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Fixed Lights

Lights vary from tall, high intensity coastal lights to battery powered lanterns on single piles. Highly visible and accurately charted, fixed lights provide navigators with an excellent source for bearings during the night.To aid in identification during the day, the building structures of lighthouses are often distinctively colored.

Today, with a few exceptions, all major lights are operated automatically.

Lights and Lighthouses

Lighthouses are placed where they will be of best use: on prominent headlands, at harbor and port entrances, on isolated dangers or at other points where mariners can best use them to fix their position. The lighthouse's principal purpose is to support a light at a considerable height above the water, thereby increasing its geographical range.

major light is a high-intensity light exhibited from a fixed structure or a marine site. Major lights include primary seacoast lights and secondary lights. Primary seacoast lights are those major lights established for making landfall from sea and coast-wise passages from headland to headland. Secondary lights are those major lights established at harbor entrances and other locations where high visibility and reliability are required.

A minor light usually displays a light of low to moderate intensity. Minor lights are established in harbors, along channels, rivers and in isolated locations. They usually have numbering, coloring, light and sound characteristics that are part of the lateral system of buoyage.

Light structures' appearances vary. Lights in low areas usually are supported by tall towers. Conversely, light structures on high cliffs may be relatively short. However its support tower is constructed, almost all lights are similarly generated, focused, colored and characterized.

Some major lights use modern rotating or flashing lights, but many older lights use Fresnel lenses. These lenses consist of intricately patterned pieces of glass in a heavy brass framework. Modern Fresnel-type lenses are cast from high-grade plastic; they are much smaller and lighter than their glass counterparts.

Description of Lights in the Nautical Chart

The nautical charts summarize the most important features of lighthouses in the following form:

 Fl(3+1)W 24s 24m 20M  
 Horn Mo (WN) 30s

The first line is the name of the light. The second line contains the phase characteristic, color, period, height of the light (not the building) in meter and the range of the light in nautical miles respectively. The third line may contain information about the characteristics of the fog signal.

Lights with different color sectors may have the following chart entry:

 Oc. WRG 4s 23m 8-5M  

The letters WRG stand for the colors of the sectors and the range is given for the white (longest range) and the green sector (shortest range). The range of the red sector will be between the ranges of the white and green sectors.

Detailed descriptions of lights and lighthouses are obtained from the "List of Lights" published by e.g. the national lighthouse authorities. A complete description of the abbreviations used in the nautical charts can be found in the international "Chart No. 1, Symbols, Abbreviations, Terms used on Charts" released by the International Hydrographic Organization (IHO), Monaco.

Leading Lights


Leading lights or range lights, consist of a pair of lights located such that they indicate a specific line of position - called "range line" - when they are observed "in line". Seen from seaward, the higher rear light is placed behind the lower front light.
When the navigator sees the lights vertically in line, he is proceeding on the range line. If the front light appears left of the rear light, the observer is to the right of the range line. If the front appears to the right of the rear, the observer is left of the range line.
Leading lights are often used to mark the center of navigable channels. In this case a vessel returning from seaward will keep the front light slightly to the left of the rear light while navigating on the right side of the channel.

Leading lights are sometimes equipped with intensity lights for daylight use. They are effective for long channels in hazy conditions when dayboards might not be visible.

Range lights are usually red, green or white. They display phase characteristics differentiating them from surrounding lights.

Sector Lights


Sector lights help to approach a harbor or coastline while navigating in a coastal channel in shoal waters or between isolated hazards.
A sector light has precisely oriented colored sectors. Such lights show different colors when observed from different bearings. This allows the mariner to approach the light from a hazard-free direction.

The white sector normally indicates the "save" range of the approaching channel. The red sector normally indicates the "danger" sector marking regions of shoal water or navigation hazards. A green sector would indicate that the vessel is off the center line of the channel in the direction of deep water. But the red and green sectors may also indicate the vessel is on the port or starbord side of the safe channel. The actual situation must be obtained from a nautical chart.

Cross-Mark Lights

These lights are used in combination with range lights or direction lights. They define turning points or areas in which the navigator has to change course to another light to continue the harbor or river approach. This lights may be used in narrow and winding navigation channels.

The "active" red sector is usually "announced" by a white sector.

Harbor Lights

Harbor light will indicate the save entrance of an harbor area. They usually consist of a red and green light. Sometimes only one light is available.

Harbor lights are often hard to identify against the background of bright city lights such as street lights, traffic lights and flashing neon lights. On approaching the harbor, the approximate position of the harbor lights should be estimated from the chart and pilot information to simplify and certify the correct identification of the lights on the spot.

Buoyant Beacons

A buoyant beacon provides nearly the positional accuracy of a light in a place where a buoy would normally be used. The buoyant beacon consists of a heavy sinker to which a pipe structure is tightly moored. A buoyance chamber near the surface supports the pipe. The light, radar reflector and other devices are located a"top" the pipe above the surface of the water.

The pipe with its buoyance chamber tends to remain upright even in severe weather and heavy currents, providing a smaller watch circle than a buoy.
The buoyant beacon is most useful along narrow ship channels in relative sheltered waters.

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