How do Paper Boats Float?
When it comes to making things float on water there is one basic fact to keep in mind: You can make any material float if the density and displacement are correct. That’s why heavy, steel ships remain afloat. Tip: Salt water will support items better than fresh water.
With paper boats, the solution is a bit easier because there is less weight to deal with. The paper boat’s design distributes this weight over a large enough area to allow the craft to float. Here’s the scientific fact: A boat floats when the weight of the amount of water it displaces is greater than the weight of the boat.
With paper boats, the key is finding a shape/design that will work. The boat must stay upright and act in the same way a larger, heavier boat will act to accomplish your goals. But paper boats can be a lot of fun because of the light weight and the nature of the material. Paper boats can be made in a lot of interesting shapes.
The sides must extend far enough above the water to keep the water from getting in and flooding the boat. Make sure your sides are even as well, so the boat stays in balance. You will be surprised how much a paper boat will hold when you build it carefully and place the “cargo” in it carefully as well.

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