Ok, for the problem of bouncing depth between 0-10ft...
First thing to check is that you have the SwitchFire option to CLEAR. (max over 15 ft+)
Next, use a Surface Clutter between 6-10.
(A too low setting will mess the depth reading because the surface clutter option diminish the 0-10 ft return signal strength)
You can also lower your main sensitivity to around 10.
And last, you can set the unit in 200 kHz mode only. Not 200/83.
Since the 83 kHz signal is not that precise in the 0-10 ft range.