Every day that goes by I’m one step closer to departing to the sea, which is by far one of my biggest dreams. There are no words to describe how happy I feel for being able to study something I really like. 😀
I decided to write this article to share one of the most fun activities of my course, which is to learn how to work with nautical charts.
Nautical charts are the maritime equivalent of terrestrial maps. They are cartographic representations of the sea, represented in diverse forms with diverse scales.
They aim to locate the seafarers and demonstrate the characteristics of a particular site, such as depths, characteristics of the funds, marine traffic corridors, relevant points on the coast, buoys, etc …
In a perfect world we would be able to use globes, since they are the most faithful representation of the earth. However to be able to demonstrate large scales they would have to be gigantic, which makes their use impracticable.
There are several ways of representing the earth in a paper, however, in the sea, these are the most used letters:
Mercator’s chart:
It’s the one we use the most because it is, in a rough way, a representation that allows the course of the ship to be marked in straight lines.
Gnomonic charts:
These charts use as a projection surface a plane tangent to the earth’s surface. This ones present all kinds of earth deformations.
The instruments used for the readings and measurements on the chart are the compasses that can be straight or curved and the squares.
Curved compass:
Straight compass:
Navigation Square:
Distances are measured in nautical miles (between seamen we only call them miles) that are read through the latitude scale (each minute of latitude is one mile). Each nautical mile is equivalent to 1852 m.
Nowadays there are also electronic charts, but I personally like the paper ones, it makes all the work more personal because, as our teachers teach us, “Navigation is Science and Art”.