Marinetalk is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. Learn more

What Do the Red and Green Markers Indicate? (Answered)

Fact checked by William Hart

what do the red and green markers indicate

Red and green buoys are one of the most popular on the water. They show up whenever you approach land masses, harbors, channels, river estuaries, and other waterways.

What do the red and green markers indicate? They are placed in specific locations to mark the sides of a waterway. When you proceed toward the sea on a river estuary, green aids indicate the right side, and red ones indicate the left side of the estuary.

These aids enable vessel operators to follow a well-defined channel. Each one also carries a number, which decreases as you proceed seaward. This system helps operators know the exact direction they are heading.

This article will introduce the meaning and characteristics of channel markers and explain how you can read them on nautical charts.

Table of Contents

Things You Should Know About the Red and Green Markers


Green and red channel markers usually come in pairs. When you spot a green aid on the right, you might see a red one on the left.

They are lateral aids of navigation, meaning they are fixed on the edges of well-defined waterways. Sometimes, they mark the safe centerlines on wide bodies of water. They indicate the route to be followed and the safe side of a channel.

What should you do when encountering these navigating channel markers? The rules are simple and clear.

If you are proceeding the sea or open waters, navigate your boat so that:

  • The green aids are on your starboard (right) side.
  • The red aids are on your port (left) side.

If you are returning to the shore or entering a channel from the open sea, pilot your vessel so that:

  • The green aids are on your port side.
  • The red aids are on your starboard side.

If you approach a land mass (e.g., harbor, dock, island) and see lateral aids without route marks, navigate clockwise around the land. This is the conventional rule of buoyage in Florida.

Following this regulation will keep your vessel in a safe zone. To remember it more easily, keep in mind the term “Red, Right, Returning”. It means you should keep red aids on your right side when returning.

Characteristics of Green and Red Lateral Markers


Besides the standout colors, these lateral markers carry light, shape, and number characteristics that boaters must understand.

  • Green Aids

Green lateral aids might have the shapes of square Dayboards, beacons, buoys, or “cans” (buoys with cylindrical shapes).

You will see odd numbers on them. The numbers increase as you proceed inland. Beacons may carry green numbers while buoys may carry white numbers.

They might be lighted or unlighted. If lit, they display a green light.

  • Red Aids

Red lateral aids might have the shapes of triangle Dayboards, beacons, buoys, or “nuns” (buoys with cylindrical shapes and conical tops).

You will see even numbers on them, which increase as you move closer to the shore. Beacons may carry red numbers while buoys may carry white numbers. Note that they are never lettered.

They might be lighted or unlighted. If lit, they show a red light.

The four factors – colors, shapes, numbers, and lights – reveal all you need to know when navigating unknown water. For example, you might see a chain of red cone-shaped buoy marks, increasing their numbers. You know you are approaching the shore and should keep them on your starboard side to stay safe.

How to Interpret Green and Red Lateral Markers on Nautical Charts


Before navigating new water bodies, a boater should check the area’s nautical chart to anticipate the route. Besides markers, a nautical map illustrates water depths, hazards, and other information you won’t find on an atlas or road map.

To interpret lateral markers, you must know the symbol system:

  • Green beacons are illustrated by green squares, while red beacons are pink triangles.
  • Green cans and buoys are shown by green diamonds, while red nuns and buoys are pink diamonds.

On the nautical chart, you will find letters and numbers next to the symbols. What do these letters on red and green markers indicate when boating?

  • The first letter indicates the color of the buoy. So, red aids start with R and green aids start with G.
  • The following number shows the number of the buoy inside quotation marks.
  • If the diamond symbol has a pink round shape underneath, that buoy is lighted. The following letters indicate the characteristics of the lights, such as Fl R 4s, meaning the buoy flashes a red light every four seconds.

For instance, you might spot a green diamond with a round pink shape on its bottom. The symbol comes with the letters “G “1” Fl G 4s”. This means you are approaching a lighted green lateral buoy. Its number is 1, and it flashes a green light every four seconds.

What Are Preferred-Channel Aids?


In addition to red and green channel markers, you might see ones with both red and green bands. Don’t get confused! They are preferred-channel aids, whose top-most colors mark the preferred channel.

Do you remember the phrase “Red, Right, Returning”? The same rules apply to the aids. When you move upstream or enter a waterway from the open sea:

  • Keeping the aids with red on top on your starboard side puts your boat in the preferred or primary channel.
  • Keeping the aids with red on top on your port side puts your vessel in the secondary channel.

On both channels, your vessel is safe. If you are a new boater, we recommend choosing the less crowded route.

Also, notice these characteristics in preferred-channel aids:

  • They have a letter designation.
  • Buoys carry white letters.
  • If lit, they display composite group flashing, two flashes followed by a short flash. This sequence repeats itself several times a minute.



What is the difference between cardinal marks and lateral marks?

You can easily distinguish them by their colors. Unlike lateral marks, cardinal marks are yellow and black. They mark safe water near a danger so boaters can maneuver accordingly.

Apart from these two systems, you will also find non-lateral markers.

Can I tie my boat to a red or green marker?

You should never tie your vessel to aids of navigation. You are permitted to tie your boat to a mooring buoy, though.

Mooring buoys can be privately owned or rental properties. So, make sure you have permission before using one.

Key Takeaways

To recap, don’t forget the term “Red, Right, Returning”. As you return, keep red lateral aids to your starboard side. Conversely, green aids should stay on your starboard side as you head to the open water.

When you see a buoy with both colors, don’t panic! Focus on the topmost color to place your vessel in the preferred channel.

If you find our answer to “What do the red and green markers indicate?” useful, feel free to save the article and refer back to it when in need. The water is safer when boaters are mindful and responsible!

5/5 - (2 votes)