high focal plane buoy

A "high focal plane buoy" is a type of buoy designed for increased visibility and range, particularly in open or deep waters. These buoys are constructed to be stable, often featuring a cylindrical tail tube extending downward from the hull to counteract vertical oscillation caused by sea motion. This design allows for a light to be mounted higher above the waterline, enhancing its range and effectiveness as a navigational aid. Buoys in general serve to guide or warn mariners, mark submerged objects, or moor vessels. They come in various standardized colors and shapes to indicate safe passageways and can be equipped with lights, radar reflectors, and fog signals.12