Navigation General · Soundings
An echo sounder measures depth by:
- ALowering a weighted line
- BReading the tide tables
- CTiming an acoustic pulse from the transducer to the bottom and back✓ Correct
- DMeasuring water pressure at the surface
Explanation
The echo sounder transmits a sound pulse and times its return from the seabed, converting travel time to depth using the speed of sound in water. The reading is the depth below the transducer, so transducer depth and height of tide must be applied to compare with the chart.
Authority: Bowditch (Pub. 9); echo sounder
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