8.1 Lateral Marks: System A and System B Comparison

8.1 Lateral Marks: System A and System B Comparison

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Global Harmonization & The Two IALA Regions

Before 1980, over thirty disparate buoyage systems caused frequent groundings. Conflicting regional codes meant red buoys marked port in Europe but starboard in North America. To establish harmony without forcing nations to replace existing inventories, IALA divided the world into two regions:

• IALA Region A: Encompasses Europe, Africa, Australasia, the Middle East, India, and most of Asia.
• IALA Region B: Encompasses the Americas, Japan, South Korea, and the Philippines.

All non-lateral marks—including Cardinal, Isolated Danger, Safe Water, Special, and Emergency Wreck marks—are standardized identically across both regions.

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The Conventional "Direction of Buoyage"

Lateral marks define the port and starboard edges of navigable channels. Because "left" and "right" depend on vessel heading, lateral marks are anchored to the Conventional Direction of Buoyage:

1. Approaching from Seaward: The standard direction taken when approaching a harbour, river, or estuary from the open sea.
2. Circumnavigating Landmasses: In coastal passages between open seas, hydrographic authorities establish the direction. Around the British Isles, the general directions are north along the west coast and Irish Sea, east through the English Channel, and north through the North Sea. Follow the charted direction for the particular waterway.
3. Chart Symbol: Nautical charts indicate this datum with an open magenta arrow pointing in the direction of buoyage, accompanied by red and green lateral buoy symbols.

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IALA Region A: Lateral Marks & Standards

In Region A, lateral buoy colors align directly with vessel navigation sidelights when entering harbour:

Port Hand Marks (Region A)

• Color: Solid Red.
• Body Shape: Cylindrical (can), pillar, or spar with a flat top.
• Topmark (if fitted): A single red cylindrical can.
• Light Color: Red.
• Light Rhythm: Any rhythm except composite group flashing Fl(2+1)R. Common examples include Fl R, Q R, VQ R, Iso R, and Occ R.
• Numbering: Even numbers (No. 2, 4, 6), increasing sequentially from seaward.

Starboard Hand Marks (Region A)

• Color: Solid Green.
• Body Shape: Conical, pillar, or spar with a pointed top.
• Topmark (if fitted): A single green cone pointing apex upwards ($\blacktriangle$).
• Light Color: Green.
• Light Rhythm: Any rhythm except composite group flashing Fl(2+1)G. Common examples include Fl G, Q G, VQ G, Iso G, and Occ G.
• Numbering: Odd numbers (No. 1, 3, 5), increasing sequentially from seaward.

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IALA Region B: The "Red Right Returning" Protocol

IALA Region B maintains the identical shapes and topmarks as Region A, but swaps lateral color assignments:

The Region B Rule

Mariners in the Americas and parts of East Asia use the mnemonic "Red Right Returning":

• When returning from seaward in Region B, keep RED marks to your RIGHT (starboard) side.

Mark Specifications in Region B

• Port Hand Marks: Solid Green; cylindrical (can) shape or pillar; single green can topmark; green light of any rhythm except Fl(2+1)G; odd numbering.
• Starboard Hand Marks: Solid Red; conical (nun) shape or pillar; single red cone topmark pointing upwards ($\blacktriangle$); red light of any rhythm except Fl(2+1)R; even numbering.

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Preferred Channel Marks (Bifurcation Marks)

Where a channel divides into two branches, a Preferred Channel Mark indicates the recommended primary route while preserving access to the secondary channel. These are modified lateral marks displaying a broad horizontal band of the opposing color:

Preferred Channel to Starboard (Region A)

• Meaning: The primary channel branches to starboard. To take the preferred route, treat the buoy as a port mark and leave it to PORT.
• Appearance: Red hull with broad green horizontal band; cylindrical (can) shape and topmark.
• Light: Composite group flashing red: Fl(2+1)R.

Preferred Channel to Port (Region A)

• Meaning: The primary channel branches to port. To take the preferred route, treat the buoy as a starboard mark and leave it to STARBOARD.
• Appearance: Green hull with broad red horizontal band; conical shape and cone topmark ($\blacktriangle$).
• Light: Composite group flashing green: Fl(2+1)G.

Preferred Channel Marks in Region B

In Region B, colors invert: Preferred Channel to Starboard is green with a broad red band and shows Fl(2+1)G; Preferred Channel to Port is red with a broad green band and shows Fl(2+1)R.

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Comprehensive Comparison: Region A vs. Region B

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Seamanship Tactics & Examination Pitfalls

1. Outbound Inversion: When departing harbour in Region A, you travel against the conventional buoyage direction. Keep green conical buoys to port and red can buoys to starboard.
2. Silhouetted Shapes in Glare: Solar glare renders colors indistinguishable. Identify lateral aids by their silhouette: cans are flat-topped, cones are pointed.
3. Bifurcation Rhythms: Any lateral mark displaying Fl(2+1) is a preferred channel mark. Look for the horizontal band to identify the primary route.
4. Cross-Tide Drift: Cross-currents set vessels toward buoy moorings. Monitor heading versus Course Over Ground (COG) to maintain clearance.