Understanding Ocean Channel Markers: Colors, Shapes And Meanings

Marine channel markers can be quite confusing to boaters new to navigating in busy areas. Here's a look at what the basic markers and their colors and shapes mean.

If you are new to boating or your boating experiences have been limited to wilderness rivers or lakes, you might find navigating in areas of busy marine traffic to be quite confusing. Water areas such as bays, big rivers, natural and man-made harbors and near shore coastal areas are often navigable to a wide range of large and small vessels, and such areas often have in place a system of buoys, channel markers and other aids to navigation that will be unfamiliar to non-mariners. These aids to navigation are essential in such busy areas, and serve marine traffic much the same as roads and highways and their associated signs and signals serve to control automobile traffic.

One of the most important functions of marine aids to navigation is to keep larger vessels or any boats that have deep draft out of shallow areas where they could run aground and be stranded. Running aground has always been one of the greatest dangers to marine traffic and shipping, so consequently an elaborate system of channel markers has evolved to help captains steer their vessels through the potentially treacherous waters that are usually found near land. Channel markers make use of natural corridors of deep water, such as river beds and tidal cuts, as well as man-made canals and dredged deep water channels created for the purpose of navigation.

The U.S. Coast Guard and Army Corps of Engineers is responsible for installing and maintaining channel markers in U.S. coastal and inland waters, and they have developed a standardized marker system that you will have to become familiar with if you expect to safely navigate using the markers. Buoys and markers do not have lengthy written instructions printed on them like highway signs, yet they are just as easy to read once you understand them. There are two basic visual means of determining what an aid to navigation means, and these are color and shape. This is more useful in the marine environment than a printed sign would be, as colors and shapes can be discerned in difficult conditions such as rain, fog or low light. Critical buoys and markers are also equipped with flashing lights to aid in nighttime navigation.



Aids to navigation come in several forms: floating buoys, fixed markers mounted on posts or pilings in the water, and fixed markers mounted on land at the edge of a channel, sometimes on a post, tower or natural rock or tree. The two basic colors of marine channel markers are red and green. These colors also have corresponding shapes, with red markers always shaped like triangles with the pointed end up and green markers shaped like rectangles. Floating red buoys also have a pointed end and are called "nuns" on nautical charts. Floating green buoys retain their shape as well, in the form of round drum-shaped floats called "cans" that look rectangular from a distance.

Along a straightforward channel, red markers will be seen on one side of the waterway and green markers on the other. The very presence of a marker of either color indicates a potential hazard to mariners and warns them which way to go in order to avoid this hazard. In a simple, straight channel you generally steer down the middle between the markers of each color. The phrase "red-right-returning" is easy to remember and will help you know which side of your boat a particular color marker should pass on, depending on where you are going. What this phrase means is that you keep the red to your right when returning from sea. This means that anytime you are entering a smaller body of water from a larger body of water, the red markers should be on your right as you pass them. An example would be entering the mouth of a river from a bay, or a harbor from an open sound, or a bay from the open ocean. Going the other way, out to sea from protected water, you would of course reverse this and keep the red to your left and green to your right.

Navigating some channels in areas of intersecting waterways or underwater obstructions such as wrecks or reefs flagged with channel markers can be more difficult than simply following the red and green colors. You will also need a nautical chart of the area. The chart will show you exactly where each channel marker or buoy is located. All these channel markers and buoys have a numeric designation painted on the side, and this will be indicated on the chart. At night, buoys are lighted with flashing red or green lights depending on their daytime color and these lights flash at differing intervals so you can tell which one you are seeing by reading its flash interval on the chart. There may also be markers of a different color, such as yellow, or markers with both red and green on them, which will indicate special situations such as intersections, and all these special markers are charted as well. Floating buoys sometimes are equipped with sound devices as well, and are designated on the chart as whistle buoys or gong buoys so you can identify them in fog or at night by their sound.

The navigation system in U.S. waters is impressive and surprisingly complete, making it much safer to take your boat to places new to you with the assurance that you won't run aground or wreck on a reef. Take the time to learn all you can about the aids to navigation and your time on the water will be much more enjoyable.

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