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The Buoy System: An Overview

With Spring weather at our doorstep, this is a good time to refresh our memory on the buoy system. The U.S. Coast Guard has produced a very handy guide which you can download for free and store on your smartphone for quick reference. I highly recommend that you do. But for now, here are the key things to remember:

Green Means Go. Red Right Return.

We’ve all heard “Red Right Return”… right? Well, “Green Means Go” so add that to the list of phrases to keep you off the sandbar. So if I’m leaving a harbor and heading out to the Long Island Sound, I’m keeping the green navigation markers on my right hand side… Going out to sea. Returning from sea, I’m keeping the red ATON’s (Aids To Navigation) on my right… Red right return. But wait, there’s more…

They Come In All Shapes And Sizes Too!

In addition to color, you will notice two shapes: Square and Triangle. Green ATON’s will always have a square shape. Red ATON’s will always have a triangular shape. Except for the large, lighted buoy, which will always have a squared top and a bell. For those, we will need to judge them by their color and their number.

By The Numbers…

There are three ways for us to identify an ATON: color, shape and last but not least is by number. I think number is the most important and here is why: when you see a change in the number sequence, it means you have entered a different channel system. For example, if I am cruising west on the Long Island Sound along the Connecticut shore, all of the primary LIS buoys will be red. Why? because if I am sailing west on the Long Island Sound I am considered “inbound” or upstream traffic. As I cruise along with those red buoys on my right, the numbers will be increasing. Then, I decide to turn to the north and go into a harbor for some lunch. What happens to the number sequence? It starts over again, with the lower numbers at the entrance to a harbor and increasing as I go inbound. So the numbers tell me where I am relative to the entrance to a river or harbor, AND can indicate when I’ve started following a different channel. One last thing about the numbers: red will always be even, green will always be odd.

What does R “2” Fl R 4s mean on my chart or GPS?

Well, I’m glad you asked! If you are looking at a chart and you want to know more about the characteristics of an ATON, it is important to know how to interpret this information. The R indicates that the color is red (substitute G for green). The “2” indicates the number of the navigation aid, and in this example it would be the first buoy heading inbound. Fl indicates that the ATON has a light that flashes. The R that follows the Fl indicates that the light flashes red (again, substitute G for green). Finally, the 4s means that the light flashes every 4 seconds. See the red lighted buoy in the illustration below for this example.

Photo courtesy of the USCG

More Free Knowledge.

In addition to this brochure by the U.S. Coast Guard, be sure to visit theirĀ Recreational BoatingĀ website dedicated to keeping all of us safe and knowledgeable on the water. Thanks for checking out my blog. I wish you fair winds and calm seas.


Capt. Frank