Vertical lines on the sonar screen means that your sonar is experiencing interference or crosstalk:
If you see this type of readings it means that there is another sonar device running nearby. There are 2 solutions:
- Move further away from the other sonar. This can help keeping the transducer cones from intersecting, but because cones get wider as the depth increases, in bigger depths the problem is harder to solve by positioning only.
- If possible, change the frequency of one of the sonar devices. Deeper sonars run on 290 and 90 kHz frequencies, so changing the frequency of one of the devices will greatly help to reduce false readings.