Thread: Sonar quiz #2

I think I no,but I'll wait

Another hint...

This snapshot was taken from my 1197c SI ...(the DI in my SI unit is from the SI piezoes so this structure was actually in my SI beam)..

Rickie

Is that really the top of the structure or is it just as far up as the 800khz will show

Originally Posted by kosmo

Is that really the top of the structure or is it just as far up as the 800khz will show

I'd assume it's the limit of the beam. Notice how you can see the waves on top as the beam moves up and down with the boat.


I'm curious if the left side of the image is downstream.

You guys are on the right track...and you actually answered Sonar Quiz #3...

Here's the depiction I drew up showing how the 800kHz (130° total coverage SI beams) scan a very tall structure...

Like kosmo and CatFan deduced...the uppermost part of the bridge piling is above the "reach" of the 800kHz SI beam... And the fact that the piling is approximately 10ft away from the xducer before the SI beam even hits the piling ...



(And the left side of the DI image is "downstream" ...as you can see the catfish hiding behind the piling in the eddy created by the bridge piling)...



Great sonar sleuthing guys ...

Rickie

So if you had been on 455 would it have shown all the way to the top? I never would have thought that thing stuck out of the water as tall as it does.

Rickie,if you had it on 455 it still would not have appear to go to the top of water even though it would have been at the top,what i am saying is the distant you are away would show up as depth in water,like 15 feet away would show up as 15 feet deep ,right? Just would not been wavy at top?

Originally Posted by genec

Rickie,if you had it on 455 it still would not have appear to go to the top of water even though it would have been at the top,what i am saying is the distant you are away would show up as depth in water,like 15 feet away would show up as 15 feet deep ,right? Just would not been wavy at top?

I'm pretty sure this is correct even tho I haven't scanned the piling with the 455kHz...which is on my list "to do" when I get back to the piling...

I guess I should have added that in the depiction somehow about how distance to the piling also shows as depth in a "DI from SI" image in the HB SI units....(so it's probably a combination of both beam reach and distance to the piling that makes the structure "not look right")...

Rickie