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Light Characteristics

Forum to discuss all areas of lighthouse technology such as optics, fuels, fog signals, radiobeacons, daymarks, construction, etc.

Postby island » Tue Apr 05, 2005 3:55 pm


The light characteristic of a lighthouse or lighted buoy is the light pattern and color observed at night with which the object can be identified. It is one thing to descibe the patterns. It is quite another to observe them. To see a unique simulation of what these patterns look like check out this site below.

On the menu open Aids of nav. Then open Character by Tobias Holgers.
http://www.fyr.org/indexe.htm

This is the site for the Swedish Lighthouse Society
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Postby Terry_Pepper » Tue Apr 05, 2005 4:53 pm


Interesting site Dave, thanks for posting it.

For those who may be new to the world of light characteristics, the US Coast Guard identifies the various light characteristics as follows:

FIXED – A light showing continuously and steadily
OCCULTING – A light in which the total duration of light in a period is longer than the total duration of darkness and the intervals of darkness (eclipse) are usually of equal duration.
SINGLE OCCULTING – An occulting light in which the eclipse is regularly repeated.
GROUP OCCULTING – An occulting light in which a group of eclipses, specified in numbers, is regularly repeated.
COMPOSITE GROUP OCCULTING – A light, similar to a group occulting light, except that successive groups in a period have different numbers of eclipses.
ISOPHASE – A light in which all durations of light and darkness are equal.
FLASHING – A light in which the total duration of light in a period is shorter than the total duration of darkness and the appearances of lights (flashes) are usually of equal duration.
SINGLE FLASHING – A flashing light in which a flash is regularly repeated (frequency not exceeding 30 flashes per minute.)
GROUP FLASHING – A flashing light in which a group of flashes, specified in number, is regularly repeated.
COMPOSITE GROUP FLASHING – A light similar to a group flashing light except that successive groups in the period have different number of flashes.
QUICK – A light in which flashes are produced art a rate of 60 flashes per minute.
CONTINUOUS QUICK – A quick light in which the flash is regularly repeated.
INTERRUPTED QUICK – A quick light in which the sequence of flashes is interrupted by regularly repeated eclipses of constant and long duration.
MORSE CODE - A 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.
FIXED AND FLASHING – A light in which a fixed light is combined with a flashing light of higher luminous intensity.
ALTERNATING – A light showing different colors alternately.

The above were transcribed from the 1994 US Coast Guard light List, Volume V11, Great Lakes.
Terry Pepper
GLLKA Executive Director
http://www.gllka.com

Seeing The Light
http://www.terrypepper.com

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Postby island » Tue Apr 05, 2005 6:09 pm


The 2005 Light List Introduction contains the same designations for flash charactistics. Nothing new I guess.

The individual Light Lists (in pdf) for each CG group are easily obtained on the Internet but the Introduction was buried 14 pages deep in another pdf document. The Intro contains everything you would want to know about lights, day marks, etc. --- and also things you might not want to know.
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Postby bert911 » Wed Apr 06, 2005 8:32 am


It is one thing to read the characteristic on a page and understand it, but it is nice to see it in "operation". Thank you for posting the site!

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