Rubber band powered race boat

This is a rubber band race boat I designed for the Maker Faire 2015 Moat Boat Paddle Battle Challenge. See it in action on a test run here: https://www.youtube.com/watch?v=8XWNFfDlJNM

The propeller is a store bought model boat propeller because consumer 3D printers are not capable of printing high strength, high resolution models that propellers require. A large pitch propeller is preferred.

I used a 2" T-pin as the propeller axle. I cut a slot in the tail of the propeller to secure