🔍 Key Concepts

• IALA Buoyage System lateral marks vs. preferred-channel (bifurcation) marks • How light characteristics are written (single flashing, group flashing, composite group flashing, quick flashing, long flashing) • Which specific light pattern is used ONLY for preferred-channel buoys in the IALA system

💭 Think About

• First, recall what makes a preferred-channel buoy different in appearance and purpose from a normal lateral mark. How is this special status shown in its light pattern? • Think about the term used in light descriptions that combines two groups in one cycle. Which answer choice best matches that idea? • Ask yourself: do preferred-channel buoys need to be seen as extra-special or just like other laterals? How does that influence the type of flashing pattern chosen?

✅ Before You Answer

• Verify which light characteristic is uniquely associated with preferred-channel (bifurcation) marks in the IALA system • Confirm the difference between group flashing (e.g. Fl(3)) and composite group flashing (2+1) (e.g. Fl(2+1)) in light lists or buoyage diagrams • Make sure you are not confusing quick flashing or long flashing lights, which are typically used for different kinds of aids to navigation, not specifically for preferred-channel buoys