I've got a 102C Lowarance depth finder on the front of my 14' jon boat. The transducer is mounted to the MinnKota trolling motor up front. Now, when the depth finder is on I'm getting noise/interference/something at the 5' to 6' depth constantly. It shows up whether the trolling motor is on or not, and no matter what depth. Both the motor and depthfinder run to separate power sources. Can anyone shed any light on what may be causing this noise to be there. I looked at the transducer and it looks fine other than some scratches. Could this be causing it? Any help would be appreciated. Thanks.

Sounds like it could be a bad line on the screen, did you try disconnecting everything but the graph? Does'nt really sound like a power issue or interference. If it it's inthe same spot all the time I would have to lean toward a bad screen

It might be that you have a nick in the cabling or a shield wire that's bad. Check your connections to the transducer and your fishfinder. Maybe you have a bad connection as well.

Thanks for the info guys.  I went ahead and sent an email to Lowrance to see if they could help as well.  They are saying it's possibly something bad in the transducer so they are sending me a new one to try out.  I'll let everyone know if that works or not in case anyone runs across it in the future.  

And just so everyone knows, it's not a consistent straight line or anything.  Sometimes it's darker, sometimes lighter and it bounces around from 5-6'.  Sometimes lower, sometimes higher.  

I'll keep you all updated.

I had a similar problem a few years ago. I had pinched the transducer cable in the trolling motor mount. The cable appeared intact however must have been damaged internally. Replacing the transducer fixed my problem. Hope it does yours as well......Al