A light characteristic is all of the properties that make a particular navigational light identifiable. Graphical and textual descriptions of navigational light sequences and colours are displayed on nautical charts and in Light Lists with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing. [1]
While light characteristics can be described in prose, e.g. "Flashing white every three seconds", lists of lights and navigation chart annotations use abbreviations. The abbreviation notation is slightly different from one light list to another, with dots added or removed, but it usually follows a pattern similar to the following (see the chart to the right for examples).
An example of a complete light characteristic is "Gp Oc(3) W 10s 15m 10M". This indicates that the light is a group occulting light in which a group of three eclipses repeat every 10 seconds; the light is white; the light is 15 metres above the chart datum and the nominal range is 10 nautical miles.
A fixed light, abbreviated "F", is a continuous and steady light.
A flashing light is a rhythmic light in which the total duration of the light in each period is clearly shorter than the total duration of the darkness and in which the flashes of light are all of equal duration. It is most commonly used for a single-flashing light which exhibits only single flashes which are repeated at regular intervals, in which case it is abbreviated simply as "Fl". It can also be used with a group of flashes which are regularly repeated, in which case the abbreviation is "Fl(2)" or "Gr Fl(2)", for a group of two flashes. Another possibility is a composite group, in which successive groups in the period have different numbers of flashes, e.g. "Fl. (2+1)" indicates a group of two flashes, followed by one flash.
A specific case sometimes used [2] is when the flashes are longer than two seconds. Such a light is sometimes denoted "long flashing" with the abbreviation "L.Fl".
If the frequency of flashes is high (more than 30 [3] or 50 [2] per minute) the light is denoted as a "quick light", see below.
An occulting light is a rhythmic light in which the duration of light in each period is longer than the total duration of darkness. In other words, it is the opposite to a flashing light where the total duration of darkness is longer than the duration of light. It has the appearance of flashing off, rather than flashing on. Like a flashing light, it can be used for a single occulting light that exhibits only a single period of darkness or the periods of darkness can be grouped and repeated at regular intervals (abbreviated "Oc"), a group (Oc(3)) or a composite group (Oc(2+1)).
The term occulting is used because originally the effect was obtained by a mechanism (e.g. a vertical or rotating shutter) periodically shading the light from view.
An isophase light, abbreviated "Iso", is a light which has dark and light periods of equal length. The prefix derives from the Greek iso- meaning "same".
A quick light, abbreviated "Q", is a special case of a flashing light with a high frequency (more than 30 [3] or 50 [2] per minute). If the sequence of flashes is interrupted by regularly repeated eclipses of constant and long duration, the light is denoted "interrupted quick", abbreviated "I.Q".
Group notation similar to flashing and occulting lights is also sometimes [2] used, e.g. Q(9).
Another distinction sometimes [2] made is between quick (more than 50 and less than 80 flashes per minute), very quick (more than 80 and less than 160 flashes per minutes, abbreviated "V.Q") and ultra quick (no less than 160 flashes per minute, abbreviate "U.Q"). This can be combined with notations for interruptions, e.g. I.U.Q for interrupted ultra quick, or grouping, e.g. V.Q(9) for a very quick group of nine flashes. Quick characteristics can also be followed by other characteristics, e.g. VQ(6) LFl for a very quick group of six flashes, followed by a long flash.
A Morse code light is light in which appearances of light of two clearly different durations (dots and dashes) are grouped to represent a character or characters in the Morse Code. For example, "Mo(A)" is a light in which in each period light is shown for a short period (dot) followed by a long period (dash), the Morse Code for "A".
A fixed and flashing light, abbreviated "F. Fl", is a light in which a fixed low intensity light is combined with a flashing high intensity light.
An alternating light, abbreviated "Al", is a light which shows alternating colors. For example, "Al WG" shows white and green lights alternately.
| Class of Light | Feature | Abbr. | Definition | Example | Representation | |
|---|---|---|---|---|---|---|
| F | A continuous, steady, light. | F R |  | ||
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| 2.1 Single-occulting | Oc | A dark period is repeated regularly. | Oc R 6s |  | ||
| 2.2 Group-occulting | Oc(x) | A group of dark periods are repeated regularly. | Oc(2) G 8s |  | ||
| 2.3 Composite group-occulting | Oc(x+y) | Light similar to group-occulting, except that successive groups in the same period contain different numbers of dark periods. | Oc(2+3) W 18s |  | ||
| Iso | The duration of the light and dark periods are equal. | Iso R 4s |  | ||
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| 4.1 Single-flashing | Fl | A flash is repeated regularly at a rate below 50 per minute. | Fl G 5s |  | ||
| 4.2 Long-flashing | L.Fl | A light flash, duration of more than 2 seconds (long flash) is repeated regularly. | L.Fl W 10s |  | ||
| 4.3 Group-flashing | Fl(x) | A group of a specific number of flashes are repeated regularly. | Fl(3) R 15s |  | ||
| 4.4 Composite group-flashing | Fl(x+y) | Similar to group-flashing, but with several groups of flashes. | Fl(2+1) W 15s |  | ||
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| 5.1 Continuous quick | Q | Quick flashes are repeated regularly. | Q W |  | ||
| 5.2 Group quick | Q(x) | Groups of a given number of quick flashes are repeated regularly. | Q(3) G 9s |  | ||
| 5.3 Interrupted quick | I.Q | The sequence of flashes is regularly interrupted by dark intervals of constant duration. | I.Q R 14s |  | ||
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| 6.1 Continuous very quick | VQ | Very quick flashes are repeated regularly. | VQ W |  | ||
| 6.2 Group very quick | VQ(x) | Groups of a given number of very quick flashes are repeated regularly. | VQ(3) G 4s |  | ||
| 6.3 Interrupted very quick | I.VQ | The sequence of flashes is regularly interrupted by dark intervals of constant duration. | I.VQ R 9s |  | ||
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| 7.1 Continuous ultra quick | UQ | Ultra quick flashes are repeated regularly. | UQ W |  | ||
| 7.2 Interrupted ultra quick | I.UQ | The sequence of ultra quick flashes is regularly interrupted by dark intervals of constant duration. | I.UQ R 6s |  | ||
| Mo(x) | The flashes have markedly different durations and are grouped together to form one or more characters in Morse code. | Mo(K) G 6s |  | ||
| F.Fl | A light that combines a fixed light with a light flashing with a stronger intensity. The flashes of light may have any of the features described in above. | F.Fl Y 5s |  | ||
| Al | Light that alternately displays different colors Note - The alternating light can be used in conjunction with most of the lights earlier classes. | Al WR 3s |  | ||
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy.
Southwold Lighthouse is a lighthouse operated by Trinity House in the centre of Southwold in Suffolk, England. It stands on the North Sea coast, acting as a warning light for shipping passing along the east coast and as a guide for vessels navigating to Southwold harbour.
A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek στρόβος (stróbos), meaning "act of whirling".
A safe water mark, as defined by the International Association of Lighthouse Authorities, is a sea mark used in maritime pilotage to indicate the end of a channel. They usually imply that open, deep and safe water lies ahead. They are also used to indicate the start and end of a buoyed section of a continuous narrow channel; and a series of them may mark a safe route through shallow areas. It is therefore important to consult appropriate charts to determine their meaning in each location. They are also known as fairway buoys and clear water buoys.
North Foreland is a chalk headland on the Kent coast of southeast England, specifically in Broadstairs.
An airway beacon (US) or aerial lighthouse was a rotating light assembly mounted atop a tower. These were once used extensively in the United States for visual navigation by airplane pilots along a specified airway corridor. In Europe, they were used to guide aircraft with lighted beacons at night.
Aviation obstruction lighting is used to enhance the visibility of structures or fixed obstacles which may conflict with the safe navigation of aircraft. Obstruction lighting is commonly installed on towers, buildings, and even fences located in areas where aircraft may be operating at low altitudes. In certain areas, some aviation regulators mandate the installation, operation, color, and/or status notification of obstruction lighting. For maximum visibility and collision-avoidance, these lighting systems commonly employ one or more high-intensity strobe or LED devices which can be seen by pilots from many miles away from the obstruction.
Cromer Lighthouse is situated in the coastal town of Cromer, in the English county of Norfolk.
The VRB-25 is a lighthouse optical system designed and built by Vega Industries Ltd. in Porirua, New Zealand. It was originally designed in 1993–95 with the assistance of the United States Coast Guard to meet USCG requirements for a robust mechanism requiring minimum maintenance. It has become the Coast Guard's standard 12 volt rotating beacon. The company's literature says there are more than 400 installations worldwide. More than a quarter of the active lighthouses in Maine have one installed.
The High lighthouse or pillar lighthouse is one of three lighthouses in Burnham-on-Sea, Somerset, England. A Grade II listed building, it is no longer functional as a lighthouse and has been converted for use as a private dwelling.
Emery Point Light is an active lighthouse located at Larrakeyah Barracks, the main base for the Australian Defence Force in Northern Territory, Australia, at the entrance to Port Darwin. It was the second lighthouse to be built in Port Darwin. It was the only navigational aid to remain functional in the path of Cyclone Tracy.
Completed in 1849, the original 20-metre (66 ft) Wadjemup Lighthouse was Western Australia's first stone lighthouse and was built to provide a safer sailing passage for ships to Fremantle Port and the Swan River Colony.
Booby Island Light is an active heritage-listed lighthouse located on Booby Island in the Shire of Torres, near the tip of Cape York Peninsula, west of Prince of Wales Island, within the Endeavour Strait, Queensland, Australia. It marks the western entrance to the navigation channel through the Torres Strait. It was the last of the major lights to be constructed along the Queensland coast.
Goods Island Light is an active lighthouse located on the highest point of Goods Island (Palilag), an island in the Torres Strait, belonging to Queensland, Australia. It serves as the rear light of the Goods Island Range, pointing out the entrance to Normanby Sound.
Cleveland Point Light, also known as Point Cleveland Light, is a lighthouse located on the north-eastern tip of Cleveland Point, at Cleveland, Redland City, Queensland, Australia. It overlooks Moreton Bay to the east and Raby Bay to the west. The old lighthouse was established in 1864-1865 as a wooden hexagonal tower. It is one of only two surviving lighthouses of this form, the other being Old Burnett Heads Light. A newer light, constructed of a concrete post, replaced it in 1976, and the old lighthouse was relocated a short distance away, where it stands today. The newer light was removed in 2009.
Wyborn Reef Light is an active lighthouse located at Wyborn Reef, formerly known as Y Reef, about 16 kilometres (9.9 mi) southeast of Albany Island, east of the tip of Cape York Peninsula, Queensland, Australia. It marks the entrance to the Albany Passage. The lighthouse was constructed in 1938 and upgraded in 1991 and 1995. The structure is a stainless steel tower with a fiberglass hut within the framework, carrying a lantern.
Black Nore Lighthouse at Portishead, Somerset, England, was built in 1894. It is a Grade II listed building.
The North Bull Lighthouse, is an active aid to navigation located at the mouth of the River Liffey, near Dublin, Ireland. It is one of four lighthouses that help guide shipping into the Liffey, and the Port of Dublin, all of which are operated and maintained by the Dublin Port Company.
The Heugh Lighthouse is a navigation light on The Headland in Hartlepool, in north-east England. The current lighthouse dates from 1927; it is owned and operated by PD Ports. It is claimed that its early-Victorian predecessor was the first lighthouse in the world reliably lit by gas.
The isle of Lundy has three lighthouses: a pair of active lights built in 1897 and an older lighthouse dating from 1797.
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