- Leading lights
Leading lights (also known as range lights in the
USA) are a pair of light beacons, used in position fixingand navigationto indicate a safe passage for vessels entering a shallow or dangerous channel.
They consist of two lights that are separated in distance and elevation, so that when they are lined up vertically, with one behind the other, they provide a bearing. So leading lights are a form of
leading linethat can be used at night.
Leading lights are often confused as being
lighthouses, as they are often built to look like lighthouse structures. Contrary to major lighthouses who usually warn offshore navigators of obstructions upon landfall however, leading lights assist the inshore navigation of ships, vessels and other watercraft into defined channels, lanes or port and harbourentrances.
Two lights are positioned in front of one another. One, known as the front light, is shorter than the other one behind it, which is referred to as rear light. At night when viewed from a ship, the two lights become aligned directly above one another when the navigator of the vessel is heading on a straight course. If the vessel is on an incorrect course, the lights will not line up. The front light would appear slightly left of the rear light, for example.
During the day, the lights cannot easily be seen and therefore leading lights are often fitted with secondary visual aids, e.g. huge red flags with thick black lines running down them. When both red flags and black lines line up, the navigator will again know that the vessel is on the correct course.
For example, a narrow channel might have shallow water at each side but deep water in the middle. If the ship veers off to either side, it risks being grounded on the sea or river bed. But as long as it stays in the middle of the channel or river, it will stay out of danger because the water is deep enough. To help the navigator stay in the middle of the river, he or she lines up the front (bow) end of the vessel with the aligned leading lights or marks, and continues along that bearing.
Some rivers, such as the
Elbe Riverin Germany, have a series of leading lines. Each time it is necessary to make a turn, the navigator lines up the next pair of leading lights. This provides guidance from Hamburgto the sea, using successive pairs of leading lights.
Leading lights and marks may also be used for pilotage to determine a vessel's exact location at sea.
The first set of range lights in the
United Stateswere privately established by subscription at Newburyport Harborin Massachusettsin 1788. [Jones & Robert (1998)] This technology was first used in Europein 1837, where the term leading lights originates.
Unlike conventional lighthouse towers, leading lights are sometimes designed to be movable; consequently, their position can be shifted in the event of a change in the sea channel.
Wikimedia Foundation. 2010.
Look at other dictionaries:
leading light — leading lights N COUNT If you say that someone is a leading light in an organization, campaign, or community, you mean that they are one of the most important, active, enthusiastic, and successful people in it … English dictionary
leading light — noun a celebrity who is an inspiration to others he was host to a large gathering of luminaries • Syn: ↑luminary, ↑guiding light, ↑notable, ↑notability • Derivationally related forms: ↑notable ( … Useful english dictionary
leading — lead|ing1 W2 [ˈli:dıŋ] adj [only before noun] 1.) best, most important, or most successful ▪ The army played a leading role in organizing the attempted coup. ▪ the leading industrial nations ▪ a leading heart specialist ▪ leading members of the… … Dictionary of contemporary English
leading light — UK / US noun [countable] Word forms leading light : singular leading light plural leading lights a very important or respected person in a group, organization, or area of activity a leading light in the toy industry … English dictionary
Leading Point Light — Infobox Lighthouse caption = Undated photograph of Leading Point Light (USCG) location = Leading Point west of the Francis Scott Key Bridge on the south bank of the Patapsco River coordinates = coord|39.2137|N|76.5518|W|type:landmark yearlit =… … Wikipedia
Leading line — A leading line is a line formed by a pair of marks, which are generally man made, that are used in position fixing and navigation, to indicate a safe passage through a shallow or dangerous channel.They are often used in the entrances to harbours… … Wikipedia
Attic Lights — Infobox musical artist Name = Attic Lights Background = group or band Years active = 2005–Present Origin = Glasgow, Scotland Genre = Alternative rock Power pop Label = Island Records Current members = Kevin Sherry Colin McArdle Jamie Houston Tim… … Wikipedia
taxi-lights — Lights similar to landing lights on an aircraft aimed in such a way that they illuminate the runway or taxiway when the aircraft is taxiing. In some aircraft, landing lights have two positions: taxiing and landing. Taxi lights are normally… … Aviation dictionary
Friday Night Lights (TV series) — infobox television show name = Friday Night Lights format = Drama, Teen drama runtime = 43 Minutes (Approximately) developer = Peter Berg executive producer= Brian Grazer David Nevins starring = Kyle Chandler Connie Britton Zach Gilford Minka… … Wikipedia
Phoenix Lights — [cite news |first=Richard |last=Price |authorlink= |coauthors=|format=pdf |title=Arizonans say the truth about UFO is out there |url=http://www.ufosnw.com/history of ufo/phoenixlights1997/usatodayarticle06181997old.pdf |work= |publisher=USA Today … Wikipedia