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
South Cardinal Buoy
- A south cardinal buoy is located so that the safest water exists to the south of it.
- Top-marks pointing downward.
- black band below yellow band
East Cardinal Buoy
- An east cardinal buoy is located so that the safest water exists to the east of it.
- Top-marks pointing away from each other:
- Black bands above and below a yellow band
West Cardinal Buoy
- A west cardinal buoy is located so that the safest water exists to the west of it.
- Top-marks pointing towards each other:
- Black band with yellow bands above and below.
Cardinal marks also have a special system of flashing white lights. The rhythms are basically all “very quick” (VQ) or “quick” (Q) flashing but broken into varying lengths of the flashing phase. “Very quick flashing” is defined as a light flashing at a rate of either 120 or 100 flashes per minute, “quick flashing” is a light flashing at either 60 or 50 flashes per minute.