Which buoy has black and red bands with a topmark consisting of two black balls?

• A. Red/green stripes, indicates main channel
• B. Black/red bands, two black balls topmark
• C. Yellow, marks features or zones
• D. Red/white vertical stripes, mid-channel

Answer: (B)

In buoyage systems, the color pattern and the topmark tell you what kind of aid you’re looking at and what it means for navigation. Two black spheres on top paired with black and red bands identify an isolated danger buoy. This buoy marks a hazard—like a rock or wreck—that is surrounded by safe water, so you should steer well clear of the hazard and pass with caution. The two black balls are a distinctive daytime cue that sets this mark apart from others.

If you see red/green stripes, that describes a lateral mark showing where the channel is and which side to pass on. Yellow marks are used for features or zones and often indicate caution or special areas. Red/white vertical stripes denote safe water marks, signaling that safe water surrounds the buoy; they aren’t there to mark a mid-channel hazard.