Parallel indexing is a radar technique that helps you monitor your position without needing GPS. You set a line parallel to your track and check if the radar echo of a landmark or coast stays on it. If the echo moves, you're off track—fix it fast before it leads to grounding. This classic skill can save you when technology fails. ⚓ Have you tried parallel indexing during your bridge watch? How did it go? #maritime #cadet | Seamansbook