Sonar depth # off but scrolling chart correct

[rocklobster]

I notice on my chart plotter that the sonar does something strange. The depth on the scrolling graph clearly shows the bottom around 10ft. BUT the depth number on the top left corner says 5.8ft. They never seem to match and are very different.

Is there a calibration off that I need to set? I know the scrolling chart is correct since I am very familiar with the depth in my area.


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[Dale777]

rocklobster,

A Keel Offset to the actual water depth can be set in your Garmin Chartplotter. Perhaps, that is set to some non zero number.

To find out, from the Home screen, select:

1. Configure
2. My Boat
3. Keel Offset

If there is a non zero number in Keel Offset, that might explain the different numbers you are seeing. On my R31S, I have the Keel Offset set so that I see the depth below the keel, not the actual water depth. Depth below my keel is all I care about, not the actual water depth.

 

[rocklobster]

Aha! This could be it. I’ll check this next time I’m on the boat. It did seem to be about a 3ft delta. Thanks. I’ll let you know


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[mjq1987]

Also, to make the Keel Offset adjustment on our chartplotters, the sonar has to be sensing the bottom. If not, the correct menu options won't be displayed.