14' Strip plank canoe sheathing

In a bid to get the hull finished I checked the humidity and temperature in the workshop to see if I could crack on with the epoxy/glass cloth stage.

 The hygrometer showed 97% and the temperature was just 11 deg C. It's important that the epoxy coating is applied when the humidity is lower (max 85%) and the temperature higher, to avoid an under-cure and a cloudy finish. I didn't want to wait for the weather to improve so I put the dehumidifier in the workshop for a day. This didn't bring the humidity down a great deal as the workshop is pretty draughty. I fitted foam tape to the door seals and a thick polythene sheet to catch any drips of condensation on the underside of the corrugated iron roofing.

The next day I got up at 6 am and set the fan heater up under the hull. The outside temp was 5 degrees. I got the temperature up to 15 degrees and the humidity down to 70%. The resin had been warmed in the house for a couple of days. I read somewhere that you should aim to to get a dew point that is at least 3 degrees lower than the air temperature to stop condensation forming on the epoxy and making it cloudy. The hull has to be the same temp or warmer than the air. I used this dewpoint calculator. Other advice is keep an eye on the temperature whilst doing the sheathing of the canoe as an increase in temp will cause air in the wood or voids to expand forming bubbles under the cloth.

The cloth is 200g/m and a little thicker than I have used before. I used West System resins and the 207 hardener which is intended for this kind of clear coating. It's great to see the first batch of resin poured on and the wood showing through. After I had wet out each quarter of the hull with a brush I went back over it with a filler card to take off the excess and get rid of air bubbles. 

Once this first coat was tacky I brushed on another coat with as few runs as possible. The idea of this is to create a chemical bond between layers. Once this was tacky (8pm) I brushed a on final coat. I left the heater running for 24hrs to keep the temp up and get as good a cure as possible. The ouside temp was only 3 degrees at night. Trying to sand chewy epoxy is bad for your health (skin and respiratory sensitisation) and uses up loads of sanding discs.

The shape of this hull has some tumblehome which meant that the spare skirt of glass cloth was trying to pull the cloth off the hull. I trimmed this as I went and smoothed it back on.
Once the three coats were all on I could get an idea what the completed canoe will look like when varnished.
This is then sanded, the moulds removed and the boat turned over.

I've just got to do the same on the inside!

Hull sheathed and 3 coats of epoxy on: time for a beer

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