What are Cardinal Marks?

Definition of Cardinal quadrants and marks

As per IALA Buoyage system, The four quadrants (North, East, South and West) are bounded by the true bearings NW-NE, NE-SE, SE-SW, and SW-NW, taken from the point of interest.

  • A Cardinal mark is named after the quadrant in which it is placed.
  • The name of a Cardinal mark indicates that it should be passed to the named side of the mark.
  • The Cardinal marks in Region A and Region B, and their use, are the same.
Use of Cardinal Marks

A Cardinal mark may be used, for example:

  • To indicate that the deepest water in that area is on the named side of the mark.
  • To indicate the safe side on which to pass a danger.
  • To draw attention to a feature in a channel such as a bend, a junction, a bifurcation or the end of a shoal.
  • Competent authorities should consider carefully before establishing too many cardinal marks in a waterway or area as this can lead to confusion, given their white lights of similar characteristics
North Cardinal Buoy
  • A north cardinal buoy is located so that the safest water exists to the north of it.
  • Top-marks pointing upward:
  • black band above yellow band