This boat, being a twin-prop, posed a problem when it came to winding them both up. So I used gears (from a broken printer) to wind both at the same time. Friction is the biggest theif of power when it comes to rubberband-powered boats…apparently. So I incorporated bearings. Bearings are great! The drive shafts are made of fiberglass rods (stolen from an umbrella frame). The casing for the shafts are Bic pen tubes. FYI, the key to making this boat propel for a considerable amount of time (about :45 seconds) is the size and shape of the props. These showed here are a bit too small, but they are as large as can be, without scraping the hull and each other. I will definitely make another boat that allows for more clearance, allowing larger fins on the props. Please excuse the ugly fiberglass job…it is my first time using fiberglass. Might I add…fiberglass is AWESOME!! I hope this sparks some creativity to those whom see this project! Thanks for looking.