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IALA buoyage



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A lateral buoy is a sea mark used to indicate the edge of a channel in terms of port and starboard. These directions are relative to the direction of buoyage which is generally placed CLOCKWISE round the continent ( with some exceptions) and in general into the harbour from the sea.This direction is labeled on the maritime navigational charts. 

A vessel heading in the direction of buoyage (e.g. into a harbour) and wishing to keep in the main channel should:

  • keep port marks to its port (left) side, and
  • keep starboard marks to its starboard (right) side

For historical reasons, two different schemes are in use worldwide, differing in their use of colour.  The IALA defines them as Region A and Region B.

In region A: port marks are red and starboard marks are green.

In region b: Starboard marks are red and port marks are green.​ 

Shape of the buoys or Topmark is common in both regions. CAN shape is used for port hand and CONE for starboard buoys

Region A comprises nations in Australia, Europe, parts of Africa and most of Asia other than the Philippines, Japan and Korea,New Zealand

Region B comprises nations in North America, Central America and South America, the Philippines, Japan and Korea.

Red buoys have red lights and green buoys have green lights of any rhythm except FL (2+1).




(main channel or primary channel terms are also used to indicate preferred channel)

Preferred channel markers are primarily lateral marks but to indicate a split in a channel a lateral marker with a horizontal colour band is used. This mark indicates that a preferred channel often, a deeper channel lies to one side, and a secondary channel on the other. Vessels wishing to use the preferred channel observe the top colour of the mark, and vessels wishing to use the secondary channel observe the band colour. 

The light phase characteristic is R FL (2+1): Red buoy indicating a preferred channel to port (in USA, Japan. or G FL (2+1): Green buoy indicating a preferred channel to starboard (in USA, Japan). 



cardinal mark indicates the position of a hazard and the direction of safe water as a cardinal direction (northeastsouth or west) relative to the mark. Cardinal marks are same in both Region A and B

A cardinal mark indicates one of the four compass directions by:

  •  Two conical top-marks, both point up, indicating NORTH; down, Two cones both point down indicating SOUTH;Two cones with apex away from each other indicating EAST and two cones with apexes meeting indicating WEST.
  • its distinctive pattern of black and yellow stripes, which follows the orientation of the cones 



Isolated dangers marks

Marks indicating isolated dangers.This type of buoy indicates the position of an isolated danger. Body: black with red horizontal band(s); Topmark: 2 black spheres. The light (when present) consists of a white flash: Fl(2). 
Marking of isolated dangers 



Marks indicating safe water

Marks indicating safe water.These marks are generally used to make landfall. Body: red and white vertical stripes; Topmark (if any): single red sphere. Lights white: Morse A, Iso, Occ or LFl 10s. 



Marks for new wrecks

The emergency wreck marking buoy, is placed as close as possible to a new dangerous wreck. 
Emergency wreck marking buoy for new wrecks

The emergency wreck marking buoy will remain in position until: a) the wreck is well known and has been promulgated in nautical publications; b) the wreck has been fully surveyed and exact details such as position and least depth above the wreck are known; and c) a permanent form of marking of the wreck has been carried out. 


  • Fitted with an alternating blue and yellow flashing light with a nominal range of 4 nautical miles where the blue and yellow 1 second flashes are alternated with an interval of 0.5 seconds. 
    B1.0s + 0.5s + Y1.0s + 0.5s = 3.0s   New wreck light character.
  • A racon Morse Code “D” and/or AIS transponder can be used.
  • The top mark, if fitted, is a standing/upright yellow cross

Special buoys and marks

Marks used for special indication.
Special Mark is used to mark areas like

Anchorages, Mooring, Waiting, Marine farms, Channel within a channel, Oil wells, Pipelines and Cables, Spoil ground, Wrecks, Protected areas, Outfalls, ODAS buoys etc,.  


You can take an interactive buoyage test now

To take a test click on the link below