USCG Exam PracticeAids to Navigation — IALA-B (US) buoyage
A vessel is navigating in IALA-A waters and observes a green lighted buoy with an odd number to port. The vessel is returning from sea. Which statement is correct regarding this aid and the vessel's position in the channel?
- A. The vessel is correctly positioned; in IALA-A, green odd-numbered aids are port-hand marks and should be kept to port when returning from sea
- ✓ The vessel is incorrectly positioned; in IALA-A, green aids are starboard-hand marks and should be kept to starboard when returning from seaCorrect
- C. The vessel is correctly positioned; IALA-A and IALA-B use identical conventions for green aids
- D. Green buoys in IALA-A are safe water marks and may be passed on either side
Why B is correct
In IALA-A, starboard-hand marks are green. When returning from sea, green starboard-hand marks must be kept to starboard. A green buoy to port when returning from sea in IALA-A waters means the vessel is on the wrong side of the channel. The mariner must verify the IALA region in the chart border before interpreting lateral marks.