USCG Exam Practice · Aids to Navigation — IALA-B (US) buoyage
Which buoyage system is used in the United States, and what numbering convention applies to red lateral aids?
- AIALA-A; odd numbers on red aids
- BIALA-B; even numbers on red aids✓ correct
- CIALA-B; odd numbers on red aids
- DIALA-A; even numbers on red aids
Why B is correct
The US follows IALA-B. Under IALA-B, red aids mark the port side of the channel when returning from sea and carry even numbers. Odd numbers are assigned to green aids.
Cited:Bowditch Ch. 5 §501
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