Light characteristics CLASS OF LIGHT


FIXED


OCCULTING (total duration of light longer than dark) Single occulting


Group occulting


Composite group-occulting ISOPHASE (light and dark equal)


e.g. e.g.


FLASHING (total duration of light shorter than dark) Single-flashing


Long-flashing (flash 2s or longer) L Group-flashing


Composite group-flashing e.g.


QUICK (50 to 79, usually either 50 or 60, flashes per minute) Continuous quick


Group quick Interrupted quick


VERY QUICK (80 to 159, usually either 100 or 120, flashes per minute) Continuous very quick


Group very quick Interrupted very quick


ULTRA QUICK (160 or more, usually 240 to 300, flashes per minute) Continuous ultra quick


Interrupted ultra quick MORSE CODE


FIXED AND FLASHING ALTERNATING


e.g. e.g. e.g. e.g.


International abbreviations


F Oc Oc(2)


Oc(2+3) Iso


Fl Fl


Fl(3) Fl(2+1) Q


Q(3) Iq


VQ


VQ(3) IVQ


UQ IUQ


Mo(K) FFl


Al WR


Illustration period shown


COLOUR


White Red


Green Blue


Violet Yellow


Orange Amber


8


International abbreviations


W (may be omitted) R


G


Bu Vi Y Y Y


NOMINAL RANGE in miles


Light with single range


Light with two different ranges Light with three or more ranges


PERIOD is given in seconds


DISPOSITION horizontally disposed vertically disposed


ELEVATION is given in metres (m) above MHWS


e.g. e.g. e.g.


e.g.


International abbreviations


15M


15/10M 15–7M


90s


(hor) (vert)


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