Actually, riding lawnmower type engines are the latest rage for "mud"
boats. Here's one with a twin cyl motor very similar to riding mower
engines. There are several manufacturers of this sort of rig:
http://www.go-devil.com/27hp_KOHLER.html I used to sell commercial
mowers in my business and got a kick out of these "lawn mower" boat
drives.

Dale
www.fishwisher.com