International Association of Light Authorities (IALA)
In years past, mariners had to be familiar with many different types of
buoyage systems worldwide, because there was no standardized system
in use. Some of the features of these different buoyage systems had
completely opposite meanings, which often led to confusion and
accidents. In the mid 1970s, the International Association of
Lighthouse Authorities (IALA) developed and secured acceptance of two
systems of buoyage known as IALA A and IALA B. Both systems use
a combination of cardinal and lateral marks plus unique marks for
isolated dangers, safe-water, and special-purpose areas.
The IALA system uses buoy shape, color, and, if lighted, rhythm of
flashes to convey the desired information to the navigator. The system
also uses special topmarks, which are small distinctive shapes above the
basic aid to facilitate identification.
IALA System A is used in Europe, Africa, and most of Asia, including
Australia and New Zealand. In this system, cardinal marks are widely
used. Red buoys are kept to port when entering from seaward; green
buoys are kept to starboard.
IALA system B is used in North, Central, and South America, Japan,
South Korea, and the Philippines. Cardinal marks are permitted in this
system but are seldom used. Red buoys are kept to starboard (red right
returning) when entering from seaward, green buoys are kept to port.
Figure 4-13 shows how the two IALA regions are divided worldwide.
Figure 4-13. The IALA buoyage system.