Lowrance HDS Fish Arches

[jestfishin']

Hey Guys (and Gals)! Just a quick survey about a problem I'm having and I'm wondering if any of you are having a similar problem. I have two Lowrance HDS units. A 10" model in the back of my boat and an 8" model in the front of the boat. Both units work fine....maybe too fine. I'm getting a ton of fish arches painted on my screens when I know for a fact that there aren't that many fish below me. I've heard rumors that Lowrance has 'enhanced' the number of fish displayed on their screens to make their units appear extrra sensitive, in order to sell more units. Can't prove that for a fact but I'm just wondering if any other fishermen are coming up with a ton of fish on their screens and might be a little suspicious about the number of fish???

 

[Harpoon]

What does the Structure Scan show? I know that the sonar is exaggerated some . This is how it works .Other brands show the same swooshing arc and in reality there is one fish at the the top of the arc. This is why I love the Sscan. It cleans things up and shows a more defined pic of whats going on down there with no froo froo.H

 

[Full_Monte]

Your observations are not unique. I have a friend who regularly tests fish finders side by side in his boat to see what different ones will do. Lawrence apparently assigns a fish arch as a "default" on any reflection that isn't bottom.
That's why I have a hard time differentiating between a school of fish and a tree standing on the bottom of a reservoir. Not all fish finders do this. It's just what Lawrence seems to do. Maybe it's good for business. Time will tell.

 

[jestfishin']

What does the Structure Scan show? I know that the sonar is exaggerated some . This is how it works .Other brands show the same swooshing arc and in reality there is one fish at the the top of the arc. This is why I love the Sscan. It cleans things up and shows a more defined pic of whats going on down there with no froo froo.H

The structure scan shows nothing, no fish. Jestfishin'

 

[Bluknight]

I have the HDS 8 as a new unit on my rig and experienced the same thing. I saw so many fish in the water the first time out I figured I would drop the anchor to 30 feet and drive around to knock them out!

I decreased my sensitivity to -5% and this seems to have helped a bit. Out last week and was more confident that what I showed on the boat were actually fish. I have not been out for kokes yet so that my be a whole new issue when I start.

Does your friend have a work around for the ghost fish?

 

[jestfishin']

I have the HDS 8 as a new unit on my rig and experienced the same thing. I saw so many fish in the water the first time out I figured I would drop the anchor to 30 feet and drive around to knock them out!

I decreased my sensitivity to -5% and this seems to have helped a bit. Out last week and was more confident that what I showed on the boat were actually fish. I have not been out for kokes yet so that my be a whole new issue when I start.

Does your friend have a work around for the ghost fish?

I've contacted Lowrance about my 'problem' and here's their two responses:

1. "What speeds is the boat moving at when you notice this to be non-accurate? Have you stopped your boat and just let the sonar page scroll? When the boat is completely stopped, you will not get arches. The fish will come across as a horizontal line until you or the fish moves away and the fish is no longer in the transducer cone." I replied that my trolling speed was approximately 1.0 to 1.5 MPH and their reply was;

2. "In order to minimize the fish arches on the screen, you will want to set your scroll speed to high. If the return is a very solid and bright color, you will want to reduce your sensitivity setting."

 

[Ken Sauret]

Lowrance does not "enhance" anything on their sonar return to get more of anything. If it shows up on the screen, then the sound "ping" hit something and it is showing on the screen. If the algae, thermocline, current or whatever is in the water is interfering with the ability to see fish then your sensitivity is set too high.

Take your boat to a very clear lake and drive over trees, brush, rock piles, cables anchoring docks, etc. and see how they are displayed on the screen. Be sure to go right over the top of these objects, off to one side or the other and observe how the unit displays these objects. It's kinda like learning a new language, when we learn how to interpret the image when we can see the bottom and know what's down there then when we can't see the bottom we will have a better idea of what we're looking at. On the HDS units use the 200 khz in shallow water, under 30 feet or so, and switch to 83 khz for deeper water. The colors change but fish show up better in deep water on 83 khz for me.

With the 455/800 khz transducer on the Structure Scan fish show up as small white marks more to actual size in comparison to the brush or surrounding objects in the water. They are still there but it takes a little while to learn what they look like.

These are two separate types of sonar both intended for different views of the water column and the bottom.

 

[jestfishin']

Thanks for the advice Ken. I’ve basically done what you’ve suggested, using the 200khz for shallow water and 83khz for deep water. These two parameters are what the instruction manual s suggested also. And I’d like to make something very clear; I’ve very much enjoyed using Lowrance products for more than 20 years, but I’d just like to find out if other Lowrance HDS users are experiencing similar indications that I’ve had with my new their HDS units, and apparently some have. I’ll be the first to admit that I haven’t driven over known brush piles or anchoring docks so I really don’t know what those objects would look like but I have fished in Lake Tahoe, one of the clearest lakes on the planet, and in 20’ of water marked multiple fish on the finder when I knew for a fact that there were no fish below me or within a short distance around me. I also must admit that practically all of the time my sensitivity is in the “Auto” mode. Perhaps that’s my problem. I don’t know. That’s why I’m asking. Attached is a photograph taken on a Montana lake last year. My new 10” HDS happened to be in the photo. If the photo can be blown up enough, I hope that you can see that my unit indicates that I’m in 285’ of water and trolling at 2.1mph. I also hope you can see that there are fish arches, a TON of them, extending well down into the water column, well beyond 125’. Trust me Ken, there weren’t that many fish below me, around me, or above me.

 

[Harpoon]

Jestfishin , are they arches or slashes all stacked up on one another? If the scan down and side show no fish there no fish. H

 

[jestfishin']

The fish arches go all the way across the screen and depending on the depth, go about 1/3 to 1/2 of the way down the water column.

 

[Fallriverguy]

jestfishin,

At another fishing site (http://www.ifish.net/board/showthread.php?t=341764) I posted a pictures of my new Humminbird. It show schools of kokanee with feeding bull trout below them. Below my initial post someone posted a picture of their HDS showing a similar picture. If you look at both of them, they seem to be telling the same story, but the HDS has fish arches that are very pronounced. It, in my opinion, it looks a little cluttered.

 

[Bduck]

On my X100C the manuel states, "Zooming" the display is a common, fast and easy method to enlarge small detail, fish signals and the bottom with its associated structure. Also by using fish arches, it helps for you to determine the size of the fish. Adjusting the sensitivity to an appropriate setting will cut down on clutter. My Lowrance is an easy system to use and the sophistication it was built with makes it easy. It'll be a while before I switch to a newer HD unit until there units starts picking up more positive notes. Its just a matter of time.

 

[jestfishin']

I hear what you're saying Bduck. I had a Lowrance LCX-111cHD for years but when I went to upload current files the thing "crashed" on me. After many calls to Lowrance it was finally determined that it needed a new off/on switch........which they no longer stocked! Gotta love it!! Once you've had that 10" screen it tough to go back to anything smaller. Oh yea, by the way, that old LCX unit never showed 1/4 of the fish arches this new HDS displays. Hmmmm.......

 

[ReelJerks]

Can any of you guys post screen shots? Take this pic....

We slammed the Kings here for a while.

It's not ridiculous to think you are looking at a recording, if in fact the 'Simulator' was ON, and I'm pretty sure this is not the case here. But to think sonar arches are pre-programmed to enhance the screen view would suggest a miss-understanding of how sonar works. I may have missed it in this thread, but I don't recall anyone mentioning where their HDS is set. That would help also. I'm a guy who can't stand factory settings or automatic modes, when in fact you can make changes. These HDS units are so powerful that I had problems at first also. To fix it, I spent a couple of weekends at the lake WITHOUT ANY FISHING GEAR. I went to an area I know to be flat and used buoy's and rigger weights to set up suspended targets. Then I started fiddling with settings until I got what I wanted. Believe me it took 2 weekends for me but some of you may get it done in one or less. Now, no matter what lake I go to, no matter how turbid the water or how much trash, I understand what I am or am not seeing.
These problems can be as simple as 'wrong transducer selection'. My suggestion is to spend time on the water with the HDS on AUTOMATIC. Turn on 'Screen Capture', and drive over your suspended targets, and take some captures. Then do it all over again and play with the manual settings until you get what you really want, and compare these shots with the screen shots in automatic mode. Then re-post with screen shots for more help.

Remember that if you start fishing, you will fish instead of school yourself on your HDS.

I hope I helped a little,
Edd