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epoxy repairs

Posted by lhedrick 
epoxy repairs
June 04, 2016 02:36PM
After dealing with low flow on the San Juan a few weeks I need to repair 2 spots on the bottom. Somewhere I slid over a sharp rock and put a 1 foot gash in the bottom the cut into the kevlar. The other a hard hit on the chine which crushed stuff a bit which now needs to be dug out filled and some new glass on top.

While look at the bottom, it's clear that past repairs are not bonding. I sand out the epoxy, the apply new layers but they are not holding.

Anyone else seeing this.

Now that we are running low on water here in the west, rock hits are becoming difficult to avoid.
Re: epoxy repairs
June 04, 2016 09:05PM
Patches alone have never worked for me. At least not on the bottom which does flex. At least when you hit. I have done patching only on the chine.

On bottom damage I grind out, wash with acetone and patch as best I can. Then I cover the entire (middle of the) bottom with a new layer of glass. I cut a 25 year old balsa wood Honk Dory up with a water feed saw two years back. I had cut the bottom off once already (also with water feed concrete saw) and replaced that with Plascore. But too much of the rest of the balsa was going to hell-----after 25 years.

That boat had three or four extra layers on its bottom, over top of Plascore that was maybe 6 years old at that point. In other words patching and a new layer every two seasons. Those were years of full time summer river trips and guiding too. I don't recall ever having a patch de-laminate.

That Rio Verde had glass that bubbled on the side over top the Plascore joint, as I recall. I could see that when we did the Deso run a few years back. I don't know what caused that but it isn't a given. It has not happened to me. Perhaps it was too much putty underneath the glass. I don't know.

Re: epoxy repairs
June 05, 2016 01:42AM
Those bubbles on the side were right over the square wave joint. I forced thickened resin into the seem to try and lock it together. For some reason I didn't get a good bond when the glass went on. Air expansion in the sell caused it lift. But it has never caused any problem. This time the cut went all they way through the heavy kevlar in a spot. There are some issue with plascore for sure but, from the hits taken I doubt anything is gong to get past the honeycomb cells and get to the inner skin. It's still floats so it not all bad.
Re: epoxy repairs
June 06, 2016 09:35PM
I too am surprised at cutting through 17 ounce bi-axial kevlar with glass on top. So far nothing has even close to getting through the core to the inner skin. The hit to the chine did very little, just a simple fill and patch. When I built the boat I really loaded up the chine with bi-axial tape. I might have 3/4 in of glassy layers inside and out. Next time less inside and more outside.
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