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Indoor activity

Rubber Band Speedboats

Engineer a high-speed paddle boat powered entirely by elastic energy, and race them across the bath!

Ages 7-12 0-1 hours Education 10/10

Materials

  • Cardboard Boxes
  • Rubber Bands
  • Scissors
  • Tape
  • Water

Illustrated Steps

1

Construct the Racing Hull

Cut a pointed boat shape from cardboard with two rear arms, and wrap it completely in waterproof tape.

2

Build the Paddle Wheel

Slot two small cardboard rectangles together to make a '+' shape, and wrap it in tape to keep it dry.

3

Install the Engine

Stretch a rubber band between the boat's arms and carefully slot your paddle wheel into the middle of it.

4

Wind Up and Launch

Twist the paddle backwards to store up massive energy, place it in the water, and release!

What You’ll Create

Get ready for the ultimate shipyard challenge! 🚤 You will build a lightweight, water-skimming speedboat equipped with a functional rear paddle wheel. By winding up an elastic band, you’ll store kinetic energy that launches your boat across the water at top speed.

Have fun!

  • 🏁 Build two boats and host the ‘Grand Bath Tub Regatta’ to see whose design is fastest.
  • ⚖️ Experiment with cargo: How many coins can your boat carry before it sinks?
  • 🎨 Decorate the waterproof tape with permanent markers to give your speedboat racing stripes.

Why It’s Amazing

  • Physics in Action: Children visually experience the conversion of ‘potential energy’ (the twisted band) into ‘kinetic energy’ (the spinning paddle). 🔋
  • Engineering Iteration: If the boat spins in circles or doesn’t move, kids must problem-solve and adjust their design.
  • Water Confidence: A fantastic, engaging activity to make bath time incredibly exciting. 🛁

Pro Tips

For ages 8-12, challenge them to make the boat out of a plastic food container instead of cardboard for ultimate waterproofing! If the boat keeps flipping over, tape a single coin to the bottom of the hull to act as a stabilising keel.