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).
A South mark cardinal buoy indicating safe passage to the south of the buoy
A cardinal mark buoy being prepared for deployment aboard THV Galatea
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
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.