Here’s a cool science experiment that kids will love! Make a baking soda and vinegar powered boat. This fun STEM challenge is perfect for summer time when it’s warm outside, but I’ll show you how you can also sail your boat indoors at any time of the year.
In this science experiment, kids will be using the reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid) to create carbon dioxide gas. The bubbles of gas will power the boat!
This is not a speed boat!
The procedure for this science experiment is very similar to our baking soda and vinegar bottle rocket. However, there is one big difference. In the rocket experiment, a cork is used to seal the bottle. As the baking soda and vinegar react, they create carbon dioxide gas which builds up in the bottle until the cork finally pops out and releases a burst of water and CO2. In this boat experiment, the CO2 is allowed to escape gradually as it forms. There isn’t going to be a huge burst of speed with this boat! It travels slowly. But it’s still a very fun science activity, and there are some great ways to experiment with it.
- A small plastic water bottle with a cap – we used a 16.9 oz bottle
- A plastic bendy straw
- A drill
- Hot glue gun
- Craft foam
- A container to sail your boat in – we used an under-the-bed storage box
- Baking soda
- Paper towels – not just for cleanup! These are important for the experiment.
Step 1: Make a hole in the cap of your water bottle.
You’ll want the hole to be the same size as your straw. If it’s slightly bigger than the straw, that’s okay because we’ll be sealing the hole with hot glue.
We used a drill, but you can also use a nail. Start with a nail hole and then make the hole larger with a pair of scissors. (Stick the pointed end of the scissors in the hole and turn them to make the hole larger.)
Step 2: Trim the straw to make it shorter.
Insert the straw into the hole in the bottle cap. Put the cap on the bottle.
Use a little hot glue to secure the straw in place and seal the hole. You don’t want air to escape around the straw.
Step 3: Add craft foam to make a boat shape. Use hot glue to attach the craft foam to the bottle.
Honestly, this step is optional! The bottle will sail on its own. But it’s fun to make it look more like a boat!
I would not recommend adding a sail, however. If you are doing your experiment outdoors, a sail will turn your boat into a wind-powered boat instead of a baking soda and vinegar powered boat. We had a bit of trouble with the wind as it was… more on that in a minute.
Step 4: Make some baking soda packets.
You’ll need to slow down the baking soda and vinegar reaction a little so that you have time to put the cap on and put the boat in the water. The paper towel will keep the baking soda and vinegar from mixing right away.
Dump about 1 1/2 Tablespoons of baking soda onto a small sheet of paper towel. I cut a select-a-size paper towel in half to make each packet.
I didn’t measure – just spooned some baking soda onto the paper towel. You want as much as you can get… but the baking soda packet must fit through the mouth of the water bottle.
Fold up the paper towel around the baking soda. Keep the shape narrow so that it can fit through the bottle opening.
Now it’s time to sail your baking soda and vinegar powered boat!
We experimented with different amounts of vinegar. The photo below shows how much we put in our 16.9 oz water bottle.
Drop in a baking soda packet and quickly screw on the cap. Point the straw so that it’s facing slightly downward.
You don’t want the straw pointing straight down because you don’t want to create a downward force. That would push the boat upwards instead of propelling it straight ahead. You want the bubbles shooting out from the back of the boat so that they push the boat forward. This is an example of Newton’s third law of motion. For every action, there is an equal and opposite reaction!
We used an under-the-bed box to sail our boat. It worked well! Didn’t give the boat super far to travel, but it worked. A kiddie pool would also work. If you want a longer distance for the boat to travel, you might want to try a rain gutter.
You won’t want to do this activity on a super windy day. A breeze is okay, but heavy winds will slow the boat down or spin it around.
Add an experimental variable to your boat!
Make this a true science experiment by comparing different amounts of baking soda and vinegar. What combination makes the boat travel the fastest? The more vinegar you add, the heavier the boats gets, which slows it down. But more vinegar also means more carbon dioxide created. Let kids try different amounts and see what works!
Another idea is to try adding a rudder. We made a rudder with two layers of craft foam, and then we glued it to the bottom of the boat.
You could also try different sizes of straws. Make two boats, one with a regular straw and one with a larger milkshake straw.
Or, experiment with the length of the straw – how much length is down inside the bottle, or how much length extends into the water.
How to do this baking soda and vinegar powered boat inside:
The easiest thing to do is to use a bathtub. There’s plenty of room for sailing a boat in there!
If you’re in a classroom, a bathtub won’t work! One idea is to use an under-the-bed box with a layer of beach towels underneath to catch any splashes.
You will end up with some vinegar getting into the water, just FYI.
Have fun with science!
If you need more science experiments for kids, we have tons! You can see them all here: Cool Science Experiments for Kids