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A 16' Searay isn't going to have a very deep transom.

I think you'ld be OK with a Short Shaft---but if you factor in gettting a low fresh water houred Honda four stroke four about $400--it would be worth buying a kicker bracket that raised and lowered (sail boat type) if you had to.

You just need to be at least low enough to contunually draw in water through the impellor inlets.