The emergency wreck marking buoy marks new dangers, including newly discovered wrecks. The competent authority determines further marking once the danger is removed or its information has been sufficiently promulgated.
- Colour: equal numbers and widths of blue and yellow vertical stripes; 4 to 8 stripes in total
- Topmark (if fitted): standing/upright yellow cross
- Light: 1 s blue + 0.5 s darkness + 1 s yellow + 0.5 s darkness; period 3 s
- Shape: pillar or spar
- RACON (if fitted): Morse code "D" (dash-dot-dot)
- AIS: may be fitted with AIS transponder
This mark was introduced to provide a rapid, internationally standardized response to newly discovered dangers.
An interactive 3D illustration is shown here. The same content is described in the rule text and key takeaways below.
Buoyage Reading Order
Read the mark in a fixed order: topmark, colour pattern, light rhythm, charted meaning, then the safe side or action required.
Confirm the conventional direction of buoyage from the chart or pilotage plan before deciding port-hand or starboard-hand treatment.
Treat every mark as one aid among several.
Cross-check with charted depth, position, radar, visual bearings and the planned track.
Exam Focus
For cardinals, use the cones first, then the colour bands, then the flash mnemonic.
If those three agree, the answer is usually secure.
For lateral marks, the region only changes the colours, not the core idea: the mark still identifies the side of the channel in the conventional direction of buoyage.
Key Takeaways
Marks new dangers, including wrecks
equal numbers and widths of blue and yellow vertical stripes; 4 to 8 stripes in total
1 s blue + 0.5 s darkness + 1 s yellow + 0.5 s darkness; period 3 s
RACON: Morse D (if fitted)
Common Mistakes
Confusing with special marks (which are all yellow)
Not giving sufficient clearance — wreck position may not be precisely charted
Test Your Knowledge
Practise this topic and review the explanation for each answer.
More rules in this Part
- IALA Lateral Marks (Region A & B)Lateral marks indicate port and starboard sides of channels. Region A: red to port. Region B: red to starboard.
- IALA Cardinal MarksCardinal marks indicate the direction of safe water relative to the mark using compass quadrants (N, E, S, W).
- IALA Isolated Danger MarksAn isolated danger mark is on or near a danger with navigable water around it. Consult charts and nautical publications for the extent of the danger and safe passing distance.
- IALA Safe Water MarksIndicate navigable water all around. Red and white vertical stripes with a single red sphere topmark.
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