Beacons and buoys indicate to a vessel operator the existence
of dangerous areas, as well as those areas which are restricted or controlled,
such as speed zones and areas dedicated to a particular use, or to provide
general information and directions:
(1) Aids to navigation are placed on shore or
on marine sites to assist a navigator to determine his position or safe course.
They may mark limits of navigable channels, or warn of dangers or obstructions
to navigation. The primary components of the U.S. Aids to Navigation System are
beacons and buoys.
(2) Beacons are
aids to navigation structures which are permanently fixed to the earth's
surface. They range from large lighthouses to small, single-pile structures and
may be located on land or in the water. Lighted beacons are called lights;
unlighted beacons are called day beacons.
(3) Beacons exhibit a daymark. For small
structures these are colored geometric shapes which make an aid to navigation
readily visible and easily identifiable against background conditions.
Generally, the daymark conveys to the mariner, during daylight hours, the same
significance as does the aid's light or reflector at night. The daymark of
large lighthouses and towers, however, consists of the structure itself. As a
result, these daymarks do not infer lateral significance.
(4) Vessels should not pass beacons close
aboard due to the danger of collision with riprap or structure foundations, or
the obstruction or danger that the aid marks.
(5) Buoys are floating aids to navigation
used extensively throughout U.S. waters. They are moored to the seabed by
sinkers with chain or other moorings of various lengths.
(6) The daymark of a buoy is the color and
shape of the buoy and, if so equipped, of the top mark.
(7) Can buoys have a cylindrical shape. Nun
buoys have a tapered, conical shape.
(8) Pillar buoys have a wide cylindrical base
supporting a narrower superstructure. They may be surmounted by colored shapes
called top marks.
buoys have a round shape.
Mariners attempting to pass a buoy close aboard risk collision with a yawing
buoy, the buoy's mooring, or with the obstruction which the buoy
Mariners should not
rely on buoys
alone for determining their positions due to factors limiting
their reliability. Prudent mariners will use bearings or angles from beacons
other landmarks, soundings, and various methods of electronic navigation. Buoys
vary in reliability because:
positions represented on nautical charts are approximate positions only, due to
practical limitations in positioning and maintaining buoys and their sinkers in
precise geographical locations.
Buoy moorings vary in length. The mooring lengths define a "watch circle," and
buoys can be expected to move within this circle. Actual watch circles do not
coincide with the dots or circles representing them on charts.
(c) Buoy positions are normally verified
during periodic maintenance visits. Between visits, environmental conditions,
including atmospheric and sea conditions, and seabed slope and composition, may
shift buoys off their charted positions. Also buoys may be dragged off station,
sunk, or capsized by a collision with a vessel.