I recently purchased a Terrova with I-pilot, I-Link, and US2 Transducer. I have this linked to my Humminbird 859ci. However, when I have the system powered up and the fish finder on, the depth will read one depth, then jump to a deeper depth and display a second depth level on the graph. For example, I will be at 20 foot of depth. The graph will read 20' then 40' and at times 60'. The graph will also display phantom lake bottom with each false increase in depth. Almost like multiple layers on the display. Are there any settings that can be changed that would prevent this annomaly and make the system more accurate? It sounds crazy but could the signal be so strong that it is bouncing off the bottom, back to the surface, back to the bottom and back to the surface?

Try setting the depth manually to about 5' deeper than the actual depth. Are you getting multiple bottom returns at the same time, could be you are on a hard bottom. Does displayed depth change also? Also try decreasing sensitivity.

Several reasons that this may be is occurring. If you are on Max Switchfire, set to clear. Also, try turning down your sensitivity on the unit. I would leave the depth setting on Auto. In extremely shallow water, this will be the result on the unit receiving the echo return so quickly.

I toyed with the sensitivity a little. I was first thinking the signal was stronger from the US2 than the stock ducer creating an echo so the sensitivity was the first adjustment. It was and still at 10. I'll look at this more when I get it out next. I had adjusted the max depth to fit the water depth I was fishing in, and the depth reading kept moving around. Only with the max dept, it prevented the additional false returns / echo from showing on the display. I prefer the auto though.

Yes the display change simultaneously with the depth and infished both rock bottom and grass / mud and was getting the same phenomenon.

Max switchfire.. that's new to me so I'll research that more.

I'm seeing something like this with the multiple layers.

It looks a bit like the Switchfire is on max, turn that off and you will see some benefit. Adjust your Surfsce Clutter down to 2. In clear mode the sonar will filter the results and give you a more clear and correct echo return. In clear mode, a large arch is a large fish. In Max mode, the echo results are not filtered at all. Therefore the results are raw and appear heavier and it produces the heavy color band at the surface. In Max mode, a large arch does not mean a large fish. If you are in an area and want to see everything in the sonar's frequency, switch to Max briefly, and then back to clear. Switching to Clear should assist in reducing the extra bottom, but it will not eliminate it. Expect to almost always see the extra bottom, that is just a byproduct of the sonar in shallower water.

I like to see the second echo of the bottom. I would set the sensitivity on about 7 or 8 and see what it looks like. Also as suggested put the dept on auto. I set the chart speed at the speed of the boat. But have been setting it faster when looking for brush piles. If you set it at say 75 and hit 77 it will start acting up.

Thank you all for the feedback. I will get back with you on results after I take it out next. The switchfire option that probably will help as I have never toyed with this. I was wondering why the bottom return was not as clear as a friend who has the same unit.

You get those multi-bottom echoes when you move to deeper water and the depth range changes.

Move from deep to shallow and you loose the recorded bottom when the depth range changes since the deeper depths are not within the depth range.

Nothing wrong with what the unit is doing with the bottom echoes. The multi-bottom echoes will not be there if you stay deep and the recorded shallower history scrolls off the left side of the display.

Same thing with the thermocline also recorded:

Man, I wish I had it dialed in to a point where I could see the thermocline that clear.

There was no "dialed in" with that screen shot. It was the default settings with a Humminbird 798ci SI Combo.

Ok I've done some tinkering with no success. The switchfire is on clear, the transducer is set to DI 200/455 kHz, and now aft r resetting to default settings, I now have a temperature reading above the water. You'll see actual photos of the screen as it is switching between the depths as I sit in 5 ft of water.

Are you using the US2 with a DI transducer setting?????

The US2 does not have a Down Imaging crystal and it is not tuned to 200/455 kHz. The US2 is 2D sonar at 83/200 kHz.