Hello Denny

[Bushwacker]

Terry, I got your text and saw post on E-TEC forum about looking for a plastic spacer between prop & gearcase. That gap might allow some exhaust gas to induce cavitation in reverse, and maybe on takeoff, much like the vent holes on some props, but I doubt it would have much effect at cruise. You might try contacting some of the prop makers like PowerTech and Solas about a plastic spacer, and also ask them for some good cruising prop recommendations as well, based on your test data with the Cyclone prop. If you still have your Shopsmith, you might also be able to make a spacer out of starboard that attached to gearcase rather than the prop! Denny