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.
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.
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 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. Check these fun instructions to build a balloon boat from ZOOM, the PBS TV show.
Note: Please be careful using balloons, and always have adult supervision. Children under 8 years can choke or suffocate on uninflated 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.
Here is a short video showing one of our trials. Bear with us, we're still learning video technology 🙂
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.