IALA buoyage system A – isolated danger marks
Isolated danger marks designate an isolated danger of limited extent which has navigable water all round it, for example an isolated shoal, rock or wreck.
Isolated danger mark features
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Colour – black with one or more red horizontal bands.
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Top mark – two black spheres positioned vertically and clearly separated.
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Light – a white flashing light showing groups of two flashes.
The characteristics may be best remembered by association of two flashes with two spheres as the top marks.
Last reviewed: 02 March 2012
