Black and red, two spheres
Isolated danger mark. Foundation level, about 2 min. IALA isolated danger marks.
The situation
Almost dead ahead is a pillar buoy, black with a broad red band, with two black spheres on top, one above the other. Use the binoculars to look at it closely.
What does this mark tell you?
- An isolated danger with navigable water all around: give it a wide berth: Black with a red band, two black spheres.
- Safe water: you may pass close on either side: Marks the middle of a channel or a landfall.
- A special mark for an area or feature: Yellow, with a yellow cross.
Lookout: Two spheres on top mean one thing in every IALA region: a danger right here, small enough to have water all around it.
The sound answer
An isolated danger with navigable water all around: give it a wide berth
An isolated danger mark is moored on or above a danger of limited extent, such as a rock or wreck, with navigable water all around. Pass it on any side, but give it a generous berth. At night it shows a white group-flashing (2) light.
Why the other options fall short
Safe water: you may pass close on either side
A safe water mark has red and white vertical stripes and a single red sphere. It marks navigable water all around it; this mark is the opposite.
A special mark for an area or feature
Special marks are yellow with a yellow X topmark and indicate areas or features such as spoil grounds or cables. Black with a red band and two spheres is an isolated danger.
Isolated danger marks
An isolated danger mark is erected on, or moored on or above, a danger of limited extent with navigable water all around it. It is black with one or more broad red horizontal bands, has a topmark of two black spheres and, when lit, a white group-flashing (2) light.