Utilizing Marine Aids to Navigation

Understanding ATONs is Vital to Boating Safety

Aug 28, 2009 Alan Sorum

Once the Aids to Navigation system is understood, boaters find they have a network of navigational aids available for their immediate use installed across the world.

The United States Coast Guard (USCG) maintains a vast network of Aids to Navigation (ATONs) to promote safe passage of vessels through navigable waters, both along the coasts and down the country’s rivers. Once a boater learns to basics of reading ATONs, this knowledge and skill becomes a benefit for future trips throughout the nation.

Navigational aids can be any kind of marker or device that provides a vessel operator with location information. This can encompass lighthouses, buoys, various markers, daybeacons, and fog signals.

Lateral Markers and Buoys

The purpose of lateral markers and buoys is to delineate the boundaries of safe water. Lateral markers are defined as being left-handed (port) and right-handed (starboard) relative to an established direction of buoyage. In general, the direction of buoyage for rivers is upstream towards the source of the river and from the sea for harbors or ports. If an area’s geography causes confusion over the proper direction of buoyage, the correct path will be shown on the applicable chart for those waters.

Red Right Returning

Navigational aids and the navigation lights found on boats are color-coded. Lateral markers and buoys have unique shapes and numbering as well. The world is divided by the International Association of Lighthouse Authorities (IALA) into two regions, A and B. The Americas, South Korea, Japan and the Philippines are in Region B. In Region B, a boat remaining in a safe channel will keep port markers to its right and starboard markers to its left when entering a bay or harbor. A memory aid used by many is Red Right Returning.

Port (Left)– Port markers and buoys marking the left side of the channel leaving the harbor are red. They will bear an even number and may be equipped with a flashing red light. Port buoys have a conical shape towards their tops and are referred to as nun buoys or simply nuns. Daybeacons are markers of often made of boards that can be seen from the water. Port daybeacons are red triangles bearing even numbers. Daybeacons are often installed in pairs across from each other along channels.
Starboard (Right) – Starboard markers and buoys marking the right side of the channel leaving the harbor are green. They will bear an odd number and may be equipped with a flashing green light. Starboard buoys have a cylindrical shape and are referred to as can buoys or simply cans. Starboard daybeacons are green squares with odd numbers.

An easy way to initially memorize the navigation terms and colors to remember that all the words starboard, green and right all have more letters in them than port, red and left do.

Non-Lateral Markers and Buoys

Non-lateral markers and buoys provide safety information or warnings to boaters. They are orange and white in color. Shapes of the these aids have different meanings:

Square – General directions or information
Diamond – Dangerous conditions like rocks or reefs
Circle – Controlled areas or speed zones
Crossed Diamonds – Areas off limits to boats

There are other ATONs such as lighthouses or fog signals available to boaters. Further information is provided in the National Oceanic and Atmospheric Administration (NOAA) United States Chart No. 1 that identifies nautical chart symbols, abbreviations and common terms.

The copyright of the article Utilizing Marine Aids to Navigation in Boating & Sailing is owned by Alan Sorum. Permission to republish Utilizing Marine Aids to Navigation in print or online must be granted by the author in writing.