In 1920’s, these were a big hit. They were originally called “Putt Putt Steam Boats”, and were fascinating toys for adults and kids alike. We’ll be making our own version that will chug along for hours. This is a classic demonstration for learning about heat, energy, and how to get your kids to take a bath.
Here’s what you need to build your own:
- Copper tubing (1/8”-1/4” dia x 12” long)
- Votive candle
- Foam block
- Scissors or razor (with adult help)
- Bathtub
Here’s what you need to do:
Download Student Worksheet & Exercises
- Wrap the copper tubing 2-3 times around a thick marker. You want to create a ‘coil’ with the tubing. Do this slowly so you don’t kink the tubing. End with two 3” parallel tails. (This is easier if you start in the middle of the tubing and work outwards in both directions.)
- Stick each tail through a block of foam. Bend the wires to they run along the length of the bottom of the boat, slightly pointed upwards. (You can also use a plastic bottle cut in half.)
- Position a votive candle on the topside of the boat and angle the coil so it sits right where the flame will be.
- To start your boat, fill the bathtub with water. While your tub fills, hold the tubing in the running water and completely fill the coil with water.
- Have your adult helper light the candle. In a moment, you should hear the ‘putt putt’ sounds of the boat working!
- Troubleshooting: if your boat doesn’t work, it could be a few things:
- The tubing has an air bubble. In this case, suck on one of the ends like a straw to draw in more water. Heating an air bubble will not make the boat move – it needs to be completely filled with water.
- Your coil is not hot enough. You need the water to turn into steam, and in order for this to happen, you have to heat the coil as hot as you can. Move the coil into a better position to get heat from the flame.
- The exhaust pipes are angled down. You want the stem to move up and out of your pipes, not get sucked back in. Adjust the exit tubing tails so they point slightly upwards.
How Do They Work? Your steam boat uses a votive candle as a heat source to heat the water inside the copper tubing (which is your boiling chamber). When the water is heated to steam, the steam pushes out the tube at the back with a small burst of energy, which pushes the boat forward.
Since your chamber is small, you only get a short ‘puff’ of energy. After the steam zips out, it creates a low pressure where it once was inside the tube, and this draws in fresh, cool water from the tub. The candle then heats this new water until steam and POP! it goes out the back, which in turn draws in more cool water to be heated… and on it goes. The ‘clicking’ or ‘putt putt’ noise you hear is the steam shooting out the back. This is go on until you either run out of water or heat.
Bonus! Here’s a video from a member that colored the water inside the pipe so they could see when it got pushed out! Note that the boat usually runs as fast as the first video on this page. The boats here are getting warmed up, ready to go, so they only do one or two puffs before they really start up.
Exercises Answer the questions below:
- Name three sources of renewable or alternative energy:
- Why is it important to look for renewable sources of energy?
- What is one example of a fossil fuel?
I made my first set of coils using 1/4 inch copper tubing. It did not work because the tubing was too thick and acted as a heat sink. This would not let the water boil and thus preventing the boat to make steam. Then I made a second coil, out of 3/16 inch steel tubing. This worked much better and the boat worked well. P.S. the 3/16 steel tubing was much easier to bend.
Why not? Let me know how it goes!
can I squish the part that blows out the gas to make it faster?
Thanks for the tip! We originally had a 25 foot piece, and made a handful of these, but I didn’t think bending the pipe would be so challenging. I’ll let you know if my team has any more suggestions for those of you who are still working on this one.
I am also stuggling with bending the copper. My dad has a tubing bender, so I went to use it. But, coiling it was still difficult with his model. I wish I would have bought longer tubing. I am on my third piece. My first was too thick (said it was 1/4 but seemed more like 3/8) to bend well at all. My second and third were bought at the same time–I had the guy cut them to length for me because I don’t have that small of a pipe cutter at home. So, these were thinner than the first. I got the second one coiled and air/water still passed through but the legs of the unit weren’t long enough. By the time it was all set up, it was impossible to get the candle under the copper. So, I went to my dad’s for the third one. I don’t think it will work any better. I just logged on to see if I was the only one having difficulty with this. My rec. is for people to buy longer lengths so the coil doesn’t have to be so tight.
this reminds me of the putput boat on looledoo.com
If you have the time, go get a tubing bender in the morning before the kids get there – it’s one of those tools that really does the trick nicely. Here are a few different models that are available at any discount auto parts store:
Tubing Bender #1
Tubing Bender #2
Tubing Bender #3
We’re using a round dowel that’s larger than a marker size. We did finally get one to coil but there are slight kinks and the whole things is sort of flattened. The water does flow thru but I don’t think it’s as good as it should be. I have 8 kids coming in the morning to do this with me but I’m going to have to make the coils ahead of time since they won’t be able to do it. Would heating or cooling the copper make it stiffer and hold its shape better?
You can use a larger pen to make the loops – the loop size doesn’t matter that much if you have a large enough flame heating the pipes. Can you make a larger coil without kinking?
HELP!!! I can’t wrap my tubing without it kinking. Is there different grades of softness for the copper? This seems just way too soft. We bought the 1/4″ because I couldn’t find 1/8″ but I think the smaller size would work better. There’s no way my kids can do this. Even my husband couldn’t get it while going very slowly.