Buoyage & Day Shapes

IALA buoyage in a nutshell

Almost every country uses the IALA Maritime Buoyage System. It has two regions that differ only in the colour of lateral marks. In Region A (Europe, Africa, Australia and most of Asia) port hand marks are red cans and starboard hand marks are green cones. In Region B (the Americas, Japan, South Korea and the Philippines) the colours swap: red is starboard, the origin of the phrase “red right returning”. Shapes never change, so a can is always a port hand mark.

Lateral marks follow the direction of buoyage: you leave port hand marks to port when heading into harbour, up a river or with the flood tide. Around coasts the direction is shown on the chart with a magenta arrow. Leaving harbour, everything reverses.

Cardinal marks

A cardinal mark is named after the side of it where the safe water is. A north cardinal has safe water to the north. The two black cones point to the black parts of the mark: both up for north (black on top), both down for south (black at the bottom), base to base for east (black bands top and bottom) and point to point for west (black band in the middle). Their white lights follow a clock face: continuous for north, 3 flashes for east, 6 plus a long flash for south and 9 for west.

Other marks

Isolated danger: black with red bands, two black spheres, white Fl(2). A small danger with safe water all round. Safe water: red and white vertical stripes, one red sphere, a white isophase, occulting, long-flash or Morse A light. Special marks: yellow, yellow X topmark, yellow light. Emergency wreck marking: blue and yellow vertical stripes, a yellow upright cross and an alternating blue and yellow light.

Day shapes

By day, vessels show black shapes instead of lights. A ball means anchored, two balls not under command, three balls aground, ball diamond ball restricted in ability to manoeuvre, a cylinder constrained by draught, two cones points together fishing, a diamond a long tow and a single cone point down a sailing yacht motoring with her sails up. They come from COLREGs Rules 24 to 30.

Want the lights version too? Try the COLREGs lights and sound signals trainer, or print the buoyage cheat sheet.