1The mark in plain words
In one sentence…
The buoy marks new dangers, including wrecks with blue-and-yellow stripes and an alternating blue-and-yellow light.
When does it appear?
It marks new dangers, including wrecks until the authority considers the information sufficiently promulgated or the danger otherwise resolved.
What pattern do you look for?
Look for blue and yellow vertical stripes, in equal numbers and widths; there are 4 to 8 in total.
What is on top?
If fitted, you will see a standing yellow cross. The shape may be a pillar or spar.
How do you recognise the light?
It alternates blue and yellow: each colour lasts 1 s, with 0.5 s darkness between; the period is 3 s.
2See it in 3D
Turn the mark to inspect its colours, shape and topmark, then switch to night to see its light.
An interactive 3D illustration is shown here. The same content is described in the rule text and key takeaways below.
3How you recognise it
- Colour
- Vertical blue and yellow stripes
- Stripes
- 4 to 8; equal number and width
- Shape
- Pillar or spar
- Topmark
- Standing yellow cross (if fitted)
- Blue light
- 1 s blue + 0.5 s darkness
- Yellow light
- 1 s yellow + 0.5 s darkness
- Period
- 3 s
4Key points
- 1.
New danger, including wrecks: do not treat it as a special mark.
- 2.
Blue and yellow stripes: equal number and width, 4–8 in total.
- 3.
Light: blue and yellow alternate, with a 3 s period.
- 4.
RACON, if fitted: Morse D; the buoy may carry an AIS transponder.
5Frequent mistakes
Wrong: "It is a special mark because it has yellow."
Right: It is not an all-yellow special mark: it identifies new dangers, including wrecks.
Wrong: "The wreck is already precisely marked out."
Right: Its exact position and extent may still be under assessment; keep a safety margin.
Wrong: "The light is yellow only."
Right: The light alternates blue and yellow, with 1 s of each colour and a 3 s period.
6Exam keys & interpretation
Exam keys
"New danger" + "blue and yellow stripes" = emergency wreck marking buoy, not a special mark.
If you see "equal number and width", remember the threshold: 4 to 8 stripes in total.
Sequence: 1 s blue + 0.5 s darkness + 1 s yellow + 0.5 s darkness; period 3 s.
How to read it
It is temporary. A risk assessment determines its duration; if the danger remains, the authority should establish regular marking.
When you see one, keep a margin: the wreck's position and extent may still be under assessment.
7Full lesson & sources
Open the full lesson (diagrams and official references)
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.
8Test your knowledge
What danger does this buoy mark?
Keep studying…
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