Sunday, June 3, 2007
Navigation Techniques for Sucessful Boating
The Development of Navigation Technology
When one is out on the open sea, sometimes there is only the horizon, the stars and the open sea that remains in full view. There are no landmarks to help you find your bearings. Consequently, there was a need to develop a system that provided this valuable information.
Celestial Navigation
Tools of the trade for this type of navigation include the latitude hook or kamal,cross-staff and backstaff, quadrant, astrolobe, nocturnal and sextant. The main
purpose of these instruments were to determine the latitude position of the user. The
altitude of known stars (eg. North Star) compared to the horizon was determined with this method.
Magnetic Compass
It is a well known fact that any magnetised material naturally points to magnetic north when it is free to move. The accuracy of guaging your direction with this method however depends on how much magnetic north deviates from true north.
Chronometer
Latitude calculations were fairly accurate, but there was a need to also determine the longitude of a position with a fair amount of precision. This was difficult in previous times because there were no accurate ways of telling the time. Longitude is determined by the time of day difference between a person's starting position and where they ended up. In the 18th Century, the chronometer was invented which gave good results in determine longitude for the mariner. Later on, an explorer by the name of James Cook used this instrument to circumnavigate the world and finally provide accurate measurements of longitude that could be added to maps.
Gyroscopic Compass
This instrument was invented in the 20th century, the main difference from its predecessor being that it always pointed to the true north. This unit proved to be a very important invention in World War 1. It works on the principle that a freely spinning object will not change the orientation of its axis, even if the base is moved.
Radar
This tool is used to identify the terrain. Basically, radar assists in navigation by first transmitting electromantic waves and then receiving the weaker relected electromagnetic wave from the nearby object. An advantage of radar is that it can communicate with other devices like GPS or chart plotters.
Loran
Loran stands for Long Range Navigation. The signals received from three or more transmitters are used to determine boat position. This triangulation method has been superseded by GPS. The technology however should not be ignored because it can be used to validate GPS readings.
GPS
GPS stands for Globe Positioning System. There are geostationary satellites orbiting the earth. Geo satellites remain at a fixed point in space relative to earth, that is, they rotate at the same speed that the earth does. The GPS picks up the transmitted electromagnatic signal from a satellite and stores the the time it took for the signal to travel through space. When this is done for three satellites, a boat's position can be determined from triangulation.
New technology has made it possible to get accurate information of a boat's position and its obstacles in its path. This does not mean that old ways of navigation should not be ignored.If technology fails, a good boat captain will have to at least know his bearings.
Tags : navigation compass GPS radar Loran gyroscope latitude longitude
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