The article explains what a waterline is, why it is needed, and when the law was first introduced requiring the use of one of its varieties.
Ships
For a very long time, ships were the only and relatively fast way to travel. Of course, their use entailed a number of restrictions, but there were simply no more convenient and safer alternatives.
Over time, when more or less reliable navigation instruments were invented, people were able to travel between continents, which was a real breakthrough. Gradually, when shipbuilders were able to improve the design of ships, waterline marks began to appear on them without fail. But what is a waterline and why is it needed? This is what we will understand in this article.
Definition
The word comes from the Dutch language, which is quite logical. After all, this kingdom was one of the first, which was distinguished by the high quality of its fleet.
The waterline is the line along which the calm surface of the water comes into contact with the hull of a ship or other floating vessel. If we consider this term from the point of view of ship design, thenwaterline is a section of the hull by a horizontal plane in the drawing. So now we know what a waterline is.
Types of waterlines
Waterline is of the following types:
- Constructive - this is the line that is taken as the basis for the construction of a theoretical drawing. Based on preliminary calculations, it shows the different types of displacement of the ship.
- The load waterline was created to determine the maximum allowable drawdown of a vessel due to its workload. Usually such a waterline of the vessel coincides with the constructive one.
- Calculated draft shows the draft, according to which the theoretical characteristics of the vessel are determined.
- The current one is not applied to the ship's hull, this is a concept that determines the current level of the ship's drawdown depending on its load or type of water.
If we talk about the current waterline, then it is determined depending on many factors, for example, the shape of the ship's hull, the density of the material from which it is built, weight, waves of water and others.
Waterline area can be used to calculate the coefficient of completeness of the hull. However, depending on the load, weather, water density and other factors, the waterline area can vary greatly, and with it the roll and stability of the vessel. If we talk about its length, then it serves as a linear dimension in determining the Froude number for ships with a displacement, and hence their speed in theory. Now we know what a waterline is.
However, let's take a closer look at thisits kind, like a load line.
Load line
In 1890, such a mark became mandatory on all cargo ships. Unlike other types of waterline, its purpose has a more practical role.
The fact is that before the introduction of such a waterline, many merchant ships sank due to overload, the difference in water density affected, depending on the region, season, its salinity and other things. Then the cargo waterline was introduced. With its help, the person responsible for loading calculates the maximum allowable load on the ship, referring to the route, weather conditions, water type and other parameters. An example of such marks can be seen in the photo below.
Simply put, the load line was introduced in order to keep track of the ship's workload, and if the water is below the waterline, then everything is in order. But as already mentioned, it depends on the type of water, seasons and other parameters. In 1890, a law was passed in Britain requiring the use of a load line.
