IALA Buoyage Memory Aid
For RYA Day Skipper, Yachtmaster, and SRC exams
IALA buoyage is one of those topics that looks intimidating until you see the pattern, then becomes one of the easiest marks in the exam. This is the memory aid — the four mnemonics that cover 95% of what you need, plus the trap that catches sailors crossing the Atlantic.
First: Region A or Region B?
The world is split into two IALA regions with opposite lateral-mark colours:
- Region A — most of the world (Europe, Africa, Australia, most of Asia, Gulf states). Entering a channel from seaward: red on port, green on starboard.
- Region B — Americas, Japan, Korea, Philippines. Reversed: green on port, red on starboard.
For UK/RYA exams: assume Region A unless told otherwise. The mnemonic for Region B is “Red Right Returning” — which is a US Coast Guard saying. When you cross the Atlantic to the Caribbean, the buoyage flips.
Lateral marks — the channel edges
Lateral marks define the sides of a channel. Region A:
Port-hand mark
- Colour: Red
- Shape (buoy): Can (cylinder)
- Top mark: Red can
- Light: Red, any rhythm except those reserved for other marks
Starboard-hand mark
- Colour: Green
- Shape (buoy): Conical (cone, pointed up)
- Top mark: Green cone, point up
- Light: Green, any rhythm except those reserved
Memory aid: “Can on the Coast” — a can-shaped (cylindrical) buoy is on the port side (the side closer to coast when entering port). The conical pointed buoy is on the starboard side.
Cardinal marks — the killer topic
Cardinal marks indicate the safe side of a hazard. A North Cardinal says: pass to the north of me. The mark is on the other side of the danger from you. Four cardinals = four directions.
The top-mark trick (this is the whole exam)
Every cardinal mark has two black cone top marks. The way the cones point tells you which cardinal it is — and the cones point towards the colour black on the mark itself:
| Cardinal | Top marks | Body colour | Light rhythm |
|---|---|---|---|
| North | Both pointing up ▲▲ | Black above yellow | Q (continuous quick) |
| East | Pointing apart ▲▼ | Black-yellow-black | Q(3) every 10s |
| South | Both pointing down ▼▼ | Yellow above black | Q(6)+LFl every 15s |
| West | Pointing together ▼▲ | Yellow-black-yellow | Q(9) every 15s |
Top-mark memory aid:point the cones in the direction of the cardinal's name on a clock face.
- North — both cones point up (12 o'clock)
- East — point apart, like 3 o'clock arms
- South — both point down (6 o'clock)
- West — point together, like 9 o'clock arms
Light rhythm memory aid: count the flashes like a clock face.
- North — 12 o'clock — continuous (no break)
- East — 3 o'clock — 3 flashes
- South — 6 o'clock — 6 flashes plus a long flash to show you have just passed the bottom of the clock
- West — 9 o'clock — 9 flashes
The other four mark types
Isolated Danger Mark — “black with a red belt”
Black body with one or more horizontal red bands. Two black spheres as a top mark. Light: white, group of 2 flashes. Marks an isolated hazard with navigable water all around it — pass on any side, but not over the top.
Safe Water Mark — “red and white candy stripes”
Red and white vertical stripes. Single red sphere as a top mark. Light: white, isophase, occulting, or one long flash every 10s. Means safe water all around — usually marks the centre of a channel or a landfall buoy. The shape and stripes are deliberately distinct from anything else so you cannot confuse it.
Special Mark — “all yellow, no warning”
All yellow. Top mark: yellow X (St Andrew's cross). Light: yellow, any rhythm not used by white lights. Indicates a special feature — water-skiing area, pipeline, military exercise area, ODAS buoy. Not a navigational warning; chart it from the chart symbol, not the buoy itself.
Emergency Wreck Marking Buoy — “blue and yellow with a cross”
Vertical blue and yellow stripes. Yellow cross as a top mark. Light: blue and yellow alternating. Used for new wrecks until permanent marks can be established. Recent addition (post-2006) to the IALA system.
The four exam question patterns
Pattern 1: identify the mark from a description
“You see a buoy with black-yellow-black stripes and two top marks pointing apart. What is it?” Answer: East Cardinal — pass east of it. The top-mark direction + colour pattern is the telltale.
Pattern 2: identify the mark from its light
“Q(9) every 15 seconds.” Count: 9 flashes = West Cardinal. The light alone is enough to identify cardinals in the dark.
Pattern 3: which side to pass
“The chart shows a North Cardinal off a rocky promontory. What side do you pass?” Answer: pass to the north of it (between the cardinal and the open sea, away from the rocks).
Pattern 4: chart-symbol matching
You are shown four chart symbols and asked which corresponds to a described mark. The shorthand: red diamond = port-hand, green triangle = starboard-hand, BYB = East Cardinal symbol on chart, etc. Practice on real charts — the symbols are tiny and easy to mis-read.
Drill it
Mnemonics get you through the first reading. Reflexive recognition comes from repetition. Use the quizzes and the full reference page: