Other HELIX adjustments you can try are ...:
*Set Beam Frequency under the Sonar tab to "High" ...
*Switchfire Max and adjust 2d Sensitivity ...
*Max Depth under the Sonar tab to 10ft deeper than deepest point in your lake ...
*Turn off CHIRP (2d) under the Setup tab ...
Still no confirmation from HB that they are looking into this erratic depth issue ...
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2 units transmitting the same frequency at the same time can commonly cause Crosstalk interference ...
If the units are networked - you can set both units to use the same xducer in the Networking tab to eliminate Crosstalk interference ...
Rickie