Chapter 3: Operating Your Boat—Safely
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.

Be Part of the Action!

Learn more about the buoys and markers described below with this interactive Flash animation. (Most students will already have Flash installed. If not, follow this link to install the Flash Player.)

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.

Colors and Numbers

The colors and numbers have the same meaning regardless of the kind of buoy or marker on which they appear.

Buoy and Marker Color and Number Descriptions	Illustrations
Red Colors, Red Lights, and Even Numbers: These mark the edge of the channel on your starboard (right) side as you enter from the open sea or head upstream. Numbers usually will increase consecutively as you return from the open sea or head upstream.
Green Colors, Green Lights, and Odd Numbers: These mark the edge of the channel on your port (left) side as you enter from the open sea or head upstream. Numbers usually will increase consecutively as you return from the open sea or head upstream.
Red and Green Colors and/or Lights: These are placed at the junction of two channels to indicate the preferred (primary) channel when a channel splits. If green is on top, the preferred channel is to the right. If red is on top, the preferred channel is to the left. These also are sometimes referred to as "junction buoys."

Shapes

Buoy Shape Descriptions	Illustrations
Nun Buoys: These cone-shaped buoys are always marked with red markings and even numbers. They mark the edge of the channel on your starboard (right) side when entering from the open sea or heading upstream.
Can Buoys: These cylindrical-shaped buoys are always marked with green markings and odd numbers. They mark the edge of the channel on your port (left) side when entering from the open sea or heading upstream.

Other Kinds of Buoys and Markers

Descriptions of Other Buoys and Markers	Illustrations
Lighted Buoys: These buoys use the lateral marker shapes, colors, and numbers discussed above. In addition, they have a matching colored light.
Daymarks: These 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). These may be lighted also.

Red right returning

In most circumstances, you can use this phrase as a reminder of the correct course when returning from open waters or heading upstream:

"Red Right Returning"

Red right returning

Variations on the U.S. Aids To Navigation System

Some waters of the United States have slight variations on the lateral navigation markers. You should be aware of these if you boat on these waters.

Intracoastal Waterway (ICW)

The Intracoastal Waterway (ICW) is a chain of local channels linked together to provide an inland passage along the Atlantic and Gulf of Mexico coasts.

Channels that are part of the ICW are identified by yellow symbols on channel buoys and markers. Buoys and markers that bear these yellow symbols are serving a dual purpose—they are navigational aids for both the U.S. Aids to Navigation System and the Intracoastal Waterway.
When following the Intracoastal Waterway in a clockwise direction starting from New Jersey and heading to Brownsville, Texas, these rules apply.
- 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.
These rules are true regardless of the shape or color of the channel marker or buoy on which the ICW symbols are displayed. When you are following the Intracoastal Waterway, the yellow triangles and squares should be used as guides, rather than the colors and shapes of the lateral navigation markers on which they appear.

Intracoastal Waterway (ICW) symbols are most commonly found on daymarks.

Green daymark

Red daymark

Western Rivers System

This system of markers is used on the Mississippi River and its tributaries above Baton Rouge, Louisiana, and on some other rivers that flow toward the Gulf of Mexico. The major difference from the U.S. Aids to Navigation System lateral markers shown on the previous page is that navigation markers on the Western Rivers System are not numbered. Numbers displayed below daymarks along this system are not associated with the right or left side of the channel; these numbers indicate the distance from the river's mouth (except on the Ohio River where the numbers indicate the distance from the headwaters).

On the Western Rivers System, this daymark indicates the right side of the channel as a boater heads upstream. The number below the marker indicates that the boater is 73.5 miles from the river's mouth.

Non-Lateral Markers

Non-lateral markers are navigation aids that give information other than the edges of safe water areas. The most common are regulatory markers that are white and use orange markings and black lettering. These markers are found on lakes and rivers and are used to:

Give directions and information.
Warn of hazards and obstructions.
Mark controlled areas.
Mark exclusion (closed) areas.

Descriptions of Non-Lateral Markers	Illustrations
Information Squares provide information such as places to find food, supplies, and repairs; and they give directions, distances, and other non-regulatory information.
Danger Area Diamonds warn of dangers such as rocks, shoals, construction, dams, or stumps. Always proceed with caution and keep a safe distance. Never assume that every hazard will be marked by a buoy.
Controlled Area Circles indicate a controlled area such as no wake, idle speed, speed limit, or ski zone.
Exclusion Area Crossed diamonds indicate areas off-limits to all vessels such as swimming areas, dams, and spillways.

Other Non-Lateral Markers

Descriptions of Other Non-Lateral Markers	Illustrations
Safe Water Marker These are white with red vertical stripes and indicate unobstructed water on all sides. They mark mid-channels or fairways and may be passed on either side.
Inland Waters Obstruction Marker These are white with black vertical stripes and indicate an obstruction to navigation. You should not pass between these buoys and the nearest shore.
Mooring Buoy These are white with a blue horizontal band. They usually are placed in marinas and other areas where vessels are allowed to anchor. These are the only buoys you may tie up to legally.