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Light characteristic
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Light characteristic
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.
The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) publishes a recommendation R1001, "The IALA Maritime Buoyage System (MBS)", which is stated within to be adopted by almost all marine aids to navigation authorities. This recommendation sets out recommended light characteristics for different types of marine aids to navigation within the categories of lateral marks, cardinal marks, isolated danger marks, safe water marks, special marks, emergency wreck marks and other marks such as lighthouses. Depending on the marine aid to navigation, this recommendation includes specification of light colours (such as "red") and light patterns (such as "Fl" for flashing).
Light colours are defined in recommendation R0201, "Marine Signal Lights-Colours (E200-1)". This recommendation specifies for each named colour a polygon within the CIE 1931 color space for acceptable shades of the named colour a marine aid to navigation may exhibit.
Light patterns, including abbreviations, are defined in recommendation R0110, "Rhythmic Characters of Lights on Aids to Navigation".
While light characteristics can be described in prose, e.g. "Flashing white every two 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.
Fixed lights, abbreviated "F", are a continuous and steady light. The IALA Marine Buoyage System does not include use of a fixed light pattern due to lack of differentiation as a marine aid to navigation light.
Single flashing lights continuously repeat a flash of light of duration followed by an obviously longer duration of darkness. Every repetition is identical. Single flashing lights are abbreviated as "Fl".
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Light characteristic
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.
The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) publishes a recommendation R1001, "The IALA Maritime Buoyage System (MBS)", which is stated within to be adopted by almost all marine aids to navigation authorities. This recommendation sets out recommended light characteristics for different types of marine aids to navigation within the categories of lateral marks, cardinal marks, isolated danger marks, safe water marks, special marks, emergency wreck marks and other marks such as lighthouses. Depending on the marine aid to navigation, this recommendation includes specification of light colours (such as "red") and light patterns (such as "Fl" for flashing).
Light colours are defined in recommendation R0201, "Marine Signal Lights-Colours (E200-1)". This recommendation specifies for each named colour a polygon within the CIE 1931 color space for acceptable shades of the named colour a marine aid to navigation may exhibit.
Light patterns, including abbreviations, are defined in recommendation R0110, "Rhythmic Characters of Lights on Aids to Navigation".
While light characteristics can be described in prose, e.g. "Flashing white every two 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.
Fixed lights, abbreviated "F", are a continuous and steady light. The IALA Marine Buoyage System does not include use of a fixed light pattern due to lack of differentiation as a marine aid to navigation light.
Single flashing lights continuously repeat a flash of light of duration followed by an obviously longer duration of darkness. Every repetition is identical. Single flashing lights are abbreviated as "Fl".
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