RE: Prop powered iceboat
RPM, I plan on using metal runners with a smooth curve in the front. I want to use reciprocating saw blades as brakes (much like the toe spikes on the front of ice skates). I want to situate them right in front of the engine, preferably under the fuel tank. A servo would run the lever that would press them down into the ice. I'm hoping to make it strong enough to lift the entire rear end off the ice about a quarter inch. That should stop it. I also plan on using the wing off the back of an RC buggy to gain downforce on the front (steering) runner. That should facilitate some grab for steering.
I was thinking about fashioning some pontoons for the summertime instead of wheels. I might have to look into wheels, as well.