I have installed a fcv1100 sounder in my boat. It is hooked up to a 1 kw through hull transducer. This unit has many more settings than my prior 582 . My problem is i do alot off deep dropping in 600 to 1000ft of water. I just can't seem to get the fish to mark on the display. It marks bottom but no fish. I know the fish are there because I'm catching them. My question is does anyone have any general settings that they are using at these depths. The fish range from 1 lb black belly rose fish to 50 lb golden tile and grouper.