Well, I'm bored to death now that classes are over, and I started thinking about building an airboat to drive around the pond in my backyard. I've built a few RC airplanes, but this will be my first attempt at designing and building from scratch. However, I know very little about boats.

What I've been thinking about is having a crude aluminum frame, with 2 pontoons, a rudder on each pontoon, a spoiler ontop of the rudders, and box inbetween the pontoons with the radio, servo's, and battery.

Here's an incredible poor MS paint, minus the engine, mount (which will be apart of the frame), and any sense of true dimensions:


Now for the questions:

First of all, is there anything inherently wrong with my idea?

Second, I have no idea how to glass things, or how I could waterproof the pontoons. Could someone point me towards a tutorial on doing this?

Is a functional spoiler necessary, or do people usually do it for cosmetic reasons? All that's needed is slightly negative angle of attack, correct?

How do you balance the boat? Where should the center of gravity be?

Do you make any modifications to the engines?

Do people usually put lips on the bottoms of their boats, or are they usually smooth? What are the upsides and downsides? I take it lips give more control but there's a possibility of flipping?

I plan on using a .46 engine, I use 11x6 2 blades for use on my airplane, but I want a 3 blade for the smaller diameter. What size 3 blade prop should I get?

Finally, as you see in my painting, I have the rudder going into the water. Does this have much of an effect?

Also, if you know of any common mistakes that beginners make, I'd like to hear them

Thanks