Everyone above has told you the truth. You can put a motor and an air propeller on the back of a jon boat, and yes it will push it, but the same motor will push it better and take you more places as a mud motor setup. Water is so much denser than air, and that fact alone means the air drive is much much much less effecient. Real airboats are designed from the ground up to make the hull and everything associated with the airboat to compliment the air drive and to best harness and extract the last little bit of performance from the available thrust. A small, mini airboat can be built to utilize a small motor like your thinking of using and will perform better than the Jon boat hull. I built a mini airboat and used a 13hp Honda and it did ok but In hindsight I should've went a different route. If it were me, I'd keep the Jon boat as mud motor boat, it'll go more places than if you put an airprop on a motor and slap that on the back . If you really want an airboat and it's a money thing then I'd suggest selling your mud boat and scouring Facebook and Craigslist for a cheap airboat hull and building one up like that, if you shop around you can find deals on every component required to complete the project and when your done you'll be the proud owner of an airboat, a real airboat. If you do decide to proceed with your original idea, you should definitely plan to include a reduction drive for the engine. It'll give you twice the performance (maybe not twice but close enough), but therein lies the dilemma, a reduction is gonna cost 700-1500 or so. When you start adding the price of required components to make it perform adequately , in the end you'll realize you could have built or bought a real airboat... But if your detetmined to do this then your in the right spot, we can help you by giving you good advice. The first advice, and you should take it, is to scrap your idea and keep the Jon boat as a mud motor boat. If you want to proceed anyways then buy or build a reduction drive. Weight is going to be your enemy because you don't have much power so you'll need to keep the entire build as light as safely possible. Your not the first to contemplate or try this and you won't be the last. You've got a lot of choices to make. Take some time and and really think this thing through. And if you decide to move forward with it, I'll help you, after all that's what we're here for.
