IALA Version A & B


There are 12 buoys in total in the system and they are split into categories of mark which will be explained in full as you go through the course. There is slight difference between IALA Version A & B which is explained below.


All buoys around the world are designed and governed by the same authority. This is the International Association of Lighthouse Authorities or IALA.

IALA is a non profit organisation whose purpose is to harmonise aids to navigation worldwide in an effort to promote safe cooperation.

When it comes to buoyage specifically, IALA helps to determine the colour and size of buoys and also their format around the world. Buoys are split into two different geographic systems known as IALA version A and IALA version B.

IALA Geographic areas

Essentially America, the Caribbean, Japan and the Philippines subscribe to version B and the rest of the world subscribe to version A.

So what’s the difference?

In IALA A, such as is in the United Kingdom, the marks that denote the edges of a channel as you enter from the open sea are a red port can on the left hand side and a green starboard cone on the right hand side.

In the case of IALA B, the colours of the lateral marks are reversed but the shapes remain the same. Therefore, as you come into a channel from the open sea, there will be a green port can on the left and a red starboard cone on the right.

Everything else in the buoyage system is the same between IALA A and B.

IALA version A
IALA A Red port can
IALA version A green starboard cone
IALA A green starboard cone

The different categories of buoy are:

  1. Lateral Marks – these include the buoys that mark the edges of a channel and also ones that denote the main thoroughfare or direction of the channel
  2. Cardinal Marks – these mark the direction of safe water so as to avoid a hazardous area
  3. Isolated Danger – an individual hazard
  4. Safe Water or Fairway – the start / end of a buoyed harbour
  5. Temporary Wreck –  marking a fresh shipwreck
  6. Special Marks – anything not covered by the rest of the buoys