The Diving Spudmarine

Fun & Games
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As a kid with two older brothers, I knew how important it was to be the first to crack open a new box of cereal and sift through the contents for the toy inside. I remember fishing out a plastic toy submarine and I absolutely loved it. When you filled the submarine’s compartment with baking powder and dropped it in a container of water, the submarine would—seemingly magically—dive and surface. When I came across Bob Knetzger’s SpudMarine project in MAKE Volume 26, these fond memories flooded back to me.

While the heyday of cereal box toys may be over, you can still make your own diving submarine toy out of a potato. It can take some trial and error, but once you find the perfect ratio of wood and tuber, you can pack it with baking powder (not baking soda) and watch it go.

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4 thoughts on “The Diving Spudmarine

  1. Kane Harrison says:

    Similar to raisin racing. Get a glass of fizzy water or lemonade, throw in a few raisins and watch them sink. Carbon dioxide bubbles accumulate on the convoluted surface and brings them to the surface where the CO2 escapes and the raisin goes down again. They’ll do this for about an hour.

    Fun for the whole family.

  2. rherndon says:

    This piece brings back memories of 1954-55. My submarine was a model of the U.S.S. Nautilus, the first U.S. nuclear-powered submarine. I spent many dives of that submarine just watching it do its thing. The process was explained, but that didn’t remove the fascination aspect of it. However, I didn’t have the larger model. I had the smaller, free one, straight from the cereal box.

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Matt Richardson is a San Francisco-based creative technologist and Contributing Editor at MAKE. He’s the co-author of Getting Started with Raspberry Pi and the author of Getting Started with BeagleBone.

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