Humminbird 570 dual beam questions

First off, this will be my first post, I've been a member for a week or two, I've just been reading and enjoying all the knowledge. I would like to say what a great site this is and would like to express my appreciation for all the posts, tips and stories. I found out about the site from a post on Arkansashunting.net, I cant recall who posted it over there but thanks to whoever that was. I'm a fisherman but I'm lacking in crappie knowledge, I didn't really get serious about them until last year and I have a lot to learn. Now that duck season is over and turkey isnt here yet I'm ate up with the crappie fever....problem is I'm just not that good at catching them yet. This website is helping.

Excuse the rambling and on to my question about sonar:
I have a Humminbird 570 dual beam with a transom mount transducer, it is about two or three years old. It seems to work great 10' and deeper. I've been getting frustrated with it lately (and last fall), I feel like its lying to me on depth sometimes in shallower water. It'll read 3' or less and I cant touch the bottom with a paddle. Sometimes it'll go from 7' to 2' and dance all around in the same general area. I think that may stem from some really soft silty bottoms? It'll show structure but sometimes I can never find it with a jig. Also, I can go over the same spot and never get the same looking structure/bottom contour. I am not that knowledgable about sonar untis, settings, reading them etc but I have been reading the wealth of knowledge on here. Are the issues above just to be expected, am I looking at this all wrong? I dont know if there is a software update for my unit? I also wonder if the dual beam has something to do with it. Am I picking up brush that is not directly under the boat? It is my understanding that the 20 degree beam lays out the bottom detail and the 60 degree beam shows fish in that cone and not structure or bottom detail, is this correct? The sporadic depth readings in shallow water really frustrate me, any thoughts on this?

Both beams show the bottom,fish, and structure. The 83 hz 60 degree beam does not show the bottom or structure with the detail of the 200hz 20 degree beam. There is a view that show the 2 beams in split screen, this should help you know what is directly under the boat 200 hz 20 degree beam and what is off to the side 83 hz 60 degree beam.

In the bottom type you describe setting the unit to just the 200 hz 20 degree beam and reducing sensitivity will help it lock to bottom better. This can be done in the Sonar menu. Also you can try increasing the noise rejection.

Where is you transducer mounted? Is it hooked to the same battery as trolling motor?

Make sure that you register the device with humminbird.
Once you do that, and set up an account, the website will let you know if an software update is available.
Looks like that model does not accept SD cards so you would need the PC interface kit (AS PC2 or 3) to upgrade software.

On my 700 series the upgrade helped in shallow water but the upgrade did included switchfire.

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Where is you transducer mounted? Is it hooked to the same battery as trolling motor?

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- carolina jim

My transducer is mounted on the transom according to humminbird's installation instructions and is powered by my optima cranking battery.

I'm not sure how to show the split screen or select the narrow beam only as you describe, it is not covered in the operations manual.

WE16,
I'll try that, thanks.

If you stir up the bottom (mud) it can give a false reading sometimes.

uaagr, sorry I just checked and that model does not have either the ability to turn off 83 khz or have split screen 83/200. I figured since my 365 has it a 500 unit would have it. So try turning surface clutter as high as it will go, then if not holding bottom start turning sensitivity down 1 notch at a time until it holds bottom.

uaagr, everyone who has ever owned a 2d sonar unit has had the same issues with seeing what seems like structure, but later couldn't find it with a jig. That's why the new down imaging and side imagining units are so popular now. The 2d sonar makes it a little tougher to distinguish between bait fish near the bottom and actual structure. It's not really that big of a problem, everyone caught tons of fish with these 2d units. It just takes a little more trial and error. Just keep trying to find the brush your seeing on the screen with something heavy enough to get down into it. Once you get over some brush that you've proven, try to adjust your settings while you pass over it and fine tune your unit. As far as never seeing the same return twice as you pass over it, those things happen when its bait fish or brush. You're never going to pass over exactly the same spot twice, so the sonar will look slightly different each time.

I have the 570 front and back. The best thing to do is play with the sensitivity settings (see what you like best) as well as clear or max mode, and keep the switchfire on. Depending on the type of water--muddy or clear--you will want to change the sensitivity settings based on that. The 570 is a very simple unit and not much to mess with--but playing around with all the settings will help alot.

Thanks for all the thoughts guys. I checked my unit online and it doesn't support the software updates. Also, my unit is between an 07'-09' so it doesn't have switchfire either. I did call humminbird to ask a few questions and the lady told me that TVG was the same thing as switchfire, they just changed the name. She said play with my settings under TVG, I dont recall ever seeing the TVG on my menu, but I'll put it in simulator mode tonight and play with it, see if I overlooked it.
Let me run through this and let me know if I have the right idea: when I'm messing with the sensitivity settings, I should turn down the sensitivity in shallower or muddy/murky water and in muddy/murky water the surface clutter should be lower to help hold the bottom? A side question, why would you ever want surface clutter on high, why not always have it on the lowest setting? In a week or two, I'll be getting a lowrance unit from a buddy to go upfront on my trolling motor, that should really help me while actually fishing off the front.
Once again, thanks for the discussion. I feel like a little kid asking why why why with all these questions, just trying to absorb as much knowledge as possible, thanks for putting up with my stupidity.

There have been some software changes over the years for the 570 unit but whether your unit would work better with these I do not know. Do you know what software version is in the unit now? The last software released for the 570 unit is version 5.890. You would have to ship your unit into Humminbird to get this software upgrade.

I would instead try setting the Surface Clutter menu to a higher numerical setting (lessening the amount of surface shown) and/or setting the Water Type menu to the Salt (deep) menu setting. Also make sure that there is no other sonar unit running on your boat at the same time.