A airboat with a rudder in the water is not what a airboat is about. A airboat is designed to go over weeds and wet grass and even on the bank if your engine is powerful enough, its not ment to have a rudder in the water its supose to have air rudders.If you want a rudder in the water build a v bottem or something and you can go realy fast and turn realy sharp. If you want better control put 2 slats on the bottom of the hull about 6 inches long on each side and make the rudders the same higth as the prop to get full forse of the air over them. I have 4 air boats electric and nitro and they run fine and turn good ,better in the direction that the prop is turning but ok the outher direction too.I have a 51 inch airboat with a 140 nitro turning a 18 inch pusher 3 blade prop and it goes where ever it wants to go and runns in the 40 mph...Bob