Buoyage is one of those things you learn for the exam, then half-forget until you're threading a rock-strewn channel at dusk with the tide pushing you sideways. IALA marks are designed to be read fast, in bad light, without a chart in your lap. If you can identify a mark and know what it means in under three seconds, you've bought yourself the seconds you need to decide. This is a refresher on cardinal and lateral buoys under IALA Region A (Europe), with the shortcuts experienced skippers actually use.

Region A versus Region B: know where you are

The world is split into two IALA regions. Region A covers Europe, Africa, most of Asia, and Australia. Region B covers the Americas, Japan, Korea, and the Philippines. The critical difference is the colour convention for lateral marks : in Region A, port is red, starboard is green when returning from seaward. In Region B, it's the opposite. If you charter abroad, this is not a trivia point. Read the chart legend before you leave the dock, because a red buoy on the wrong side of the hull will introduce you to the bottom quickly.

Cardinal marks, thankfully, are identical everywhere. Same colours, same topmarks, same light sequences.

Lateral marks: the channel edges

Lateral marks tell you where the safe channel lies when you're heading in from open water. In Region A :

  • Port-hand mark : red, can-shaped (flat top), red light of any rhythm. Leave it to port when entering.
  • Starboard-hand mark : green, conical (pointed top), green light of any rhythm. Leave it to starboard when entering.

The shape is your friend at night when colours wash out under a spotlight or in fog. A can silhouette is flat. A cone is pointed. If you can only make out the outline, you already know which side to pass.

Two more variants worth knowing :

  • Preferred channel to starboard : red with a green horizontal band, can shape. The main channel lies to starboard of the mark, but you can still pass either side if the water is deep enough.
  • Preferred channel to port : green with a red horizontal band, conical. Main channel lies to port.

These preferred-channel marks appear where a channel splits. They're a strong hint that a shallower secondary channel exists, and you'd better know which one your draft can handle. Cross-check with the chart before committing. If you're planning a coastal passage through unfamiliar buoyage, building the route properly beforehand saves a lot of on-the-fly interpretation.

The "direction of buoyage" trap

"Returning from seaward" is the phrase every course teaches, and it's usually obvious : you're entering a port, so red goes to port. But along a coast, or in an estuary with multiple entrances, the conventional direction of buoyage is defined by the chart, not by common sense. It's shown by a magenta arrow symbol.

Classic examples : the English Channel is buoyed generally from west to east. If you're sailing east down the French coast, red marks are to your port. Sail the same stretch westbound and you'll be seeing them on your starboard side, which feels wrong until you remember the convention. Around the UK, the direction runs clockwise. In river systems, it typically follows the flood tide upstream.

The habit to build : before entering any unfamiliar buoyed area, glance at the chart and confirm the direction of buoyage. Ten seconds now, no confusion later. This is one of the small routines that separates confident pilotage from the recurring beginner errors you see repeated every summer.

Cardinal marks: danger and where to pass

Cardinal marks indicate the direction of safe water relative to a danger. The name tells you which side to pass : a North cardinal means safe water lies to the north of the mark. You pass north of it.

All cardinals are yellow and black, with two black triangular topmarks. The topmark arrangement is the fastest way to identify them :

  • North : both triangles pointing up. Black over yellow. Pass to the north.
  • South : both triangles pointing down. Yellow over black. Pass to the south.
  • East : triangles pointing away from each other (like an egg shape). Black, yellow, black bands. Pass to the east.
  • West : triangles pointing towards each other (like a wineglass or wasp waist). Yellow, black, yellow. Pass to the west.

The shortcut that sticks : think of the topmarks as clock arrows pointing to the black band. Down for South, up for North, apart for East, together for West.

Lights are where cardinals really pay off at night. All cardinal lights are white and quick or very quick flashing. The number of flashes matches a clock face :

  • North : continuous quick or very quick flashing (12 o'clock, uninterrupted).
  • East : 3 flashes (3 o'clock).
  • South : 6 flashes plus a long flash (6 o'clock, the long flash is the tell you didn't miscount).
  • West : 9 flashes (9 o'clock).

Count the flashes, add the clock analogy, and you have the direction. The long flash after South is deliberate : six quick flashes in the dark are hard to count accurately, so the long flash confirms you're looking at a South cardinal and not a miscount of West.

Isolated danger, safe water, and special marks

Three more marks complete the picture :

  • Isolated danger mark : black with one or more broad red horizontal bands, two black spheres as topmark. Marks a small danger with navigable water all around. Light : white, group flashing (2). Pass on any side, but not too close.
  • Safe water mark : red and white vertical stripes, single red sphere topmark. Indicates navigable water all around, often used as a landfall or fairway buoy. Light : white, isophase, occulting, one long flash every 10 seconds, or Morse "A". These are the buoys you actually aim for when arriving from offshore.
  • Special marks : all yellow, yellow X topmark, yellow light. Not primarily for navigation. They mark cables, spoil grounds, aquaculture, military exercise areas, or data buoys. Meaning depends on the chart, so check.

Special marks are proliferating around European coasts as more sea areas get designated for offshore wind, cables, and marine reserves. Don't assume a yellow buoy is decorative. If you're not sure what it delimits, the chart or the almanac will tell you.

Reading buoyage in practice

The theory is one thing. Doing it at 15 knots in a rolling sea, with a low sun behind the buoys, is another. A few habits that hold up in real conditions :

  1. Identify by shape first, colour second. Colours degrade with distance, backlight, and weathering. Can versus cone versus pillar with topmark is more robust.
  2. Time the lights. Don't guess. Use a stopwatch or the second hand. A "quick flash" is 60 per minute, "very quick" is 120. If you're unsure whether you're looking at East (3) or West (9), count for a full period.
  3. Cross-check with the chart. Every buoy on the chart has a label giving its light characteristic, colour, and often a name or number. If what you see doesn't match, something is wrong : either you've misidentified the buoy, or you're not where you think you are.
  4. Watch the tide. Buoys lean with the current. A leaning cardinal is not lying to you, but the topmark angle can confuse quick identification. Look at the shape of the whole mark.
  5. Use AIS-fitted aids where available. Many major marks now transmit their identity by AIS. If you're already using AIS to track traffic, the same screen shows named aids to navigation, which removes any ambiguity.

And a note on charts : paper or electronic, the symbology for buoyage is standardised, but abbreviations vary. Learn the shorthand for light characteristics (Fl, Q, VQ, Iso, Oc, L Fl) and the colour codes (R, G, Y, BW, RW). If you're rusty, spend an evening with a chart and its legend before your next passage. It's the cheapest safety investment you'll make.

When buoyage changes, or disappears

Buoys move. Storms drag them, ships hit them, authorities reposition them, and seasonal marks come and go. The Notices to Mariners published by your national hydrographic service (SHOM in France, UKHO in Britain) list changes. Skimming them before a passage takes ten minutes and occasionally saves an afternoon.

Winter buoyage is a real thing in northern Europe : some marks are lifted before ice season and replaced with smaller unlit substitutes, or removed entirely. If you sail shoulder seasons, don't assume last summer's chart is still accurate on the water.

Finally, if visibility drops and you lose the buoys entirely, you're back to GPS, depth sounder, and your pilotage plan. Which is why serious skippers keep a written or plotted route with waypoints between marks, not just a mental note. When you can log every passage, replay it, and compare what you saw against what you did, buoy identification stops being an exam question and becomes muscle memory. That's the kind of practical review the Oria Box was built to make effortless : every mark you passed, every course change, timestamped and there when you want to learn from it.