USCG Exam PracticeAids to Navigation — IALA-B (US) buoyage
A mariner is approaching a US port at night and observes a flashing green light on a buoy bearing 045° T. Applying IALA-B rules, what action is consistent with safe navigation if the vessel is inbound?
- A. Pass the buoy with it on the port side, as green marks the port hand when returning
- ✓ Pass the buoy with it on the starboard side, as green marks the starboard hand when returningCorrect
- C. Treat the buoy as a safe-water mark and pass on either side
- D. Pass the buoy with it on the starboard side only if it also displays an odd number
Why B is correct
In IALA-B, green is used on starboard-hand lateral aids. When returning from sea (inbound), green aids are kept to starboard. The light color alone establishes lateral significance; the buoy number confirms it but is not required to determine the correct passing side.