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IALA buoyage system A cardinal marks

A cardinal mark indicates where the best and safest water may be found and is used with a compass. It shows where the mariner has safe passage. A cardinal mark may indicate:

  • the deepest water in an area
  • the safe side on which to pass a danger
  • a feature in a channel such as a bend, junction or an end of a shoal.

Cardinal mark features

  • Top marks: black double cones clearly separated.
  • Colours: black and yellow horizontal bands with the position of the black band or bands relative to the respective cardinal points.
  • Lights: a cardinal mark exhibits a white light and its quadrant is distinguished by a specific group of quick or very quick flashes.
North—top mark points up, black
band above yellow band.
example of a north cardinal mark in daylight
North—uninterrupted flash.

example of a north cardinal mark at night
 


East—top mark points outward,
black bands above
and below yellow band.
example of an east cardinal mark in daylight
East—3 flashes in a group.


example of an east cardinal mark at night
 


South—top mark points down,
black band below
yellow band.
example of a south cardinal mark in daylight
South—6 flashes in a group
followed by a long flash (that
will flash for at least 2 seconds).
example of a south cardinal mark at night
 


West—top mark points inward,
black band between
yellow bands.
example of a west cardinal mark in daylight
West—9 flashes in a group.


example of a west cardinal mark at night
 


To assist in remembering cardinal marks, associate the number of flashes of each group with that of a clock face. That means that north is at 12 o'clock, east is at 3 o'clock, south is at 6 o'clock and west is at 9 o'clock.

To ensure that no confusion occurs between east, south and west marks, a long flash (for at least 2 seconds) immediately follows the 6 flashes of the south mark.

Last updated
04 July 2013