The history of ships as human transportation is almost as long as the history of human civilization.

From ancient canoeing to modern transportation ships, it has generally experienced four eras, namely the era of rafts, sailing eras, steam engines, and diesel engine vessels.

The canoe is the most common tool for primitive people to go to sea and the oldest water transportation tool. Primitive humans process the huge trunk with fire or use a stone ax to process it into a hollow canoe.

Its traces are all over the world. Residents of South America and the South Pacific Islands still use canoes for production and transportation.

According to records, in the four thousand years of BC, ancient Egypt had sailed. On pottery unearthed in Egypt, the oldest sailing boat was drawn on the pottery of AD.

The front end of the boat was bent upwards, and there was a sail on the front of the boat. This kind of ship can only drive down the wind and cannot drive against the wind. The 15th century to the middle of the 19th century was the heyday of the development of sailing.

After the 18th-century steam engine was invented, many people tried to use the steam engine on the boat. In 1807, the Americans Felton first installed steam engines on the "Clemund" ship as a driving force for the ship.

Subsequently, the ship was successful on the Hudson River. Since then, natural forces have been replaced by mechanical forces, and the development of ships has entered a new stage.

With the development of science, the current hull material is basically steel, and the volume of the ship is also becoming larger. The weight of a ship ranges from several tons to tens of thousands of tons.

But a nail will sink into the water at the water. Why can such a heavy ship float at sea?

First of all, we need to understand the basic structure of the hull. A ship is basically composed of the bottom plate, cabin, and deck. The cabin volume is very large and hollow, in order to increase the displacement of the hull.

The hollow structure allows the ship to have more buoyancy space, enabling the ship to float well on the horizontal surface without sinking.

In the history of development, ships have changed from wood materials in the early days to steel hulls now, and the anti-sinking performance of ships is becoming stronger and stronger.

The shape of the boat is similar to the box, and there is much space inside the ship. Therefore, compared to its huge volume, its weight is small, so the buoyancy is large.

The ship is like a hollow steel ball made of processing. At this time, it makes its overall density less than water, and the ship can float on the water.

Of course, with the increase of the loading objects, the weight of the ship will become larger and larger.

When it reaches a certain degree, the volume of the ship is unchanged, and the weight has been increasing until the density of the water is greater than the density of the water, and a shipwreck will occur at this time.