Module 16 - Pilotage
Lateral Marks
What you will learn
Use Region A normal and preferred-channel lateral marks in the charted direction without inventing priority, relying on number alone or passing too close.
Lateral marks describe channel sides. In Region A, red marks the port-hand side and green the starboard-hand side when following the conventional direction; a contrasting band and 2+1 rhythm identify a preferred branch.
A Region A port-hand mark is red and may be can-shaped or carry a can topmark; a starboard-hand mark is green and may be conical or carry a cone topmark. Pillars and spars also occur, so shape is not always available. If lit, each uses its side colour and a rhythm other than the reserved preferred-channel 2+1 pattern.
Proceeding in the conventional direction, leave the port-hand mark to port and starboard-hand mark to starboard. Travelling against that direction changes which side of the yacht they appear on, not what they mean. IALA recommends even numbers on red and odd on green where numbering is used, but the charted identity and local system remain authoritative.
At a junction, red with one broad green band means preferred channel to starboard; green with one broad red band means preferred channel to port. If lit, the rhythm is composite group flashing 2+1 in the main colour. 'Preferred' identifies the competent authority's primary route; it does not guarantee that branch suits this vessel or confer traffic priority.
Read the main lateral colour first, then the contrasting junction band.
| Region A mark | Day cue | Night cue if lit | Meaning in direction |
|---|---|---|---|
| Port hand | Red; can shape/topmark when fitted | Red | Port side of channel |
| Starboard hand | Green; cone shape/topmark when fitted | Green | Starboard side of channel |
| Preferred to port | Green with one broad red band | Green Fl(2+1) | Preferred branch to port |
| Preferred to starboard | Red with one broad green band | Red Fl(2+1) | Preferred branch to starboard |
Read a junction mark before choosing the branch
Following the direction of buoyage, the yacht approaches a mainly green mark with one broad red band. The chart shows the intended route taking the port branch.
1. Read the main colour
Mainly green means this is modified from the Region A starboard-hand family.
2. Read the band
The red band makes it preferred channel to port, consistent with the intended branch.
3. Verify suitability
Check actual depth, traffic and local directions before taking the branch; the mark does not guarantee conditions.
Sense check: Reading only the red band reverses the answer. Main colour establishes the lateral family before the band modifies it.
Common mistake or limitation
- Preferred-channel marks are read by main colour plus contrasting band, not by the band alone.
- A correctly identified lateral buoy is not a target to shave closely; swing, current, traffic and uncertainty still require clearance.
Recap
- Use Region A colour and shape together in the charted direction.
- Read a 2+1 junction mark from its main colour before the band.
- Confirm branch depth and local controls rather than treating 'preferred' as permission.
Optional quick check
Section 6 of 10
In Region A, what does a mainly green mark with one broad red band indicate?
Sources and factual review
Reviewed 2 September 2026 - Coastal Skipper Revision.
Continue studying Pilotage
This public lesson is part of Revision Module 16. Full revision access adds the guided Learn, Practise and Test flow, flashcards and revision progress.