Part of the IALA maritime buoyage system which indicates there is navigable water all round it. It may also be used as an alternative to a cardinal or lateral mark to indicate a landfall. It is either a spherical or pillar buoy, or a spar buoy with a spherical topmark, and is the only type of mark to be coloured with red and white vertical stripes. If it is lighted it is white using isophase, occulting, one long flash (a single flashing light in which the light appears for not less than two seconds duration and is regularly repeated), or Morse code ‘A’ rhythms. See characteristic.
Subjects: Maritime History.