How do Boats Float?

Boat Floating on Clear Water

A very old dude, although a very cool one, I might add, known as Archimedes is the one behind the theory by which any object designed to float, including boats, functions. The principle he came up with, which was also named after him, called the Archimedes Principle, talks about what makes things float. For example, what happens when you get in a bathtub filled with water? The correct answer is that the water level rises. It might rise to the point that it even goes over the side. The main reason behind this is that the water was “displaced” by you, and then it had to go somewhere else. So the key thing about floating is that an object will displace an amount of water, this being equal to its own weight.

So Why Do Boats Float?

What makes ships float? To help you better understand the principle, let’s consider a block of wood of about 1 square foot. And let’s consider a random weight of about 50 pounds for that block of wood. So now we go ahead and just lower it into the water. As the wood will go down into the water, it will have to displace exactly 50 pounds of water. This also means that around fifty pounds of water will be pushing upwards on the block as it pushes down, making it float.

Why Would a Boat Float and Not Tip Over?

Although the main principle behind floating isn’t all that complicated, if you don’t just want the boat to float but also want to remain in it and get to your destination, then you should also consider the stability and ability to float for it. Stability is what will ensure that the boat will be made in such a way that it won’t tip over as soon as it gets in the water. This, of course, isn’t a guarantee that it won’t tip over at some point and under certain conditions.

As a tanker or an ocean liner is made to safely carry considerable weight, the movement of just one person on such a large ship will basically have no effect on its stability. But when it comes to fishing boats or other smaller boats, your actual weight, and even the weight of the gear you’re carrying with you, will have a strong effect on the stability of the vessel.

When it leans over to one side, a boat is known to “heel” (kind of like when you’re leaning on one foot”. This is why stepping or sitting onto the side of a smaller boat isn’t really a good idea. If the boat “heels” too much due to your weight, it will ultimately tip over. You should try to create a balance between the weights of all the items you bring with you. So if you’re traveling using a small boat, you should try to stay low along with all of the heavy items, occupying the center of the boat. It’s also a good idea to step right in the center of the boat when trying to get into it, especially if it’s a smaller one.

Of course, you will probably be displacing enough water to float if you fall from your boat, so you would probably be ok, but you’d still get cold and wet. Keep in mind that boat tipping is always a possibility. So if this ever happens, try to stay close to the boat and yell for help or blow your whistle. So what should you do if someone asks what makes your boat float? Just talk about Archimedes and factors on stability. You can also talk about the importance of wearing a life jacket while going on the water.

Can you actually a boat float better?

If you’re thinking of building your own boat that would float better, then you should first start with a model that is considerably smaller. The shape of the hull is what you should be trying to modify, to make a vessel float slightly better. You can test a hull by making miniature versions with different changes and testing their performance.

The hull’s shape can be improved so that the boat can displace more water and then fill the remaining gap with air, which is known to have a density considerably smaller than water. Buoyancy and water will be affected differently by different types of hulls. For example, shallower hulls could carry more weight, while deeper ones could have more stability. If this sounds too confusing for you, then it might be a good idea to experiment a little at home so you understand everything a lot better.

To do this, just grab some aluminum kitchen foil and then find a container that you can fill with water.

Try to build small boats with the help of squares of foil with sizes of 12” x 12” and then use them to transport pennies. With each boat you build, try to see how many pennies can you actually move before it starts to sink.

My personal recommendation is to let your imagination play and build a few different little boats, each with its own size and shape. The results might be different than what you expect.

You can always cheat by using one simple trick: You will always be able to carry heavy loads better with the help of boats that have a wider flat bottom.

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This is one of the main reasons why a barge will always be flat, long, and wide. So that they can carry heavier loads. There are situations in which carrying a very heavy weight isn’t the main priority of a boat. If you test the flat bottom barge with a few splashes in the water to create some waves, you’ll notice that it won’t take long before it starts to sink. And for this exact reason, deep keel ships have been invented.

A ship with a deep keel will be considerably more stable while the weather and water conditions are rough. This is why you should also try to construct a boat using foil, that won’t sink regardless of how much the water inside the container is splashed.

I don’t want to take the fun of building boats from you, so I won’t give you details on how to do this easier.

Try it for yourself and see how you can make your boats float a lot better during this interesting home experiment.

Some terms that you should know:

Try to remember these terms and what each of them means if you want to understand floatation a lot better. Boating and floatation in general will be a lot easier if you know the proper language.

Upward Force

The term “upward force” is used quite a lot when talking about things that float. A couple of examples of upward forces are upthrust and buoyancy because they will act upwards. Although gravity seems more like a downward force, it can also be described as a type of upward force.


Pressure is used by a lot of people that try to explain the science that makes floating possible. When an object will come in contact with another, pressure is the physical force that will occur between them. Simply put, it will be used to measure the force used when it is distributed over a surface area.


Floating BoatDisplacement can be explained by something being moved from one place to another. When talking about nautical issues, it will usually refer to the mass of water that will be moved when an object will occupy its place. A good example is an ice cube placed in your drink. When the ice cube is thrown in your drink it will cause the water level to rise because the ice actually displaces the liquid. This means that the drink inside will have to accommodate the ice cube in it.


The actual mass of an object is also known as its “density”. If you’re interested in a more exact explanation, then density is actually a way to measure the degree of compactness of a certain substance. But, when it comes to boating, Your boat will only be able to float if it is lighter in density than the water below it.


You will use buoyancy as a way of explaining the upward force that would oppose the weight of a certain object that you place in the water. Buoyancy can also refer to objects that are floating in the air and not just those that float on water. You will also hear people talk about buoyancy as thrust.

In Conclusion: How Do Ships Float?

The displacement of water is what causes ships to flat, as well as the upward force that is created from this displacement. And the upward force needed isn’t all that great either, considering that the density of the ocean is much higher than the density of your boat. This is the case even for heavier types of ships. And this is the easy answer around the floating of a boat.

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