Tin Foil Water Craft

In this science experiment you will be designing a tin foil boat that will hold the greatest number of marbles. Get together with some friends and have a contest to see who can design a cargo boat that will hold the most pennies.


  • Tin foil

  • Large container to hold water (or a sink)

  • Marbles

  • Water


  1. Use a steel straight edge to tear tin foil into 150 mm square sheets

  2. Design a craft that will hold as many marbles as possible.

  3. Place the boat in the bowl of water. Begin adding pennies for the boat's cargo.

  4. See how many pennies your boat can carry before it sinks.

  5. Have some friends over and try this experiment with them. See which one of you can create the boat that will carry the greatest amount of cargo.

  6. Be sure to dry the pennies before you begin adding them as cargo because remember water has weight!

  7. Have the person who created the boat begin adding pennies to their boat while another person counts the number of pennies as they are added to the boat.

  8. Try different ways to distribute the weight of the pennies on your barge so you can carry the maximum number.

Try another science experiment.

  1. Create a boat out of tin foil that is 4 x 5 inches. Make a prediction about how many pennies you will be able to carry as cargo in this boat.

  2. Create boats out of clay and see if you can make them float and carry cargo.

Science behind the experiment

There are two primary forces acting on this science experiment. The first force is gravity. Gravity is trying to pull the tin foil and pennies downward. The force of buoyancy is pushing the boat toward the surface.

The gravitational force is determined by the weight of the tin foil and the weight of the pennies in the boat. The force of buoyancy is the weight of the water displaced by the boat.

Your boat will continue to float as long as the force of buoyancy is greater than the force of gravity and you do not overload the boat so it will tip over or leak

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