Skysail Training


Buoyage - Cardinal Marks 

IALA = International Association of Lighthouse Authorities.  Trinity House ( ) is the authority for the UK, they maintain all the lighthouses and navigation marks.There are two lighthouse regions - IALA  A and IALA B.  Region A is Europe, Africa, Middle East, Australasia:  Port hand mark (PHM) is a red can, when going with direction of buoyage - entering harbour. Green marks are cones, they are Starboard hand marks (SHM). Cardinal marks are the same in both regions.

Pierre Noire West Cardinal Mark

NE of Cherbourg.

Tide running at 3 knots +

Click for more pictures

North Cardinal No topmark

Cardinal Marks indicate a danger and indicate which side to pass

On a chart, a vertical mark is fixed, a leaning mark is buoyed and floating.

Cardinal marks are located to the North, East, South or West of a hazard - ie the Cardinal Points of the compass. They each have a distinctive topmark, colour scheme and light sequence.

The Top Marks are logical:

North - 2 black cones pointing upwards.

East - 2 cones pointing up and down. You can remember this as an Egg or a Greek letter Eta  Σ

South - 2 cones pointing Down.

West - 2 cones point to point.  Like a Wineglass or Mae West

If the topmarks are missing, the Black and Yellow stripes are distinctive - the top mark cones point to the Black Stripe(s)

The lights are based on the clock face: the lights can be Quick Flash or Very Quick Flash, at 15 sec or 10 sec intervals to avoid confusion with similar marks close together.

East cardinal is at 3 o'clock - 3 flashes.

South cardinal  is at 6 o'clock - 6 flashes - plus a long flash to avoid confusion with a West cardinal. At night it can be difficult to count a large number of flashes, with the waves hiding some.

West cardinal is at 9 o'clock - 9 flashes. So if you see a large number of flashes with no long flash, that is a West Cardinal.  

North cardinal at 12 o'clock  - In theory 12 flashes, but actually it is continuous flashing.  So a large number of flashes with no dark interval is a North Cardinal.


The RNLI has an excellent on line teaching program at:   RNLI training program

 New wreck buoy   For more information see

Alternate Flashing
Blue / Yellow

Moiré Light is used to provide a directional beam: example - a transit for  narrow bridge  see  Moire_light.pdf and Moire light and HAT Vertical clearances

Posted 15th June 2011