Thanks Jim,
I need an 80 tooth cogged pulley and cannot find one. I have an aluminum pulley that is large enough to machine to the size needed. Rough cutting tomorrow. I may just cut for a 90 tooth pulley. The math is simpler - four degrees per cut. I have found a nice step through alloy frame at the Goodwill. I like the thought of building a carbon fiber foil but a standard boat hydrofoil is cheap and easy to replace. I have purchased a few 16" X 16 pitch model airplane props. I hope to have a test model in time for spring.
Todd.