Straw-Cat Sailboat

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The Shoebox Regatta makes physics fun by creating 3D-printed toys. Teach kids how sailboats work by building Catamaran sailboats from printed parts, soda straws, and plastic wrappers. The boats can be raced in a plastic shoebox of water and powered by blowing on the sails through straws. Adjusting the sail, rudder, and wind direction teaches how sailboats can sail in directions other than the way the wind is blowing. - Print the set of sailboat parts (designed to fit on the small Printerbot Simple bed) - Cut four equal straw pieces (three long) for pontoons - Cut a one-inch straw for centerboard support - Cut a three-inch straw for mast - Cut a triangle sail from cellophane and tape it to printed spars - Assemble the sailboat - Fill a plastic box halfway full of water - Float in water and adjust the tiller and sail for broad reach - Gently blow on the sail through a straw - Each boat in the regatta has a shoebox, and sailors provide their own wind at the starting signal - The winner is the first boat to go the length of the box without touching the side - The winner of the tournament gets to keep the winning boat, which is replaced by the one printing during the competition Materials needed: * 3D printed parts: sail spars, forward frame, aft frame, centerboard, rudder, and tiller * Four colorful soda straws * Colorful cellophane food packaging * Plastic shoebox and water Lessons learned include: * Center-of-gravity * Angle of incidence and resulting forces on the sail * How to steer a sailboat to go in directions other than the way the wind is blowing * The iterative design process for improving performance Teachers can reuse the apparatus with subsequent classes.