Topic: 2D sonar interference

[ben2kona]

Hello,
I am having some diagonal lines on my 2D sonar image. I have seen this before on intermittent occasions but now it shows up heavy most of the time. No other electronics are running and no other boats are around me. Any idea what is causing this. Could it be the GPS antenna wire that is zip tied with the transducer cable?

[Humminbird_Greg]

I don’t see anything that I would call interference in that picture.  Those diagonal lines are fish farts!  Don’t laugh because they could actually be just that… Okay, it is more likely to be some other sort of gas that is being released from the lake bottom or water itself.  From the almost perfect straight diagonal line shape of the targets they are moving upwards at a steady rate and seem to go to the surface of the water.  I would not think that these are fish due to the vertical distance that they would have moved.  Although I do not know what your unit settings were at the time; they also seem to reflect a lot of sonar as would an air/gas bubble.

Did you notice any bubbling at the surface at all?

Was this the only place that you saw this or was it more wide spread?

Could the fish at the bottom have been stirring up debris that had trapped air?  If not than I’m sticking with my fish fart theory!

[ITGEEK]

Just throwing things out there:

Are you running any kind of motor when this is happening?
If so, could the transducer be too close to the propeller and you are having aerated water around the transducer?

As Greg said it doesn't look like typical interference, but is your motor and your
sonar wired to the same battery?

Is anything else wired to the battery that your sonar is wired to?

Is your transducer clean.  Maybe have some string/grass on or around it.

Are you fishing with 50 lines straight down around the transducer.
Sorry, couldn't help it.

I'd start with eliminating the obvious.
The first thing I'd do is to get the GPS wire away from the transducer wire.
Your suspicions may be correct.
Test results, and go from there.

Good Luck.