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{{short description|Navigational tool}}
[[Image:NantucketRangeLites.jpg‎|thumb|right|Range lights in Nantucket, Massachusetts. The red and white striped panels are one of tweleve color combinations of [[daymark]]s which may be used on range lights in the United States.<ref>{{cite web |url=http://www.uscgboating.org/SAFETY/aton/non_lateral.htm |title=Non-Lateral Aids to Navigation |accessdate=2007-06-21 |work=U.S. Aids to Navigation |publisher=[[United States Coast Guard]]}}</ref>]]
{{for|the racehorse|Leading Light}}
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'''Leading lights''' (also known as '''range lights''' in the [[United States]]) are a pair of light beacons, used in [[navigation]] to indicate a safe passage for vessels entering a shallow or dangerous channel; and may also be used for [[position fixing]]. At night, the lights are a form of [[leading line]] that can be used for safe navigation. The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing.
{{more citations needed|date=May 2012}}
[[Image:NantucketRangeLites.jpg|thumb|right|[[Nantucket Harbor Range Lights]]<ref name=cgll>{{cite uscgll|1|2009|135}}</ref> The [[dayboard]]s are type KRW, see below.]]
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[[Image:Bremerhaven Unterfeuer 1.jpg|thumb|[[Bremerhaven Lighthouse|A pair of leading lights in Bremerhaven]], Germany, with the rear light in a proper lighthouse and the front light on a smaller tower. No standardised markings are used here.]]


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'''Leading lights''', also known as '''range lights''' in the [[United States]], are a pair of light beacons used in [[navigation]]<ref>{{cite web|url=http://www.ialathree.org/dictionary/index.php?title=Leading_Lights_%28G.B.%29 |title=Dictionary of the International Association of Lighthouse Authorities |publisher=[[International Association of Lighthouse Authorities]]}}</ref> to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for [[position fixing]]. At night, the lights are a form of [[Piloting#Piloting in channels and rivers|leading line]] that can be used for safe navigation. The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing. Range lights are often illuminated day and night.
Leading lights are often confused with [[lighthouse]]s, as they are often built to look like lighthouse structures. In contrast to lighthouses which warn offshore navigators of dangers upon landfall and can be used for offshore navigation, leading lights assist the inshore navigation of [[ship]]s, vessels and other watercraft into safe channels, lanes, or port, and [[Harbor|harbour]] entrances.

In some cases the two [[beacons]] are unlighted, in which case they are known as a ''range'' in the United States or a ''[[Navigational transit|transit]]'' in the UK. The beacons may be artificial or natural.


==Operation==
==Operation==
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Two lights are positioned near one another. One, called the front light, is lower than the one behind, which is called the rear light. At night when viewed from a ship, the two lights only become aligned vertically when a vessel is positioned on the correct bearing.<ref>{{cite book |last1=Bowditch |first1=Nathaniel |title=The American practical navigator : an epitome of navigation |date=2002 |publisher=Paradise Cay Publications |location=Bethesda, Md. |isbn=9780939837540 |page=64 |edition=2004}}</ref>
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[[Image:Bremerhaven Unterfeuer 1.jpg|thumb||A pair of leading lights in Bremerhaven, Germany, with the rear light in a proper lighthouse and the front light on a smaller tower. No standardised markings are used here.]]
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Two lights are positioned in front of one another. One, known as the '''front light,''' is lower than the one behind, which is referred to as the '''rear light.''' At night when viewed from a ship, the two lights only become aligned vertically when a vessel is positioned on the correct bearing. If the vessel is on an incorrect course, the lights will not line up.


During the day, the lights may not 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 know that the vessel is on the correct bearing. The structures themselves are usually painted to make the structure more prominent.
During the day, the lights may not easily be seen and therefore leading lights are often fitted with secondary visual aids, e.g. large red flags with wide black lines running down them. When both red flags and black lines line up, the navigator knows that the vessel is on the correct bearing. The structures are usually painted to make them more prominent.


Some major rivers, such as the [[Elbe|Elbe River]] in [[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 [[Hamburg]] to the sea, using successive pairs of leading lights.
Some major rivers, such as the [[Elbe|Elbe River]] in [[Germany]], have a series of leading lines. When it is necessary to make a turn, the navigator lines up the next pair of leading lights. This provides guidance from [[Hamburg]] to the sea, using successive pairs of leading lights.<ref>{{cite book |last1=Wendemuth |first1=Ludwig |title=The port of Hamburg, with plans, charts and numerous illustrations |date=1927 |publisher=Meissner & Christiansen |location=Hamburg |oclc=586327105 |page=204}}</ref>


Leading lights were used in Great Britain as early as 1763 to mark the [[Port of Liverpool]].<ref>{{cite book|title=Lighthouses of Liverpool Bay |first=John |last=Robinson |first2=Diane |last2=Robinson |publisher=[[The History Press]] |year=2007 |isbn=978-0752442099}}</ref> The first set of range lights in the [[United States]] were privately established by subscription at [[Newburyport, Massachusetts|Newburyport Harbor]] in [[Massachusetts]] in 1788.<ref>{{cite book |last1=Roberts |first1=Bruce |last2=Shelton-Roberts |first2=Cheryl |last3=Jones |first3=Ray |title=American lighthouses : a comprehensive guide to exploring our national coastal treasures |date=2012 |publisher=Globe Pequot Press |location=Guilford, Conn. |isbn=9780762779604 |edition=3rd}}</ref>
Leading lights and marks may also be used for navigation to determine a vessel's exact position at sea.


Leading lights are sometimes designed to be movable, allowing their position to be shifted in the event of a change in the safe channel; these include one at [[Hilton Head Range Rear Light|Hilton Head, South Carolina]], the original [[Chatham Light]], and the [[Nantucket Beacon]], predecessor to the Nantucket Harbor Range shown above.
The first set of range lights in the [[United States]] were privately established by subscription at [[Newburyport, Massachusetts|Newburyport Harbor]] in [[Massachusetts]] in 1788.<ref>Jones & Robert (1998)</ref> The technology was first used in [[Europe]] in 1837, where the term '''leading lights''' originates.


==Gallery==
Unlike conventional lighthouse towers, leading lights are sometimes designed to be movable; allowing their position to be shifted in the event of a change in the safe channel.
<gallery>
Image:NOAA Chart 13296 detail showing Range.png|[[Doubling Point Range Lights]] on NOAA chart 13296.
Image:USCG Daymarks.png|The twelve standard dayboards used on [[USCG]] ranges.
Image:Margaree Harbour Range Lights.jpg| Range lights at [[Margaree Harbour, Nova Scotia]].
File:Seili Leading Lights in Archipelago Sea in Finland.JPG|Marking the approach to the island of [[Själö|Seili]], Finland
</gallery>

==See also==
{{Portal|Engineering}}
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*[[Daymark]]
*[[Sector light]]
*[[PEL sector light]]
*[[Visual approach slope indicator]], similar lights used in aviation to guide pilots to the right approach angle for landing
*[[Moiré pattern#Inogon light|Inogon light]]


==References==
==References==
{{reflist}}
{{Reflist}}


== See also ==
==External links==
{{commons category-inline|Leading lights}}
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*[[Daymark]]
{{nautical portal}}


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{{Lighthouses}}
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[[Category:Navigation]]
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[[Category:Lighthouses]]
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[[Category:Nautical terms]]


{{DEFAULTSORT:Leading Lights}}
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[[Category:Navigational aids]]
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Latest revision as of 17:59, 25 May 2024

For the racehorse, see Leading Light.
Nantucket Harbor Range Lights[1] The dayboards are type KRW, see below.
A pair of leading lights in Bremerhaven, Germany, with the rear light in a proper lighthouse and the front light on a smaller tower. No standardised markings are used here.

Leading lights, also known as range lights in the United States, are a pair of light beacons used in navigation[2] to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing. At night, the lights are a form of leading line that can be used for safe navigation. The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing. Range lights are often illuminated day and night.

In some cases the two beacons are unlighted, in which case they are known as a range in the United States or a transit in the UK. The beacons may be artificial or natural.

Operation

[edit]

Two lights are positioned near one another. One, called the front light, is lower than the one behind, which is called the rear light. At night when viewed from a ship, the two lights only become aligned vertically when a vessel is positioned on the correct bearing.[3]

During the day, the lights may not easily be seen and therefore leading lights are often fitted with secondary visual aids, e.g. large red flags with wide black lines running down them. When both red flags and black lines line up, the navigator knows that the vessel is on the correct bearing. The structures are usually painted to make them more prominent.

Some major rivers, such as the Elbe River in Germany, have a series of leading lines. When it is necessary to make a turn, the navigator lines up the next pair of leading lights. This provides guidance from Hamburg to the sea, using successive pairs of leading lights.[4]

Leading lights were used in Great Britain as early as 1763 to mark the Port of Liverpool.[5] The first set of range lights in the United States were privately established by subscription at Newburyport Harbor in Massachusetts in 1788.[6]

Leading lights are sometimes designed to be movable, allowing their position to be shifted in the event of a change in the safe channel; these include one at Hilton Head, South Carolina, the original Chatham Light, and the Nantucket Beacon, predecessor to the Nantucket Harbor Range shown above.

[edit]

See also

[edit]

References

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  1. ^ Light List, Volume I, Atlantic Coast, St. Croix River, Maine to Shrewsbury River, New Jersey (PDF). Light List. United States Coast Guard. 2009. p. 135.
  2. ^ "Dictionary of the International Association of Lighthouse Authorities". International Association of Lighthouse Authorities.
  3. ^ Bowditch, Nathaniel (2002). The American practical navigator : an epitome of navigation (2004 ed.). Bethesda, Md.: Paradise Cay Publications. p. 64. ISBN 9780939837540.
  4. ^ Wendemuth, Ludwig (1927). The port of Hamburg, with plans, charts and numerous illustrations. Hamburg: Meissner & Christiansen. p. 204. OCLC 586327105.
  5. ^ Robinson, John; Robinson, Diane (2007). Lighthouses of Liverpool Bay. The History Press. ISBN 978-0752442099.
  6. ^ Roberts, Bruce; Shelton-Roberts, Cheryl; Jones, Ray (2012). American lighthouses : a comprehensive guide to exploring our national coastal treasures (3rd ed.). Guilford, Conn.: Globe Pequot Press. ISBN 9780762779604.
[edit]

Media related to Leading lights at Wikimedia Commons

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