IALA Buoyage
Road signs on the water

Buoys, Beacons and Marks

The IALA Buoyage System is a worldwide standard sea mark system used in navigation to mark the edge channels. There are two international Buoyage Regions A and B where the lateral marks differ. In Region A starboard buoys are green and port buoys are red. In Region B the colours are reversed, starboard buoys are red and port buoys are green.Region A includes part of the Atlantic Ocean, Africa, Europe, Asia, Middle East, Australia and part of the Pacific Ocean. Region B includes North and South America.

These road signs on the water are made up of five buoy types - cardinal, lateral,isolated danger, special and safe water marks. These buoys and marks indicate where safe water lies and where you should navigate safely within a channel. Always refer to a local chart to identify where potential hazards may be.

ialaResource large

These show well-established channels and indicate port (left) and starboard (right) sides of the channels. Port marks are a red can shape. At night, a red flashing light may be shown. Starboard marks are a green conical shape. At night a green flashing light maybe shown.

Coloured yellow and black each indicates where there is deep water close to a danger and they show this relative to the compass. NORTH - white light continuous quick flashing light. Pass to North. SOUTH - white light 6 quick flashes + 1 long flash. Pass to South. EAST - white light 3 quick flashes. Pass to East. WEST - white light 9 quick flashes. Pass to West.

Indicates an isolated danger, such as a submerged rock. It tells you not to pass too close. Coloured black with one or more horizontal red bands. If lit at night it shows a group of two white flashes. The top mark has two round spheres.

Indicates a special area which should be kept clear of. Coloured yellow, if lit at night it shows a flashing yellow light. The top mark is a single yellow cross. Check your chart to find out what is special in the area you are boating in.

Safe water marks - are red and white striped beacon or buoy, often an isophase or occulting white light. It is used to signify that you [are in safe waters. This sea mark implies that open, deep and safe water lies ahead, though it is sometimes used to indicate the start and end of a buoyed section of a continuous narrow channel or a line of these marks can be used to mark a safe route through shallow areas. In Sydney Harbour it is used as a 'centre line of the channel' and vessels are required to leave it to port when navigating past Bradley's Head in either direction. Pass this mark to port when traveling up (coming in from sea) or, down stream (going out to sea)

New Danger Marks (also known as Emergency Wreck Marking Buoys) are used to identify newly discovered hazards such as a sandbar, rock, reef or wreck which has not already been marked on boating maps or nautical charts.  The new danger mark displays blue and yellow vertical stripes in equal number dimensions around the mark.

Heading in Heading out Rule


When heading in a direction UPSTREAM from sea you must keep the (green) starboard buoy to your starboard side, keeping the (red) port buoy over to your port side to travel safely within the channel.

When heading in a direction DOWNSTREAM towards the sea you must keep the starboard (green) buoy to your port side, keeping the (red) port buoy over to your starboard side to travel safely within the channel.

You must be able to identify the buoys beacons and marks you see out on the water in order to pass them safely on the correct side.

Back to top

Subscribe to the Bowline Newsletter to get the latest information and training news from the College. It's filled with course information and boating advice. Get a taste for what is coming up, be the first to get information on events and enjoy special offers open to subscribers only.

To show you are a person filling in this form rather than a spamming script, what day of the week comes after Wednesday