Aids to Navigation (ATONs) … The acronym ATON refers to a system of visual and audible devices that helps the Deck Officer (Navigator) stay on course and keep a ship out of harm’s way. These devices include buoy’s, light houses, light ships, flashing lights, day markers, radio beacons, fog horns, and private aids, etc. In conjunction with charts and electronics, these aids help keep the vessel on course in all types of sea and weather conditions. The US Coast Guard maintains the ATON system in US coastal waters, the Western Rivers (the Mississippi river and its tributaries, plus the Great Lakes up to the demarcation lines identifying the Canadian border), and in other commercial waterways such as the Columbia and Hudson rivers, Puget Sound, Chesapeake Bay, and the ICW. Lakes and inland waterways are managed by state jurisdictions that use the Uniform State Waterway Marking System (USWMS). In both cases ATONs are not randomly placed. They accurately mark channels, hazards, and directions into and out of ports. Used in conjunction with charts and electronics, they provide a chain of visual markers used to navigate through inland and near coastal waters.
Types of ATONs … ATONs come in many different shapes, sizes, and colors. As the skipper you should be able to identify each ATON’s message while underway in daylight, at night, and in restricted visibility. Can and Nun Buoys … These are likely the best known type of ATON. They mark the way into a harbor, and out to the open sea. Cans are green and have odd numbers. Nuns are red and have even numbers. In some cases they have matching colored lights to help mark the way at night. A well-known navigational phrase is “red right return”. It means keep the red buoys on the right hand (starboard) side of the ship to mark the channel heading into a harbor. However, if you keep a green buoy on your starboard side you will be returning to sea. Day Marks … A day mark is a colored signboard used to identify channels in shallow waters that are not suitable for the use of buoys. They can be lighted, but some have colored reflectors to aid boaters at night. The Intracoastal Waterway is a good example. In addition, some harbors switch from buoys to daymarks as the waters become more shallow at the head end of the channel. Day marks perform the same function as buoys. Dayboards … These ATONs assist a navigator find the ship’s position on a chart. When you see a Dayboard, you can find its corresponding shape, color and light identified on the chart. Using this knowledge, you can identify your precise location on the chart. Safe Water Buoys … These are frequently used to indicate the beginning of a channel when approaching from near coastal waters. They can also be seen at the beginning, end, or along the centerline of the channel. The message they convey is “Safe Water on All Sides”. Proper decorum is to pass them on their starboard side (your port side) as you proceed. Safe Water marks are most commonly buoys. While they come in different shapes and sizes, all can be identified by their stark red and white vertical markings. Most safe water buoys have a single red ball shape at the top. Many will show a constant white light at night and in restricted visibility. Others will flash Morse code letter “A ( short, long, short flashes), and still more will show a long flash every 10 seconds. In addition, some safe water marks include radio beacons. Lastly, colored charts display safe water beacons with a red cloud shaped rectangle surrounding its location. Isolated Danger Marks … These indicate a danger which may be passed on all sides. They are erected or moored on or near dangerous conditions under the surface . They should not be approached closely without special caution. They may be lighted, and they may be lettered. Information and Regulatory Buoys … These are buoys that show hazards and inform boaters of speed limits, no wake zones, swimming areas, skiing areas, underwater obstructions, proximity to dams, etc. They are placed and maintained by local maritime authorities, not the Coast Guard. Mostly you will see these near the shore close to the beach in inland waters and harbors. They are white, with orange circular and diamond shape markings that feature black lettering defining its message. When you see such a buoy slow down, make sure you understand the message being communicated, then proceed at a slow speed until you are safely out of the area. Special Marks … These buoys are a form of an ATON. They are located at sea, and in some cases on land, to mark the proximity of a channel, hazard, or regulated area. They also provide visual navigational safety messages. Special Marks are yellow with a St. Andrew’s cross ‘X’ on top. They communicate using lights, reflectors, bells, horns, whistles, and reflectors. Chart Symbols … These are icons printed on the chart. They are not navigational buoys such as Nuns and Cans. Chart symbols are used to identify special charted features. Examples are areas designated for anchoring, the location of fishing grounds, and dredge zones. On the water Chart Symbols may be lighted buoys, and if they are they will include a fixed or flashing yellow light. They usually follow the shape of the navigation buoy closest to it.
Be Prepared … A competent skipper always has an eye out for the unexpected event. Smart boating is safe boating.