Since the inception of shipbuilding, people have made a lot of efforts, trying to create ships that do not sink. But the development of science and knowledge of the laws of physics made it possible to build both steel and even reinforced concrete ships.

Reinforced concrete ships were built in North America in the first half of the 20th century, when during the two world wars there was a shortage of steel.

The laws of physics help the ship not to sink

The buoyancy of a vessel is determined by the law of Archimedes: a fluid pushes the body with a force equal to the weight of the liquid in the volume of the body part immersed in it. The main trick here is volume - the larger the volume of the ship, the thicker its metal sides can be made and the more additional cargo it can take on board, while remaining afloat. This is because the main internal volume of the ship is filled with air, which is 825 times lighter than water. It is the air that makes the ship buoyant.

By the same principle, submarines can be immersed and ascended - when immersed, the ballast tanks are filled with water, the boat loses buoyancy and sinks. At ascent - they are supplied with air under pressure, displacing water. According to the same principle, a metal basin floats in the bath - inside it is air, which occupies most of the entire basin. If the internal volume of the basin is filled with stones or metal, it will drown, because its weight will become too large.

Engineering Solutions - Ship Stability

On the buoyancy of the ship, its ability to resist the forces of wind and waves, the principle of leverage. If the basin, which swims calmly in the bath, is launched into a river, it will soon draw up water and drown, because it will be tilted by the wind and swamped by waves.

Something similar can happen to a ship, too, if it has little stability. There have been cases in history when hundreds of passengers gathered at one side caused the ship to roll and flood. Many ships died during storms due to the fact that they were turned over by wind and waves.

The stability of a ship is its ability to maintain a stable position in the water. It depends on the place where the center of gravity of the vessel is located. The closer it is to the surface, the easier it is to turn the ship over and the less stability.

That is why modern ships have the heaviest units - propulsion engines, generators, tanks with water and fuel reserves located in the lower part. Cargo holds are also located there. Sailors know that on a fully loaded vessel - pitching is felt much less than on an empty one.

To offset the center of gravity as low as possible, the designers specifically weight the keel with lead pads. In sports courts, the weighted keel is generally attached separately to the beams under the vessel and is called remote.

The shape of the side also greatly affects stability - vessels with a semicircular bottom have the smallest, sports trimarans, which have two outboard hulls on each side, have the greatest.Indeed, the presence of additional supports in the upper part of the side helps to maintain stability, preventing the vessel from tilting. This was known in antiquity and attached along the upper part of the side of the boat bundles of dry reeds. And modern tourists for this purpose use inflatable balloons, tying them on the sides of kayaks.

Mandatory rules of the seafarer

To avoid shifting the center of gravity, when loading modern ships, computer programs are used to help calculate where and how much cargo can be placed to preserve the seaworthiness of the ship. Responsible for the correct placement of the cargo is the senior assistant captain. He commands the loading and, according to calculations, the heaviest loads are placed in the holds, and the lighter ones are on the deck. The cargo on the ship is surely “found”, that is, it is tied. This is necessary so that during a storm it does not roll over the holds and does not change the center of gravity of the vessel.

The entire ship's hull is divided into airtight compartments. In normal condition, the partitions between the compartments are open. When the ship receives a hole, the compartment where it is located is blocked by hermetic partitions so that water cannot fill the entire hull.

It is dangerous during a storm to deploy the ship "lag to the wave", that is, sideways. It is too likely that a strong wave will turn the ship over. The wave in the stern is also dangerous. Therefore, often ocean vessels during strong storms begin to move their noses against the waves, leaving the intended course - this is the safest way for the ship to survive the weather. And only after the end of the storm they return to the desired course.

The buoyancy and stability of the vessel are its main qualities that ensure safety. Therefore, the rules that help to preserve them are mandatory. And design solutions that contribute to their improvement are always welcome.