Navigation General · Depth Sounding — Verifying Position
Comparing echo-sounder readings to charted soundings along the track is valuable because it:
- AMeasures wind
- BProvides an independent check that the vessel is where the navigator thinks it is✓ Correct
- CCalibrates the radar
- DSets the magnetic variation
Explanation
If the depths under the keel don't match the charted soundings expected along the plotted track, the position is suspect. A line of soundings is a classic independent confirmation (or contradiction) of an electronic or visual fix.
Authority: Bowditch; piloting practice
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