IALA Buoyage System — Region A & B

🛟 Schematic diagrams, not to scale — for the exact position and rhythm of a specific mark, always use the official chart and List of Lights.

Colour: Red
Light: Red, any rhythm except Fl(2+1)

Shape: can (cylindrical) · Topmark: Cylinder (can shape)

Leave to port when entering harbour from seaward (Region A) — colours swap in Region B.

Colour: Green
Light: Green, any rhythm except Fl(2+1)

Shape: conical · Topmark: Cone, point up

Leave to starboard when entering harbour from seaward (Region A) — colours swap in Region B.

Shape: pillar or spar · Topmark: Two black cones, both points up

Colour: Black above yellow
Light: White, continuous very quick or quick flashing (VQ or Q)

Safe water is to the north of the mark — pass north of it.

Shape: pillar or spar · Topmark: Two black cones, base to base

Colour: Black band on yellow
Light: White, VQ(3) every 5s or Q(3) every 10s

Safe water is to the east of the mark — pass east of it. Three flashes: think 3 o'clock.

Shape: pillar or spar · Topmark: Two black cones, both points down

Colour: Yellow above black
Light: White, VQ(6)+long flash every 10s or Q(6)+long flash every 15s

Safe water is to the south of the mark — pass south of it. Six flashes plus a long flash: think 6 o'clock.

Shape: pillar or spar · Topmark: Two black cones, point to point

Colour: Black band on yellow
Light: White, VQ(9) every 10s or Q(9) every 15s

Safe water is to the west of the mark — pass west of it. Nine flashes: think 9 o'clock.

Shape: pillar or spar over an isolated danger · Topmark: Two black spheres, one above the other

Colour: Black with one or more broad red bands
Light: White, group flash 2, Fl(2)

Marks a small, isolated hazard — a wreck or rock — with navigable water all around it.

Shape: spherical, pillar or spar · Topmark: Single red sphere

Colour: Red and white vertical stripes
Light: White — isophase, occulting, one long flash every 10s, or Morse "A"

Marks a landfall, centre of a channel, or mid-channel approach — navigable water all around.

Shape: optional — often a spar or float · Topmark: Single yellow X (St Andrew's cross)

Colour: Yellow
Light: Yellow, any rhythm not used above

Marks something other than navigation danger — a cable area, spoil ground, traffic separation, or similar.