A plain yellow buoy is a special mark. It does not mark the side of a channel or a danger to navigation, but shows a particular area or feature, such as a racing mark, a speed limit zone, a cable, an outfall or a marine farm. The chart says which.
Special marks are yellow, and any topmark is a single yellow X (St Andrew's cross). If lit, the light is yellow, with a flashing pattern that is different from those used on white-lit marks. The shape of the buoy is optional.
They are used to show areas or features that are not mainly aids to navigation, such as:
- racing marks laid by a yacht club;
- speed limit zones, swimming areas and other areas set aside by local bylaws;
- outfalls, cables and pipelines;
- military exercise areas, spoil grounds and marine reserves;
- marine farms, often marked by yellow buoys and lights around their edges;
- a channel within a channel, such as a small-craft lane beside a shipping channel.
Because a special mark could mean many things, the chart, local notices and local bylaws are where you find out what a particular one is for. Treat an unfamiliar yellow buoy as something to understand before you go near it: a marine farm, for example, has lines and floats between the marker buoys that can wrap around a keel or propeller.
Two other marks are sometimes confused with special marks:
- a cardinal mark is yellow and black, with two black cones on top, and marks a hazard;
- an emergency wreck marking buoy has blue and yellow vertical stripes, a yellow upright cross on top, and an alternating blue and yellow light. It marks a new wreck that has not yet appeared on charts, and you should keep well clear.
Plain mooring buoys and fishing floats are often yellow or orange too. They are not navigation marks, so use the chart and the shape to tell them apart.
More in the book: Chapter 14, Buoys, charts and tides