Travel through any body of water, especially one with a lot of traffic, and you will see a bewildering array of buoys and beacons in all shapes, colors and sizes – even some that make noise. While the purpose of many is obvious, others are less clear and there is always a temptation to ignore them.
Yet it is worth every captain's time to learn these navigational aids. Buoys can verify your boat's position, steer you away from shallow water, keep you on course and tell you where to head. They can also notify you of pending decisions, such as a split in the channel, and warn you of hazards to avoid.
There are two different systems of buoyage used throughout the world. In the United States we use what is known as the Lateral system. That means that the buoys generally mark the edges of a navigable channel, though there are many Non-lateral marks indicating everything from danger to a no wake zone. The lateral system is used throughout the Western Hemisphere, so once you learn the system you are good to go anywhere on the continent. You may note some minor differences in Canada, but nothing to cause any problems.
By understanding a few simple rules, the system becomes relatively simple to decipher, despite the many different types of marks one can encounter on the water. We'll start by discussing the marks themselves, then cover the rules for interpreting those encountered most frequently. For further study, the U.S. Coast Guard's web site has detailed information and illustrations (see link below). Chart books and laminated information cards also include illustrations.
RELY ON YOUR CHART
The key to understanding what you see on the water is your navigational chart. Whether on paper or on screen, an up-to-date chart should show every buoy and beacon, its position and its characteristics. It allows you to identify which mark you are looking at, and gives you an overview so you can identify patterns. If what you see on the water does not align with what you see on your chart, it is often a sign that something is wrong with one or the other – and a warning to be cautious.
Graphic by Gene BjerkeA bell bouy can be seen and heard.The lateral system consists largely of floating aids, called buoys, and fixed aids, called beacons. You will often hear both referred to as marks, which is a generic term that can be used for either. Beacons with lights are simply called lights, and those without are called daymarks. Most marks also have reflective material on them so they can be picked out with a spotlight, and buoys are frequently equipped with radar reflectors as well.
Buoys come in various shapes, colors, and configurations. The simplest are basically a metal cylinder shape, called a can, or a cylinder with a tapered top, called a nun. Other buoys are more complex, including some that produce sound so they can be located in limited visibility. Common types include a bell buoy, which has a bell with four external clappers (see photo). Wave action will cause the clappers to strike the bell, and it will remain silent in calm water. There is also a gong buoy that operates similarly, except it has three or four different metal gongs, each with a different pitch and its own clapper (see photo). There are also less-common types such as whistle buoys, which sound when air within them is compressed, and horn buoys, which are powered electronically and do not depend on wave action. Again, each buoy's characteristics are shown on the chart.
Many marks have lights on them so you can spot them at night. Red marks have red lights, green marks have green lights. If you see some other color light, such as white or yellow, you are often looking at a special-purpose mark that is not part of the lateral system. There are a number of different lighting characteristics – flashing, occulting, quick-flashing – to differentiate buoys, and these are abbreviated next to each buoy's symbol on the chart. When boating at night near a large city, be careful not to confuse lights on buoys with the lights on shore.
