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Buoyage - Cardinal, Lateral and Special Marks - IALA A Buoyage system  

IALA = International Association of Lighthouse Authorities.  Trinity House ( http://www.trinityhouse.co.uk ) is the authority for the UK, they maintain all the lighthouses and navigation marks.

Pierre Noire West Cardinal Mark

NE of Cherbourg.

Tide running at 3 knots +

Click for more pictures

North Cardinal No topmark

Lateral marks - IALA A

Mark a channel, danger or area

The colour of lateral marks may be unclear when the sun is behind them - remember the cone or can shapes.

Cardinal Marks  

Mark a danger or 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 Up.

East - 2 cones pointing up and down. You can remember this as an Egg.

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 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 http://www.trinityhouse.co.uk/pdfs/pdf_wreck_buoy.pdf

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