You are approaching a busy commercial port at dusk. The navigator hands over the watch and mentions the channel is marked by IALA System A buoyage. You spot a red conical buoy to starboard. Something feels wrong — you know that in System A, red marks are kept to port when entering harbour. You are alert, and that instinct matters.
The Core Distinction
The world is divided into two regions:
- Region A – Europe, Africa, India, Australasia, most of Asia. Red to port, green to starboard when entering from seaward.
- Region B – Americas, Japan, Philippines, South Korea. Red to starboard, green to port when entering from seaward.
The mnemonic used in Region B: "Red Right Returning" (from sea). In Region A, the opposite applies.
Lateral Marks
System A lateral marks:
| Mark | Colour | Shape | Topmark | Light |
|---|---|---|---|---|
| Port hand | Red | Can | Single red can | Red, any rhythm |
| Starboard hand | Green | Conical | Single green cone (point up) | Green, any rhythm |
In System B, the colours are reversed; shapes and topmarks remain the same.
Cardinal Marks (same in both systems)
Cardinal marks indicate safe water lies in the named cardinal quadrant relative to the mark. They are yellow and black, use pillar or spar shapes, and carry double cone topmarks — the key to identification at close range or by day.
- North – cones point UP (both above band); light Vk or Q white
- South – cones point DOWN; light Vk(6)+LFl or Q(6)+LFl white
- East – cones base-to-base (points away); light Q(3) or VQ(3) white
- West – cones point-to-point (egg shape); light Q(9) or VQ(9) white
Other Mark Categories (both systems)
- Isolated danger – Black with red horizontal band(s); two black spheres topmark; light Fl(2) white
- Safe water – Red and white vertical stripes; sphere topmark; light Iso, Oc, or one long flash white
- Special marks – Yellow, any shape not conflicting with others; X topmark; light yellow
- Emergency wreck marking buoy – Blue and yellow vertical stripes, alternating blue and yellow lights. Placed rapidly to mark a new wreck.
Exam-Aware Notes
Examiners regularly ask candidates to identify a buoy from a description alone. Work through shape → colour → topmark → light in that order. Know which system applies in the area you are navigating — it is easy to state the rule without knowing which region you are in. The oral examination syllabus (underpinned by MSN 1858) assesses knowledge of IALA conventions; confirm the current amendment status of MSN 1858 before your exam.