I have no experience with this kind of thing, but have a few skeptical thoughts and questions after looking over their web site:
The basic heat units seem expensive -- hundreds of $$ -- and seem designed for flat surfaces, whether horizontal or vertical. Of course, a canoe interior is seriously curved, not flat, and it combines horizontal, vertical, and everything in between. For much of a canoe’s interior, the heat unit could not just be set down as on a flat floor, or held in place with a simple fixture as with a flat wall.
Unless you can rig some way to easily rotate the canoe through 180 degrees so the heat unit can always be just set down, you will end up holding the unit in place a lot of the time while it heats that little rectangle of varnish. The “super light” unit is 3 lbs. -- and 3 lbs. could get heavy to hold for the time needed to strip a canoe. I didn’t see a weight spec for the other units.
But you can invest hundreds of more $$ for various of their “hands free” gizmos that hold the heating unit in place. It is clear from their demo video and illustrative photos that they expect “hands free” devices to be used on vertical surfaces. With a fixture, a heated 5” x 12” area of a wall can be scraped while the next area is heated. Without a fixture, for much of a canoe interior, it could mean removing the heating unit and setting it aside after heating each little rectangle, then scraping, then holding the heating unit over the next 5” x 12” area -- and repeat. Seems like it may be slower and more tedious than other methods of stripping.
A canoe interior surface is also not level -- it alternates between the surface of the planking and the surface of the ribs ¼ “ higher (+/-) than the planking. I don’t know if this matters in practice, but I would expect the rib’s top surface to heat up faster than the planking surface -- but maybe the difference here is so small as to not matter. However, because the sides of the ribs would seem to be receiving very little direct radiant heat, I would expect the rib sides to heat up quite a bit slower than either the planking surface or the rib top surface. I would wonder if you would not be scorching or burning the surfaces of the ribs before the varnish on the sides of the ribs was soft. Maybe this is not a problem in reality, but the skeptic in me would want a good answer from someone with actual use in a wooden canoe or wooden boat interior -- not just on the flat floors or walls of a building -- before I would spend the amounts of money called for.
As near as I can see, there just ain’t any easy or fun way to strip paint or varnish.
