Does that prop look like it's mounted backwards to anyone else? If you want it to be a "pusher" engine, (and I'm guessing you will for an airboat), you will have to get a reverse "pusher" prop. You can't just reverse the prop & run the engine backwards, even if it runs that way, it'll run poorly & try to self-loosen the propnut. I'd suggest finding an engine meant for rc use w/ throttle control and maybe finding someone at your LHS or local flying club to help show ya how to get it running & get the needles set for ya. Oh, and never stand in line with the prop while it's spinning! A blade letting go at 12,000 rpm can do serious bodily damage to ones bad self! Ask the one-eyed smiley->

Do a search here on RCU in the boat forums, I'm sure there's alot of guys building airboats there that have alot of valuable info for you to read up on.

Good luck, be safe & enjoy ctrain7,
-rep