Boating Basics: On the Water with Your Vessel

U.S. Aids to Navigation System (ATON)

Buoys and markers are the “traffic signals” that guide operators safely along some waterways. They also identify dangerous or controlled areas and give directions and information. As a recreational vessel 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 are used to mark the edges of safe water areas; for example, to direct travel within a channel. They use a combination of colors and numbers which may be applied to 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 returns from the open sea or heads upstream.

Green colors, green lights, and odd numbers
indicate the left side of the channel as a boater returns from the open sea or heads upstream.

Buoy with green stripe on top, red below, and light on top

Red and green colors and/or lights
indicate the preferred (primary) channel. If green is on top, the preferred channel is to the right; if red is on top, the preferred channel is to the left as a boater returns from the open sea or heads upstream.

Lighted Buoys use the lateral marker shapes, colors, and numbers discussed above; in addition, they have a matching colored light.

Nuns are cone-shaped buoys marked with red colors and even numbers.

Cans are cylindrical-shaped buoys marked with green colors and odd numbers.

Red triangle daymark with even number, green square daymark with odd number

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) and may also be lighted.

Intracoastal Waterway System

The Intracoastal Waterway (ICW) is a chain of channels providing an inland passage along the U.S. coast. Buoys and markers in this system are identified by yellow symbols and serve a dual purpose—they are navigation aids for both the lateral system of markers and the ICW.

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

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

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

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

Vessel entering open sea: red buoy on port, green on starboard

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Online boating safety handbook last modified: April 22, 2008
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