As a lighthouse tower is called, wearing a beacon. Lighthouses stand at important points for navigation or in dangerous places where they even at night used for shipping a tangible navaids.
Due to their light signals ( beacon ) Lighthouses have ships the way and allow the navigation and driving around dangerous places in the waters.
In a figurative sense (metaphor ) is called the lighthouse or beacon often what is visible and of which a significant effect or role model to be released ( lighthouse project). In the English-speaking world, the modern legend of the lighthouse and warship is a popular metaphor for occasional inflexibility of great powers.
After probably the first lighthouse in the history, the ancient Pharos of Alexandria, lighthouses are also referred to as the Pharos Lighthouse and the customer as Pharologie.
Functions and technology of lighthouses
We can distinguish several basic functions:
- Navigation aid for accurate positioning at sea
- Warning of shoals ( reefs, sandbanks )
- Fairway markers by sectors of different identifiers. They are generated by color filters or covers that show a colored or rhythmically flashing signal in the direction of the fairway. The relevant sectors and flashing frequencies (so-called timings ) are indicated in the charts. With narrow fairways also leading lights are used.
As beacons optics Fresnel lenses are used (after Augustin Jean Fresnel ), which have a compact design, a relatively low weight and a high light output since about 1820.
The rotating lens system has multiple (up to 20 ) sectors with focal lengths up to about 70 centimeters. Each tower has its characteristic rotation time and Blinkart ( " return" and type). They are published for each area periodically in Beacon directory.
The construction of the lighthouses is very diverse. In addition to metal, wood, concrete and stone towers, there are also tube and mast -like structures. Lighting and optics sit on larger buildings mostly in the so-called lamp house ( in the lantern ). Previously, there were also radio beacon on the same principle: radio beams with specified identifiers that were used as turning and radio fire. Today this term has gone almost entirely to the radio stations of aviation.
Until the late 20th century were in the North and Baltic Sea, where the construction of lighthouses has not been possible numerous lightships positioned with beacons in up to 45 meters in height. Today will be entertained by the German Waterways and Shipping Administration only two lightship positions.
Reach "Fire in the Kimm "
The range of the most beacon is - depending on the type and circumstances - 5-20 nautical miles. It depends mainly on four factors:
On the one hand plays the " height of fire" above sea level, a role which is related to the curvature of the earth, on the other hand, the luminosity of the light source and optics. In addition, the weather and visibility conditions have the same effect on it as the light sector and its color.
The theoretical range of (1) increases with the square root of the height of the tower, but also plays the eye height of the Navigator (ie the height of the ship ) play a role. At 50 m/10 m, it is 21.5 miles or 40 km, 15 m / 2 m only 11 nautical miles ( 20 km). Therefore, it makes sense to build the lighthouse on a hill near the coast or on a dune. Thus, for example, in Northern Germany with 40 m high towers " fire heights " reach up to 65 m. The famous tower on Borkum so achieved a visibility of 24 nautical miles. On "Signal Mountain" Wismar before the beacon is even (75 20 ) m = 95 m high.
Sometimes, however, it makes more sense to build a lighthouse on a deeper point, though it also stands in clearer air layers. Thus, the old, 238 m high lighthouse at Cape Point in 1911 replaced by a lower-lying lighthouse, as the old tower too often was in the fog and its light was therefore not visible as far as originally thought.
The second factor of the range is determined, inter alia, of effort, power supply and the cost of maintenance. The light intensity can be in the millions Candela. The influence of weather conditions are taken into account by a visibility scale, similar to airfields and in astronomy.
When a powerful flare just in " the horizon " ( the nautical horizon) appears or disappears, its distance can easily be calculated and so the ship's position be determined. The method has indeed now lost its meaning, but is still used by skippers and also for guests on the ship its charm. In addition, it is one of the navigation methods that require little or no aid. The formula can be derived by means of the theorem of Pythagoras. In the simplified form, when both heights compared with the radius of the earth are small, they are:
Competition from new methods of navigation and tourism
Although now occur numerous harmful navigation aids with the beacons in competition, visual aids to navigation, particularly in coastal areas can not be replaced. In case of failure of harmful navigation aids ( GPS / DGPS, refer Volpe Report of the U.S. Department of Transportation), they provide the essential fallback dar. In certain cases, they are the most accurate navigational aids at all (Table Fire / Sektorenleitfeuer ).
Previously, the towers were the workplace and partly residence of the lighthouse keeper. This profession is practically no longer practiced in this form, since the operation of the beacon is automated for a long time.
Despite the latest electronics such as satellite navigation and radar but have lighthouses still their place in the navigation, though mostly only as a backup system. Event of failures of the electronics, the power supply or when uncertainties in locating Mostly located in the vicinity of beacons and beacon.
Many lighthouses have now opened the usually Viewing platform for tourists. They can be reached normally via a staircase inside the tower. Chance of towers serve as a shelter or can be rented for some time. One of the first such occasions was in the 1980s, the island of Scalpay between Scotland and the Hebrides. In Germany the Roter Sand lighthouse in the Weser estuary stands as quarters available.
Brief history of the lighthouse
As the history of lighthouses began today is not precisely known. In the eastern Mediterranean, there were centuries before the birth of Christ encourage maritime trade - and probably also a beacon to find the home port, even in adverse conditions.
At least two antique fire are delivered which originated around 300 BC: The Colossus of Rhodes and the Pharos of Alexandria. However, it is uncertain whether the Colossus really served as a beacon. He is said to have been only a few decades, until he collapsed 224 BC. The Egyptian tower, however, did not leave until 1303 when an earthquake lost.
Seafaring was looking right at the beginning for simple ways " heimzuleuchten " sailors. Torches and small fires reported to the fishermen during the night on their way. Monks recommended their operation as godly task.
In Western Europe, probably was the " Tower of Hercules " (Spanish: Torre de Hércules ) in Galicia A Coruña, Spain one of the first. The still -used tower was completed in the year 110 of Caius Sevius lupus and was originally 36 meters high and measured 18 m × 18 m at the base. Since a renovation and expansion in 1791, its height is 50 m. The dimensions of the foot are 20 m × 19.5 m. Also the Hook Head lighthouse in Ireland is ranked among the first. It was built in 1172 allegedly over the cliffs of the southern Irish town in County Wexford to Waterford. Today, the tower bears his fire in height 35 m.
In the 13th century, built the cities of the Hanseatic League (Lübeck and Wismar ) Candle Lanterns in Travemünde and offshore islands. The existing harbor characters in Travemünde 1226 Imperial privileged. 1299 Hamburg received the North Sea island of Neuwerk to build a Feuerblüse there; this was completed in 1310 and still stands today. 1625 was followed by a constant beacon on Wangerooge. The use of the church tower but did not prove itself over time.
Under fire Sandstedt (1898), DSM Bremerhaven
An optical system - the Fresnel lens
Rotating lens apparatus, Lighthouse Kullen, Sweden
Were significantly improves the beacon in 1782 by the Geneva physicist François Pierre Ami Argand ( 1750-1803 ) with the hollow wick lamp, a forerunner of the later kerosene lamp. Only later translated gradually Gasglühlichter. Finally, Augustin Jean Fresnel developed (1788-1827) on behalf of the French Government a light focusing ( compression of the light beams ) by specific, named after him, Fresnel lenses, which the beacon reached a much wider scope. A special form of the Fresnel lens for horizontal bundling the entire 360 ° area is also referred to as a belt lens.
Being the tallest lighthouse in the world shall be the lighthouse of Jeddah in Saudi Arabia with 140 m height of fire. Currently the tallest lighthouse in Germany is in camping at the Ems estuary. The three-legged lattice tower measures 65 meters. Is currently being developed on the Elbe, the new rear light in the leading lights Blankenese, the tower will reach a height of 70 meters. Required construction was due to the planned deepening of the Elbe, which has a broadening of the fairway and a shift of the leading lights result.
The highest German lighthouse sits on the 118 -meter-high hotel " Maritim " in Lübeck -Travemünde, 114 m above the mean water level of the Baltic Sea.
One of the smallest lighthouses may be the former beacon Bunthaus (1914-1977) on the colorful houses tip ( Lower Elbe near Hamburg) with 6.95 meters tower height.