Psychron

As soon as they let me post links, I'll send you one or two to my scratch hovercraft in operation. Same idea, just two motors. I'm running 2204 2400kv's (stop me if I said this already) but that's what's required to get enough thrust from the 6040 props I installed on them. Despite my issues with building a reliable skirt that isn't going to tear off the underside of the deck or just get 1000 holes on it the first time I take it up and down the street, ruining the bag inflation. most of the construction techniques follow some of the flitetest techniques, but there's also a lot of stuff I had to build custom including the cage and ducts. Personally, without the skirt it actually hovers about an inch above the ground but once I get it a bit down the street it stats to knock off pieces of the styrofoam body.

Anyway, for your airboat, really, use the bigger prop. Like our friend said, you will not get the thrust you want out of a 5" prop at those slow speeds, and I know you want to get up on plane so..