Epoxy w/ Graphite Powder on Bottom of Wood Canoe + How a Wood/Dacron Canoe is Made

[Iskweo]

Dacron is a little more fragile than #10 canvas so some sort of abrasion resistance would be good to have. I have no experience with Dacron but a lot with canvas. I dont have much trouble with rips punctures etc using canvas and traditional fillers. A friend here does use epoxy now on some canoes. I have thought about it but worry about cracking when the wooden part of the canoe flexes. Just using the wrong paint has caused me a lot of cracking in three canoe that we recanvassed, so I am loathe to try epoxy.

I would love to try Dacron. I worry about the loss of strength that it would impart to a fragile wooden hulll though. The hull and covering work together to compliment each other. Weakening either may not be a great idea. I sure would enjoy a bit lighter canoe though.

I do have some shellac here and was thinking of trying that but dont want to mess about on a canoe that is being sold. Same for using epoxy. We did try some test strips with epoxy a while ago and found that the first layer has to go on very light so as not to bleed through the canvas and bond with the hull. Second coat required. Since we use about 6 pounds of silica in a traditional filler I am not sure that is much of a weight savings to use epoxy. The big weight savings is the lightness of the Dacron if you use it instead of canvas. The epoxy test strips did crack when flexed off the backer boards but I was not really able to gauge this very well when they were installed on a wooden panel. I am mostly thinking that a twisting motion would be the biggest problem.

I know YC has a nice little Dacron covered canoe that she likes and has had a long time. Between her and Waterdog I have heard only good things. Most of the alleged issues are theoretical? I will have to compare the costs.

 

[Glenn MacGrady]

My understanding was that the slipperiness of a graphite bottom, if it were to actually be more slippery, would be when the bottom is actually being abraded and those slippery little graphite particles are being scraped off the hull to act as lubrication.

That sounds right and surely the graphite-epoxy coat will eventually scrape and wear off. The question is whether that will happen less drastically and more slowly than the traditional wood/canvas-Dacron alternative of paint. Waterdog's experience and this photo from Tom's review posted by Frozentripper, which shows common scratches extending from the graphite area to the varnish area and damaging the varnish more, indicate that the answer is yes.

I would love to try Dacron. I worry about the loss of strength that it would impart to a fragile wooden hulll though. The hull and covering work together to compliment each other. Weakening either may not be a great idea. I sure would enjoy a bit lighter canoe though.

I don't think anyone would deny that Dacron makes a weaker canoe than canvas, including the makers who use it such as Alex Comb and the late Tom MacKenzie. Also, every "mistake" on the fairing of the hull will show though the thin Dacron. Reducing weight is really the only benefit, but the reduction can be be significant. Also, Dacron will not soak up nearly as much water as canvas will when saturated, hence also reducing that kind of weight. Using Dacron vs. canvas is simply a matter of paddler priorities.

 

[Jim Dodd]

As far as sanding graphite/epoxy ?
I can testify it is more difficult ! One of my first graphited hulls, had a wavy pattern, ( I believe caused by the heat of the epoxy curing). I sought to sand it uniform. What a pain ! The amount of time, and effort ? I would have been clear into the wood, had I just sanded a glassed hull.

Scratches on my graphited hulls are very similar to the one above that Glenn posted. They show no damage, until you get to the varnished part

If I was building a racing hull ? I would certainly, give Graphite a try ! If I has planning to use are hull hard ? I would graphite.

Jim

 

[Alan Gage]

Glenn: That is an interesting picture although I think it could be a little misleading. Is there really less damage or is it just that the scratches in the graphite don't appear white and blend in better? I can't judge the depth or extent of the scratches.

Jim: It's also interesting that you observed the same thing as Glenn's picture. I put a lot of weight in your personal experience so maybe there's something to it after all. I'm not going to rush out and coat my bottoms with graphite but I might give some more thought and experimentation to it in the future.

It's been an interesting thread so far.

Alan

 

[Glenn MacGrady]

Glenn: That is an interesting picture although I think it could be a little misleading. Is there really less damage or is it just that the scratches in the graphite don't appear white and blend in better? I can't judge the depth or extent of the scratches.

I thought of that, too: Do the scratches on the varnish (or enamel paint) simply look worse than scratches on epoxy-graphite because of the cosmetic way scattered light reflects and diffracts more off a shiny surface than a matte or dull surface? I'm not sure, but for the sake of argument I'll assume that epoxy-graphite is actually harder than varnish or paint and that the average scratch is less deep.

That, however, just raises a related question: What is the relative difficulty of removing or repairing scratches on paint (varnish) vs. epoxy-graphite. I have no experience with either on hulls, although I have sanded and re-varnished wooden paddles, which is easy. I would think it's similarly not difficult to sand and repaint scratches on yacht enamel, or maybe even to use chemical paint strippers in large areas. Don't know; no experience. On the other hand, expert stripper Jim Dodd has already commented twice on how difficult it is to sand epoxy-graphite.

Therefore, as part of any decision for a wood-Dacron canoe bottom coated with enamel paint vs. epoxy graphite, I would want more information on the ease of scratch repair for a non-builder and novice restorer like me.

 

[Waterdog]

Therefore, as part of any decision for a wood-Dacron canoe bottom coated with enamel paint vs. epoxy graphite, I would want more information on the ease of scratch repair for a non-builder and novice restorer like me.

I possibly could oblige in the next couple weeks. Alex Comb suggested that some 400 grit would blend all the scratches into a solid color which I assume will be a shade of gray. I never bothered because the scratches dont bother me and I have no intent on maintaining the aesthetics of the canoe bottom per se. If the boat is in good shape and can make a two week trip I see no reason to mess with it. I do touch up the sides every season. It is as easy as 320 and 400 grit (wet sand), wipe with cheese cloth and paint. I keep my boats in a rented garage across town but if I can get the Stewart river to the house in August I will sand the bottom and post pics.

Barry

 

[Jim Dodd]

That, however, just raises a related question: What is the relative difficulty of removing or repairing scratches on paint (varnish) vs. epoxy-graphite.

That has entered my mind also. For one ? You can't see what the cloth and wood bond is like, under the graphite. It's covered in Black. What appears to only be a scar, may be a major delamination.

I don't see a repair on a graphied bottom that much more difficult. A Carbide scraper would be a handy tool .

On a W/C canoe ? The cloth isn't bonded to the hull. In my view that would be a benefit. Leading more into the direction of using graphite on one.

I have an older stripper (no graphite) that had a hole punched in it, and needs repair. Due to it's age. The patch will be tough to match, in color !

I'm looking forward to Barry's ( Waterdog) Report !

Jim