Wreck Marking Buoy

The emergency wreck-marking buoy marks a new danger, typically a recent wreck, before charts and notices catch up. It carries equal blue and yellow vertical stripes, an upright yellow cross topmark, and an alternating blue-and-yellow light (Bu Y, one-second each) so it is not confused with the standard cardinal or lateral marks. IALA introduced it after the 2002 Tricolor collision exposed the gap in marking sudden hazards. It is removed once the wreck is permanently marked and charted.