Monday, October 21, 2013

Instruments Used In Navigation

By Carey Bourdier


There are various navigational instruments used by the U.S. Navy and Coast Guard, as well as all the other ships navigating the world's waterways. These navigational instruments are used in ships for various purposes. Some are used to determine the present position of the ship and some to indicate the speed as well as determine the direction and some to indicate when the vessel will arrive at its destination. Some of these have been used for years like charts and maps and some are electronics and computer operated. Here are just a few of the instruments used on board sea-faring vessels.

Telescopic marine alidades are navigation instruments used in ships. These are navigational instruments used to take terrestrial bearings of the vessel. The instrument is mounted on a bearing compass or bearing compass repeater when used. It is used to obtain the bearing of the vessel and is equipped with a telescopic sight and prismatic optical system. Through the use of the telescopic marine alidade, an accurate bearing can be made of the object in the distance. This instrument helps provide accurate marine data while at sea.

Another piece of equipment that needs no electricity but still is very helpful is the three-arm protractor. In these modern days, a GPS system is often used, but the three-arm protractor still can be used to quickly determine a ship's location, which certainly can be important if electrical systems fail. Calculations can be made with data measured from this instrument, and the latitude and longitude can be determined. Jointly used with this navigational instrument are navigational charts.

Other equipment such as binoculars and telescopes also are used in navigation. These are optical instruments that are used so that when a person looks through the instrument, objects will look bigger. A binocular is two similar telescopes mounted together and the person using will use both eyes. Telescopes are only with one scope and the person will only use one eye with the instrument. Three dimensional images will be seen with binoculars since both eyes are used. With the use of binoculars, images are more natural, and the object is bigger. Objects that are very far can still look natural and the image is clear and bigger despite the distance. However, high-powered telescopes can be mounted to a ship and these provide excellent viewing of faraway objects.

Navigational sextants are also instruments used in ships and in general navigation. A sextant is an instrument and device used to measure angles between two objects. Two mirrors are used and in navigation, the horizon is viewed through this mirror. The other mirror is movable and light from an object or the sun is used for its reflection. The angle between the two is then read through the scale in the instrument. Navigational sextants are very important instruments used in navigation because of the accuracy of these instruments.

Other instruments important in navigation are electronic equipment such as radar and sonar. These instruments are used to locate objects by sending out a sound wave or radio wave and these waves bounce off of an object, helping determine the objects position. Sound waves are mediums used in sonar and radio waves with radar. These can be used to determine the distance between the ship and another ship or perhaps to locate something under the water.




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