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IALA Maritime Buoyage System
Navigation Aids

During the IALA conference in November 1980 two navigation marking systems, ie the System A (red colour for the left hand of the ship) and the System B (red colour for the right hand of the ship), were combined into one - the IALA System.

In the IALA System the regional (of the systems A and B) principle of painting of the lateral signs was maintained. The countries that accepted the red colour for the left hand lateral sings were included in the region A. The countries that use the green colour for the left hand lateral signs were included in the region B. In the both regions, the fairway direction is the one leading from the sea (when a different manner is used than an adequate notice is provided).

 IALA System

Following to the division into the IALA System regions, marine maps contain respective notice, ie the "IALA System Region A" or the "IALA System Region B".

The IALA System has five types of signs that are used in various associations. The signs have specific identification elements that make them easily recognizable to the sailors. The lateral signs in the Regions A and B are different, but the other four signs are common for these both regions.

The lateral buoys and marks are placed according to the direction accepted for marking of the right and left side of the fairway. In the Region A, during the day and night, the green colour is used to mark the right side of the fairway, and the red colour - to mark the left side.

In the Region B the colours are reversed, ie the red colour is used for the right side, and the green colour - for the left side.

When the path is divided on a fairway, then the direction of the main path is shown with a modified lateral buoy in order to indicate the direction of this main path.


Modified Lateral Buoys and Marks for the Region A


Modified Lateral Buoys and Marks for the Region B


Cardinal Buoys indicate that the deepest water occurs at the side of the mark’s name. They are placed to the north, south, east or west from the hazard. The cardinal buoys have mainly the shape of columns or poles. They are painted in horizontal, yellow and black stripes, and their topmarks (two cones) are painted black. The arrangement of cones at the top is an indication of the black stripe (or stripes) position on the buoy.

  • cones with tops up: the black stripe is above the yellow one,
  • cones with tops down: the black stripe is under the yellow one,
  • cones with bases towards one another: the black stripes above and below the yellow one,
  • cones with tops towards one another: the black stripe with the yellow stripes above and below.
Cardinal buoys

Cardinal buoys are equipped with white light characterised by a special rhythm. The main types of rhythms are as follows: flashing (Q) or fast flashing (VQ). The flashing light has 60 or 50 flashes per minute. The fast flashing light has 120 or 100 flashings per minute.

The lights in individual quadrants have the following characteristics:

  • N quadrant: VQ or Q - continuous.
  • E quadrant: VQ(3) or Q(3) with a blackout afterwards.
  • S quadrant: VQ(6) or Q(6) with a long flash and a blackout.
  • W quadrant: VQ(9) or Q(9) with a blackout afterwards.

The number of flashes - 3, 6 and 9, in the respective quadrants E, S and W facilitates the identification of the cardinal buoys, as the number can be associated with the positions of the 3, 6 and 9 hours on the clock dial. A longer flash (not less than 2 seconds) just after the VQ (6) or Q (6) is typical of the S quadrant. There are two other marks with white light, however, their rhythm is very different and cannot be confused with the rhythm of the white light used in the cardinal buoys.

Marks indicating Isolated dangers



Marks indicating Isolated dangers are placed directly over minor obstacles around which the water is navigable. The have shapes of columns, poles or other, however, they are difficult to confuse with the cardinal buoys. They are black with horizontal red stripes. The topmarks consists of two black spheres one above the other. The light is white - a group flash light Fl(2) with two flashes in a group.


Marks indicating Safe waterMarks indicating Safe water. They indicate that water is navigable around the mark and they do not show any hazards. They can be used to mark, eg a fairway axis or as approach signs. The safe water marks appearance is completely different from the one of the buoys that indicate the hazard. Their may have a shape of a sphere, a column or a pole, with a red sphere as a topmark. These are the only marks painted in vertical stripes (red and white). When the light is installed, then its colour is white and its rhythm may be isophase, occulting, long flash or the Morse Code letter "A".


 Znaki specjalne Special Buoys and Marks do not represent navigational aids. They indicate a special area or an object mentioned on maps or in other nautical documents and publications.

These special marks are painted yellow and have a topmark in the shape of a yellow lying cross (X). The light (if installed) is also yellow. As in poor visibility it is possible to mistake the yellow colour for the white, the yellow lights of the special marks cannot have the rhythm adopted for marks with the white light. The shape of the special marks cannot be confused with the shape of navigational marks, ie if special marks have been used to mark, eg the left side of the fairway, then they must have a cylindrical and not conical shape. The special marks may have letters or numbers painted on them.


New danger. Attention is being drawn to the fact that a "new danger" that has not yet been announced in nautical documents may be indicated with a duplicating mark being identical (in all details) with the principal mark. The duplicating mark should stay until the news about the new danger has been adequately announced. The "new danger" mark should be equipped with a Racon sending out the letter "D" in the Morse Code.

Many thanks to Piotr Wargan
for translating this chapter into English.
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