Above (Left to Right): North, East, South and West Cardinal Type 2 Solar Buoys

Mariners will be safe if they pass north of a north mark, south of a south mark, east of an east mark and 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).

At night, the lights of Cardinal Marks are programmed with distinct identifying characters; as an aide memoire they can be considered to flash in accordance with positions on a clock face whereby an East Cardinal flashes three times, a South Cardinal six times (but with an added long flash to make it more distinctive) and a West Cardinal nine times. The North Cardinal doesn’t quite fit the pattern – having a continuous quick or very quick flash.

The buoy illustration shows Type 2 configurations of buoys. These are approximately three metres in diameter and weigh approximately six tonnes excluding moorings. Buoys need to be recognised both in daylight and at night and use topmarks to assist in identification. A topmark on a Cardinal Buoy is triangular and coloured black. Topmarks and buoy colours themselves are arranged in order to represent the points on a compass.