Cardinal marks
These are used to indicate the location of the best navigable water, to show the safe side on which to pass danger (rocks, wrecks, shoals, etc.) and to draw attention to a feature in a channel.
To understand the meaning of a particular cardinal mark, the navigator must be aware of geographical directions and therefore needs a compass to determine where the best navigable water lies.
The mark is placed in one of the four quadrants: north south, east or west. If in doubt, consult the chart.
Shape
The shape of a cardinal mark is not significant, but in the case of a buoy it will be a pillar or spar.
Topmark
The most important daylight feature of the cardinal mark is the black double cone top mark and the four different arrangements that indicate the relevant direction from the mark.
West cardinal mark
Topmark consists of two cones point to point. The mark has yellow/ black/yellow bands. When lit, a west mark exhibits a white light flashing in groups of nine quick or very quick flashes. Pass on the western side of
this mark.
North cardinal mark
Topmark consists of two cones pointing up. The mark has a black band over a yellow band. When lit, a north mark exhibits a continuous quick or very quick flashing white light. Pass on the northern side of this mark.
South cardinal mark
Topmark consists of two cones pointing down. The mark has a yellow band over a black band.
When lit, a south mark exhibits a white light flashing in groups of six quick or very quick flashes followed by a long flash. Pass on the southern side of this mark.
East cardinal mark
Topmark consists of two cones pointing away from each other. The mark has black/yellow/ black bands. When lit, an east mark exhibits a white light flashing in groups of three quick or very quick flashes. Pass on the eastern side of this mark.
Colour
Black and yellow horizontal bands are used to colour the cardinal marks and indicate the type of cardinal mark. Top mark cones point in the same direction as the location of the black bands on the marks.
Lights
f lit, the mark will exhibit a quick flashing (about 1 per second) or very quick flashing (about 2 per second) white light. The rhythm of the light will indicate the particular quadrant of the mark.
The number of flashes corresponds to the numbers on a clock face:
N = continuous flash
E = 3 flashes
S = 6 flashes (and one long flash)
W= 9 flashes.