What defines a "buoyage system"?

A "buoyage system" is fundamentally defined as a system that marks safe channels with buoys. This system utilizes floating devices, usually made of buoyant materials, which are strategically placed in bodies of water to aid in navigation by indicating the safe paths for vessels to follow. These buoys may display various colors, shapes, and markings to communicate specific information to mariners regarding channels, hazards, and navigation rules.

The importance of a buoyage system lies in its role in ensuring safe navigation, especially in areas where there are shallow waters, rocks, or other obstacles. It provides visual guidance that complements other navigational aids, such as lighthouses and navigation charts.

While the other options may relate to navigation in some capacity, they do not encapsulate the essence of a buoyage system like marking safe channels with buoys does. For instance, the idea of a navigation system using lights only does not cover the broader context of buoyage systems, which are not limited to visual signals such as lights and may include various physical buoy markers. Similarly, towing vessels and underwater navigation techniques are entirely different nautical practices that do not pertain to the specific function of buoys in marking navigational routes.