Quoting I Scream Clone
The problem with the water course Dennis is it takes a 90% turn. It doesn't seem like it would have sufficient directional power to turn the wheel well enough. Perhaps make the water area extend into the castle at least where the wheel sits, you could even run a small via duct to above the wheel and have water flowing onto the top of the wheel, utilising gravity as well to drive it?
Yep, you're right. I'm going to modify it some more with your idea in mind. The idea for the joke came into my head while tinkering with this, so I hadn't thought it all the way through. Dang you, comedy!