Understanding Marine Navigation Buoys and Marks

Brief History

Originating from simple markers, they evolved through medieval times with the advent of purpose-built, colour-coded wooden buoys. Maritime organisations like the UK’s Trinity House, established in 1514, further enhanced these systems, contributing to global uniformity.

These systems evolved alongside maritime technology, introducing robust, visible buoys to withstand challenging sea conditions. The transition from wooden to iron, the addition of lighting systems, and the creation of varied types all catered to diverse requirements.

In 1948, establishing the International Maritime Organization (IMO), a UN agency, was pivotal. In 1977, they introduced the International Association of Lighthouse Authorities’ buoyage system, eventually developing into today’s globally recognised International Buoyage System.

Types of Navigation Buoys

Lateral buoys

These indicate the safe passage for vessels by marking both sides of a channel or waterway. 

Port buoys (red)
Port mark buoys are red and placed on the channel’s left side when entering a harbour or navigating upstream. They can be either spherical, cylindrical, or pillar-shaped and might display a fixed or flashing red light.

Starboard buoys (green)
Starboard buoys are green and placed on the right-hand side of a channel when entering a harbour or navigating upstream. These can be pillar, conical, or spar-shaped and may feature a fixed or flashing green light.

Cardinal buoys

Cardinals indicate the safest and deepest water in an area concerning the cardinal points of the compass (North, South, East, or West). These buoys are coloured yellow and black, with their top marks showing the specific direction of safe water.

1. North cardinal
The North cardinal indicates that the safest course is found north of the buoy. Its top mark consists of two black cones pointing upwards.

2. South cardinal
The South cardinal signifies that the safest route is located south of the buoy. Its top mark has two black cones pointing downwards.

3. East cardinal
The East cardinal indicates that the safest route is found east of the buoy. Its top mark comprises two black cones pointing away from each other.

4. West cardinal
The West cardinal shows that the safest course lies west of the buoy. Its top mark displays two black cones pointing towards each other.

Safe Water Buoys

Mid-channel buoys (red and white)
Mid-channel or safe water buoys mark the centre of a channel, usually in deep waters or harbours. They are characterised by red and white vertical stripes and may feature a red or white flashing light.

Isolated Danger Buoys

These mark hazards like wrecks, rocks, and other dangers. They are distinguishable by their black and red horizontal stripes and two black spheres placed on top of each other as a top mark. They typically display a white flashing light.

Special Marks

These indicate particular areas or features relevant to mariners, such as race routes, restricted areas, pipelines, or cables. They are recognisable by their solid yellow colour and cross as a top mark. They may also exhibit a yellow flashing light.

Weather Buoys

These collect meteorological and oceanographic data to help predict storms, winds, and other weather phenomena. They can be found offshore, near coastlines, or in other strategic locations. They have various sensors and communication devices to transmit real-time information to weather monitoring centres.

Restricted area marks

Restricted area buoys are essential for identifying regions with limited access due to conservation initiatives, military operations, or other reasons. They often mix blue and yellow vertical stripes and may display a flashing yellow light. 

The International Buoyage System

Navigating would be nearly impossible without a consistent, well-organised system of markers across the different oceans. Enter the International Buoyage System, a comprehensive set of rules governing the use of maritime marking devices worldwide. The system, created under the authority of the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA), standardises buoyage systems to ensure safe navigation for vessels of all shapes and sizes.

Region A and Region B comparison

The International Buoyage System is split into Region A and Region B. While both regions share many similarities in their cardinal marks and other navigation aids, they differ mainly in lateral marks.

Key Differences

In Region A, which covers Europe, Africa, Asia (excluding Japan, South Korea, and the Philippines), and Australasia, port buoys (pass on the left) are coloured red, and starboard buoys (pass on the right) are coloured green. Conversely, in Region B, which includes North and South America, Japan, South Korea, and the Philippines, the arrangement is the opposite – green buoys show the port side, and red buoys show the starboard side.

Mooring Buoys

These floating devices enable watercraft to safely and securely anchor at designated locations without the need for a conventional anchor, thus reducing the risk of damage to the seabed and other underwater habitats. These are commonly found in harbours, marinas, and other sheltered areas that provide temporary or long-term berthing for boats, yachts, and other vessels.

Different Types

Several types are available, catering to various boat sizes and purposes. Some of the most prevalent designs include:

1. Polyform: These durable, air-filled buoys provide floatation on the surface and come in various sizes to accommodate different vessels. The versatile design allows for easy attachment of mooring lines and ensures sufficient buoyancy to keep the line afloat.
2. UK style mooring buoys: More common around Britain, they feature a metal rod running through their centre and a swivelling eye at the top, making it simple for boaters to attach and detach their mooring lines swiftly.

Lighted Buoys and Beacons

These illuminated markers guide mariners through preferred channels, alert them of hazards, or point out locations of interest. Lighted buoys and beacons convey crucial information to boaters by emitting specific patterns and colours.

Types of lights

Various light patterns are used, each signifying different information to mariners. Flashing lights, which emit regularly, often indicate hazards or obstructions. Rhythmic lights produce a regular sequence of varied light and dark intervals, serving as navigation markers. Other light patterns include occulting (a light with longer periods of light than darkness), isophase (equal durations of light and darkness), and long-flash lights (single long flashes with darkness in between).

Fog signals, automatic identification systems, and other additional features

In addition, some have advanced features. Fog signals, such as horns and bells, produce distinct sounds to alert ships of their presence when visibility is low due to fog or heavy rain. Automatic identification systems (AIS) transmit location and identity information, allowing nearby vessels to track their position. 

Shapes, Colours, and Marks

1. Spherical: Spherical buoys are round and often used as lateral or special marks. They can be found in various colours based on their function.
2. Conical: Conical buoys, also known as cone-shaped, are easily identifiable by their tapering shape. They typically serve as starboard marks when navigating.
3. Pillar: Pillar buoys are tall, cylindrical structures with a broad base. Commonly used for cardinal marks, they may display lights or be equipped with additional markings.
4. Spar: Spar buoys have a slender, elongated shape resembling a pole or mast. They are often used where shallower waters or narrow channels might pose a risk to other buoy types.

Colour Schemes and Their Significance

1. Lateral marks: Port marks are red, while starboard marks are green. These buoys indicate the safe channel sides when navigating.
2. Cardinal marks: Cardinal mark buoys utilise black and yellow colours to denote their orientation (north, south, east, or west) concerning a hazard or specific point of interest.

Top Marks and Their Role in Identifying Buoy Types

1. Cone or triangle shapes are seen on lateral marks, indicating either a port (single red cylinder) or starboard mark (single green cone pointing upwards).
2. Cardinal marks have double-cone shapes pointing inwards for north (upward) and south (downward) and outwards for east (two cones, base-to-base) and west (two cones, tip-to-tip).

Horizontal and Vertical Stripes, Numbers, and Other Markings

These often feature horizontal or vertical stripes, numbers, or other markings to provide additional information to mariners. Examples of these include:

1. A red and white vertical striped pattern on a mid-channel or safe water buoy indicates the navigable channel’s middle.
2. Cardinal marks have distinctive yellow and black stripes to indicate the direction they should be passed relative to the hazard.
3. Buoys, particularly lateral marks, may display numbers to specify a boat’s position in the navigational sequence.

Tips for Navigating and Identifying

Using a Nautical Chart or GPS Device

Nautical charts are essential for boaters, showing their locations, water depths, hazards, and other vital information. Familiarise yourself with nautical charts and learn to read the symbols indicating different buoy types. Modern GPS devices can also provide a wealth of information and are particularly useful when combined with paper charts as a secondary reference source.

Cross-Referencing Markings with the Surrounding Environment

When identifying buoys, it’s crucial to cross-reference the markings and colours with the surrounding environment, such as water depths or known hazards. For example, a red lateral mark may indicate the portside edge of a channel, but it’s essential to check that the water depth is appropriate for your vessel based on the information from charts or depth sounders. 

Final Thoughts

Understanding marine navigation buoys and marks is indispensable for anyone engaged in seafaring, be it professional or recreational. The complex system of these navigational aids, marked by various shapes, colours, and markings, serves as the guiding map for vessels traversing the vast expanse of the seas. As maritime technology continues to evolve, the buoyage system also adapts, incorporating advanced features like light patterns, automatic identification systems, and more, reinforcing its importance in maritime safety.