How can steel boats float?

Boat is a vehicle used for water travel. The structure is made of steel, for the strength to withstand the waves in the sea. But why is the ship made of iron heavier than the sea? Can float on the sea.

Picture 1: Illustration of an iron boat floating on the water.

In principle, Steel is denser than water, so drowns. But if we make the steel into a thin sheet and then shape it into the body of a ship. The volume will increases despite the same mass. Making the steel ship less dense than water, so they can float. And the water has the pressure to float the ship up. This force is called “Buoyant force “, which depends on the amount of water being replaced by the object. The more objects are exposed to water, or the more water is replaced (distinguish from the amount of water in the bowl that is higher). The density of the object will decrease and the buoyancy will increase. The object can therefore float in the water. So if the object is spread out to a large size and has a curved edge up like a boat, the object will float well.

The Principle of Archimedes 

When the object is replaced with liquid will have the same resistance as the weight of the volume liquid. From this principle, help us to understand in many more principles such as why are steel ships can float.  The different liquid types have different densities. Archimedes points out the density and compared with water called specific gravity.

Picture 2: Floating Rules

Picture 3: In case of liquid sinking and rope tied


This density depends on the mass per volume. If the same object has the same mass but different volume, the density will be different, for example, when we put the steel that is denser than the water and put into the water, it will sink. But when the steel is spread out into a curved sheet like a boat, it will have more volume. As the weight is constant and volume increase, the density will decreases to less than the density of the water. So the boat is floating.

In addition to the boat, the plane also uses this principle. By mimicking the wings of birds, which when the air pass through under the plane’s wings, it will cause the wing to lift and the plane will float in the air.

With the ship that’s made from steel, which is heavy and has a lot of mass, and if it is just a steel rod, it would drown immediately. With human intelligence therefore uses techniques from the above formula. By increasing the volume of steel as much as possible with the same mass. Therefore resulting in density changes. The structure is heavier than water when the volume is added. Make the steel airy and floats.

The Source
Assoc. Prof. Yuen Phuworawan. Principles of Archimedes. Retrieved on 27 July 2017 from .htm.

Krunuttachan. Density and utilization. Retrieved on 27 July 2017 from Density with the introduction /

Sameera Chathuranga. How did the ship float? Retrieved on 27 July 2017 from

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