Hi John, I use a lagging compound called Bakor 120-09. There are a number of us who use this and after dozens of canoes I've never had any issues. If you've ever seen a Pam Wedd canoe and the finish she was able to get using this process then you'll know it works. One benefit is its drying time, ready for painting after about a week.
I buy a 5 gallon pail for about $330 Canadian which I then get about ten canoes out of.
If you're interested get back to me via my email and I can send you the instructions on how to use it and where you can purchase it in Canada?
Gary