Quote Originally Posted by Mike Goodwin
20" fits the boat and keeps the prop in the water.
Add another vote for 20" from me.

The longer shafts (9.9 merc long shaft, and johnson 8) I have seen on Ariels don't 'bite' any better then mine, and my 20" Yamaha 6 has never come out of the water on me.

I agree with Peter, in that I might not go with a 15" shaft for fear it would not stay below the surface.

The old Suzuki 8 that I had was a couple inches shorter(17"?), and it never came out, but would get close enough to cavitate in a bad chop (but still useable). I would not use a short shaft on an outboard if it were going to hang on a bracket mount or a transom (like the P-26) since they tend to pop out of the water more then the 'outboard in the well' like we have.

I am sure that with a 25" shaft, the prop gets 'cleaner' water deeper, but it also produces more drag there when sailing. Having motored Ariel's with both, I prefer a 20" shaft, and will probably re-power with the same. (and will not go over 8 hp FWIW).