landmasses given in Sailing Directions, and, if
necessary, indicated on charts by a symbol
A cardinal mark is used in conjunction with the
compass to indicate the best navigable water. It is
placed in one of four quadrants (north, east, south, or
west) from the best water. A cardinal mark takes its
name from the compass point in which it is placed.
Figure 9-15 shows the IALA Maritime Buoyage
System cardinal marks.
The mariner is safe if he/she passes north of a
north mark, east of a east mark, south of a south mark,
and west of a west mark. A cardinal mark may be used
to do the following:
Indicate that the deepest water is an area on the
named side of the mark.
Indicate the safe side on which to pass a danger.
Draw attention to a feature in a channel, such as
a bend, junction, branch, or end of a shoal.
Figure 9-15.IALA Maritime Buoyage System cardinal marks.