What should you apply to a fathometer...

What should you apply to a fathometer...

Question 1 of 2707066636ee928f7522a1c519153

What should you apply to a fathometer reading to determine the depth of water?

Question 1 of 27070

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Q

What should you apply to a fathometer reading to determine the depth of water?

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🔍 Key Concepts

• Fathometer transducer location – Is it usually near the waterline or near the bottom of the hull? • The difference between depth of water and under-keel clearance (distance from keel to seabed). • How the vessel’s draft affects what the instrument is actually measuring.

💭 Think About

• Think about what a fathometer actually measures: is it from the sea surface, from the transducer, or from the keel? • If the fathometer reading is already close to the keel, what adjustment would you make to get the total water depth from the surface to the bottom? • Which correction (sea water vs. draft) is normally used when converting between instrument reading and true depth?

✅ Before You Answer

• Be clear whether the question is asking for total depth of water (surface to bottom) or clearance under the keel. • Consider where the fathometer is mounted and therefore from what point the reading starts. • Verify which corrections are typically applied in echo sounder/fathometer use: draft correction vs. sea water correction.