DFF1-UHD/B275LHW: maximizing deep water capability

[southatlantic]

Hi Snips and Johnny,

I have the above combination, well installed by a competent installer. Overall, I am very happy with it. Up to 600 ft or so, it is outstanding, showing individual fish images where before (I had the DFF1/B270W) I could only see a school of fish.

About 30% of my fishing, though, is in deeper waters... up to 2100ft. This weekend I had the chance to get to deeper water ( 1550 ft) for the first time with my new sounder/ducer. I was able to track bottom OK, but the digital readout got lost (it did not go off, it just showed inaccurate, lower depths) above 1200 ft or so. I attach a picture of what I was looking at: (note: the depth is set in meters). It shows the bottom at 480m, but the digital readout says 332m.

I had the UHD in manual, LF, with 15% clutter rejection.

Any tips to help me optimize the capability of the unit at these depths? I would ideally like:
- Digital readout showing correct depth
- The ability to see fish at least in the top of the water column ( top 120 ft or so).
Thank you! :furuno

 

[southatlantic]

 

[Snips]

Southatlantic,
The digital readout is independent what you see on the display. The digital readout is controlled by the Bottom Level setting, normally we like to set this at -20. The more minus the number the more sensitive the digital readout becomes and sometimes if you set it to low it can start jumping around. You screen shot is showing interference. Do you have another sounder running, if so I would turn it off to see if that helps the digital readout.

Snips

 

[southatlantic]

Thank you, Snips.

I do not have another sounder running. The weak spots and vertical bars only show up at high gain - which I needed due to the depth. Is that interference or clutter? Should I use the Interference Rejection to get rid of them? Or is it clutter, from plankton or particles in the water? Is increasing clutter rejection better than reducing gain?

I did, briefly, try to set bottom level at -20 (you had advised me on this for my previous, DFF1, sounder), it did not seem to help. The digital readout does jump around a bit, as it is. But perhaps I had not tried for long enough. Will play a bit more with the bottom level setting the next time I am in deep water (in more than one sense...).

 

[Snips]

Southatlantic,
Those marks are to random to be clutter, if it is not from your vessel were you around other vessels? If your not using interference rejection you may want to try it.

Snips