788ci Losing bottom

[bomac]

Why is my 788ci losing the bottom? Updates current, transducer secure to bottom of boat, put transducer on outside of boat no help, changed transducer no help. It loses bottom when the boat is still or slowly moving on the trolling motor. Keeps bottom when running big motor at slow idle or up on plane. It happens everytime I take the boat out. Help!!

[SilmarilS]

Is it in shallow or deep water?

[bomac]

Both. I don't fish in water over about 30ft so that might still be considered shallow by some. But either way the Lowrance unit on the front of the boat doesn't lose the bottom while the Hbird is going nuts. And I tried turning the Lowrance off while the Hbird is lost and it didn't help.

[SilmarilS]

Normally unit perform fine up to 5ft.

in the 0-5ft range, you must do some tricks to have accurate bottom depth.

Set your surface clutter in the 8-10 range.
Then, lower the sensitivity down in the 1-5 range.
Next, you can try the Switchfire Clear Mode.
Final, you can set the unit to 200kHz only.


Surface clutter is important, since it dumb down the signal in the 0-10ft range to avoid clutter.
But it will also weaken the unit capabilities to fix the bottom.

Personally, I use a 778C which have the same 2D sonar portion as your unit.
I always run Surface Clutter at 10, Switchfire at max, 200/83.
And I change the sensitivity between 1 and 20 depending on depth.
0-5 ft around 1-5
5-30ft around 10
30 ft+ around 15 to 20 (always in MAX mode)

And the unit can track down to 0.7-1ft

Hope it helps

[bomac]

Thank you very much. I will try those setting and see if it helps. Thanks again!!