Buoyage Made Easy: The UK Guide to IALA Region A (with clear examples)
Good pilotage starts with knowing what the floating, flashing furniture is trying to tell you. UK waters use the IALA Region A buoyage system—simple in principle, but easy to muddle when the light’s fading or the tide’s running. This guide strips it back to essentials, then adds practical tips so you can translate theory into clean, confident boat-handling.
First principles (and a big rule)
Region A means port is red and starboard is green when entering a harbour or following the “direction of buoyage” (usually from sea into harbour, or upstream in a river). When in doubt, check the chart for arrows or notes indicating buoyage direction.
If you’re new to electronic nav, our primer on waypoints & chart plotters shows how to build routes that respect buoyed channels—not just straight-line shortcuts.
Lateral marks (channel edges)
- Port (red): Can, pillar or spar; keep them to port when proceeding with the direction of buoyage. Lights (if fitted) are red, any rhythm except Fl(2+1).
- Starboard (green): Cone, pillar or spar; keep to starboard when proceeding with buoyage. Lights (if fitted) are green, any rhythm except Fl(2+1).
Preferred channel at a junction? You’ll see a modified lateral mark with a top band signalling the preferred route. For example, a red buoy with a single broad green band indicates the preferred channel is to starboard; the reverse for a green buoy with a red band.
Cardinal marks (where the safe water lies)
Cardinals tell you where the danger is by pointing to where the safe water lies: North, East, South, or West of the mark. Their black/yellow colour bands and cone topmarks make them readable even at a distance.
- North: Black above yellow, cones up. Quick/very quick continuous white flashes.
- East: Black with yellow middle band, cones base-to-base. Q(3)/VQ(3) in groups of three.
- South: Yellow above black, cones down. Six quick flashes + one long (Q(6)+LFl) or very quick equivalent.
- West: Yellow with black middle band, cones point-to-point. Q(9)/VQ(9) in groups of nine.
Memorisation tip: For East and West, think of the number of points on a compass rose to the side—3 for East, 9 for West—to recall the flash groups.
Other key marks you’ll actually use
- Safe Water: Red-and-white vertical stripes; topmark is a single red sphere; white light Iso/Occ/Long-Fl 10s. Often at fairway approaches. Treat it as the centre of a safe approach, not a guaranteed “aim here at full chat”.
- Isolated Danger: Black with red band; topmark two black balls; white light Fl(2). Pass well clear. These often guard rocks that “live” uncomfortably close to the channel.
- Special Marks: Yellow; X-shaped topmark. Light is yellow with any rhythm not used by white lights in the area. They mark all sorts (cable areas, race courses, wildlife zones). Check the chart notes.
Night sense: reading lights when everything looks… dark
At night, rhythm recognition keeps you safe. Build a little routine:
- Is the light white, red or green?
- Is the flash single, a group, or continuous quick/very quick?
- Does it “fit” the charted mark you expect here?
When you’re tired or it’s drizzly, confirmation bias is a real thing—so train yourself to double-check group counts out loud. It slows you down just enough to avoid silly errors.
Quick-reference downloads
IRPCS - Light Definitions (Rule: 21)
IRPCS - Sound Signals (Rule: 34 & 35)
Pilotage workflow you can trust
Buoyage isn’t a quiz; it’s a system to integrate with your overall plan. Use the APEM framework and make buoyage checks part of each stage:
- Appraise: Note buoyage direction, junctions and cardinal “gateposts” on the chart. Flag any isolated danger marks that sit near your track.
- Plan: Build waypoints that keep you near the middle of buoyed channels, not scraping along the cans. Avoid placing waypoints directly on marks (give yourself room and time). See our waypoint guide.
- Execute: Read the water as much as the plotter. In tight cross-tides, a touch of ferry gliding can hold you sweetly mid-channel while you sort the next leg.
- Monitor: Confirm each expected buoy and light pattern as you pass it. If something doesn’t tally, slow down and reassess—there may be new Notices to Mariners or a temporary relocation.
Common mistakes (and how to dodge them)
- Assuming direction of buoyage. Rivers are upstream; harbours are inwards—until they’re not. Always check the chart for the arrows or notes.
- Using buoys as slalom poles. Don’t “tag” them with your waypoints. Leave searoom, especially with set and drift in a narrow channel.
- Forgetting preferred channel marks at junctions. The colour of the broad top band tells you which way the main route goes. If you’re unsure, slow down, look twice, and read the chart.
- Confusing Safe Water with an “OK anywhere” signal. It marks a centreline or landfall, not a carte blanche. Depth and traffic still matter.
- Night-time group-count errors. Count aloud. If you’re not 100%, don’t commit to that turn yet.
Practice that sticks
Turn your next harbour approach into a micro-lesson. Before you go, sketch the buoy sequence you expect to see (port/starboard order, any cardinals, any preferred channel marks). After the entry, jot what matched and what didn’t. This tiny habit quickly builds a mental library of patterns.
Want a quick drill? Grab our revision tools and articles:
- Flashcard practice: Use the buoyage flashcard tool on our Free Resources page (see “Learn your buoys”) to hard-wire colours, shapes and light groups.
- Waypoint sanity: Rehearse route selection with waypoints and keep your track in safe water.
- APEM rhythm: Fold buoyage deliberately into passage planning so it becomes muscle memory.
Weather matters too
Buoys don’t live in a vacuum—tide and wind shape how you approach them. A fresh cross-tide and poor visibility can make a simple entry feel busy. Read the sky before you commit to a narrow approach: our plain-English refresher on clouds and wind shifts helps you anticipate squalls and veers that might complicate your turn.
Enrol when you’re ready
Good pilotage looks calm from the pontoon—make it feel calm in the cockpit, too.
