Echomap UHD 93sv - Side imaging dark and narrow?

[Functional]

Been noticing this and playing with settings to try and figure it out. I was going about 4-6mph with SI in 17FOW and noticed I could see maybe 50 ft out each side and then it got too dark to see. Tried playing with contrast and brightness and got maybe a few extra feet once both were cranked up to max. Got down to 5 FOW and I could see 100-120ft out with my original settings (around 50% contrast and 70ish% brightness). 

 

Is there something I'm missing? All imaging was run in the 1000kHz. Didnt think 17 fow was deep enough to cut image down to 50ft at 1000khz. 

[WIGuide]

Did you try changing to a lower frequency in deeper water? Also, what was the bottom composition in that area. Something very soft has a tendency to absorb sonar signals and not provide a very strong return which would look very dark on side imaging. 

[Fishingmickey]

Maybe running a bit too fast for a good return in deeper water? I have the same unit and never had a problem with the side imaging. I am fishing out of a kayak though, so not too much speed.

 

FM

[Functional]

9 hours ago, WIGuide said:

Did you try changing to a lower frequency in deeper water? Also, what was the bottom composition in that area. Something very soft has a tendency to absorb sonar signals and not provide a very strong return which would look very dark on side imaging. 

I feel like I did but can't recall for sure. I'll be sure to try next time I'm in that lake. As for bottom composition I couldn't say either. I fished mostly shallow and was just cruising around trying to get the lay of the land on a new lake. Could be it and never popped into my head. 

[WIGuide]

15 hours ago, Functional said:

I feel like I did but can't recall for sure. I'll be sure to try next time I'm in that lake. As for bottom composition I couldn't say either. I fished mostly shallow and was just cruising around trying to get the lay of the land on a new lake. Could be it and never popped into my head. 

Although nothing can be completely ruled out, I'd be guessing it has to do more with the bottom composition in combination with the frequency since it seemed to be reading just fine in shallow water. Maybe try idling around more on the same frequency and see if you can find an area with a harder bottom or if you can find some deeper rip rap you can check to make sure a harder surface is still giving you a good return. If that doesn't work, then try changing frequencies and see if that's the issue. 

[Functional]

So I got a chance to go out yesterday and water was like chocolate milk so I played with the sonar a lot. Here are some images, sorry for the glare, still learning how to take images to the SD card and upload them. I did notice my transducer seemed to be tilted up (back side towards sky) more than what I set it at so I lower it 2 clicks back to where I thought it was set. I think its possible the screw loosened up and when I'm on plane/WOT its causing the transducer to move adjustment. May look at tightening that up more, possible that effected the results today. 

 

These first 2 are at 12-14FOW and had a good return.

 

Both of these are at a different part of the lake/river and deeper at 26FOW. Still a better return than what I was getting on my last trip but clearly darker. Settings were the same as the images above. 

[Tennessee Boy]

It looks normal to me and mostly bottom contour related.   In that last image you have clear echoes at 80 feet then nothing.  I would assume that’s a ridge on the bottom and side imaging can’t see what’s on the other side or the ridge.  On some of the images you can see much more on one side than the other.  This is probably because the bottom is sloping away from you on the side with shorter returns.  Bottom composition could also play a role as has been mentioned.

[AlabamaSpothunter]

Looks perfectly fine to me, and I'm a Garmin user.  

[Functional]

yea, I have a feeling the ground was just really soft in the area at the other lake I was trying to scan. At 17FOW there I could only see out to the 40 mark before it was too dark to see anything. Next time I go I'll see if I can get a photo or screen shot to show the difference. 

 

I tried changing the frequency but at 800ish hrz the range cut down pretty far. 

[WIGuide]

They look pretty decent to me. 

 

Is the 800 frequency chirped too or is it just constant. Normally the lower the frequency the more range you have but less detail sometimes you have to mess with the settings though too. 

[12poundbass]

They look good to me as well. I watched a video a couple weeks ago Fish the moment, and Johnny was talking about side imaging. He explained that you need to take your depth and subtract it from your width. 
 

Example, your’s is set to 100’ each side. Your depth is around 26’, so, you’ll only be able to see 75-80’ out and it looks like your image is fading out around 80’. 

[txchaser]

That's not the bank on one side and just dropping off too fast to get a return on the other? 

[@reelChris]

8 hours ago, 12poundbass said:

They look good to me as well. I watched a video a couple weeks ago Fish the moment, and Johnny was talking about side imaging. He explained that you need to take your depth and subtract it from your width. 
 

Example, your’s is set to 100’ each side. Your depth is around 26’, so, you’ll only be able to see 75-80’ out and it looks like your image is fading out around 80’. 

 

It's a little more complicated than that but not too much so.  This page explains the math behind it.  It's basically applying the pythagorean theorem.  E.g.:

 

 

The device thinks it's seeing directly sideways when in reality it's looking diagonally. Therefore, you know the one leg (depth) and the hypotenuse (distance as measured by the device) and you solve for the other leg, which is the real distance to the object.  There's a bunch of online pythagorean theorem calculators you can use to calculate your true distance to an object like this one.

 

The important part of this is that if you put a waypoint using side imaging on an object, you're actually putting it further away than the object's true location on the bottom.  The deeper the object is, the greater the distance error.  

[Functional]

13 hours ago, txchaser said:

That's not the bank on one side and just dropping off too fast to get a return on the other? 

 

First 2 images im riding down the center of a arm that is about 300ish ft wide. What you see is elevation going up on both ends and I'm assuming getting too shallow to give decent readings at the far stretches. If I recall its only about 4-5ft deep off either shore line.

 

The second 2 images the shore is on the right and I'm not sure what happens on the left for it to end abruptly like that. It should either continue to gradually get deeper or be flatish for the part I was at. Definitely not bank though.