Which color is used for a special purpose buoy?

• A. Red and white vertical stripes
• B. Black and red bands
• C. White with blue horizontal band
• D. Yellow

Answer: (D)

Special purpose marks use yellow. This color is reserved for buoys that indicate features or restrictions that don’t fit the usual channel or safe-water marks. They tell you there’s something specific to the area—like a pipeline, dredging zone, mooring area, or military exercise area—and the exact meaning is given by symbols or letters on the buoy and in charts. So, when you see a yellow buoy, you should treat it as a cue to check the chart or local notices for the exact instruction, rather than treating it as a regular navigation aid. The other color schemes are used for standard navigation marks with different, more routine purposes, not for conveying these special-area notes.