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A Complete Guide To Boating Buoys And Markers

Nautical Beacons And Markers Guide By Boating Guide Magazine

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Driving down the road, we’ve all seen the various signs that help direct traffic. But how do you know where to go when you’re in a boat? Boat buoys and markers, that’s how. Boating buoys can be confusing, though. There are many different types and many meanings, including telling boaters where the rocks are so they can be avoided, for example. You can see that the importance of knowing your boating buoys is not only vital for safe boating but could save you from being involved in a shipwreck.

We will review the international buoy and marker system here. Explanations of all the different buoys and markers and the meanings they hold will be defined for you in this easy to follow guide. Feel free to bookmark this page so you can easily reference it from the helm of your boat.

Useful Definitions Relating To Buoys And Markers

  • Bifurcation – A division of something into two or more branches
  • Buoy – An anchored float serving as a navigational mark, to show hazards, or for mooring.
  • Fairway – A fairway is a channel that may be navigated by a ship or vessel. The channel can be considered a ‘highway’ in the water. It is often in the center of a body of water, typically bays, rivers or harbors. The idea is to control the flow of boat traffic in an area by directing it along a fairway.
  • Marker – An object used to indicate a position, place, or route.
  • Mooring – A point of anchor for a boat, ship, or vessel.
  • RACON – A radar transponder (RAdar beaCON) that can be identified and located by its response to a specific radar signal.

A Little Info About Navigation In International Waters

The best defense is a potent offense, in terms of information that is. Arming yourself with knowledge before you decide to take a boat out on the water in another country is always a smart idea. You can land yourself in some pretty hot water by not following the rules, no pun intended.

There may be some variations to the rules you may or may not be accustomed to. For example, when traveling inland on a boat, sounding a horn is a signal of your intent to move your vessel a certain way. When you are out in international waters, sounding your horn is a signal that you are taking action, not just that you intend to do so. Therefore, it’s smart to know what the rules are before you embark on your adventure.

Most countries around the world follow the international system of navigation. It is the set of rules that boaters must obey, just like obeying the speed limit when driving your car. Not obeying these rules can have some moderately severe penalties, so stay informed and boat safe.


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Systems Of Navigation 

Here in North America, we abide by the International Association of Marine Aids to Navigation Lighthouse Authorities Maritime Buoyage System. Say that three times fast. For short, it is known as the IALA Maritime Buoyage System, often referred to as merely IALA.

This system is present around the world. However, there is one HUGE difference depending on where in the world you happen to be. The IALA system divides the world map into two distinct regions, A and B. North America is in region B.

Here’s this huge difference I’m referring to here. In region B, starboard buoys are red, and port buoys are green. In area A, the colors are reversed from that which you would find in region B. As I mentioned, this is a huge difference and a costly mistake if you are unaware and trying to traverse waters in the region you aren’t familiar with navigating. See the map below for the two areas.

Map of the 2 regions for nautical symbols are shown in this map graphic.
Map of the two systems of navigation on Earth.

Fixed Navigational Aids – Markers

Markers are similar to buoys in the sense that they convey a lot of navigational information. However, there is one big difference. Markers are attached to solid ground. Whereas buoys are anchored floats. Markers might be marking where rocks are, anchorage points, and so on. Not to be confused with military marker buoys, which are typically used in warfare. Naval marker buoys are distinguished by the pyrotechnic flare or smoke they use to mark a particular location. Common locational markers do not use any type of pyrotechnics or smoke-producing effect.

Major Lighted Navigational Aids

These structures are typically equipped with a large emergency light. They are often also equipped with a fog signal or RACON. Each country has its list of lights, buoys, and fog signals, which are far too much for this article (It would take well over 300 pages for me to list all the world’s MLNAs). So, I’ve included Canada, and The United States references only.

Canada’s List Of Lights, Buoys and Fog Signals

United States Department of Homeland Security Navigation Center Light List


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So, what is a major lighted navigational aid? Commonly we know the most famous as the lighthouse.

A lighthouse on a rocky shore is shown in this file photo.
A Lighthouse is the most famous nautical marker.

If you are using navigational equipment or maps correctly, then you will see these sorts of markers on your map. They will look something like shown in the following example.

An example of a nautical map is shown in this graphic.
An example of a nautical map showing a RACON beacon.

As you can see in the above example, the position of the lighthouse is on this map. It is marked with a purple pointer and the letters RC and the word Racon, in italics below. There are also some other letters and numbers in black, off to one side of the marker location on the map. These letters and numbers are a form of coded information about how the light looks and displays. That way, if you are out on a boat on the water, you can identify the major lighted marker by the way it looks and then corresponds that to the information on your navigation system or map. Here’s how this code works. We’ll use the code from the example above.

How To Read The Nautical Code

FI 6s 21m 17M

Fog Sig (2)60s

In the first part of the code, in this case, “Fl” tells us the description of the light flash type. Take a look at the following chart for the different flash types you might come across when navigating your boat.

The next part of the sequence is the first number set.


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FI 6s 21m 17M

Fog Sig (2)60s

In the example, the 6s tells us the length of time for the flashing sequence from beginning to end.

FI 6s 21m 17M

Fog Sig (2)60s

Nautical Example – More To Go, See Below!

Next, the 21m tells us that the elevation of the light is 21 meters (68.89 ft). The height of the light is essential for triangulating distance. And speaking of distance:

FI 6s 21m 17M


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Fog Sig (2)60s

The last part of the first line of numbers and letters; in this example, 17M tells us that the nominal range of the light is 17 nautical miles. That means that past this distance in clear conditions; you won’t be able to see the light. It helps ships identify how far away the hazard is through triangulation calculations.

FI 6s 21m 17M

Fog Sig (2)60s

The final line of our example tells us that there is both a fog signal which sounds twice every 60 seconds.

DescriptionVisual CharacteristicAbbreviation
AlternatingAlt. R.W.G.
Group FlashingGp Fl.(2)
Group OccultingGp Occ(3)
Quick FlashingQk.Fl.
Very Quick FlashingV.Qk.Fl.

Minor Lighted Navigational Aids

These are the same as marker buoys, but they are secured to solid ground. These aids are often found on either side of narrow channels that may not have room to have in water buoys. These, too, will be marked on a map similar to the example above.

A graphic of the two minor navigational aid markers are represented.
Port and Starboard Minor Navigational Aids


A graphic showing a pair of range markers.
A pair of range markers, viewed from the side.
A pair of range markers viewed when lined up in this file graphic.
This is how the range markers would look from a boat when in line with the pair of markers.

A range is made of two or more navigation marks that are set apart and at different heights. Again, these, too, will be marked on a nautical map. Range markers are used by the boat to ensure they are on the recommended path. It is the case if the markers line up to the view from the ship. Notice how they will look from the perspective of a boat when lined up (picture on the right).


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Sector Lights And Landfall Aids

Sector lights and secondary landfall aids are, again, fixed beacons. They indicate a specific area by the use of multicolored and multi-directional lighting. Take a look at the following graphic. Notice how the light that is visible from the water will change, depending on the perspective of the boat. Or to be clear, the light does not change, but depending on the position of the ship, the ship will see different colored light.  

A graphic shows how a sector light will display different colors depending on the direction the boat is viewing the light from.
Sector Lights appear different colors from different perspectives.

No Anchorage Signs

These are pretty straight forward. You are not allowed to drop anchor in areas designated as no anchor zones. It may be due to a gas or fiber optic line running along the seabed. The zone will be identified on a map using a dotted T line with an anchor in the middle that has an X through it. This area may be noted via signage on the shore nearby. Or, if out away from the coast, then a sign on a buoy will be in the no anchor zone.

On the left we see how the zone will be marked on a nautical map. On the upper right is a typical sign denoting the same.

Standard Day Beacons

When I first saw the term day beacon, or day beacon as some write it, I thought these must only be used during the day. And I was right. Day beacons are just a sign, typically used in shallow water and relatively inexpensive.  

There are four primary day beacons, each with its meaning. You’ll find them below.

Port Hand Day Beacon

A port hand day beacon is shown in this file graphic.
A Port Hand Day Beacon

This beacon typically has a green fluorescent or black central square with a white border. The entire thing then has an additional border in green reflective. Sometimes, there is also a number in white in the central square.

This number can be referenced on marine charts when it is displayed on the day beacon.  

When you are traveling upstream, you must keep this day beacon on your port side (left).

Port Junction / Bifurcation Day Beacon

A port junction also known as a port bifurcation day beacon is shown in this file graphic.
A Port Junction Day Beacon

The port side junction day beacon, also referred to as the port bifurcation, begins with a green reflective square in the center. Around it is a diamond in white, or rather another white square, but turned 45 degrees to appear oriented like a diamond. This white diamond then has a red border, usually fluorescent.

This day beacon tells us that there is a split in the channel. This division can be taken in either direction. If the course you want to consider is the right one, for example, then you would keep this day beacon on your port side (left side).


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Starboard Junction / Bifurcation Day Beacon

A starboard junction day beacon is shown in this file graphic.
A Starboard Junction Day Beacon

This day beacon begins with a red reflective triangle in the center. Again, like the port junction day beacon, it then has a white diamond bordered with red.

Just like the port junction day beacon, this day beacon tells us there is a junction, or split in the channel.  

This day beacon should be kept on your starboard side (right side), when the direction you want is the left one, for example.

Starboard Hand Day Beacon

A Starboard Hand Day Beacon is shown in this file graphic.

A Starboard Hand Day Beacon

The last of the four standard day beacons is the starboard hand day beacon. This beacon has a central red fluorescent triangle with a white border. Another red fluorescent triangle then borders the entire thing.

The starboard hand day beacon is to be kept on your starboard or right side when traveling upstream.

Lateral Navigational Buoys

Navigational buoys are buoys that mark out boating lanes and correctly deal with navigating your boat in the appropriate direction and place. Although technically even a marker is navigational, we think the buoys deserve their section. What is the difference? Markers are anchored to solid ground. Buoys float out in the water and are anchored in place. 

The following are all the standard buoys. On each graphic, there are two bars that represent the light sequence and color, which the buoy provides when equipped with a light.

Fairway Buoys 

The types of Fairway Buoys are shown in this file graphic.
Fairway Buoys

A lateral fairway buoy is red and white. If you are traveling upstream, you should keep this buoy on your port side (left side). Likewise, if you are going downstream, you should keep the buoy on your port side again.  

If lit, the light will be white. If not lit, the top will appear rounded. The white is usually retroreflective.

The fairway buoy purpose is to mark entrances to a channel, channel centers or landfall locations.

Port Hand Buoys

Port Hand Buoys are shown in this file graphic.
Port Hand Buoys

The port hand buoy marks out the port side (left side) of a passageway or channel. It might also mark out that you must remain on the port side of danger when traveling upstream. Either way, stay to the left of this buoy when traveling upstream.


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The port hand buoy is colored green. If it has a light, it will also be green in color. With no light on top, the top will be flat. The paint is usually retroreflective as well. The topmark will be a cylinder if equipped. It will appear to be square from any angle along the horizon when looking at the buoy from a distance.

Sometimes, these buoys have a letter and an odd number(s) on them. This number will correspond to a nautical chart location if posted. 

Starboard Hand Buoys

Starboard Buoys are shown in this file graphic.
Starboard Buoys

A Starboard hand buoy is red. When equipped, it will have a red light. If unequipped with a light, it will have a top mark that is in the shape of a cone. This way, it will appear as a triangle from all directions along the horizontal when viewed from a distance. The red color is typically retroreflective as well.

Sometimes these buoys will be marked with a letter and a number. The number will be an even number or numbers if this is the case. These numbers would correspond to a nautical map location as well.  

The starboard buoy marks out the starboard side (right side) of a channel or passageway when traveling upstream. It can also mark out a danger in which you have to stay on the left side of, making the buoy (or danger in this case) to be on your right or starboard side.

Isolated Danger Buoys

Isolated Danger Buoys are shown in this file graphic.
Isolated Danger Buoys

The Isolated Danger Buoy marks out dangers that must be avoided. Usually, this is some kind of submerged threat like rocks or a shipwreck. This buoy is typically mounted directly above, sometimes right on the obstacle itself. The isolated danger buoy also tells us that the danger which it marks has navigable water all around it in all directions.

The buoy for isolated danger is black, with a single red band horizontally in the middle. There are two spherical topmarks, also in black. Sometimes the buoy is marked with a letter or letters, but not with numbers. This letter will correspond to a noted danger on a nautical chart. That is where you will typically find information about the size and depth of the threat in which the isolated danger buoy is marking.

Port Junction / Bifurcation Buoys

Port Junction also known as Port Bifurcation Buoys, are shown in this file graphic.
Port Junction / Bifurcation Buoys

The port junction or bifurcation buoy is green in color (retroreflective) with a single red band horizontally across the midsection of the buoy. The top will be flat. Sometimes this buoy has a light, and when this is the case, the light will be green in color. The light will flash a sequence, as noted in the graphic. When the buoy is equipped with a topmark, it will again be a green cylinder like the port hand buoy. This topmark is seen from all directions along the horizontal as a square from a distance. Like the isolated danger buoy, this buoy too may have markings on it. These will be in the form of a letter or letters, never numbers. These letters will correspond to a junction on your nautical map as well.

This buoy marks where a channel splits (there is a junction) when you go in the upstream direction. When you are proceeding to the main channel (preferred channel), then this buoy should be kept on your port side (left side).


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Starboard Junction / Bifurcation Buoys

Starboard Junction, also known as Starboard Bifurcation Buoys, are shown in this file graphic.
Starboard Junction / Bifurcation Buoys

The starboard junction or bifurcation buoy is the opposite of the port junction buoy. This buoy is retroreflective red. It also has a horizontal band in the middle of the buoy, which is green in color. The top of the buoy will be a cone shape. The topmark will be seen from any direction along the horizontal as a triangle, from a distance that is. When equipped with a topmark, it will also be a cone shape. When equipped with a light, the light will flash a red sequence, as noted on the above graphic.

This buoy can again be lettered, but not numbers. The letters will correspond to a point on your nautical map as well.

As mentioned, this buoy is the opposite of the port junction buoy. When this buoy is in place, it marks a split or junction in the channel when traveling upstream. When the main channel (preferred channel) is desired, you should keep this buoy on your starboard side (right side).

Cardinal Aids Buoys

The cardinal aid buoys are sort of like the isolated danger buoys. With one big difference. The cardinal aid buoy tells you which side of the buoy is safe to travel. For example. If you have a north cardinal aid buoy, then you would want to travel along the north side of the buoy for safety.

Likewise, if it were any of the other cardinal directions, south, east, or west even, then the path the buoy marks is the side of the buoy you want to be navigating.  

The cardinal aid buoys are marked in black and yellow and often have a white light. This light flashes a corresponding sequence to let you know what direction it is telling you is safe to pass along.

The following are the four cardinal aid buoys and their corresponding light sequences. Note the special topmarks for each.  

North Cardinal Aid Buoy

North Cardinal Aid Buoys are shown in this file graphic.
North Cardinal Aid Buoys

South Cardinal Aid Buoy

South cardinal aid buoys are shown in this file graphic.
South Cardinal Aid Buoys

East Cardinal Aid Buoy

East Cardinal Aid Buoys are shown in this file graphic.
East Cardinal Aid Buoys

West Cardinal Aid Buoy

West Cardinal Aid Buoys are shown in this file graphic.
West Cardinal Aid Buoys

Special Purpose Buoys

Special Purpose Buoys are those which mark a specific location for a particular danger or purpose. These buoys have no unique designated shape. The buoy will sometimes have a light, and if it does, the light will flash yellow in the described sequence. Special Purpose Buoys are typically not labeled, but if they are, they will be letters and not numbers.


A Yellow Anchorage Buoy is shown in this file graphic.
A Yellow Anchorage Buoy

The Anchorage Buoy marks out the edge of a designated area where you can anchor your boat. Again this buoy is yellow retroreflective. The buoy doesn’t have to have a light or a topmark, but when it does, the light will be yellow, and the topmark will be an “x” when equipped. This buoy will have an anchor symbol on it, denoting the buoy’s purpose. Just make sure you check your nautical charts for the water depth in the area if you are operating anything other than a flat bottom boat.  


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A yellow Cautionary Buoy is shown in this file graphic.
A Cautionary Buoy

The Cautionary Buoy is always yellow in color and retroreflective. There is no real importance to the buoy’s actual shape; it is merely a cylinder in most cases but does not have to be this shape. Sometimes, the buoy is equipped with a light that will be yellow. Sometimes the buoy also has a topmark, which would be an “x” topmark. The Buoy may be lettered, but is never numbered.

Cautionary Buoys mark a danger. It could be an underwater pipeline, a firing range, seaplane base, or another area where no through channel exists and boating is not permitted except under the circumstances specifically associated with the location such as a boat used to go out for repairing an underwater pipeline or similar maintenance type of ships. In other words, no general boating traffic is allowed.


A control buoy is shown in this file graphic.
A Control Buoy, this example is showing a speed limit.

Control Buoys are used to note things like speed limits, wash restrictions, that sort of thing. The limitation is indicated in the orange circle. There are also two orange bands, one above and one below the ring. No topmark is used on control buoys, but sometimes they do have a light that flashes in yellow with the same sequence as many other special buoys.


A Diving Buoy is shown in this file graphic.
A Diving Buoy

Just as the name says, this buoy marks out a location where scuba or other such diving occurs. It is advised that boaters steer clear of this area to avoid potential accidents that could harm a diver who may be rising from the depths beneath.

The Diving Buoy is often yellow or white, and the shape of the base does not matter. The buoy is evident as a diving buoy based on the large red square with a white stripe passing across the square diagonally.

These buoys do not have a topmark but sometimes have a yellow light. The light will flash yellow in the same sequence as many other particular purpose buoys, as noted in the graphic above.


A hazard buoy is shown in this file graphic.
A Hazard Buoy is similar to an Isolated Danger Buoy, but don’t get them mixed up!

Hazard Buoys note a hazard, such as a shoal or rocks. The type of danger is often pointed out inside the orange diamond on the buoy. These buoys do not carry a topmark. They can have a light, though, and this will flash in the customary way of many of the special buoys. If a light is equipped, it will flash in yellow.

The difference between the Isolated Danger Buoy and the Hazard Buoy is that the Isolated Danger Buoy warns of a danger which is otherwise in the middle of, or surrounded by, navigable waters. Whereas the Hazard Buoy typically warns of hazards which may increase with distance, like a rocky shoal jutting out from shore.


An information buoy is shown in this file graphic.
An Information Buoy

An Information Buoy looks very similar to the Control Buoy or Hazard Buoy. Again, this buoy has two horizontal orange bars. This buoy also has an orange outline of a square in between the two orange horizontal bars. The square will typically share some form of local information about something like a campsite, marina, or other such location. 


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The Information Buoy does not carry a topmark. Sometimes, this buoy is also equipped with a flashing yellow light. This light, if equipped, will flash the same yellow sequence like most other special buoys, as noted in the graphic above.

No Trespass / Keep-Out Buoy

A No Trespass also known as a Keep Out Buoy is shown in this file graphic.
A No Trespass also known as a Keep Out Buoy

The No Trespassing Buoy or Keep Out Buoy, as some call it, designates an area where boats are prohibited entry.

This buoy is similar to several other special buoys in a few ways. First, it has two horizontal orange bars across the top half and bottom half of the buoy. Between these is another orange diamond. However, unlike the hazard buoy, this buoy has an orange cross in the center of the orange diamond.

The No Trespassing Buoy has no topmark. Sometimes, however, it is equipped with an orange flashing light. This light will use the same flashing sequence like most other special buoys. See the above graphic for the light sequence. 


A Mooring buoy is shown in this file graphic.
A Mooring Buoy with white spherical topmark

Just as this buoy says, it notes a place of mooring. This is an area where boats may tie off to a dock or other mooring points. There may be other ships moored in this area, so caution and lower speeds are a must.

The Mooring Buoy is typically white with an orange cap on the top. This buoy usually also has a topmark in the shape of a sphere; and white rather than the orange of the top of the buoy.

Scientific (ODAS)

A Scientific Buoy also known as an Ocean Data Acquisition Buoy is shown in this file graphic.
A Scientific Buoy is also known as an ODAS Buoy. ODAS stands for Ocean Data Acquisition System.

The Ocean Data Acquisition System Buoy, or Scientific Buoy, which is often referred to as is a buoy which collects meteorological data. This buoy might record things like weather, water temperature, currents, and that sort of thing. It is an offense to disturb this buoy, so don’t try to moor to it or anything like that.

Again in a retroreflective yellow, this buoy often has a light on it, which flashes a sequence of five flashes every twenty seconds. This is the only unique buoy with its own distinct flashing sequence.


A plain white swimming buoy is shown in this file graphic.
A common Swimming Buoy is shown. Note that these are often sphere shaped and connected via a large floating rope.

The last of the conventional special buoys is also the simplest. The Swimming Buoy is commonly just a white retro-reflective buoy with no distinctive markings or topmark. Sometimes, there is a light equipped, which is yellow and flashes the customary sequence of the majority of conventional special buoys. Although light is rarely provided so don’t expect it. These buoys are also not often marked on nautical charts.  

You have likely seen these buoys before. Many times they are circular and connected via a floating rope. This “ropes-off” the swimming area, which provides a sort of barrier for the swimmers in the area to stay inside. Boats are not permitted in swimming areas for obvious reasons.


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