Sonar Quiz #24

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Originally Posted by kosmo

It's an empty river barge.its down in the water about 1 ft.thats why there's no shadow in the shot.my transducer is mounted on my trolling motor and I'm moving it slightly as I'm going by the barge and that's why it's not showing a straight line.

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Ahhhh..........I see said the blind man.

IF I UNDERSTAND U RIGHT RICKIE, I THINK THE ROPE TO DRIFT SOCK IS STAYING IN SI BEAM ALL TIME

If I am figuring it correctly isn't it 30" in diameter? Maybe that is something else to address, how big is the actual object appearing on the snapshot?

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Originally Posted by vic n

I think that as Spearfish III is trolling, he is making course corrections, which causes the wind sock to drift in and out

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Quote:

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Originally Posted by Redge

Because the sock is moving left to right? Ie steering corrections?

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As we don't really know how Spearfish III trolls for trout ... We can't be sure if the sock is moving away from the xducer (maybe sinking with no float)... or the xducer is moving away from the sock (as the boat turns)...

We can be sure that the distance between the xducer and the sock is changing ...

Rickie

Okay....now let's talk about the shadow. I was over on BBC and saw virtually the same shadow on another SI shot

I don't have a clue on the shadow! Looking forward to learning something new.

"Dark lines" aka "Ghost Lines" aka "Washboard lines" anomalies show up in side scanning images most commonly in examples of side scan images captured while using an xducer that has both "side pointing" SI piezoes and a "down pointing" DI piezo ...

LSS 1
Attachment 274211
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LSS 2 (not as prominent but still there) ...
Attachment 274212
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Onix
Attachment 274214
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Garmin
Attachment 274213

Overlapping slice beams can create an effect similar to this beam form example which end up showing in the SI image as the dark lines ...

Attachment 274215

Rickie

Thanks Rickie!!

There is another SI anomaly that shows up sometimes as a matching left and right SI dark line called the "null sector" of the beam form ... But it's usually less prominent and not necessarily in an xducer with both "side pointing" SI piezoes and a "down pointing" DI piezo ...

Attachment 274216

Rickie

That's what I thought...:biggrin