I'm setting up a waterwheel for use in villages in Sri Lanka and am taking power off the rim of the wheel.  I've decided to use tooth belts.  The 2m diameter waterwheel drives a 165mm pinion - (ratio approx. 1 to 12), which drives a synchronous motor backwards (step up 1 to 9).  The signal goes through an IC controller, producing a.c. 50Hz.  At the moment, strategically placed strips of tooth belt on a side drum of the 2m waterwheel help to transmit the power,but they're not all in mesh.  Was wondering if there is a way to calculate whether the friction without strips would be great enough to transmit the power, getting rid of the meshing problem.  Belt is polyurethane, 20mm pitch, drum is galvanised steel.  Small pinion has 10 teeth in mesh and is mounted on a spring loaded hinge which works well to absorb imperfections in the waterwheel. Any help or questions would be much appreciated.  

Ruairi