So I just installed a new Eagle 320 in the dash of my fish and ski. I have the transducer mounted on the back of the boat. It is level across the beam and tilts maybe the slightest bit forward.

Everything seems to be working correctly when I am moving. However, when I stop I get all kinds of garbage being displayed on the graph from about 5 feet to about 20 feet. It seems to get worse the shallower I get. I backed the sensitivity all the way back to 50% and the big clouds of garbage just get alot smaller. I also played with the grayline and it seems to do nothing for the problem.

I just replaced my old Lowrance x71 with this unit. The x71 was doing the same thing. I even tried to drop a 1oz slab down below the transducer and I can't see it on the graph.

I was thinking there may be something causing intereference but when I reached down and put my finger over the transducer I can see a blank spot on the graph from where I covered the transducer. That makes me think that there isn't any interference.

Does anyone know what may be causing this?

sounds like its working great. you need to understand how sonar works. when your still your getting the same image over and over, so a fish will then become a horizontal line or bait will become a constant cloud esp when shallow you can pick up any kind of air esp when runnining it 50% r higher in less than ten foot of water. just think everytime your unit pings it will show a pixel on screen from any air iterference, fish or not. over and over again...

So should I back the sensitivity down into the 50s? Right now I have no idea if there is anything under me when I am stopped or going slow.

For some reason, since the rains, I have been marking more junk in the water than usual.

I think 50% is too low for your sensitivity setting. I run mine between 75 and 85%.

Is your unit connected to the trolling motor battery? If so, that may be causing interference. Also, your main engine can cause interference. Try running the unit with everything else in the boat turned off. If the clears it up, try turning on each item one at a time. That will help you narrow down the culprit if its an interference issue.

Also, my front unit interferes with my back unit lots of time. Sometimes I can just reboot one of the units and the problem clears. When it gets too bad, I have to turn of my back unit to use my front unit.

Well, I still get the problem when my big motor is off, and all accessories turned off. The unit is wired into the fuse block on the boat which attaches to the cranking battery. My front graph is off and the trolling motor is off and I still was getting the interference.

Even between 75% and 85% I was getting just big globs of black under the boat. The cable routes into the boat through the main grommet for all the controls for the big engine. So the cable runs beside all the wires for the big engine controls. But I get this problem only at slow speeds or with the engine off.

I might try running it directly to the battery, fuse in line of course.

Anybody else have any ideas? If 50% sensitivity is to low then I wonder if something else is wrong. If this is just the way it is I don't know how I am ever going to differentiate brush or fish from all the other garbage.

bigdad brought up a good point. if your lake just came up a bunch you will mark a ton of suspended particulate and debris. what depths are you getting this at and will it show it on auto? which unit are we talking about?

You might try adjusting Surface Clarity and Noise Rejection. I usually run both of these on Low.

This a brand new Eagle 320. On Auto sensitivity it seems to be even worse. I was on Lavon which not only is way up but they are letting alot of water out.

I tried upping the Noise Rejection to medium and that seemed to help a little. If this is something that has to be dealt with until the lakes stabalize that is fine, I am just concerned that something is not set up correctly.

Could the wires for the main engine be causing the interference even with the engine off? I did put my hand over the bottom of the transducer and the finder painted nothing on the screen while I had the transducer covered. To me this would suggest that there is no interference.

Big Poppa,
Here in Australia , we have a little gem call Ferrite Irons, these are similar to what you will see on Digit Cams / PC interface cables, they are in line suppressors, you can buy them from electronic stores here Call Dick Smiths. They are reasonably cheep, starting around 4 Aussie dollars, they just simply clip on the Power side of the wires.
Strange thing to me is that it was an issue with your last unit too, Was this an on going concern or did it just pop up?

Whats my chances of a Pic of your set up?, Maybe with a ruler along the Hull, so we can see the angle and depth of the 'Deucer. lt could be a position issue with the 'ducer it self
Option #2
Does the Transducer Cable travel down the same side as your Power Cables? Being LHD , that would be your Port Side, if so
re-route it down the Starboard side.
Option #3
It could be Bubbles from the Prop. The 'ducer Maybe too close or it could be on the up Stroke and not the Down Stroke, this is where we need a Pic.
Option #4
Hopefully you don't get offended with this, But do you have the Battery Poles to the Sonar correct?
IE: Positive ->Positive/ Negative -> Negative

This is a link to a Ferrite Iron.
Good Luck, & let us know how ya go

http://www.dse.com.au/cgi-bin/dse.storefront/46a852c60610f8e62741c0a87f9c072a/Product/View/R5124

Lavon can be a very dirty lake. I was out Sunday evening playing with a new 997 Humminbird. I would flip between sonar and side imagining. At a couple locations, on the side imagining I would see plumes of ??? coming off the bottom. Looked like a spring putting out water. Before I spent a lot of time making adjustments, I would suggest taking a trip to Hubbard. Even though Lavon feeds Hubbard, for some reason it is a always lot clearer.

this is what I would check--