glass draped over

By far the most nerve wracking part of the whole build this far is applying the fibreglass. I’m pretty confident in my woodworking skills. Most of the mistakes I made in planking I could repair or hide. But I’ve always been lousy at painting. Which is mostly the same skill set as fibreglassing I think.

Above you can see the layer of fibreglass draped over the hull. It’s 6oz standard weave glass. This is what Canoecraft recommends and what most people use. The book says make sure you buy it on a roll, not folded because creases are hard to deal with. Apparently you need to ensure that the roll was rolled well because mine still had some creases from being rolled too loosely on its tube. Because I paid so much for the shipping and I am on a fairly tight time schedule I couldn’t send it back. So I forged ahead and thought of it as a challenge.

 

mixing epoxy

Part of the reason that the fibreglassing is so stressful is that you need to get it right the first time. You also have a limited time to work. Once you put the first dab of epoxy on the glass the process can’t stop until it’s finished. Your epoxy has a pot life and a working time so you need to get it done, and done well before those times are up.

The trouble is that if you’ve never done it before, you’re learning as you go. The materials are so expensive that it’s not something most people can afford to practice before hand. This also affects the final look of your canoe, probably more than anything else. So yeah, that’s why it’s an intense part of the build process.

The stuff I’m using is MAS epoxy with the slow hardener. After doing some reading and consulting the vast collective experience of the internet it had a lot going for it. The viscosity is fairly low compared to a lot of other epoxies out there. This means it saturates the cloth and fills the gaps more easily. Less pressure is required when squeegeeing to ensure the weave is completely filled. It also has a long pot life and working time. So it takes some of the pressure off you if you’re working by yourself and learning as you go. Which I was.

I don’t have experience with a bunch of other epoxy systems to compare it to. That being said, I was very pleased with the MAS epoxy. It seemed very easy to work with. I feel pretty comfortable with it now, and would use it again for the next canoe.

 

wetting out

The way this works for those unfamiliar with fibreglassing, is that liquid epoxy is applied to the cloth draped over the wood substrate. The epoxy soaks through the cloth and into the wood. You then run a flexible plastic squeegee over the cloth to force out any air bubbles. The trick is using enough pressure to do that and still leave the cloth fully saturated. Too much pressure and you squeeze out the epoxy and starve the cloth.

You also want to do this with the temperature falling in the workshop. As the chemical reaction of the epoxy setting takes place, it creates heat. The warmth causes the air inside the wood to expand, and this forms tiny bubbles. If the temperature of the workshop is falling faster than the epoxy is heating up then you avoid these bubbles more. This is another plus for a slow cure epoxy. The slower the reaction the more time the heat has to dissipate and less trouble you have with bubbles.

If you were to starve the cloth, not saturate the cloth, or have bubbles form under the cloth and not catch it then once the epoxy sets you will forever see the cloth. There were a few places that I did this. The only remedy would be to sand through all the expensive epoxy and fibreglass down to bare wood and start again. If the bubbles were large or the wet out was very¬† poor than that would affect the strength of the canoe. Tiny bubbles and some visible weave are just aesthetic. Some of my visible weave will be covered by the graphite finish I’m going to be applying on the bottom. The rest I determined I could live with. Most of it will only be visible in bright light to the discerning eye. I hope.

 

all wetted out

All wetted out it looks like this. You can see the two creases in the cloth that I just couldn’t work out to the right of the post and halfway down the hull. It could have gone much worse, and I learned a lot from it. So I’m calling this a success. But probably only a B, or B+ at best. It’s sound structurally but far from presentation grade.