Module 16 - Pilotage
IALA Buoyage System — Region A
What you will learn
Classify an IALA mark by family, confirm the region and charted purpose, then translate recognition into a depth- and traffic-aware route decision.
The IALA Maritime Buoyage System uses colour, shape, topmark, light and charted context together. Lateral colours differ between Regions A and B; the other principal families share common logic.
The UK uses Region A, where port-hand lateral marks are red and starboard-hand marks green in the conventional direction of buoyage. Region B reverses those lateral colours. The direction must be shown in appropriate charts and documents and may follow a harbour approach from seaward or a direction set by the competent authority; do not infer it only from whether land lies ahead.
IALA R1001 defines six principal mark types: lateral, cardinal, isolated danger, safe water, special and emergency wreck. Marks may be fixed, floating, mobile or electronic. At sea, cross-check the visible or electronic cue against charted position, depth and surrounding geography because a buoy can be off station and a virtual mark has no physical body.
Recognition is only the first task. State the operational message—channel side, named safer-water side, danger at the mark, navigable water around it, chart-defined special feature or new danger—then choose a route that also accounts for draught, tide, current, traffic, visibility and local instructions.
| Family | Primary message | Question before acting |
|---|---|---|
| Lateral | Channel side or preferred branch | What is the charted direction of buoyage? |
| Cardinal | Safer water lies on the named side | What feature is charted and what clearance is needed? |
| Isolated danger | Danger at or near the mark | How large is the hazard and what passing distance is suitable? |
| Safe water | Navigable water around the mark | How does it relate to the planned fairway or landfall? |
| Special | Chart-defined area or feature | What do the chart and local notice say? |
| Emergency wreck | New danger | What updates and conservative avoidance are required? |
Avoid a colour-only decision
At dusk a mark appears red near a junction, but its body bands and topmark are indistinct and the charted direction changes nearby.
1. Delay the label
Red alone is insufficient to separate a normal port-hand mark from a preferred-channel pattern or an unrelated light.
2. Use the chart
Check the charted mark, junction and direction, then compare the observed body pattern and light rhythm.
3. Protect the route
Keep conservative clearance and verify depth and traffic until the family and safe-water message are clear.
Sense check: Naming a colour without confirming the family and direction has not yet answered which water is suitable for this yacht.
Common mistake or limitation
- 'Red to port entering' is a Region A shortcut, not a substitute for the charted conventional direction.
- A buoy's charted position supports identification but is not infallible; off-station or electronic marks require independent checks.
Recap
- Start with family, region and direction rather than colour alone.
- Use independent physical and charted cues to confirm identity.
- Connect every mark to depth, hazard, traffic and local-control decisions.
Optional quick check
Section 5 of 12
What should be checked before using a red lateral mark to decide the passing side?
Sources and factual review
Reviewed 2 September 2026 - Compass Revision editorial review.
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