catamarans.co.ukHistory of Sea Navigation
Fishermen living and fishing just off the coast have always used landmarks to help them find their way on the water. To study the history of sea navigation to find out how people developed systems of finding their way to various ports when no land was in sight, one has to go back to about 2000 B.C. to time of the Phoenicians. These sailors developed primitive methods of navigating the seas using charts and by observing the Sun and the stars. However, up until the 15th century, few sailors ventured far off from shore because they believed the world was flat and that they would fall off the edge.
Even though the early sailors did not know latitude and longitude as we understand it today, they could use the sun to help them determine various positions. In the Northern Hemisphere, they measured the angle of the North Star at night and the sun by day to help them determine the latitude.
The compass was one of the earliest methods of determining direction for navigational purposes at sea. The mariner’s compass was the predecessor of the magnetic compass, but quite often the sailors thought it was inaccurate and only used it when the sun was not visible. Nautical charts first appeared in the 13th century, but they were mainly in the form of maps and were not very accurate. Although they did not contain coordinates, they did contain a compass rose for direction. Mariners developed their own charts and kept them secret from others.
The astrolabe was first used in ancient Greece to help sailors tell time, but in later centuries it was used to help measure the angle of the sun and the North Star. Early instruments used for sea navigation also included the sextant, which was developed by John Hadley in the early 18th century. This instrument was more accurate in determining the angle of the sun and North Star for determining latitude. The ship log was used to measure the speed of the ship. This was a long rope with knots tied in it at regular intervals and had weights at the end. The line was dragged through the water and the speed at which a number of knots went over the side helped to determine the speed.
To determine the amount of water in an area and to prevent the ship from running aground or up on rocks, there were sailors on the side with long poles that reached far down into the water. Measurements were printed on the side of this stick and by hitting the bottom in shallow water, mariners could determine how deep the water was and if the ship could safely navigate in this area.
The first seagoing chronometer for determining latitude and longitude was developed in 1764. This invention was an important advancement for mariners of this time. Captain James Cook used this instrument and kept detailed records of the longitude. He used this information to develop detailed charts of the world that have proven to be accurate within 13 km. When the Prime Meridian was established at Greenwich, England in 1884, latitude and longitude were also established as coordinates making navigation much easier.
Today there are many specialized pieces of equipment for sea navigation. These include radar and sonar and the Global Positioning System. Just by looking at the screen of one of these instruments, a captain can determine the ship’s position.