A fork in the channel · Region A
Preferred channel and charted danger. Advanced level, about 3 min. IALA Region A. IALA modified lateral marks · preferred channel.
The situation
You are proceeding north with the direction of buoyage in Region A. Ahead is a banded junction mark. The fictional chart shows a wreck near the western branch and a recommended track through the eastern branch.
Which passage follows the preferred branch and clears the charted danger?
- Alter to starboard and leave the junction mark to port: Follow the eastern branch.
- Alter to port and take the western branch: Pass west of the junction.
- Continue straight toward the junction: Treat the contrasting band as decoration.
Answers and explanations
Lookout: A broad contrasting band marks a channel division. Read the dominant lateral appearance and the chart together.
The sound answer
Alter to starboard and leave the junction mark to port
A red port-hand form with a broad green band identifies a junction. Following buoyage, leave it to port for the preferred branch to starboard. The chart still determines whether either branch suits your vessel. Your track follows the charted eastern branch and clears the authored wreck extent.
Why the other options fall short
Alter to port and take the western branch
This takes the secondary branch toward the charted wreck; the marking does not guarantee either branch is safe for every vessel.
Continue straight toward the junction
The band conveys a channel division. Read the charted branches and danger before choosing the passage.
Modified lateral marks · preferred channel
A red port-hand form with a broad green band identifies a junction. Following buoyage, leave it to port for the preferred branch to starboard. The chart still determines whether either branch suits your vessel.