Regions A and B: where red goes
1The lesson in plain words
In the direction of buoyage, Region A uses red to port and green to starboard; Region B reverses the colours. The other five mark types stay the same.
One system, two regions
The IALA Maritime Buoyage System (MBS) is the worldwide set of rules for buoys and beacons, written by IALA, the international body for aids to navigation. It has six types of mark. Five are the same everywhere. Only lateral marks, the red and green marks that show the sides of a channel, differ between the two buoyage regions: Region A and Region B.
How it came about
Before the 1970s more than 30 conflicting buoyage systems were in use. IALA completed the rules for System A (red to port) in 1976 and for System B (red to starboard) in 1980. In November 1980 a conference merged them into one system with a regional choice of colour, because the Americas and parts of East Asia already used red to starboard.
Where each applies
Region A covers Europe, Africa, most of Asia, Australia and New Zealand. Region B covers North, Central and South America, Japan, the Republic of Korea, Taiwan and the Philippines. Some islands and territories are exceptions: Greenland, for example, uses Region A. The chart and the pilot book for your area are the final word, not a world map.
What changes, what stays
Only the colours of lateral marks and their lights swap. Shapes do not: a can (flat-topped cylinder) marks the port side and a cone the starboard side, in both regions. Cardinal, isolated danger, safe water, special and emergency wreck marks are identical worldwide. Full lateral rules: /iala/iala-lateral.
Crossing between regions
When you change region, for example sailing from Europe to the US East Coast or from Australia to Japan, brief the crew before the first channel. Read the shape and topmark as well as the colour: shapes never change, so a can is a port-hand mark everywhere. At night, where shapes are hidden, check the colour of each light against the chart.
2Key data
- Region A
- Red to port, green to starboard, in the direction of buoyage
- Region B
- Green to port, red to starboard, in the direction of buoyage
- Region B areas
- The Americas, Japan, Republic of Korea, Taiwan, Philippines
- Same in both
- Shapes; cardinal, isolated danger, safe water, special, wreck marks
- Standard
- IALA Recommendation R1001, edition 2.0 (June 2023)
3Key points
- 1
Only lateral marks differ between the regions; the other five mark types are the same worldwide.
- 2
Region A: red to port. Region B: red to starboard. Both in the direction of buoyage.
- 3
Shapes never swap: can to port, cone to starboard in both regions.
- 4
Region B covers the Americas, Japan, the Republic of Korea, Taiwan and the Philippines.
4Frequent mistakes
Wrong: Region B reverses every mark, including cardinals.
Right: Only lateral marks change. Cardinal, isolated danger, safe water, special and wreck marks are the same in both regions.
Wrong: In Region B a cone marks the port side.
Right: Shapes do not change. A can marks the port side and a cone the starboard side in both regions; only the colours swap.
Wrong: A world map tells you the region of every harbour.
Right: Use the chart and pilot book. Some islands and territories are exceptions to the broad map.
5Practice case & exam keys
You charter in Japan after sailing in Spain. Entering from seaward at dusk, a crew member says, “Keep that red cone to port, as usual.” Do you agree? What should you check and tell the crew?
Show the answer
No. Japan uses Region B, so leave the red cone to starboard when entering with the direction of buoyage. The cone confirms a starboard-hand mark in either region. Check the local chart and pilot book. Brief the crew that lateral colours have changed; at night, identify lights against the chart.
Exam keys
- Two regions; only the colours of lateral marks differ.
- In the direction of buoyage: Region A red to port; Region B red to starboard.
- Shapes are the same in both: can to port, cone to starboard.
- Region B: the Americas, Japan, Republic of Korea, Taiwan, Philippines.
Finish this unit
When you've read it, match the terms, then answer three questions. Get them all right to finish the unit; opening the page alone doesn't count.
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