In response to a request stemming from a discussion on social media here’s my article on the differences between IALA A and IALA B buoyage which I wrote some time ago:
Here in the UK, and most of the rest of the world, we use the IALA A system: When entering a harbour or heading up a river, the cans you leave to port are painted red and the cones you leave to starboard are painted green.
The mnemonic is “Is there any red port left”.
In North, Central and South America, Japan, Korea and the Philippines these marks are painted the opposite way around: Port hand markers are still square cans but they’re painted green, and starboard markers are conical but they’re painted red. This is the IALA B system.
The mnemonic is the much slicker “Red right returning”.
Only lateral buoyage is affected – port and starboard marks and their associated bifurcation marks, those striped ones which show the preferred side of a wide channel. We’re not talking about cardinal marks or special marks; they’re the same in both systems.
Navigation lights on vessels are the same in all areas – green is starboard, red is port.
The direction of buoyage is the same in both areas – towards the harbour or towards the source of a river – unless stated otherwise on the chart.
If buoys are numbered the number goes with the colour, not the shape. Red marks have even numbers in both systems; green marks have odd numbers in both systems. Numbering starts from seaward and increases towards shore.
So, that’s clear then. I think I need to go and lie down.