787 second sonar return

I’m having problems with the second sonar return on my 787 unit. It shows up on the screen, and then the depth readout shows the depth of the second return. This means, when I’m in lets say 10 fow, it will read 20. Then it keeps switching from reading 10 to 20 back to 10 and so on. I played with the settings but still can’t figure this out. Does anyone have ideas how to fix this?

Not really sure but what angle is your transducer at from front to rear. To much angle and your transducer may be missing the first return.

Make sure you have the latest software version installed.