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Compass Marine How To | all galleries >> Welcome To >> Sealing Deck Penetrations to Prevent Core Rot > Chaneling & Voids
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Chaneling & Voids

Chaneling & Voids

In my years working on boats I have yet to see any cut up section of hull or deck, unless made using vacuum bagging or SCRIMP, that does not have some voids. I will go so far as to say that I know of no builder, who hand lays a hull or deck, where having no voids is even 100% possible. Many builders also use thickened resin or "deck putty", as they often refer to it as, on the back side of the hull or deck skin to lay the balsa into during lay up. If this begins to kick, or the balsa in not padded down enough, there will be voids. Voids lead to channeling of epoxy, or water for that matter.

Why do I bring this up? I took this photo to show what is happening when you fill a hole with epoxy and come back 5 minutes later to find it has "settled". In reality the epoxy has not in fact settled, unless the tape failed, but rather it has channeled into the voids in the balsa or deck putty. If this happens to you you'll need to wait about 30 minutes then mix up another batch to re-fill or top off the holes. Don't let the epoxy cure entirely or you'll need to remove the amine blush and this can be a royal pain in a small hole.

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Geoff Adams 24-Dec-2016 15:21
You comment on what a pain it is to remove amine blush especially in a small hole, wouldn't it be better to just use an epoxy that mixes at a 2:1 or 1:1 resin to hardener? Epoxy that mixes at a lower ratio does not blush and thus you no longer have to worry about removing it. Duckworksbbs sells marine epixy that mixes at 2:1 with no blushing. One less thing to worry about I think. Just my $.02.
Pat 11-Apr-2013 15:47
Thank-you so much, this is such a great presentation, and has proved invaluable to me during a recent project!
joel 13-Mar-2013 17:12
Great explanation! Would it be better to modify technique 2 to drill from the inside to leave more gelcoat and less exposed epoxy?
Vincent 26-Jul-2012 12:15
Excellent and very Helpful. Re amine blush, according to my reading and experience, it is not a problem if the secon coat is applied iwithin about 12 hours. The epoxy is still green and there will be a chemical bond.
Guest 07-Apr-2011 20:58
This is the most helpful and visual explanation of how to fix deck hardware I've ever seen (and I've searched and searched), however it's still not 100% clear how the hole can be wider in between the skins: do the Dremel bits expand out after insertion or am I missing something?
Guest 30-Nov-2008 20:14
Very helpful. Some thoughts:
Another advantage of your preferred method is that it is easier to position the redrill hole when the top skin hole remains smaller.
Method #2 is helpful if one wants to get a good look at the core.
I am about to deal for the first time with a boat that has a headliner in the cabin deckhead (ceiling), hence there is a barrier to reaching the inside skin hole, so it is not possible to place tape over the hole in the inner skin prior to filling the potted hole with epoxy from the top. I am still looking for an efficient suggestion for a plug. Thought about using a bit of butyl, but it would press up inside the inside skin hole and displace epoxy a bit.
Guest 27-Nov-2008 06:04
Thanks for such a thorough treatise. My C-Dory is balsa cored and your techniques are more developed than mine. Your point on beveling is a real eye-opener.