Build an unsinkable boat

HomeBuild an unsinkable boat

Build an unsinkable boat

HomeBuild an unsinkable boat

Summary: use whatever you have to hand at home to build a boat, and see if it can carry different objects across the water

Set-up: 10 mins preparation, 30 mins until ready

Play: 30 mins – 2 hour

Complexity: Varying complexity according to ability


  • Recycled boxes
  • Tubs
  • Plastic trays
  • Plastic straws
  • Aluminium foil
  • Clay
  • Plasticine or blu-tack
  • Paper
  • Tape
  • Glue
  • A bath tub or sink to test the boat
  • A set of uniform items, such as coins, marbles, small blocks, or tin cans, as boat “cargo” to test the boat’s flotation capacity

What to do

Challenge your child to build a boat that floats and can’t be sunk. Get out your supplies and get them to think about what they might use for a boat. Ask questions such as what’s important in the design of a boat? What shape does it need to be? Why is that? Are all these materials waterproof? If not, could you make them waterproof?

Explain that after the boat is made, you will see if it can carry some of the objects you have chosen for the flotation test (coins, marbles, small blocks, or tin cans). If several family members each design and build their own boat, you can have a competition to see whose boat can hold the most “cargo” before it sinks. Count the objects into the boat one by one, and find out: whose boat can hold the most? (Ask older children to work out how many more, and so on).


Limit the materials you give your child: for example, give them just a 30cmx30cm piece of foil and challenge them to make a boat out of that.

Ask your child to design a boat for a specific item – a toy, vehicle, or a soup can (heavy!).

Make sailboats and test them for speed by using a fan or a hairdryer to push them across a shallow tray of water (NB keep water and electric items far apart).

What learning does this activity promote?

Thinking skills, design, problem-solving, scientific concepts, concepts of mass and weight, counting, concepts of more and less

By Dr Vicki Hargraves


Dr Vicki Hargraves

Vicki runs our early childhood webinar series and also is responsible for the creation of many of our early childhood research reviews. Vicki is a teacher, mother, writer, and researcher living in Marlborough. She recently completed her PhD using philosophy to explore creative approaches to understanding early childhood education. She is inspired by the wealth of educational research that is available and is passionate about making this available and useful for teachers.

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