🔍 Key Concepts

• Preferred-channel buoys and how they differ from simple red or green lateral marks • The light characteristics used to show a preferred channel (also called junction buoys) in the IALA-B system used in the U.S. • How composite group-flashing patterns indicate the main (preferred) side of the channel

💭 Think About

• First, recall what a preferred-channel buoy is used for and where you might encounter one (e.g., at a channel junction). What colors and topmarks are normally associated with that buoy? • Think about which light characteristics are commonly used to convey extra information beyond simple lateral marking, especially to indicate "preferred" side of the channel. • Eliminate any light types you know are used for other specific purposes (for example, special purpose buoys, safe water marks, or isolated danger marks).

✅ Before You Answer

• Verify the U.S. Aids to Navigation System (IALA-B) description of preferred-channel (junction) buoys and note their color pattern and topmark. • Check which answer choice corresponds to a composite group-flashing characteristic and why that is associated with preferred-channel marks. • Confirm that options involving white or yellow lights are generally linked with other types of aids (safe water, special purpose, etc.), not lateral preferred-channel buoys.