Know Your Channel Markers // Navigating the ICW
The U.S. Aids to Navigation marker system has several types of markers. The markers on a stick, with no light on them, are called “day marks.” The markers on a stick, but also with a light on them are called “lit markers.” The markers floating in the water are called buoys, and are referred to as “nuns” or “cans.”

US ATONS
The U.S. Aids to Navigation marker system has several types of markers. The markers on a stick, with no light on them, are called “day marks.”
The markers on a stick, but also with a light on them are called “lit markers.” The markers floating in the water are called buoys, and are referred to as “nuns” or “cans.”

Memorization Method
I have developed some red and green memory tricks, as well as introducing the numbering and shape system devices for identification.
When a “red marker” is sitting in the water, it is called a “nun.” When a “green marker” is sitting in the water, it is called a “can.”

Nuns / Red Marks
A nun buoy is shaped like a nun’s habit – complete with the fitted headpiece that flows out into a wimple around the neck, and finally the wide large body of the habit. They are shaped like a big triangle.
A nun is red, and I figure, nuns, with their basic daily garb, must wear red underwear. They travel in pairs, to make sure “none of them get nun.” So, the numbers on the nuns are even – 2, 4, 6, 8…
I’ve only recently heard the memory device; “Even Nuns Blush.” That helps you remember all three identifying characteristics!

Cans / Green Marks
A can buoy is shaped like a soda can – flat on top, and straight up-and-down sides. They are shaped like a big square if they are a marker on a piling.
A can is green, and I like to think about the few sodas that come in a green can; Seven-Up, 5-Alive… And so, the number on a green marker is odd – 3, 5, 7, 8…
In either case, red or green, the shape assists you in distinguishing markers even when the sun is in your eyes, and you see a black “thing” ahead. I imagine there might even be some color-blind boaters, so the shape greatly helps with determining markers.

Intracoastal Waterway
The numbers on the East Coast increase as you travel south, starting over again at every inlet, and arbitrarily in the middle of nowhere; whenever the numbers reach 99.
With so many miles of waterway, if the numbers did not start over, you would come across marker 1,235, 768. Even with binoculars, that would be hard to read, so, markers never go to three digits on the board.

Numbering System
The numbers also increase as you travel from sea to land; “R2” is the typical name of the first red marker in an inlet. “Let’s sail out to R2 and back again,” would mean sail the inlet, then return.
The three indicators on the markers – number, shape, and coloring help you identify where in the channel you are located. The numbers match up with numbers on your chart. The color helps you determine which side of the marker to travel, and the shape ensures that even when the sun is directly in your eyes, or you are color blind; you will be able to distinguish red from green.

Safe Water Mark / Sea Bouy / Mid-Channel Mark
One more marker – the “safe water mark” or sea buoy OR mid-channel mark. This mark is red and white striped vertically. The letters on it identify its location – “STA” for St. Augustine, or “STJ” for St. Johns River. They are safe to circle around completely; you can pass on either side. It’s typical to mark their location on a gps when heading offshore, then when returning, head for the sea buoy, then locate the reds and green and proceed inland.
I’ll cover other markers in a future article – danger marks, preferred channel marks, and information and regulatory marks.
What to read next: Teaching Sailing on Small Boats
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