U.S. waterways provide a system for boaters similar to
street signs,
stop signals,
road barriers,
detours,
and traffic lights for automobile drivers.
Aids to Navigation or ATONS are deployed to assist mariners in determining their position and maintaining a safe course.
ATONS include buoys,
day beacons,
lightships,
radio beacons,
fog signals,
marks,
and other devices to facilitate safe piloting.
They are positioned and serviced
by the U.S. Coast Guard,
U.S. Corps of Engineers,
state governments,
and approved private authorities.
Aids mark isolated dangers,
assist in making landfall,
and provide a continuous chain of channel markers.
ATONS are designed for use
with nautical charts that provide valuable information regarding depths, hazards,
and other features not shown
on land maps.
Buoys are anchored floating objects
with distinctive shapes and colors indicating their purpose in navigation.
Beacons are permanently fixed structures, such as lighthouses
and single-pile poles;
and lighted beacons are called "lights"
while unlighted ones are known as "day beacons."
Both buoys and beacons can have lights and may also have sound producing devices
such as gongs,
bells,
or horns;
and both may simply be called "marks."
As a result of anchor drift and changing sea bottom conditions,
buoys don’t always maintain their precise charted position;
so, allow extra room near floating aids,
especially if they mark an obstruction;
and check for consistency with your GPS
or paper chart.
Lateral aids to navigation are generally used for well-defined channels to indicate the route to be followed.
This can be remembered with the mnemonic, "red right return,"
meaning that red even-numbered buoys, beacons, and dayboards
should be kept on the right or starboard side of your boat
when you are returning from open water and entering a harbor.
Green odd-numbered buoys, beacons, and dayboards, conversely,
should be kept on the left or port side of your boat
when you return from the sea.
Even numbers should increase as you proceed inland;
odd numbers should decrease as you proceed to open water.
Diamond shape dayboards help determine location.
Safe water marks designate unobstructed fairways,
mid-channels, and offshore approach points.
Information and regulatory marks are used
to alert vessel operators to various warnings or governance matters.
An open diamond shape signifies danger,
and a diamond with a cross through it signifies an exclusion area that you may not enter.
A mark with a circle indicates an upcoming operational restriction,
such as a speed limit.
A square or rectangular shape is used for conveying helpful information,
such as directions, distances, or locations.
Isolated danger marks come in various shapes
and are located near dangers that should be approached with caution.
Special aids are yellow in color
and are used to identify a unique feature
such as the boundary for an anchorage, fishing ground, or dredging area.
Mooring buoys are white with a sold blue horizontal line,
typically found in anchoring areas,
and are the only buoys to which you may legally attach your boat.
For additional information about these and other types of ATONS,
visit USCGboating.org
and search for "US Aids to Navigation System."