #12 of 28 Old 08-03-2009
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I recently went through this. I considered all options and after people pounded in "get rid of the bad", I decided to recore the area. I'm glad that I did because now I know that its solid.

After carefully marking off, cutting and removing the top skin from the damaged area, I realized that the damage was larger and I had to keep cutting. I think that its typical to find that the damaged area is about 15% larger than you thought.

Good luck.

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post #13 of 28 Old 08-03-2009
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It's best to re-core because CPES does NOT displace water. The core has to be totally dry to use epoxy on it.
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post #14 of 28 Old 06-16-2017
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I injected with 35 cc syring and large needle I cut short. I drilled with a tooth pick sized bit. i injected three times wih day cure between each. You could tell by drilling if voild. Some holes took 35 cc. More than 10 ounces would set before injected. Some would come out other holes
I made. sure all 60 holes about 1.5 inch apart were filled. Sand and painted. i am sure it strong enough. Solid no give.
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post #15 of 28 Old 06-16-2017
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Re: Injecting epoxy in wet core

I had a 3 X 6 foot area drilled and filled, the wood beneath was not rotted, though, just wet. A shop vac was used to dry things out, and nearly a gallon of epoxy was injected in the holes, then the holes were sealed, gelcoated and painted. There is absolutely no wet in there at all now, and the water was coming in from around the base of the mast boot, which looked good on visual inspection, but you could follow the water using a moisture meter.

I can assure you that my deck is now more rugged that it was originally and though it had been wet it never got soft and soggy like some that had been overlooked for decades. Once you get the wood dried out, and the epoxy injected, there is little chance it will ever rot. Balsa is a fairly soft, but resilient wood and not prone to rotting as some would like to believe.

Good luck,

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post #16 of 28 Old 06-17-2017
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Re: Injecting epoxy in wet core

I was just talking about this the other day with a friend. I was told (with no verification about this info), that if you use fast cure epoxy, you're likely to burn the boat down with the heat build up. Best to use slow cure and maybe do it on a cool day...
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post #17 of 28 Old 06-18-2017
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Re: Injecting epoxy in wet core

You're not supposed to thin West System epoxy to make it penetrate. It will just weaken the epoxy. Use heat instead.

Thinning WEST SYSTEM epoxy - Sailfeed

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post #18 of 28 Old 02-25-2018
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Re: Injecting epoxy in wet core

Clearly replacing the core is the best option, but often is not logical in an older boat used for coastal cruising, where the cost of the repair could easily exceed the value of the boat. It's a lot of work, make no mistake. I have done the job and my repair is in an issue of Good Old Boat in 2004. I wouldn't do it again. First, why return an ancient deck to as new condition? Have you seen decks fail? In my 45 years of being around boats, I've never seen one failed deck. So ask yourself "what am I trying to achieve here"?
If the core is not rotten epoxy injection is good. Very expensive yards use this as the method of choice, including Morris Yachts. It makes zero sense to rip out sound core to replace with more sound core. (Although many will happily charge you thousands of dollars to do just this). Acetone can be injected periodically until it's dry. Or you can use Boatlife Aquapoxy which cures well in wet wood. Size of the repair does not matter. Then inject unthickened epoxy. Do not thin it. If the deck core is rotten, you might consider injectadeck, which is a 2 part structural marine foam that remains liquid for the first 30 seconds or so, and penetrates into any cracks, crevices or gaps. It is attracted to moisture, and cures better in the presence of moisture. It then expands, and cures rock hard. Of course, you might get some small voids, but the deck I have seen repaired with this method is absolutely rock hard. Another approach might be the one taken by Aeromarine Industries, (see their video on deck repair). They inject structural foam between the overhead liner and deck, then epoxy into the dry deck core. This looks massively strong. If the core was wet and rotten, I'd use injectadeck into the core or Aquapoxy, but definitely not regular epoxy. None of these methods are perfect, but they do work, and can keep your boat going safely for many, many years. They are also about 1% of the work of replacing the core. Replacing the core would be an absolute last resort for me, and only if I planned to use the boat in extreme offshore conditions.
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Last edited by JamesRichy; 02-25-2018 at 04:31 PM.
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post #19 of 28 Old 02-25-2018
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Re: Injecting epoxy in wet core

I've done both - drill & fill falls into the same category as painting a rusty car before selling it.

You can vacuum out the liquid water but everything is still wet. It just plain doesn't work.

I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.
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post #20 of 28 Old 02-26-2018
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Re: Injecting epoxy in wet core

Well, a painted rusty car will show the rust again in a few weeks. There are epoxy injected decks going strong after 20 years. Hardly the same thing. Yours may have failed, but it can and does work in many cases. As I mentioned, it is used by excellent yards and recommended in certain cases by the Goudgeon Bros. Take some wet, rotten wood. Put it in a plastic or aluminum tray. Pour aquapoxy over it, until covered. In a day or two, you will have rotten wood encapsulated in rock hard epoxy. I'm not saying it's a good as replacing the deck. Far from it. But it definitely does often work, it adds structural rigidity, lasts a long time, and makes the most sense for may boats. Of course, a quick and dirty job probably will fail.
Like blister repair, many self-proclaimed experts will advise you on repairs far, far in excess of what is warranted or logical.
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