Straw-Cat Sailboat

Summary

• The Shoebox Regatta teaches physics with 3D-printed toys.
• Teach kids how sailboats work by making Catamaran sailboats from printed parts, soda straws and plastic wrappers. 
• The boats can be raced with each in a plastic shoebox of water and powered by blowing on the sails through straws. 
• Adjusting the sail (lateen rig like a sunfish), rudder and wind direction facilitates learning of how sailboats can sail in directions other than the way the wind is blowing.

Instructions

• -Print the set of sailboat parts (designed to fit on the small Printerbot Simple bed)
• -Cut 4 equal straw pieces (3 long) for pontoons
• -Cut a 1 inch straw for centerboard support
• -Cut a 3 inch straw for mast
• -Cut triangle sail from cellophane and tape to printed spars
• -Assemble sailboat
• -Fill plastic box half full of water.
• -Float in water and adjust tiller and sail for broad reach.
• -Gently blow on sail through a straw.
• -Each boat in the regatta has a shoebox and the sailers provide their own wind at the starting signal.
• -Winner is the first boat to go the length of the box without touching the side.
• -Winner of the tournament (regatta) gets to keep the winning boat (which is replaced in the fleet by the one printing during the competition.)

Materials:

• -3D printed parts: sail spars, forward frame, aft frame, centerboard, rudder and tiller.
• -4 colorful soda straws.
• -colorful cellophane food packaging
• -plastic shoebox and water
• Lessons include:
• -center-of-gravity
• -angle of incidence and resulting forces on the sail,
• -how to steer a sailboat to go other than the way the wind is blowing,
• -the iterative design process for improving performance,

Teachers can re-use the apparatus with subsequent classes.