A Sinking Feeling: The Science of How Boats Float
If you've ever tossed a coin into a fountain, you’ve likely wondered why a massive ship can float while the coin sinks. Boats, though made of heavy materials, float on water and are able to sail the seas. So, what makes boats so special in this regard, that they have no fear of sinking unless some outside factor affects them? Proceed with caution as we sink into the science of boats, but worry not, this article will not “drown” you in jargon.
The key concept here is density, which is basically how much stuff is packed into a certain amount of space. Think of it like this: density is how much stuff you can cram into a very small area. The more stuff you can fit into this area, the denser the object is. Now, consider a boat, which, while being heavy, is built with a lot of air inside its hull. This makes the boat less dense than the water, so it floats. The boat’s weight is spread out over the larger volume of water because of all that air, and that’s what keeps it from sinking.
Another concept that’s important to know related to floating is Archimedes’ principle, which is more commonly known as buoyancy force. This rule basically states that when an object is placed in a liquid, the water will exert a force that is equal to the weight of the object, which causes it to float. An example of this is when you place ice in a drink; while it looks like there’s more liquid in the cup, in reality, it’s the exact same amount, except that it’s just taking up more space. That's why the next time you order milk tea, consider asking for no ice—you'll get more of the drink without the ice taking up extra space.
Combining these two concepts, the buoyancy force of an object is determined by the density of the object and the amount of water it displaces. Objects with a density lower than the density of water and that displace more water than their weight will float. In the case of boats, they are able to float because they can create a strong enough buoyant force to keep them afloat due to their massive weight.
So, the next time you are on a boat, be grateful that it will not be sinking anytime soon. While it could very well turn out to be the next Titanic, at least you would understand how and why it sank as the boat started its descent into the abyss.
Sources:
https://www.scientificamerican.com/article/bring-science-home-how-metal-boats-float/
https://www.britannica.com/science/density
