down imaging

**polarcrafter** · 02-21-2014, 11:38 AM

Does anyone have screen shots using down imaging sonar to show what bream/shellcracker beds would look like. I have seen them using side imaging; but was wondering if they could be found using downimaging.

**Cane Pole** · 02-21-2014, 10:26 PM

This is a poor mans down image. I wuz looking down when I tools the pic.

**genec** · 02-21-2014, 10:26 PM

most would be too shallow

**Billbob** · 02-22-2014, 10:21 AM

just P and the lake will rise

**cache22** · 02-23-2014, 09:15 PM

**CrappiePappy** · 02-24-2014, 02:03 PM

Originally Posted by polarcrafter

Does anyone have screen shots using down imaging sonar to show what bream/shellcracker beds would look like. I have seen them using side imaging; but was wondering if they could be found using downimaging.

Being as down image units are looking "~ straight down", it's highly unlikely they would show beds. That's not really what they're designed to do. Their main function is to show a picture-like image of the cover coming off the bottom, more so than the bottom itself. Now, it "could be" possible to get such an image from DI ... if the beds were on a fast sloping bank bottom, since the signal would be at a sharper angle. SI has a wider angle signal field, and would give a better "bottom" image .... as the screenshot from Cache22 shows.

... cp

**polarcrafter** · 02-24-2014, 06:51 PM

Originally Posted by CrappiePappy

Being as down image units are looking "~ straight down", it's highly unlikely they would show beds. That's not really what they're designed to do. Their main function is to show a picture-like image of the cover coming off the bottom, more so than the bottom itself. Now, it "could be" possible to get such an image from DI ... if the beds were on a fast sloping bank bottom, since the signal would be at a sharper angle. SI has a wider angle signal field, and would give a better "bottom" image .... as the screenshot from Cache22 shows.

... cp

Thanks for the reply and information, this brings another question to mind. If a degree cone that gives a 20 ft. coverage at 20 ft. depth using either 2D or DI equipment shows an object, can it be determined where the object is in the coverage; ie, 10 ft.left, 5 ft. left, center, 10 ft. right, etc????

**CrappiePappy** · 02-24-2014, 07:14 PM

Originally Posted by polarcrafter

Thanks for the reply and information, this brings another question to mind. If a degree cone that gives a 20 ft. coverage at 20 ft. depth using either 2D or DI equipment shows an object, can it be determined where the object is in the coverage; ie, 10 ft.left, 5 ft. left, center, 10 ft. right, etc????

Not really.

... cp

**BobB** · 02-24-2014, 07:23 PM

SI is your best bet

**rnvinc** · 02-24-2014, 10:02 PM

Originally Posted by polarcrafter

Thanks for the reply and information, this brings another question to mind. If a degree cone that gives a 20 ft. coverage at 20 ft. depth using either 2D or DI equipment shows an object, can it be determined where the object is in the coverage; ie, 10 ft.left, 5 ft. left, center, 10 ft. right, etc????

As the 2d is cone shaped...any echo target that appears at the right edge of the display can only be descerned as ..."x" ft away from the xducer-somewhere in that cone shape...(and the deeper the water - the bigger that somewhere is)...

As the DI is fan shaped...any echo target that apppears at the right edge of the display can not only be descerned as ..."x" ft away from the xducer...but also ...that echo target cannot be forward or behind the xducer...because the target must be in that fan shape that is 90° to the forward path of the xducer...

In a nutshell...when an echo target appears on the DI view...that target is either "directly under the xducer"
...or left or right of (and in line 90° with) the xducer a few feet...

Rickie

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