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: white, isophase, occulting, or one long flash every 10 seconds
- Shape: spherical, pillar, or spar
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
Navigable water all around — safe to pass on any side
Red and white vertical stripes
Single red ball topmark
Used as fairway, mid-channel, or landfall marks
Common Mistakes
Confusing with lateral marks — safe water marks have vertical stripes
Not recognizing the single red sphere topmark
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