Lateral Marks, Buoys, and IALA Explained

Lateral Marks and Buoys

Lateral buoys and marks indicate the channel’s edges, whereas cardinal and special purpose marks serve different purposes. Using these marks, you can safely stay within the waterway’s boundaries and identify the correct path through a channel, minimizing the risk of an accident.

Port and Starboard Markers

These indicate which side is the correct passage when traveling in a specific direction. They are differentiated by their color schemes and shapes, with port marks appearing red and cylindrical (can), while starboard marks have a conical (nun) shape and are green. Port marks display a red flashing light, and starboard marks have a green flashing light. The lights may exhibit different flash patterns based on location and situation.

They are typically numbered to help you keep track of progress through the channel, with odd numbers assigned to port buoys and even numbers assigned to the starboard ones. Some may be assigned letters or unique names to make navigation simpler.

Safe Water Marks

Safe water marks are easily recognizable due to their red and white vertical stripes, indicating the presence of navigable water. These often signal the mid-channel or entrance to a fairway, guiding vessels through the safest route. Safe water marks can assist in positioning vessels within the channel and avoiding potential dangers. Safe water marks feature a white light, which may be isophase, occulting, or flashing, depending on the specific mark.

Preferred Channel Marks

Preferred channel marks indicate the best route when a channel divides into two branches, which is important in complex waterways. They have red and green horizontal bands, with the top color showing the preferred direction when heading to port. They can have cylindrical (can) or conical (nun) shapes.

Preferred channel marks display a flashing white light, which may be composite group flashing to signify the preferred channel side (e.g., two flashes for the top band color followed by one flash for the lower band color).

In IALA Region A, the mark has a red top band for the preferred channel to port, while a green top band signifies the preferred channel to starboard. In Region B, the colors are reversed: a green top band indicates the preferred channel to port, and a red top band indicates the preferred channel to starboard.

Isolated Danger Marks

Isolated danger marks warn of potential hazards like submerged rocks or wrecks isolated within an otherwise navigable channel. They are easily recognizable due to their black and red horizontal bands and double-sphere topmark. To avoid the danger that isolated danger marks signal, you should keep a safe distance from them.

Cardinal Marks

Cardinals provide essential information about the safest side to pass an obstruction or danger. They show the best route around hazards like submerged rocks, shoals, or sandbanks and are strategically positioned around the obstruction. 

Each type of mark corresponds to a specific cardinal point – North, South, East, and West – and provides directional guidance. Cardinal marks always feature a combination of yellow and black colors, regardless of the cardinal point they indicate, making them easily recognizable. For instance, a North cardinal mark indicates that vessels should pass to the north of the mark.

North cardinal

• Black-yellow-black bands
• Two vertical black cones with touching bases (upward-pointing arrow)
• Quick or very quick continuous white light with an uninterrupted sequence of flashes

East cardinal

• Black-yellow-black bands, the lower part is yellow
• Two vertical black cones with points facing away from each other (hourglass shape)
• White light with a group of three quick or very quick flashes, followed by a brief pause before repeating the sequence

South cardinal

• Yellow-black-yellow bands
• Two vertical black cones with points touching (downward-pointing arrow)
• White light with six quick or very quick flashes, followed by a long flash and a pause before repeating the sequence

West cardinal

• Yellow-black-yellow bands, the lower part is black
• Two vertical black cones with bases facing away from each other (inverted hourglass shape)
• White light with nine quick flashes, followed by a pause before the sequence repeats

Special Purpose Marks

Special purpose marks help boaters navigate safely by identifying various features or areas. They come in different types, each with a unique purpose, appearance, and light characteristics.

1. Anchorage buoys: Show safe anchoring areas, usually yellow with an “A” symbol, and may have a yellow light.

2. Channel limit buoys: Indicate channel limits, typically yellow with varying top marks, and exhibit yellow flashing lights. The flash patterns differentiate between the port and starboard sides of the channel.

3. Cautionary, information, and control buoys: Yellow buoys with different purposes, topmarks, and light patterns.

4. Cable or pipeline crossing buoys: Mark underwater cables or pipelines, usually yellow, with a “C” or “P” symbol and a yellow flashing light.

5. Mooring buoys: Secure points for vessels, often yellow, orange, or white with a blue band, and may display an “M” symbol. Usually no lights.

6. Scientific data collection buoys: Collect scientific data, typically yellow with a “D” symbol, and may have flashing lights.

7. Diving buoys: Mark diving areas, often red or orange with a white stripe, may have red or orange lights.

8. Traffic separation scheme buoys:  Mark traffic boundaries, usually yellow with varying topmarks, and display yellow flashing lights.

IALA Buoyage System and Channel Markers

The IALA (or International Association of Marine Aids to Navigation and Lighthouse Authorities) established a standardized maritime buoyage system with two regions, A and B, to promote uniform navigation aids and reduce confusion. Region A covers Europe, Africa, Asia (excluding Japan, South Korea, and the Philippines), and Australia, while Region B includes the Americas, Japan, South Korea, and the Philippines.

Channel markers in the IALA system have consistent characteristics for cardinal, safe water, and isolated danger marks across both regions. The main difference lies in lateral marks. In Region A, red marks indicate the port (left) side, and green marks the starboard (right) side when entering a channel (i.e., heading to a port or harbour). In Region B, the colors are reversed, with green marks for the port side and red marks for the starboard side.

Common Mistakes and Misconceptions

• Not all channel markers are lit at night, so it is important to use charts, GPS, and other aids to supplement them in low visibility conditions.
• Channel markers should not be relied on as the sole source of information, as they can be misplaced, damaged, or missing. 
• Be aware of regional variations in the Buoyage System. Knowing the correct color schemes and configurations for lateral marks in your sailing area is essential.
• Misinterpreting cardinal marks can result in accidents – ensure you are familiar with the unique characteristics of each cardinal mark and its meanings.

Conclusion

Lateral marks are essential in guiding boaters through waterways. You can confidently pass through channels, bypass hazards, and maintain a safe course by understanding the various kinds of lateral marks and their functions. The IALA Buoyage System’s global standardization significantly contributes to navigational safety and consistency worldwide. 

Nevertheless, you should utilize multiple tools, such as charts, GPS, and radar, to supplement channel markers and prevent potential mistakes. By remaining alert, familiarizing themselves with regional variations, and keeping a proper watch, you can navigate effectively with channel markers and guarantee a safe voyage.

FAQs

Q: What are lateral marks?

A: They indicate the edges of navigable channels and provide safe passage through waterways.

Q: What are the primary types of lateral marks?

A: The primary types include port and starboard markers, cardinal marks, and special purpose marks.

Q: How do port and starboard markers help?

A: They use distinct color schemes, shapes, and numbering to guide vessels through channels, ensuring they stay within safe limits.

Q: What are cardinal marks and their purpose?

A: Cardinal marks indicate the safest side to pass an obstruction or danger, such as submerged rocks, shoals, or sandbanks.

Q: What are special purpose marks used for?

A: Special purpose marks highlight specific features or areas of interest within a waterway, such as anchorages, channel limits, or controlled areas.

Q: How does the IALA Buoyage System help improve navigational safety?

A: The IALA Buoyage System establishes a standardized set of marks and buoys worldwide, reducing confusion and promoting consistent navigation aids for boaters.

Q: How can I identify lateral marks at night or in low visibility conditions?

A: Lateral marks often have specific light characteristics, such as color and flashing patterns, that help a mariner identify them in low visibility conditions. However, not all marks are lit, so it’s crucial to use charts, GPS, and other aids to supplement them.

Q: What is the difference between the IALA Buoyage System’s Region A and Region B?

A: The main difference between Region A and Region B is the color schemes for lateral marks. In Region A, red marks indicate the port side and green marks indicate the starboard side when entering a channel. In Region B, the colors are reversed, with green marks for the port side and red marks for the starboard side.