Spar Buoy : A buoy shaped like a spar. Usually indicates special areas, such as a quarantine anchorage (yellow) or normal anchorage (white), but may be used to indicate a channel (painted red or green, as appropriate)
Compass (The National Training Portal of The U. S. Naval Sea Cadet Corps), appendix I, Glossary, VA, USA 2012. http://compass.seacadets.org/pdf/nrtc/bmr/14325_in d.pdf, (Mrtm/Nav - Amer) {558}