RE: 50cc gas engine air boat?
The 3-point hydros work best with the smaller more powerful nitro engines, not saying the gasser will not work. The best place for a gasser your size (IMO) would be on a flat bottom hull 24" x 48" 50" max. Then drop the prop down to the 20" size. The airboat engines are always under a heavy load, the engine will need to be freed some.