Access keys and skip links

IALA buoyage system A – special marks

Special marks indicate a special area or feature such as traffic separation marks, spoil, ground marks, cable or pipe lines marks including outfall pipes.

They can also define a channel within a channel, for example a channel for deep draught ships in a wide estuary where the limits of the channel for normal navigation are marked by red and green lateral buoys.

Special mark features

  • Colour: yellow
  • Topmark: when a topmark is carried, it takes the form of a single yellow X.
  • Light: it is yellow and the rhythm may be any other than those used for the white lights of cardinal, isolated danger and safe water marks.
example of a special mark in daylight
example of a special mark at night
 

Blue middle channel mark

Fixed blue lights are identified as lead lights. They are commonly used to mark the centre of the channel on overhead bridges.

Last reviewed: 05 March 2012