Trying to figure out what these lines are when sounding in deep water


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I frequently get these vertical lines on my display when I deep bottom fish. Take a look at the bottom lock side of this screen shot. This shot was taken in 124 fathoms, or 744 feet. 1971F using a 260 transducer. Settings: LF, gain set to 70, TVG was max, Interference setting was off, clutter at 50, erase weak echos at 18, and display speed set at 4/1.

I'm thinking this has something to do with my display speed? Should I be displaying slower when in deep water?


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How steep is the bank you're fishing? It could be how the cone is striking the bank and how the machine is interpreting the depth at the deeper range.

This looks like some sort of interference, either caused by electrical or acoustic noise. I would repeat this same test, and then slowly start powering off all the electrical items on the boat to see if this line goes away.

Is there any other sounders onboard the vessel, and does the GP1971F have an earth ground that is connected..? :unsure:

- Deep Blue
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