Overshot, (where the water comes in from the top), wheels are more powerful than undershot, (where the wheel is driven from current passing underneath), but are still relatively inefficient.
Have you considered a submerged turbine style? Most folks want the sex appeal of an overshot wheel, which depends on having enough water volume to fill the buckets, AND having sufficient fall to impart weight to the wheel.
On a 12' wheel, you'll probably need to bring the water in at a height of 13' or so.
Sounds like a cool, but very labor intensive project. Would love to see the pics also.
