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Special mark

Examples of Special Marks
A Special mark indicating an outfall pipe in the Irish Sea off Helen's Bay, Northern Ireland. It has the group flashing sequence "Fl(2) Y" meaning it flashes yellow twice followed by a longer period of darkness.

A Special Mark, as defined by the International Association of Lighthouse Authorities, is a sea mark used in maritime pilotage. It is recognisable by its yellow colour and "X" (also referred to as a St. Andrews Cross or saltire) top-mark. If a light is fitted the light is always yellow in colour and can have any light characteristic which differs from those used for cardinal marks, isolated danger marks, mobile aid to navigation marks and safe water marks.[1][2]

Purpose

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Special marks can indicate:

Other uses

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  • Buoys, such as a Weather buoy or Mooring buoy are coloured yellow or have a yellow light to indicate it is not an aid to navigation.

See also

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References

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  1. ^ "R1001 The IALA Maritime Buoyage System". International Association of Marine Aids to Navigation and Lighthouse Authorities. Retrieved 2025-07-09.
  2. ^ "R0110 – Rhythmic Characters of Lights on Aids to Navigation". International Association of Marine Aids to Navigation and Lighthouse Authorities. Retrieved 2025-07-09.