cylindrical buoy
Floating beacon with a cylindrical superstructure.
light 
Encoded light beam that serves as a navigation aid at night.
photovoltaic panel 
Device that converts solar energy into electricity to power the light.
daymark 
Navigation aid that is visible by day only; it displays various colors and signage.
mooring chain 
Long, very sturdy chain that links the buoy to the sinker.
sinker 
Heavy object often made of concrete; it rests on the bottom of the waterway to keep the buoy in place.
bridle assembly 
Two chains that link the flotation section to the mooring chain.
flotation section 
Lightweight base that keeps the buoy afloat and upright.
superstructure 
Metal frame that forms the buoy’s body and contains all its elements.
topmark 
Metal cone-shaped part atop a buoy that serves as a navigation aid during the day; its position signifies various meanings.