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IALA Maritime Buoyage System - Navigation Buoys and Channel Markers

Sections: Buoyage System Marker Buoys & Channel Markers Cardinal Marks Additional Marks Navigation at Night

Marine buoys meanings navigation markers australia iala system channel markers colors. The cardinal buoys are yellow and black. Isolated danger mark marine navigation buoys and marking buoys part of the iala system. Included is a buoy identification chart for navigation buoys and markers.

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A yellow buoy may mark which of the following?

What color is a marker that indicates safe water?

What does a white marker with red vertical stripes indicate?

What do lateral markers indicate?

IALA Maritime Buoyage System

Sailing along coasts and in estuaries requires an understanding of the IALA Maritime Buoyage System. This aid to navigation is the method of buoys and other lateral markers which identify features such as channels or obstructions. Two [ IALA maritime buoyage systems ] Lateral A and Lateral B were adopted in 1976 by the International Association of Lighthouse Authorities (IALA) and implemented in 1990 worldwide.

Lateral A is the standard used in the British Isles, Europe, Australia, New Zealand, Africa and most of Asia, including India while the Lateral B standard operates in North, Central and South America, Japan, South Korea and the Philippines.

Marking the sides of shallow, winding channels was required early on in sailing. The original system were markers comprising of sticks, tree branches or floating barrels, but a more sophisticated aid to navigation was needed when larger vessels required access to inland ports.

The IALA maritime buoyage system, where the marker colour coding scheme of red for port (left) and green for starboard (right) was implemented worldwide. Europe had the channels marked for a ship coming into port while in America the scheme conformed to the port/starboard colouring as the ship left port. These different lateral buoyage systems operate successfully and confusion only arises when sailing from one system into a country using the other, or where there is neither system.

Where there is an island close off the mainland, the 'direction' of buoyage is determined by the direction in which the flood tide flows. Where two tides meet, the IALA maritime buoyage system changes direction at a determined point, and this is marked on charts.

Lateral A

Lateral B

Marine Navigation Buoys and Channel Markers

  • [ Lateral A ] system has red flat-topped cairns to port on entering, and green conical marks to starboard.
  • [ Lateral B ] has green flat-topped marks to port on entering and red conical marks to starboard.
  • With both systems, the buoys and markers may or may not have lights mounted on them.

The edges of channels are indicated with channel marker buoys and channel markers and are arranged according to the direction of buoyage. Channel marker buoys and channel markers are often [ numbered ], starting from seaward with even numbers on red marks and odd numbers on green marks. Where a channel divides, preferred channel marks which are modified lateral marks, indicate the main channel.

IALA buoyage system around coastlines is typically arranged in a clockwise direction. Check the maritime chart if the direction of buoyage is not obvious and will be marked using an [ arrow with two dots ].

Cardinal Markers and Buoys

The [ Cardinal System ] of buoys has been universally adopted in conjunction with the lateral system. Large or individual hazards are designated with cardinal marker buoys. Named after the points of the compass, they indicate which side to pass by them to avoid the danger, i.e. keep to the north of a north cardinal mark and south of a south cardinal mark.

Being pillar or spar shaped buoys the cardinal buoys are painted yellow and black. All have two black cones on the top variously arranged one above the other along with white flashing lights that flash in a sequence indicating which quadrant they sit in. In principle, minor estuarial channels are marked with the lateral system and the approaches and major obstructions are marked with the cardinal mark system.

The top marks of cardinal buoys consist of the combination of two black cones, mounted one above the other on the top of the buoy with the following combinations:

  • Both cones pointing up = north cardinal;
  • Both pointing down = south cardinal;
  • One pointing up and the other down with their bases together = east cardinal; and
  • One pointing up and the other pointing down with their points together = west cardinal.

If there is confusion between east and west cardinals, think of the (w)est as being (w)aisted.

The colours used in the Cardinal system are yellow and black.

  • North is a black pillar on a yellow buoy;
  • South is a yellow pillar on a black buoy;
  • East is a black and yellow pillar on a black buoy, and
  • West a yellow and black pillar on a yellow buoy.

The colours of the cardinal buoys can be hard to identify when weed or bird fouling occurs, and recognizing the colour of the buoy as yellow signifies north or west and a black buoy as south or east, while identifying the top mark positively, ensures that no fouling confuses the issue.

Additional Marine Markers and Buoys

Three additional types of channel markers and buoys and meanings in the IALA system are the:

  • Isolated danger mark;
  • The safe water mark;
  • The special mark.

Isolated Danger Mark

The meaning of an [ isolated danger mark ] is used to indicate a small, solitary danger with safe water all around.

An isolated danger can be a rock or a sunken boat. The marker has horizontal black and red bands and two black spheres on top.

Safe Water Mark

A [ safe water mark ] is used for mid-channel or landfall marks. It means that there is safe water all around the position. The safe water mark is a spherical buoy, or a pillar or spar, with vertical red and white stripes and with a red ball on top.

Special Marks

[ Special Marks ] which zone off recreational areas, such as water ski areas are yellow and may have an X-shaped top mark or any shape preventing them being confused with a navigational mark. They are not primarily intended to assist in marine navigation and where cones, cans, or spheres are used, they show the side on which to pass.

Marine Navigation at Night

Marine navigation using lights that [ identify buoys ], shore beacons, leading marks, and lighthouses make marine navigation at night possible. Buoys are lit with short-range lights and medium-range lights on shore beacons while long-range lights are used on lighthouses. There may be difficulty in identifying marks at night in the vicinity of ordinary shore lights.

To differentiate between shore lights, different lighting characteristics are used for specific marks to aid in identification. The light characteristic of each mark is noted on the chart of the area and in sailing directions. Usually, lights are white, red, green, or yellow, but purple, blue, and orange may also be used.

Light Sequences

In addition to the light’s colour, a flashing pattern and time taken to complete the sequence is used to identifying buoys. To ensure that the mark has been correctly identified, check the timing of the flashing through three full sequences.

Prior to entering a channel, be familiar with the abbreviations and the patterns associated with the maritime buoyage system on the chosen passage. Terms used on charts are:

  • isophase - meaning that there are equal periods of light and dark in the sequence and
  • occulting - meaning periods of darkness are shorter than the periods of light.

When approaching a harbor at night with many shore lights, it can be difficult to pick out the next buoy in the sequence. A [ hand bearing compass ] sighted along the expected bearing of the buoy may make it easier to find. Do not assume the light seen is the expected one as the boat’s position may be miscalculated so double-check.

Lighthouses, and other beacons, use coloured sector lights indicating safe and dangerous areas. The chart shows details of the colours and sector angles. The edges of the sectors are given in pilot books as bearings, and are always from seaward towards the lighthouse in degrees true (°T).

IALA and iala b and bouy markers

aid to navigation
buoyage light sequence
special marker
safe water marker
isolated danger
cardinal markers
marker buoys and channel markers
iala numbering system
iala region b
iala region a
iala buoyage system