I made a couple of rabbet planes out of 1/2" chisels, they aren't nearly as pretty as the Ancient Kayaker's one, but they are
angled, allowing for a tighter clearance between strips on a station.

Mine is based on the Stanley #95 One for each direction. 30 degree down angle and 12 degree angle off path. (I never push any plane perpendicular to the edge, always at a skew)

They have a handle (you can see sticking out behind the red one on the right) so you can guide it with your other hand, while you push it with the chisel handle, or the body.

I think there are more photos on my Flickr page.

They work pretty good--much much better than free-handing a chisel or knife.

Always,
Will N

: Typical cutting blade angle for planes is 45 degrees to the surface
: with the bevel down. Try rotating the chisel 180 degrees to what
: is shown in your picture.

: Bevel up blades are typical in low angle planes. Which would make
: it difficult to hold the blade with a wedge.