Before you purchase a mechanical propulsion unit, you may want to consider a
Yuloh sculling oar. Following are two links with information about yuloh
oars and how to make them for under $10 material costs.
The lanyard attached to the yuloh automatically changes the angle of the oar
blade at the end of each stroke. Once the blade is turned to the correct
angle of attack, water pressure from the stroke maintains the angle of
attack through the stroke. If you decide to build a yuloh oar, I would
used an 8 degree bend per the original design instead of a 11 degree bend as
was done at simplicityboats. I have studied the hydrodynamics of the oar, I
believe most the “power” is derived from lift not thrust. After a few
hundred years of develop, I believe the originated, “got it right.”
Regardless, yuloh’s are interesting and well proven.
BTW, we plan to build our own oars for the nesting dinghy we are building -
a Two Paws.