1The mark in plain words
In one sentence…
Safe-water marks show navigable water all around: they serve as fairway, mid-channel or landfall marks.
What do they show?
They show navigable water all around the mark, on every side.
How do you recognise one?
It has red and white vertical stripes and a single red sphere as topmark.
What lights can it show?
If fitted, the light is white: isophase (Iso), occulting (Oc), one long flash every 10 s (LFl 10 s), or Morse A.
Where is it used?
It can be a fairway, mid-channel or landfall mark; its shape may be spherical, pillar or spar.
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
- Red and white vertical stripes
- Shape
- Spherical, pillar, or spar
- Topmark
- Single red sphere
- Light
- White: Iso, Oc, LFl 10 s, Morse A
- Use
- Fairway, mid-channel, or landfall
4Key points
- 1.
Navigable water all around: it does not show one specific side.
- 2.
Red and white vertical stripes.
- 3.
A single red sphere as topmark.
- 4.
It may mark a fairway, mid-channel or landfall.
5Frequent mistakes
Wrong: "If I see red, it is a lateral mark."
Right: Check the stripes: this mark has red and white vertical stripes.
Wrong: "I must leave it on one specific side."
Right: It does not show one side; it indicates navigable water all around.
Wrong: "Its topmark has two red spheres."
Right: The topmark is a single red sphere.
6Exam keys & interpretation
Exam keys
If you see red and white vertical stripes, do not choose a lateral mark because of red alone.
A single red sphere as topmark points to safe water, not two spheres.
With Iso, Oc, LFl 10 s or Morse A, check that the light is white.
How to read it
Think of a zone of safe water around the mark, not an arrow forcing you to pass on one side.
The combination of vertical stripes, a red sphere and a white light identifies this family.
7Full lesson & sources
Open the full lesson (diagrams and official references)
Safe water marks indicate that there is navigable water all around the mark. They are used as fairway, mid-channel, or landfall marks.
- Colour: red and white vertical stripes
- Topmark: single red sphere (ball)
- Light (if fitted): white: isophase (Iso), occulting (Oc), one long flash every 10 s (LFl 10 s), or Morse A (dot–dash)
- Shape: spherical, pillar, or spar
8Test your knowledge
What does a safe-water mark indicate?
Keep studying…
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