NAP-Section

2. Navigation methods and tools used today
Navigation is what makes seafaring possible in open waters. Contemporary navigation, as is easy to guess, has advanced greatly since instruments as those described above were used. One could say that navigation has grown into an important science over the ages.
Like any science, navigation has its foundation. The basics of this particular science are: "dead reckoning" (determining the location of the ship by means of its speed, distance, and direction of travel; this is not a very accurate method of navigation due to winds, currents, steering errors, that may interfere); piloting (steering the ship with the help of navigational tools, geographical landmarks, etc.); electronic navigation (probably the most sophisticated and most accurate method which uses radio signals and electronic equipment); celestial navigation (nowadays navigation by the stars uses the same concepts as ancient navigation tools, but with much more advanced accuracy).
a) Maps and Charts

 
"Morski Sviat" magazine, permission obtained
A navigator's job begins before the voyage is underway. First, the course for the trip needs to be plotted on a map. The location of the ship is plotted on paper by means of something like a coordinate system: longitude and latitude.
Since earth is round, when it is represented on a flat map, certain distortions are inevitable. There are a number of different ways in which a map of the earth could be drawn and in each case the image of the planet is deformed in some way. However, maps of all kinds exist and are in use. The most common and probably the one with which everyone is familiar is the Mercator map.
Yes, you have seen it, but you might not have heard the name. Gerardus Mercator was a Flemish mathematician and geographer who first created this particular map.
In this kind of map, the earth is stretched out at every point, other than the equator line. The parallel, vertical, equi-distant lines on a Mercator map are called meridians and represent longitude lines. The horizontal parallel lines - parallels - stand for the latitude lines. They are drawn further apart as they get close to the poles, to make up for the distortions.
The Mercator map is a very commonly used tool, because even though it is not a fair image of the earth, the distances on it can be measured in straight lines.
In today's world of information, navigation has been simplified?c or has it? There are such great amounts of information captured in annually published almanacs and reference books for navigators, that to the outside observer it may as well seem very confusing. But the earth's bodies of water have been surveyed and described on maps and charts in order to make navigation easier and safer.

b) Piloting

 
"Morski Sviat" magazine, permission obtained
Piloting a ship could be a very tricky business and an extremely risky one, when waters are shallow, ports are busy, visibility is poor, or territory is unknown. Natural phenomena such as currents and winds often times make piloting an even harder task.
Piloting a ship is not the same as steering a motorboat. A navigator needs to know where the ship is going to be in the next moment. That is achieved by observation. But since the invisible forces of currents, winds, tides etc. are also at work, the way that a navigator can determine their effect is by comparing the dead-reckoning position of the ship with his own observations.

c) Electronic devices and technology
Electronic navigation is somewhat of a lifesaver in this day and age. Keeping a constant radio connection with land and with other vessels is essential to preventing collisions, escaping sea storms, and sometimes determining the ship's location.
The radio was introduced to navigation in the early 1900s. The Direction Finder (D/F) device, which was used back then, is now probably the most widespread navigational instrument.
In a few words, here is how a D/F works. The ship connects via radio with a static radio station whose location is known. The antenna of the D/F radio receiver has a loop on top of it and is highly sensitive to the signal it receives. When the loop's axis points directly to the radio station, it will receive no signal. If the loop's plane faces the radio station, it will receive a strong signal. Thus by pointing to loop so it doesn't receive any signal at all, a navigator knows in what direction is the radio station.

 
Electronic navigation
"Morski Sviat" magazine, permission obtained

An automatic direction finder (ADF) is a more advanced version of a D/F. It has a motor that turns the loop and keeps it in the null position at all times (when no signal is received).
Another very common device used today is the radar. It obtains information about objects, which are out of the range of vision. Electronic equipment is used to record and analyze the behavior of radio waves sent out from the vessel. Those waves, which do not encounter obstacles, simply disperse. Those, which meet an object, bounce back to the vessel that sent them and provide data about the shape and position of objects in the area.

d) Nautical Astronomy
Celestial navigation is known to man from ancient times, ever since stars and planets have been identified. The advantage of this kind of navigation is that it allows travel in open waters. Those voyages would have no limitations, if it weren't for the only downside of nautical astronomy - poor visibility. Anything from a fog to an ocean storm can prevent navigators from orienting by the stars.
Time in celestial navigation is measured by the apparent movement of the sun westward at 15 degrees longitude per hour. Hence the time difference between two places on the face of the earth, located at different longitudes.
Consequentially, accurate time is vital to navigators using nautical maps and charts.

 
Electronic navigation
"Morski Sviat" magazine, permission obtained


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