thumb|400px|Visual buoyage, IALA region B, by day. Lateral marks in IALA region A have the same shapes but opposite colours.

A lateral buoy, lateral post or lateral mark, as defined by the International Association of Marine Aids to Navigation and Lighthouse Authorities, is a sea mark used in maritime pilotage to indicate the edge of a channel.

Each mark indicates the edge of the safe water channel in terms of port (left-hand) or starboard (right-hand). These directions are relative to the direction of buoyage; this is usually a nominally upstream direction. In a river, the direction of buoyage is towards the river's source; in a harbour, the direction of buoyage is into the harbour from the sea. Where there may be doubt, it will be labelled on the appropriate chart. Often the cardinal mark system is used instead when confusion about the direction would be common.

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.

IALA System

thumb|right|A Region A lateral mark, showing both the green color and the triangular symbol, denoting the channel at the entrance to the [[Port River near Adelaide, South Australia]]

Marks are distinguished by their shape and colour, being red or green.

For historical reasons, two different schemes are in use worldwide, differing in their use of colour. Previously there had been 30 different buoyage systems, before IALA rationalised the system. In 1980 on a conference convened by IALA, they agreed to adopt the rules of a new combined system, which combined the previous two systems (A and B) into one system, with two regions (A and B).

The IALA defines them as Region A and Region B:

Region A

thumb|IALA region A: Red port / green starboard marks when entering from sea into [[Le Palais, France]]

  • comprises Europe, Africa, and most of Asia and Oceania, as well as Greenland.
  • port marks are red and may have a red flashing light of any light characteristic except composite group flashing 2+1 (having abbreviation "Fl(2+1)").
  • starboard marks are green and may have a green flashing light of any light characteristic except "Fl(2+1)". the Philippines, Taiwan, Hawaii, and Easter Island.
  • port marks are green and may have a green flashing light of any light characteristic except "Fl(2+1)". See the buoy by the island in the diagram above.

In Region A only, the phrase "Is there any red port left?" (referring to the red colour of the fortified wine "port") may be used as a mnemonic, indicating that a red mark must be kept on the left when "returning" to (i.e., entering) a harbour or river.

In Region B only, the phrase "red right returning" may be used as a mnemonic, indicating that a red mark must be kept on the right when returning to (i.e., entering) a harbour or river.

See also

  • Cardinal mark
  • Isolated danger mark
  • Light characteristic
  • Safe water mark
  • Special mark
  • Emergency wreck buoy

References

  • A web site of Transport Canada, showing lateral buoys in Region B.

es:Sistema de boyado marítimo IALA

it:Segnalamenti marittimi ottici