What is the term for an anchored float used as an aid to navigation or to mark the location of an object?

A buoy is indeed the correct term for an anchored float used as an aid to navigation or to mark the location of an object. Buoys serve essential functions in maritime navigation, including indicating safe waters, hazards, or guiding vessels along channels. They can also be equipped with lights, sounds, or colors to convey specific information to mariners. The use of buoys is integral to ensuring safe passage and navigation in waterways.

The other terms, while related, do not fit the specific definition of an anchored float. A beacon typically refers to a fixed structure that provides light or signals, such as a lighthouse, rather than a floating object. A marker can be any device indicating a location but does not specifically denote a buoy. A signal generally refers to any communication method that conveys information, which may or may not involve a buoy. Therefore, the term 'buoy' is the most accurate choice in this context.