Hi Bev,
Some people advocate taking canoes to a professional furniture stipping company. These guys can be great- mainly because they do it for you. But it can be tough to find one close by with a large enough tank for a canoe. Professionals are expensive enough (at least more than if you do it yourself), but if someone did it for you by hand, it would probably cost a fortune.
I find it a fun process to do, though, unocovering that gorgeous wood from under layers of blackened old varnish. Personally, I prefer the brand Strypeeze, the orange semi-paste. It is methylene-chloride-based, nasty on the skin and nasty in the environment, so if you use it, protect both. It will sure give you a burn if it gets on your skin or in your eyes. I use it outdoors so there's plenty of ventilation, and despite warnings from family and friends (and my own extensive training in biochemistry), I don't wear anything heroic when I use this stuff. Not even gloves, because I find that I end up with a pinhole that lets the stuff in, and then it's trapped against my skin. So I just work carefully- quickly but carefully- and keep it off of me.
One layer left alone for 10-15 minutes will get the finish bubbling up. For tough finishes, lay a second coat over the first after those 10-15 minutes, let it work more, then scrape out the goo with a wooden spatula (or very carefully with a metal putty knife- don't damage the wood!). Any residue cleans up nicely with a scrubbing of TSP in water. Collect all of that waste and dispose of it properly. It's nasty stuff.
Michael