Types of Buoys

The IALA buoyage system provides for five types of buoy:

Lateral Marks, “lateral” means “side”, for port and starboard side.

Cardinal Marks, which relate to the cardinal points of the compass

Isolated Danger Marks

Safe Water Marks

Special Marks, for example:

·         ODAS (Ocean Data Acquisition System) buoys

·         Traffic Separation Schemes

·         Spoil ground

·         Military exercise areas

·         Cables or pipelines, outfalls.

·         Recreation areas

·         A channel within a channel.

By day, buoys are identified by their shape and colour

There are five basic shapes:

·         Can

·         Conical

·         Spherical

·         Pillar and

·         Spar.

The first three indicate which side to pass, (port, starboard or either side, in that order  – see explanation under Lateral Marks).

The shape will be indicated by a topmark if the buoy itself does not follow that pattern.

“Pillar” is used to describe any buoy which has a tall central structure on a broad base. A “Spar” is a stout pole; when used as a buoy, it is provided with additional buoyancy and moored so that it stands straight up.

At night they are identified by a flashing light:

·         Cardinal Marks               White (four sequences shown below)

·         Lateral Marks                 Red or Green

·         Isolated Danger              White (group flashing 2)

·         Safe Water                     White (isophase, occulting, long flash or Morse A)

·         Special Marks                 Yellow.

Isophase means “equal on, equal off”

Occulting means “on more than it is off”

Although it is important to be able to recognise instantly all of the marks and their identifying lights at night, it is also important to remember that they are not always necessarily lit (so don’t bump into any).

Unlit buoys are identified by retro-reflectors, which are also fitted to lighted buoys in case of light failure. There are two methods distinguishing unlighted marks at night. The Standard Code and the Comprehensive Code

The Standard Code uses the following markings:

·         Red Lateral:                   Red band or shape similar to topmark

·         Green Lateral:               Green band or shape similar to topmark

·         Preferred Channel          As for Red or Green (see below)

·         Special Marks                Yellow band, “X” or symbol.

·         Cardinal                        White band with letters, numbers, or symbols.

·         Isolated Danger              White band with letters, numbers, or symbols

·         Safe Water                                White band with letters, numbers, or symbols

The Comprehensive Code uses the following markings:

·         Lateral Marks                 Same as above.

·         Cardinal Marks               Blue and Yellow bands (imitating the black and yellow)

·         Isolated Danger              Blue Band over Red Band

·         Safe Water                    Red Band over White Band (could also be vertical)

The history of world buoyage is long and tortuous, and it is only in the last 20 years or so that the IALA system has been in operation. Even as late as the 1970’s there were 9 different systems in European waters alone. IALA has managed to narrow it down to two systems by dividing the world into two Regions, A and B.

Region B is the Americas (N & S) and Japan.

Region A is everywhere else.

The only real difference is that Region B reverses the colours for Lateral Marks. For example when entering a harbour in a Region B port, you will have green cans on your port side instead of red ones. Information on localities which do not follow the IALA system, or supplement it with additional features, can normally be found in Sailing Directions (Admiralty Pilot Books)


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