IALA Buoyage Region A vs B — Lateral Marks Explained

IALA Region A and Region B differ only in the colours of lateral marks. In Region A (Europe, Africa, most of Asia, Australia and New Zealand) port hand marks are red and starboard hand marks are green. In Region B (the Americas, Japan, South Korea and the Philippines) the colours are reversed: 'red right returning'. The shapes are the same in both: cans to port, cones to starboard, going with the direction of buoyage.

A red can-shaped port-hand lateral buoy at sea — A port-hand lateral mark in IALA Region A: red, can-shaped, and left to port when entering harbour. Photo: Ian Paterson, CC BY-SA 2.0.

Region A and Region B channels side by side: in Region A port cans are red and starboard cones green; in Region B the colours are swapped — Entering harbour in each region: the shapes are the same, only the colours swap.

Lateral marks in each region, heading in the direction of buoyage.
	Region A	Region B
Port hand mark	Red can, red light	Green can, green light
Starboard hand mark	Green cone, green light	Red cone, red light
Preferred channel to starboard	Red with green band	Green with red band
Preferred channel to port	Green with red band	Red with green band

The direction of buoyage

Lateral marks are laid out for a vessel coming in from seaward: into harbour, up a river or estuary. Along coasts the direction is set by the authorities and shown on charts with a magenta arrow. Around the British Isles it generally runs north through the Irish Sea, east up the English Channel and north through the North Sea.

A green conical starboard-hand lateral buoy in open water — A starboard-hand mark in Region A: green and conical. In Region B the colours swap. Photo: Ian Paterson, CC BY-SA 2.0.

What is the same everywhere

Cardinal marks, isolated danger marks, safe water marks, special marks and emergency wreck marks are identical in both regions. See cardinal marks explained.

Drill both regions in the buoyage trainer and keep the buoyage cheat sheet aboard.

Related guides

Frequently asked questions

Which IALA region is the UK in?

Region A. So is the rest of Europe, including the Mediterranean.

Which IALA region is the USA in?

Region B, as are Canada, the Caribbean, Central and South America, Japan, South Korea and the Philippines.

Do shapes change between regions?

No. Port hand marks are can-shaped and starboard hand marks conical in both regions. Only the colours swap.

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