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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 in conjunction 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 – three 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 – six flashes in a group
followed by a long flash.

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 – nine 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 twelve o'clock, east is at three o'clock, south is at six o'clock and west is at nine o'clock.

To ensure that no confusion occurs between east, south and west marks, a long flash immediately follows the six flashes of the south mark.

Last reviewed: 05 January 2012