I would guess that it wasn't designed for a canoe because there is little curve in the piece to be clamped to the boat; it looks like it was designed to clamp onto a small vertical stick or board in the middle of a flat transom. It looks like it could be adapted easily enough -- some material might have to be removed from the piece to be clamped so that it will better fit to the curve of the canoe's stem.
However, it does look like the ends of the clamps are designed to fit into holes. If you were able to clamp it tight enough to stay attached to just the surface of a wood/canvas canoe, I would expect to see serious unsightly dents in the canoe when the clamps were released.
Depending on how stout the stem of your canoe is, you may be able to drill through the stem and line the holes with brass or copper tubing to reinforce the holes. If the stem is not stout enough and/or if the arms of the clamps reach beyond the stem (which is what I would expect), two trapezoidal-shaped backer blocks could be affixed inside the canoe against the stem and planking, and the holes drilled through them. If the holes were left unlined, I would think the stress imposed by the rudder might soon distort the holes, depending on the kind of wood used for the stem/backer blocks. Putting holes through the canvas skin creates an obvious point for water entry under the canvas, and you would have to figure out a way to seal those points (a bit of epoxy?).
Just clamping something to the flat surface of the pointed end of a canoe seems an exercise in futility -- the clamping forces would tend to squeeze the clamped item right off -- like squeezing a watermelon seed -- and it would, of course, happen at just the wrong time, when the rudder is exerting force to turn the canoe. I think that's why the ends of the clamps are bent or cast at 90 degrees -- to go into holes or fittings that are meant to overcome the tendency to squeeze the rudder off.
My 2 cents.
