# How does a boat the size of a small city float?

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How does a boat the size of a small city float?

In: Engineering

It floats because as big as it is, and as much steel as its made out of, it still weighs less/the same as an equivalent volume of water it displaces.

Water.. is heavy. Solid steel is heavier, but a hollow steel box is – comparatively – way less heavy than an equivalent solid steel or block of water. Ergo… it floats.

The way any boat floats- by being, on average, less dense than water.

As long as the weight of the boat is less than the weight of the water it displaces, it will float. It’s the same for a paper boat as it is for an aircraft carrier.

An aircraft carrier generally displaces about 100,000 tons of water. This means that as long as the total weight of the ship is less than that (and it definitely is), it will float

Anything will float if it displaces enough water.

When an object is submerged, it occupies a volume of water. The underwater volume is called the displacement. If the weight of the water that gets displaced weighs the same as the ship, then the ship will float. If the volume is less than the weight ship, the ship will sink. In a sense, all ships sink, until they get deep enough so that they don’t. It may not look like it, but when you see a ship in the water, their hull can be 10 metres or so under water, which displaces a large volume of water. When the ship is deep enough, the underwater volume will be large enough to displace water equal to its weight.

Ships float because they have a large displacement/underwater value, but don’t weigh as much. Ships are huge and heavy, but they are mostly empty. Rocks sink because that small volume of water they displace does not weight the same as the rock. If a rock could displace more water—it it could occupy a large underwater space—it would float.

* Boat goes in water.
* Sinks a little.
* Pushes some water out of the way.
* That water pushes the water next to the boat up.
* So the boat is essentially lifting some amount of water.
* But water is heavy and pushes the boat back up.
* As long as the boat is lighter than the amount of water it pushes out of the way, the water will win the battle and force the boat to stay up, also known as floating.

Despite how heavy steel (or fiberglsss, aluminum or even cement) you also count the empty space inside the ship as part of the volume.

For example you could measure the dimensions of your boat in cubes, then divide it by the weight. This gets you the density of your boat, we’ll use pounds per cubic foot.

Seawater is 64 lbs/ft^3

If you boat is less than that, Despite outer dimentions, it should float

Since it’s so big it displaces a *lot* of water, so even though it’s heavy it’s still less dense than the water it displaces and it stays afloat. When it comes to floating what matters isn’t size but overall density of the object. Aircraft carriers float because they are big but mostly hollow, while tiny pebbles sink because they are solid.

I thought it was due to the flotation power of citrus???

Water has a density of 1 let’s say. Density is the amount of material within a certain space, so more material means more density. Some materials are more dense than 1 and do not float, like solid a rock. Some have so little density that they float above water, like air and balloons that have air on the inside. If an object has enough air inside it then it can be as big as it wants, so long as it can maintain a density of less than 1. If you take a ball of clay and toss it in water it will sink. But if you spread that same amount of clay into a very thin and broad sheet, it would float, of you spread it out enough. Boats are the same. If you had a giant grab a boat and squish to boat into a ball it would sink, but boats are made in a way that used air to keep itself above the water.

The best way I saw it explained and where it sunk in for me, was the way a 55 gallon drum floats. If an empty 55 gallon drum weighs about 40 pounds and 55 gallons of water weighs almost 460 pounds (according to some googling), as long as the drum weighs less than the water it could possibly hold, it’ll float.

You can probably extrapolate further with big ass boats. If the big ass boat weighs 100,000 tons, but could potentially hold 1 million tons of water, it’ll float.

That’s probably way way over simplifying it, but at least that’s how I keep it straight in my head 😁