Tag: boat propulsion

Beach Science- Boats

To continue the theme of beach science from the last few weeks, today let’s investigate something else found at the beach.



Children are fascinated by boats and floating. You can do a lot of interesting science projects with boats, starting with some basic questions: How can huge pieces of heavy metal float? How are boats propelled? Can you really make a boat out of paper?

We already have covered some floating and boat topics in previous posts.

Why Things Float contains some experiments on floating and sinking.

The How long can a paper boat float? challenge, with the early results for paper boats challenge.
The yellow legal pad boats lasted five days.


The Bathtub Buoyancy Challenge asked kids to find ways to propel boats across a bathtub without using their hands or electrical motors. The Bathtub Buoyancy results show several ways to propel toy boats.

It is always fun to build bathtub-sized boats. This video shows two handmade boats powered by battery packs and small electric motors that my son invented recently. A modified toy car powers the paddle boat; the air boat fan is a modified toy airplane propeller.

Why don’t you try inventing a boat?

For more ideas, try

A Simple Steam Boat at Curious Cat

Miniature Boats at HowStuffWorks

Hope you have fun and let us know what kind of boat you invent!

Edit: To check the rest of the posts on beach science, follow these links:

Sea Horses and Other Fish

Shore Birds

Tide Pool Invertebrates

Beach Science Algae

Beach Science-Sand

Beach Science-Seawater

Bathtub Buoyancy Challenge 1 Results

Do you remember the challenge, to propel a homemade boat across a bathtub without using your hands to touch it, batteries or electricity? We came up with more than six ways to do this. Did you come with any that we didn’t? Let us know!

1.    Wind or air movement
Probably the most obvious way to propel a boat without touching it is to use air movement or wind. We tried both creating a sail and blowing on it and also using a fan to create air. Both were effective, although somewhat slow and hard to steer.

2.    The classic balloon boat –

You may have seen instructions for these or tried out a kit. I found some available for sale on the Internet (see Resources below) or you can make your own.

Note:  Please be careful using balloons, and always have adult supervision. Children under 8 years can choke or suffocate on underinflated or broken balloons.

3.    Wind-up propeller
My son took a wind-up propeller from a balsa wood airplane and modified it to propel a flat wooden boat. The stretched rubber band creates the potential energy which is then transferred to kinetic energy. It is fast for short distances.

See the red propeller on the right, rubber band across the center and nail holding it on the left.

4.    Magnet Repulsion
Okay this one was my idea. I remembered moving train cars in a wooden train set by reversing the magnets. It works with an egg carton boat, too. I think this type of boat has the best steering once you get the hang of it.

5.    Detergent Power / Soap propulsion

You may have seen instructions for a soap boat that actually moves. We created one using a top of a Styrofoam egg carton and a squirt of dish detergent. This is not technically a chemical reaction, the movement has to do with the surface tension of the water.

6.    Chemical reactions

My dad told me that as a kid he had a boat that ran on Alka Seltzer tablets. You can also make boats propelled by baking soda and water, or vinegar.

Instructions at the Children’s Museum of Indianapolis

Good luck and I hope you try some of these. They were fun and we learned a lot too.

Resources for Further Explorations (Affiliate links to Amazon):

Balloon Powered Wooden Boat

Rubber Band Paddle Boat

Let’s Try It Out in the Water : Hands-On Early-Learning Science Activities by Seymour Simon, Nicole Fauteux, Doug Cushman (Illustrator)

Teaching Chemistry with TOYS by Jerry Sarquis, Mickey Sarquis , and John Williams

Science in Seconds with Toys: Over 100 Experiments You Can Do in Ten Minutes or Less by Jean Potter

Magnetic Boats in the Tub