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.
East—top mark points outward,
black bands above
and below yellow band.
East—3 flashes in a group.
South—top mark points down,
black band below
South—6 flashes in a group
followed by a long flash (that
will flash for at least 2 seconds).
West—top mark points inward,
black band between
West—9 flashes in a group.
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.