Boating Basics: On the Water

U.S. Aids to Navigation System (ATON)

Buoys and markers are the "traffic signals" that guide vessel operators safely along some waterways. They also identify dangerous or controlled areas and give directions and information. As a recreational boat or PWC operator, you will need to know the lateral navigation markers and non-lateral markers of the U.S. Aids to Navigation System.

Lateral Markers

These navigation aids mark the edges of safe water areas; for example, directing travel within a channel. The markers use a combination of colors and numbers, which may appear on either buoys or permanently placed markers.

Illustrations	What the Markers Mean
	Red colors, red lights, and even numbers indicate the right side of the channel as a boater enters from the open sea or heads upstream.
	Green colors, green lights, and odd numbers indicate the left side of the channel as a boater enters from the open sea or heads upstream.
	Red and green colors and/or lights indicate the preferred (primary) channel. If green is on top, the preferred channel is to the right as a boater enters from the open sea or heads upstream; if red is on top, the preferred channel is to the left.
	Lighted Buoys use the lateral marker colors and numbers discussed above; in addition, they have a matching colored light.
	Nuns are red cone-shaped buoys marked with even numbers.
	Cansare green cylindrical-shaped buoys marked with odd numbers.
	Daymarks are permanently placed signs attached to structures, such as posts, in the water. Common daymarks are red triangles (equivalent to nuns) and green squares (equivalent to cans). They may be lighted also.

Red Right Returning
is a reminder of the correct course when returning from open waters or heading upstream.

Boat entering channel: red buoy on starboard, green on port

Boat entering open water: red buoy on port, green on starboard

Intracoastal Waterway (ICW)

Red triangle daymark with a yellow triangle indicating and Intacoastal Waterway channel

The Intracoastal Waterway (ICW) is a chain of local channels that are linked together to provide an inland passage along the Atlantic and Gulf of Mexico coasts. Channels of the ICW are identified by yellow symbols on channel buoys and markers. They are aids for both the U.S. Aids to Navigation System and the Intracoastal Waterway.

If you are following the ICW from New Jersey to Brownsville, Texas, in a clockwise direction:

Any marker displaying a yellow triangle should be passed by keeping it on the starboard (right) side of your vessel.
Any marker displaying a yellow square should be passed by keeping it on the port (left) side of your vessel.

When you are following the Intracoastal Waterway, the yellow triangles and squares supersede the colors and shapes of the lateral markers on which they appear.

Green square daymark with yellow square indicating and Intacoastal Waterway channel

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Online boating safety handbook last modified: January 9, 2009
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