What indicates the navigation significance of a buoy?

A buoy's navigation significance is primarily indicated by its lettering, which serves to convey important navigational information to mariners. The letters or numbers on a buoy can indicate its purpose, such as whether it is marking a channel, indicating dangers, or serving as a reference point. Each type of buoy is associated with specific characteristics and meanings as designated by the U.S. Aids to Navigation System (USATONS) or the previously established Lateral System, where specific colors, shapes, and markings correspond to navigational rules.

While the buoy's location is important, it does not alone indicate its significance without understanding what the buoy represents. The vessel type passing by is not relevant to the buoy's purpose and does not provide any navigational guidance. Likewise, while the size and shape of a buoy can contribute to its identification, it is the lettering that provides the definitive information about what the buoy signifies in terms of navigation.

Thus, the lettering on a buoy is crucial for mariners as it encapsulates vital information needed for safe navigation.