Channel marker

A channel marker is an aid to navigation, a buoy or a fixed beacon, that marks the edge of a dredged or natural channel so vessels stay within safe water. Under the IALA Maritime Buoyage System these are lateral marks: in Region A a vessel entering port keeps red can-shaped port marks to its left and green conical starboard marks to its right; Region B reverses the colors (red right returning). Each carries a charted light character, topmark, and number so the mariner confirms position against the chart and ECDIS. Markers may add a racon or an AIS AtoN broadcast. They define the navigable width a pilot uses against the ship’s beam.