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History of Navigation:
Navigation: the 20th Century to the Present |
The nineteenth century was the century of longitude, factory-produced high quality instruments, charting, and oceanography. The twentieth was the age of electronic navigation, which has made celestial navigation almost obsolete.
Radio was developed in the early 1900s. By the mid 20th century, radio direction finding using beacons was common. Using the science of the 1920s, developments during World War II in sonar and radar made these available to large vessels and then to anyone, in the late 20th century, due to electronic miniaturization.
A mid-nineteenth century concept, not practicable until the twentieth, was the gyroscopic compass. It holds its position relative to the rotation of the earth, when the flywheel is kept spinning. The availability of shipboard electricity let Elmer A. Sperry devise a gyroscope in 1911 that showed true north. It was particularly valuable as magnetic compasses proved less reliable on board steel ships. After World War I, gyro compasses became standard on large naval and merchant ships.
Electronic position finding, or loran, used beacons to fix positions. Developed during World War II, it is a system that uses master and slave transmitters and calculates position based on the time between the signals arriving at the ship. This system and others like it had to be used near land.
Today’s Global Positioning System has made other electronic systems obsolete. It is based on the Doppler effect of radio signals sent from two or more satellites. Its accuracy and reliability has made celestial navigation no longer a required skill for merchant or naval officers.
Guides for Navigators
With the availability of GPS and computers, most charts are now available in digital form. They can be read on electronic chart plotters or on laptop computers, and when connected to a GPS and radar, the screen can tell the navigator most of the information needed for safe navigation. For those who want to use paper charts for piloting, charts are now available either in single sheet form or as books of many charts not unlike the nautical atlases of the seventeenth century.
Updates of chart information, weather and tide information, and other useful navigational data are available now on the World Wide Web; a satellite telephone lets a ship at sea connect.
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