Picture of Build a Baking Powder Submarine
I have long wanted to build a baking powder submarine from commonly available materials. I had one of these in the 1950s when Kellogg's gave them as a prize in cereal boxes. Those were a little over two inches in length. A couple of years later l saw a much longer one in a store window. Mr_o_uk got me thinking about it again with his Baking Powder Diving Submarine Instructable, but his is a concept submarine he has not actually built. There are some practical problems I had to solve before my concept would be a working bathtub submarine that goes to the bottom, rests there, rises, discharges a bubble of CO2, and sinks to the bottom again in endless cycles until the baking powder is depleted. I have done that in a way someone reading this Instructable can replicate.
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Step 1: Materials and tools

Picture of Materials and tools
The bulk of the submarine is made from a gray PVC nipple nominally 1/2 inch by 6 inches. (The actual internal diameter of the PVC is a tiny bit more than 9/16 inch.) 

All materials--
  • 1/2 x 6 gray PVC nipple
  • Wine bottle cork (synthetic [plastic], not real cork)
  • Sheet metal screw
  • Axle cap for a 1/2 inch axle
  • 5/8 inch internal diameter (nominal) braided rubber hose (actual internal diameter measures about 9/16 inch
  • Hot glue
  • Finish nail
  • Clear finger nail polish
  • Baking powder (not baking soda)
  • Fine tooth saw
  • Sandpaper
  • Screwdriver or nutdriver
  • Drill and bits
  • Dremel tool and burring bit
  • Grinder and wheel
  • Knife
  • Hot glue gun
  • Side cutter pliers

Step 2: Saw threaded ends from the PVC nipple and fit the conning tower

Picture of Saw threaded ends from the PVC nipple and fit the conning tower
Saw the threaded ends from the PVC. One will be discarded and the other will become the conning tower on the submarine.

Place a piece of sandpaper over the remainder of the nipple. Move one of the threaded pieces over the sandpaper until its contour fits the contour of the PVC. See the second photo.
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cracra11 months ago

Does it matter if the water is hot or cold?

Phil B (author)  cracra11 months ago
I have always used water just as it came from the faucet--neither hotter or colder than that.
cparedes2302 made it!11 months ago

hello Phil B.!

I just finished the Baking Soda Submarine and it works great. I had to change the design a little to accommodate the materials I had in hand

1. I used a soda cap for skirt for holding the gas.. I had to use a washer for the plug of the "baking powder reactor" so my model was a little on the heavy side. I will try to work the weight problem on a second submarine.

2. Another problem I had was that the submarine would not tilt to release the bubble due to the weight of the washer so I glued a little wood plug on the side of the reactor to help the tilting and releasing the bubble

3. I have to keep on sanding the bottle cap so it does not have to tilt as much for releasing the bubble

Congratulations as it is an easy project and a very fun one! Thankyou very much as the baking Powder Submarines have always amazed me


here are a couple of videos of the submarine in action. Just a tiny change in the cap position and it behaves diferently. ENJOY!

Phil B (author)  cparedes230211 months ago
Thank you for trying this project and for reporting your results, as well as sharing your modifications. I am very pleased for your that it works. It is a joy to hear from you.
akri1 year ago
wonderful science..
akri akri1 year ago
video link is not playable..
Phil B (author)  akri1 year ago
The video link is good. If you read the text below the photo you know not to click on the photo, but on the hot link in the words below the photo.
bigJAGfan1 year ago
Does anyone remember the little boat you used a candle and water to propel around a sink or bathtub? Hope someone makes an instructable for one
I don't know if there are any on Instructables, but you can find a variety of designs on the internet and in old children's magazines (from when we actually trusted our children to build things.)

They are very simple and can be made with nothing more than a boat that can hold a candle and a coil of copper tubing. More efficient designs can be found with a little research.
Phil B (author)  bigJAGfan1 year ago
I made a little boat powered by the bubbles from an Alka-Seltzer tablet inside a 35mm film canister in contact with water also inside the canister. You can see it here. I hope it is close to what you have in mind, even though it does not use a candle.
mr_chris1 year ago
this is really great. an ideal project for my 6 yr old and me. Thanks for making this ible.
Phil B (author)  mr_chris1 year ago
Thank you for looking and for commenting. I looked at customer reviews for commercially available small submarines of this type. Some found their small children were enthralled by a baking powder submarine, while others found small children in their families tired quickly of this water toy. I hope it goes well for you and your 6 year old.
oilitright1 year ago
I got such a kick out of reading this. I played with something like this 50+ years ago. My mother got so mad when I left the can of baking powder i the bathtub!
Phil B (author)  oilitright1 year ago
I am glad you enjoyed reading this. We are close to the same age. You probably had some of those Kellogg's issued in the mid-1950s. There was no extra money in the average house at that time. It is not surprising that your mother would have been angry about replacing a can of baking powder, although it is funny now.

I just wanted to see if I could make a working example of a baking powder submarine that others could copy if they chose to do so. I had no idea how many people would respond to it based on reliving personal childhood experiences.
Cool! I had a couple of the 2" Kellogg plus a 6" Nautilus you had to send away for. There was also a 6" baking powder powered PT boat.
Phil B (author)  davidsweeney1 year ago
Some of those are still available at times on eBay, but they cost considerably more now. Thank you for your comment.
rimar20001 year ago
Phil, you should put a video of it "swimming".

I remember when many years ago (I was a child) Popular Mechanics published a baking powder submarine. It was made of galvanized sheet, a lot more complicated than yours.
Phil B (author)  rimar20001 year ago

I did a search for a baking powder submarine in Popular Mechanics Magazine, and found this from MAKE Magazine. It uses carbide tablets to produce (flammable) acetylene gas in water. To see the full original article from the December 1924 Popular Mechanics (p. 999), go to this link and scroll down to the heading for "A Mysterious Submarine." Then click on the highlighted page number, which is p. 999.
Bill, I think it was not that article, but not sure. My memory is a bit moth-eaten ...

Thanks for the link, is very interesting.
I did a search and found the same artucle,lol.The one I was thinking of with soup cans was in an old 2" thick book of projects I have packed away somewhere.The title escapes me,if I find it,I'll post the title.There is also an electric one in the May '32 issue,I guess it could be adapted to more modern batteries(LiPo,etc.)
I think I remember the same article! But the one I remember consisted of soldering soup cans together and ran on carbide.I know googlebooks has them back to the 20's-30's for PM and PS,if I find the article,I'll post it.
Phil B (author)  Bowtie411 year ago
I posted it in response to rimar2000. Look below.
Phil B (author)  rimar20001 year ago

I am thinking about a video, but would have some problems to solve to make the video show what needs to be shown. My PVC submarine is heavier in water than I thought it would be. Galvinized sheet metal would be even heavier. Even though a buoyancy balance can be found, the additional mass adds to inertia and makes the submarine sluggish and slow to respond. That is my theory. Thank you for looking.
andamas1 year ago
Great instructable! I had one of those when I was a kid (had forgotten all about it) and will be following your instructions to build one of my own. Thanks!
Phil B (author)  andamas1 year ago
Thank you for looking and commenting. Please report back with a picture or two when you have it working.
WOW, haven't thought about this is years! I also had one and it was a pure joy to play with.... Great post. Thanks...
Phil B (author)  ronkrifchin1 year ago
You are not too old to make one and enjoy it again. Thank you for looking and for commenting.
Phil B (author) 1 year ago
I did make a video and linked it in the last step. Those who have looked and commented will now be aware of the video. Here is the link.
rippa7001 year ago
I love this and my little boy will never leave the bath after I make him one. Thanks! It looks great and great, easy to follow directions. When I have a moment (I have an eco-build to finish too) I will make one although from different tubes I think. Good post thanks!
Phil B (author)  rippa7001 year ago
Thank you for your comment. Many materials will work so long as you can tune the buoyancy so the submarine just crosses the threshold at which it will sink by itself. The baking powder runs out before long, and will need a consenting adult to replenish it. There is some built in control on getting the kids out of the tub!
Love it! We used to build these out of potatoes!
Phil B (author)  LaffyDuck1871 year ago
Yes. I never did, but I did include a link to a YouTube video about the Spudmarine. It is a submarine made from a potato. There is also a version made from a carrot.
how it works???
Phil B (author)  HamidStranger0071 year ago
Some of the links in the Instructable give some detail on how it works, but here is a very simple explanation. When water comes into contact with baking powder (not baking soda), carbon dioxide gas bubbles form. The submarine is tuned to be almost buoyant in normal water from the pipes in your home. As it rests on the bottom of a water container, a bubble of carbon dioxide forms under the submarine. When the bubble is large enough, the submarine becomes buoyant and it rises to the surface. The submarine tips a little to one side and the bubble escapes from under the submarine. It is no longer buoyant and sinks to the bottom of the water container. It does this until the baking powder is too depleted to make carbon dioxide in sufficient quantities.
ericgus1 year ago
Someone should make this using a 3d printed submarine.
Phil B (author)  ericgus1 year ago
I linked an Instructable in the Introduction, and that Instructable is the plans for a 3-D printable baking powder submarine. As I mentioned, it is a concept. It has never been built. If someone wanted seriously to make an Instructable on a functioning 3-D printed submarine, a prototype would need to be made and tweaked until the buoyancy was just right. Then the working prototype would need to be digitized for printing. My experience tells me this submarine will not work without testing prototypes in actual conditions, unless someone is very good with the right kind of engineering.
ericgus Phil B1 year ago
Ah sorry I missed that on my mobile.. still a great instructable none the less.. thanks for posting it.
Phil B (author)  ericgus1 year ago
Thanks for looking and for commenting. I did actually compose and post an entire Instructable on my smart phone. It worked, but some things just do not work as well. That is for certain.
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