A buddy and me have been kickin around the idea of building a surface drive motor. We both built longtails, and decided we'd like to see more speed. Being students and pretty mechanically inclined we were wonderin if anybody had ever done this with much success. We're kinda in the what if and plannin stages right now and have kinda decided on a GDSD style model without a clutch unless we can work around something cause neutral would sure be nice. Biggest obstacle I see is findin a way to turn the prop. Ive been lookin at timing belts thinkin the grooves would help keep the belt from slippin, but find something to fit the engine shaft and the prop shaft that is the right ratio may be tuff. I'm gonna look around some salvage yards and see what i can come up with but i just wanted to get your guy's opinons and thoughts to see if im over thinkin this deal or not. Thanks!

Get 2 of the same pullies and run it 1:1. A lawn mower shop will probably have pullies to fit your engine and you make your shaft the same size. If your prop shaft and engine shaft are different sizes, I don see a problem weld the pulley onto the prop shaft. Just make sure you have a woodruff key on your engine shaft. If you do make one with out a clutch, make sure you get it balanced. What size motor are you planing in running?

Not too sure on the engine, It'll probably be in the 20hp range. We were thinkin about trying a 2:1 or 1.5: 1 with the belts. But still are unsure of which way the project is headed with duck season approaching so quickly, could be spring project...

Stay with a 1.5-1.3:1 ratio then you can at least base your prop size on the hours of development that have done by the existing surface drive companies. If you go 1:1 you would likely be struck running a 9" sub-surface prop. Go to the Gates website and down load there drive design program. Stay with a Polychain GT2 timing belt. I built a 13 hp belt drive about 7 years ago and working on another 13 and a 16 this winter. Shoot me a PM if you get stuck with anything.