Navigation General · Aids to Navigation — Safe Water Mark
A safe water mark (red and white vertical stripes, often a single red sphere topmark) indicates:
- AA wreck
- BNavigable water all around, such as a fairway or landfall/midchannel mark✓ Correct
- CA prohibited area
- DShallows ahead
Explanation
Safe water marks (also called fairway or midchannel buoys) show that there is navigable water all around the mark and are often used as landfall buoys at the seaward end of a channel. They may show a single long-flash or Morse 'A' light.
Authority: IALA Maritime Buoyage System
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