IALA Buoyage System

IALA Buoyage System — The International Association of Marine Aids to Navigation and Lighthouse Authorities.

Established in 1980, the IALA system is divided into two primary buoyage regions: Region A and Region B.

• Region A encompasses Europe, Australia, New Zealand, Africa, the Gulf countries, and certain Asian nations.

• Region B encompasses North, South, and Central America, Japan, Korea, and the Philippines.

The fundamental difference between the two regions lies solely in the color coding of the lateral marks. Specifically, in Region A, red lateral marks are used to indicate the port (left) side of a channel when entering from the sea, while green marks indicate the starboard (right) side. In Region B, these colors are reversed. It is critical for the OOW (Officer of the Watch) to maintain situational awareness regarding the vessel’s current IALA region. Note: It is highly recommended to explicitly indicate the transition between IALA regions in the Passage Plan, a practice strictly evaluated by vetting inspectors.

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Section 1: Identification of Marine Buoys

The IALA Maritime Buoyage System distinguishes buoys based on the following characteristics:

1. Shape Standard buoys are manufactured in specific shapes:

 

	Cylindrical (Can)
	Conical (Nun)
	Spherical
	Pillar
	Spar
	Barrel

 

 

2. Topmark A buoy or beacon may be fitted with a topmark on its uppermost part, comprising a sphere (single or multiple), a cylinder, a cross, or a configuration of cones. Alternatively, it may have no topmark at all.

3. Light Lights are described using three primary characteristics:

• Color: W (White), R (Red), G (Green), Y (Yellow/Orange), or Bu (Blue). If no color is specified in the charts or light list, white is used by default.

  • On paper charts, light colors are indicated by the general color symbol.

  • On ECDIS, specific lights are designated by colored light flares (teardrops) emanating from the symbol.

• Period: The time in seconds required for one complete cycle of light changes (e.g., FL (2) 10s indicates a 10-second period containing two flashes and a subsequent eclipse). Most navigational lights have a period of 3 to 10 seconds.

  

• Phase Characteristic: The specific pattern of changes within one complete cycle. Generally, the faster the flash rate, the more imminent the navigational danger. Common abbreviations include: LFL, Q, Iso, F Fl, Oc, Al, Mo. Detailed light characteristics can be found in the Admiralty List of Lights and Fog Signals and NP735.

	LFL 10s
	Q(3) G 9s
	Iso 6s
	F Fl Y 5s
	Oc 5s
	Al WR 4s
	Mo (U) 8s

Section 2: Types of Marks by Function

1. Lateral Marks

Lateral buoys define the port and starboard boundaries of a route or channel. Their characteristics (color, shape, topmark, and numbering) indicate the direction of buoyage, which conventionally corresponds to the incoming tide or, on a larger scale, a clockwise direction around landmasses.

• Region A: Red buoys indicate the port side when returning from sea. (Mnemonic: “With aching heart (left side) we leave the open waters”).

  

• Region B: Green buoys indicate the port side when returning from sea. (Mnemonic: “Red Right Returning”).

Numbering: If lateral marks are numbered, the sequence increases from seaward towards the coast/port. According to the system protocol, green buoys carry odd numbers, while red buoys carry even numbers. Alphabetical sequencing may also be utilized. Lights: The color of the light corresponds to the color of the buoy (Green / Red).

2. Preferred Channel Marks

Where a channel bifurcates into a primary and a secondary route, “Preferred Channel Marks” are deployed to indicate which branch is the main navigable channel. These buoys feature both red and green horizontal bands. The predominant color (the top and bottom bands) indicates the preferred channel, while the secondary channel is represented by the middle band. Phase characteristic: Composite group flashing — FL (2+1) with the light color corresponding to the preferred channel.

3. Cardinal Marks

Cardinal marks indicate the direction of safe water relative to the mark itself, based on the compass azimuth. For instance, a West Cardinal mark indicates that safe, navigable water lies to the west, while the danger lies to the east.

• Color: Black and yellow horizontal bands.

• Shape: Pillar or spar.

• Topmark: Two black cones. The orientation of the cones points towards the location of the black band(s) on the buoy’s body (e.g., for a North Cardinal mark, both cones point upwards, and the black band is at the top).

• Light: White light, either Very Quick (VQ) or Quick (Q) flashing. Mnemonic for light phases based on a clock face:

• 3 o’clock (East): 3 flashes

• 6 o’clock (South): 6 flashes + 1 long flash

• 9 o’clock (West): 9 flashes

 

4. Isolated Danger Marks

These marks are erected on, or moored directly above, an isolated danger of limited extent that has navigable water all around it (e.g., a submerged wreck, shoal, or reef).

• Color: Black with one or more broad red horizontal bands.

• Shape: Pillar or spar.

• Topmark: Two black spheres arranged vertically.

• Light: White light showing Group Flashing (2) — Fl(2).

5. Safe Water Marks

Safe Water marks are used to indicate that there is navigable water all around the mark. They are typically used as centerline marks, mid-channel marks, or landfall buoys.

• Color: Red and white vertical stripes.

• Shape: Spherical, pillar, or spar.

• Topmark: A single red sphere.

• Light: White light showing Isophase, Occulting, Long Flash (10s), or Morse code “A”.

6. Emergency Wreck Buoy

This mark provides a clear and unambiguous means of marking a newly discovered, uncharted wreck.

It is maintained in position until:

• The wreck’s position has been widely promulgated in Notices to Mariners.

• The wreck’s details (exact position, least depth, clearance) are fully surveyed.

• Permanent buoyage (e.g., Cardinal or Isolated Danger marks) has been established. Historical Note: Following the sinking of the car carrier Tricolor in the Dover Strait in 2002, several other vessels collided with the wreck despite standard radio warnings, guard ships, and a lighted buoy. This incident catalyzed the development of the Emergency Wreck Buoy.

• Color: Blue and yellow vertical stripes.

• Shape: Pillar or spar.

• Topmark: An upright yellow cross.

• Light: Alternating occulting blue and yellow light — Al Oc Bu Y 3s (Blue 1.0s + 0.5s darkness + Yellow 1.0s + 0.5s darkness). Note: These buoys are frequently equipped with an AIS transponder and/or a RACON.

7. Special Marks

Special marks indicate a special area or feature whose nature may be apparent from reference to a chart or other nautical publication. They are not primarily intended to assist navigation but rather to mark features such as ODAS (Ocean Data Acquisition Systems), cables/pipelines, recreation zones, anchorage boundaries, military exercise areas, and renewable energy installations.

• Color: Yellow.

• Shape: Optional, but must not conflict with navigational marks.

• Topmark: A single yellow ‘X’ shape.

• Light: Yellow light, with any phase characteristic not used for white lights (e.g., Fl Y or Fl(4) Y).

 

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Navigational Checklist for OOW

• Radar Fixing: Only fixed shore marks/beacons should be used for radar position fixing. Floating buoys are subject to displacement by weather, tides, or collisions, potentially providing a false position.

• Passage Planning: Always explicitly indicate the relevant IALA Region in your Passage Plan.

• Publications: NP735 (IALA Maritime Buoyage System) and the Admiralty List of Lights must be readily available on board convention vessels and subjected to regular NTM corrections.

• Vetting: A thorough knowledge of the IALA Buoyage System by navigating officers is routinely verified during Port State Control (PSC), SIRE, CDI, and Flag State inspections.

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