How to Make a Toy Boat That Moves – DIY Rubber Band Boat STEM Project

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There’s something magical about watching a homemade toy boat zip across the water—all powered by a rubber band! In this fun and simple STEM activity, we’ll show you how to make a toy boat that moves using cardboard, duct tape, and rubber bands. Perfect for bath time fun, backyard water play, or a creative extension to a favorite book!

This project is based on the Virtual Book Club for Kids theme of boats, and inspired by the lovely picture book Toy Boatby Randall de Sève. It’s a charming story about a small toy boat with a big personality—and it inspired my kids to make boats of their own!

Book Connection: Toy Boat by Randall de Sève

This sweet picture book follows a handmade toy boat on an unexpected adventure. After reading it together, we decided to try building our own toy boats—ours are powered with rubber bands for extra STEM fun!

How to Make the Rubber Band Boats:

How to Make a Toy Boat That Moves (Rubber Band Paddle Boat)

Supplies:

• Cardboard (thin, sturdy kind works best)
• Scissors
• Marker or pencil
• Colored duct tape
• Rubber bands
• Water bin, bathtub, kiddie pool—or a calm day at the pond!

Instructions:

1. Draw a boat shape on cardboard. Ours looks like a small rectangle with a “notch” or “door” cut out at the back.
2. Cut out the shape and save the square you removed—it will become the paddle.
3. Trim the paddle slightly smaller on all sides so it can spin freely.
4. Cover the boat and paddle in duct tape. This makes it waterproof and adds durability. Make sure all edges are sealed to keep water out!
5. Wrap a rubber band around the back of the boat and slide the paddle through the rubber band.
6. Wind the paddle several times away from the boat (so it propels forward).
7. Place your boat gently on the water and let it go!

Tip: Try different paddle sizes and shapes to see how they affect speed and movement.

Why This Is a Great STEM Project

This project explores important science and engineering concepts in a fun, hands-on way:

• Buoyancy – Why does the boat float? It displaces water, and its shape and materials help keep it afloat.
• Newton’s Third Law of Motion – For every action, there is an equal and opposite reaction. As the paddle pushes water backward, the boat moves forward.
• Tension and Propulsion – Twisting the rubber band creates tension; when released, this energy turns the paddle and pushes the boat.
• Potential and Kinetic Energy – This is a great visual demonstration of how energy can be stored and then released to produce motion.
• Propeller Mechanics – The paddle acts like a simple propeller, pushing against the water to move the boat.

Ask your kids:

• What happens when you twist the paddle more or less?
• Can you race two boats with different paddles?
• What if you use a different material like foam board?

Extension Ideas

• Build a boat racetrack in your bathtub or kiddie pool.
• Chart the distance each boat travels.
• Add a flag or sail using a straw and paper.
• Create a design challenge: fastest boat, most stylish boat, longest float.
• Experiment with other propulsion methods (like magnets or balloons).

Now let them go in your tub!  We made a few because the kids wanted to all have their own favorite colors to play with and we needed to have some boat races, of course!

Watch Them Go!

More Boat-Themed Activities:

Submarine Science– made with a plastic bottle
Raft Craft– popsicle stick rafts
Magnet Boats– milk cap boats
Fishing for Spelling Words

And see ALL of our Book Activities for Kids.

This DIY rubber band paddle boat is one of our favorite projects—it’s budget-friendly, easy to build, and full of learning! Plus, your kids will love having their own toy boats that actually move.

Whether you’re doing this for a spring STEM unit, a book-based activity, or just for fun—don’t forget to bring your towel. You will want to race them more than once!

See what other bloggers have done with the boat theme:

Fishing for Letters (with a FREE printable) – Preschool Powol Packets
How to Make a Boat with Recycled Materials– JDaniel4’s Mom
Geometric Shapes boat– Mama Smiles
Paint Resist Toy Boat Art Project– The Educator’s Spin on It
Floating Foil Boat Experiment– Messy Little Monsters