Module 16 - Pilotage
Other Marks
An isolated danger mark is black with one or more broad red horizontal bands, carries two black spheres when fitted and shows white Fl(2) when lit. It is placed on or near a danger with navigable water around it, but that does not invite a close pass: the chart establishes the hazard and a prudent clearance.
A safe water mark has red-and-white vertical stripes, may carry one red sphere and, when lit, uses a white isophase, occulting, one long flash every 10 seconds or Morse A characteristic. It may serve as a fairway, mid-channel or landfall mark. 'Safe water' still requires the normal depth, traffic and route checks.
A special mark is yellow, may carry a yellow X and uses a yellow light whose rhythm does not conflict with another mark family. It identifies a special area or feature; the chart or local notice supplies the meaning. An emergency wreck marking buoy instead uses blue-and-yellow vertical stripes and, when lit, alternating blue and yellow to warn of a new danger.
Two spheres and two white flashes reinforce the danger-at-the-mark message.
- Isolated danger: black/red bands, two black spheres, white Fl(2)—hazard at or near mark
- Safe water: red/white vertical stripes, one red sphere, one of the prescribed white rhythms
- Special: yellow with optional X—read the chart for the local purpose
- Emergency wreck: blue/yellow vertical stripes and alternating blue/yellow light when lit
| Mark | Day cues | Light if fitted | Immediate interpretation |
|---|---|---|---|
| Isolated danger | Black/red bands; two black spheres | White Fl(2) | Danger at or near the mark |
| Safe water | Red/white vertical stripes; one red sphere | White Iso, Oc, LFl.10s or Mo(A) | Navigable water around the mark |
| Special | Yellow; yellow X if fitted | Yellow, non-conflicting rhythm | Chart-defined area or feature |
| Emergency wreck | Blue/yellow vertical stripes | Alternating blue/yellow | New danger requiring caution and updates |
Optional quick check
Section 8 of 8
What is the essential difference between an isolated danger mark and a safe water mark?
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