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carbon fiber repair question

Posted: Wed Jun 10, 2009 2:48 am
by GUMB0
This is not exactly boat building but I know there is a great group of craftsman that read and contribute here. So I thought, I would pose a question regarding the repair of a carbon fiber paddle that I have beat the end up on pretty bad. It looks like two layers have split just before the end of the paddle. I was told by a Factory Rep that they could be fixed with 2 part expoxy or would even take a little glass if I wanted to. I would like to hear any suggestions you gentleman may have. The only picture I have is a quick scan I made before I taped up the paddle and went back to the river. My questions are what type of epoxy? What kind of surface prep? Can you put the epoxy on heavy then sand and shape it? Will the epoxy bond or will it chip off? Is this a lost cause?

Thanks

Image

Re: carbon fiber repair question

Posted: Wed Jun 10, 2009 6:45 am
by gerald
I have repaired some of my carbon fiber paddles. Hard to see from the pictures but I understand you have delamination between the front and back. In that case you'd need to spread it as much as possible, get some epoxy in there then let it close to cure. Don't clamp it tight because you squeeze out the epoxy. Just gentle pressure to line everything up. After that has cured you can add strips of cloth (I use 4 oz. s-glass but whatever yo have will probably work) on the edges, or even the entire blade. No need to curl, or fold, the fiberglass around the blade--just run it to the edges. Coat as you normally would for a saturation coat. When that hardens you can sand, shape, etc.. You'll probably have to add at least another fill coat. The last coat can cover the entire blade. Let harden, sand and buff till you get the finish you want. I usually just sand and go paddle. It's going to see more hard useage anyway.

Maybe somebody else will have another method. We can never have too much information.

Re: carbon fiber repair question

Posted: Wed Jun 10, 2009 10:46 am
by Crazy Yak
Like Gerald said you should be able to repair with Epoxy, you may or may not need a piece of Glass or CF to repair. I would try with Epoxy 1st.

Also, if you want your paddle to look new again (if that's important). You can lightly sand the entire paddle and spray with Polyurethane. I refinished an AT Paddle this winter but the Polyurethane coating scratches easy, if you find a better final coating let us know.

Re: carbon fiber repair question

Posted: Wed Jun 10, 2009 12:07 pm
by gerald
A word about using carbon fiber. CF is great stuff. It can be very stiff, strong, and lightweight. It is also very expensive. S-glass costs twice as much as e-glass (the standard). Kevlar costs twice as much as s-glass. Carbon fiber costs twice as much as kevlar. Carbon fiber also "plumps" when saturated with resin, so you can get a resin rich composite unless you are vacuum bagging. The resin rich composite negates a big part of the weight savings of using carbon fiber. In fact--I would venture to say that vacuum bagging is the biggest single part of saving weight in most composites--not just CF.

Re: carbon fiber repair question

Posted: Wed Jun 10, 2009 5:45 pm
by Pogo
Joe, I'm gonna be hanging out on the San Marcos next week, maybe we need to grab Moder for a fishing trip and let me have a look at that paddle while we're at it. Should be an easy fix, and 5 minutes explaining in person would be worth a lot of typing and reading. If at all possible, shoot a couple more photos this way, would like a better look. I can bring some 4-oz s-glass scraps that'd be perfect, maybe some 'poxy too, if I can figure a way to "package" a small amount.

Re: carbon fiber repair question

Posted: Wed Jun 10, 2009 7:25 pm
by Iamdamoder
I am pretty sure I can buy a small amount of Epoxy right there in the campground. Made in SA how does that sound? We better bring our own seal a meal if we are going to play with the CF.:roll:

Re: carbon fiber repair question

Posted: Wed Jun 10, 2009 7:36 pm
by Pogo
Holy crap, I plumb forgot about that! :lol: No seal-a-meal required, vacuum-bagging isn't essential to a simple repair like this. :D Joe, put 'er in gear, son, we're gonna get together on de bayooo . . . I mean, de ribber . . . and had us a good ol' time y' heah? :D

Re: carbon fiber repair question

Posted: Thu Jun 11, 2009 6:03 am
by GUMB0
Thanks for all the suggestion. Pogo, When will you arrive in Centex next week? I got some folks in from out-of-town Next weekend but the afternoons during the week look pretty good. I will wait on the repair till you get a first hand look at it. The Gaffers tape is doing a great job holding it together, justa a small split what you see in the picture is less than 1/8" if the epoxy makes a good bond I don't think I would need to put glass on it.

Cheers!

SYOTR

Re: carbon fiber repair question

Posted: Thu Jun 11, 2009 9:04 am
by Pogo
You're probably right about not needing glass. I'll hit the vicinity on or about the 18th and be there 'til early the following week. Or later the following week if I'm having that good a time. :D

PM me your cell number, or just stay in touch thru Moder.

Re: carbon fiber repair question

Posted: Thu Jun 11, 2009 10:35 am
by gerald
I don't know about this particular paddle but many paddles of this type have a foam core. Nothing wrong with a foam core in ordinary circumstances. The problem arises when the foam core extends too close to the edges of the paddle. You can wear through that thin layer. If that is the case you may have to add a little bit to build up the edges. Certainly looks like you can repair the paddle though.