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; 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.
7-645: The Nantucket Beacon formed a range with the Brant Point Light to guide vessels into Nantucket harbor. Operated at various times in the 19th century, it was deactivated sometime after 1870. This range was eventually succeeded by the Nantucket Harbor Range Lights , which are still in operation. There have been many lights at Brant Point, dating to well before the American Revolution . The history of range lights
14-403: A 21-inch (53 cm) reflector lamp, as pictured. This structure was relocated many times, and in 1869 was positioned on Brant Point itself as the front light of the range; this proved unsatisfactory, and the light was moved back across the harbor the following year. Land was acquired around 1872 to relocate the light again and to provide for a keeper's house. The date for removal of this light
21-462: Is a bit murky, and different sources give different dates. A researcher for the Coast Guard historical office dates a separate range beacon to 1794, but congressional records show this beacon established in 1820. Correspondence from 1838 describes the original beacon as an 11-foot (3.4 m) tall building with a two oil lanterns hung in it; in 1856 this was replaced with a pyramidal tower housing
28-459: Is unclear. An 1879 chart shows the beacon, and the following year's chart omits it; this is not a definitive indication, however, since no edition of the same chart prior to 1879 shows the beacon, even though other documents state it to have been operating. In the early 20th century new range lights were built on Brant Point, and the light itself was relocated to a new tower, obviating a separate rear range light. Leading lights In some cases
35-937: 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. Leading lights were used in Great Britain as early as 1763 to mark the Port of Liverpool . The first set of range lights in the United States were privately established by subscription at Newburyport Harbor in Massachusetts in 1788. Leading lights are sometimes designed to be movable, allowing their position to be shifted in
42-410: The correct bearing. 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
49-524: 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. 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
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