Build a remote bottle boat

Not the best of write-ups on how the author built the boat.  And its not as cheap as it could be (using an arduino for the controller, full UNO board).  But still a good learning project.  I wish the author put a little more into how the motors where waterproofed.  My 2 cents, a cheaper solution would be to use a cheap $10 RC car and gut it out.

http://www.instructables.com/id/Pepsi-Bottle-RC-boat/