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Aids to Navigation
Nav Aid Basics

Unlike the roads and highways that we drive on, the waterways we go boating on do not have road signs that tell us our location, the route or distance to a destination, or of hazards along the way. Instead, the waterways have AIDS TO NAVIGATION (or ATONs), which are all of those man-made objects used by mariners to determine position or a safe course.

These aids also assist mariners in making a safe landfall, mark isolated dangers, enable pilots to follow channels, and provide a continuous chain of charted marks for precise piloting in coastal waters. The U.S. Aids to Navigation System is intended for use with nautical charts, which provide valuable information regarding water depths, hazards, and other features that you will not find in an atlas or road map.

The term "aids to navigation" includes buoys, day beacons, lights, lightships, radio beacons, fog signals, marks and other devices used to provide "street" signs on the water. Aids To Navigation include all the visible, audible and electronic symbols that are established by government and private authorities for piloting purposes.

The Coast Guard is the agency responsible for maintaining aids to navigation on U.S. waters that are under federal jurisdiction or that serve the needs of the U.S. armed forces. On bodies of water wholly within the boundaries of a single state, and not navigable to the sea, the Coast Guard grants the state responsibility for establishing and maintaining aids to navigation. The U.S. Corps of Engineers is responsible for many of the canals, dams, locks, and other man-made waterways in the country. The Corps also is responsible for the regulation of mooring buoys in all navigable U.S. Waters.

The individual Coast Guard districts also may grant permission to private groups and citizens to place "Private" Aids to Navigation. These aids allow individuals or organizations the ability to mark privately maintained channels, zones or waterways. These aids must be pre-approved, and must be maintained by the individual or organization.

Types of Aids to Navigation

The term "aids to navigation" encompasses a wide range of floating and fixed objects (fixed meaning attached to the bottom or shore), and consist primarily of:
  • Buoys - floating objects that are anchored to the bottom. Their distinctive shapes and colors indicate their purpose and how to navigate around them.
  • Beacons - structures that are permanently fixed to the sea-bed or land. They range from structures such as light houses, to single-pile poles. Most beacons have lateral or non-lateral aids attached to them. Lighted beacons are called "LIGHTS", unlighted beacons are "DAYBEACONS".
Both Buoys and Beacons may have lights attached, and may have a sound making device such as a gong, bell or horn. Both Buoys and Beacons may be called "marks".


Do not count on floating aids to always maintain their precise charted positions, or unerringly display their characteristics. The Coast Guard works constantly to keep aids on station and functioning properly, but obstacles to perfect performance are so great that complete reliability is impossible. Only use floating aids for use as a navigation fix when you cannot see a fixed point of reference.