OK figured out what is going on as long as I stay in 40 feet or less of water my sonar screen stays as it should no matter what speed I go . BUT when I start going over 40 feet deep and above 8 MPH the lines start and at 50 feet deep entire screen is almost black with lines top to bottom of my screen. When I get into water under 40 feet or do just 8 MPH the screen clears up.

Anyone have any ideas changing the sensitivity and scroll speed makes no difference?

I changed the sensitivity but when on high maybe get 1 more MPH before the lines appear. I mounted it on the right side of the pontoon and underneath still get the lines.

Have to figure it out or it is worthless to me.

I had a small nick in my prop so put my spare on will try it Monday and see what happens do not think that will make any difference.

They are horizontal bottom of screen to top covers the entire screen.