Balloon Powered Boat

Bathtub STEM? Sure, why not? You will just need a few things to have more than a few moments of fun with a perfect balloon powered boat.

For step-by-step video instructions for kids to work independently, head to The Winkle YouTube channel!

Collect the following items for a balloon boat:

1 flat kitchen sponge.

1 balloon 9”-12”

5/8” diameter plastic tube.  3” will do. (Find this at the hardware store.)

1 zip tie

How you do it:

Cut a point into the boat.

Cut a point into the sponge for the front of the boat. Drawing or measuring first is always best.
It doesn’t have to be perfect to work!

This next step will secure the plastic tube/balloon to the sponge to ensure the tube points backwards. Your boat may work without this step, but I would recommend not skipping it. You can also do this step after you thread the balloon and tube through the sponge.

Make two dots about 1″ apart near the back of the boat.
Poke your pencil through each dot so you can thread the zip tie ends through.
Loop the zip tie through the holes. Tighten it after you finish the next steps. 

Attach the top end of the plastic tube to the balloon.

Stretch the balloon nozzle over the end of the tube. You will blow it up later.

Find the center and poke another hole for the balloon to go through.

Your best guess of where the center is will be fine.
Thread the balloon/tube through the hole. You will want to entire tube on the underside of the sponge. The balloon will empty slower if the nozzle is squeezed slightly by the sponge. 
Secure the tube through the zip tie and tighten. This will keep the tube stable.

Hang on to the balloon nozzle and blow through the tube until the balloon is full.

After you get the balloon blown up, put your finger over the hole until you get it in the water. 

After you get the balloon blown up, put your finger over the hole until you get it in the water. 

Place the boat in the water and let it go.


The balloon may lose its power after a while so be sure to have some extra balloons on hand.

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