Cardinal mark buoys

Indicates the direction from the buoy in which the deepest navigable water lies

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Left to right: North cardinal, East cardinal, South cardinal, West cardinal


Cardinal marks indicate that the deepest water in the area lies to the named side of the mark. They are used in conjunction with the compass to indicate the direction from the mark in which the deepest navigable water lies, to draw attention to a bend, junction or fork in a channel, or to mark the end of a shoal.

There are four types of cardinal mark which indicate the mariner will be safe if they pass;

  • North of a North Mark
  • South of a South Mark
  • East of an East Mark
  • West of a West Mark.

Cardinal Marks are also used for permanent wreck marking whereby North, East, South and West Cardinal buoys are placed around the wreck.

In the case of a new wreck, any one of the Cardinal buoys may be duplicated and fixed with a Radar Beacon (RACON).

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A South mark cardinal buoy indicating safe passage to the south of the buoy

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A cardinal mark buoy being prepared for deployment aboard THV Galatea

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Class A cardinal buoy being deployed from THV Galatea


Buoy services

Buoys are available for hire, contact us for more information.

Colour, shape and light

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CARDINAL MARK

NORTH

EAST

Colour

Black above yellow

Black with a single broad horizontal yellow band

Shape of buoy Pillar or spar Pillar or spar
Top-mark*

2 black cones, one above the other, points upward

2 black cones, one above the other, base to base

Light (when fitted)
Colour White White
Rhythm

VQ or Q

VQ(3) every 5s or Q(3) every 10s



CARDINAL MARK

SOUTH

WEST

Colour

Yellow above black

Yellow with a single broad horizontal black band

Shape of buoy Pillar or spar Pillar or spar
Top-mark*

2 black cones, one above the other, points downward

2 black cones, one above the other, point to point

Light (when fitted)
Colour White White
Rhythm

VQ(6) + Long flash every 10s or Q(6) + Long flash every 15s

VQ(9) every 10s or Q(9) every 15s


* The double cone top-mark is a very important feature of every Cardinal Mark by day, and should be used wherever practicable and be as large as possible with a clear separation between the cones.