Unique wheel

So most people would look at these pictures and say "yep its a water wheel". But look again. Whats different about it? 

 Every other water wheel you've seen has the spokes on the outside of the wheel. Usually there are two sets of spokes. Not mine!! One set, centered in the wheel like a gigantic wagon wheel. Its a lot more work to build it this way, as the spokes have to be very large and heavy. The center hub is reclaimed from an old steam engine tractor wheel.

These are examples of traditionally build water wheels.