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At the begining of the season I purchased a new depth finder. I thought that the price and specs. would give me what I wanted. I have been very disappointed with it's performance. I also downloaded a video program that simulates it's operation. (For practice).I use the manual operation when I fish. I never get any fish arches,and srtucture and (fish?) show up as solid black blobs. It seems it's impossable to distinguish what these displays are. I thought a large pixel count would give me the detail I need, 480 by 480. If I get blobs off the bottom, I'm hoping I'm looking at fish. So basicly all it's good for is depth, alot of blobs on the bottom, and water temp. I've emailed Eagle with no response. Does anyone have any tips on how to correct it or how to interpret the readings? Any info. would be greatly appreciated. Carl

Carl,

Don't throw out your unit yet...

Assuming that your unit has been installed correctly and you are not getting interference from your trolling motor, gas engine or other electronic devices, the following should help:

Understanding your electronics is a very important part of fishing. The most important feature you can learn to use is your unit's "Sensitivity" or "Gain" control. If your gain is not turn up high enough, you won't even pick up fish let alone baitfish. If you are going to start playing around with these settings, the first thing you need to do is find out how to turn off your "Fish ID". The Fish ID lets your unit decide what is or is not a fish. Turn it OFF!!! Then start playing with your gain. Start by turning up your gain to the highest setting and slowly backing it off. It usually works best somewhere between 95%-100%. If you want to know what rocks look like, find some visible shallow rocks and run over them with your transducer. Same goes for wood. Fish will appear as arches which will vary in size, shape and even grouping. Bait fish look like a blob on the screen. (That might have been what you have been seeing, but I would need to see it myself to confirm).

If you have any friends who are good with electronics, ask them if they would mind taking you out and showing you a few things.

When all else fails, spend some time reading your manual.

BC

If your screen ever looks like this, you've hit the mother load!!!



These fish are actively feeding on a point (could also be a hump). See the arches making contact with the blobs and coming in contact with the structure?

Carl,

I probably should not be posting this as I work for another depth sounder company (Humminbird) and I am not on the Prostaff… but I couldn’t pass up the opportunity to help someone (it’s the Boy Scout in me – do a “Good Turn Daily”). I’m not singling you out here but am just taking the opportunity to pass one some information that I hope you and others will take in a positive way.

Most fishermen don’t understand what they are seeing on their depth sounder and think that buying the latest, greatest, and most expensive one on the market will give them the magical ability to see what is under their boat. This is far from the truth as a depth sounder is just another tool to be used and abused by fishermen. Unless you take the time to use any tool properly, you cannot reap the benefits of it. A new depth sounder is no different and can no more help someone catch more fish than a new rod & reel if they don’t take the time to learn how to use it. While I am unfamiliar with Lowrance/Eagle depth sounders, the basics and principals of all depth sounders are the same.

A fish arch forms as the depth sounder’s transducer moves over the fish (or the fish swims through the depth sounder’s transducer beam). Due to the transducer beam angle the distance to the fish decreases as it moves into the transducer beam, and then increases as it moves out (thought you would never use that Geometry you had to take in High School didn’t you!). When the depth sounder graphs this distance change, an arch appears. The true depth of the fish is the top of the arch when the transducer is directly over the fish. Boat speed and movement greatly affect the shape and formation of an arch. When moving slowly or with a high rate of display update speed, a fish will create an elongated arch or possibly a horizontal line. With the boat moving at a fast speed or with a slow display update speed, the same fish will produce a much shorter arch or possibly appear as a ‘blob’. If the fish does not pass through the entire transducer cone angle, it will be shown as a partial arch. In any of these instances, the user may not recognize that the fish was shown as an arch. I wrote a document that contains additional information on this. Although written for Humminbird, most of it should apply to your Lowrance as well. Send me an e-mail if you would like it ( [email protected] ).

The best way to interpret what you are seeing on a depth sounder is through experience. Brendan is right; you need to go to an area that you are familiar with and watch what the depth sounder is showing you as you pass over various bottom types and structure. You can also use an underwater camera or the most low-tech depth sounder of all - a few ounces of lead and a treble hook on a really stout rod with heavy line! Don’t laugh, as this is still one of the best ways I’ve found to confirm trees in deep water on a stained lake.

You should also consult the operations manual for your FishMark 480 as well as the Lowrance and Eagle web sites for their Sonar Tutorial.


Greg Walters at Humminbird

Greg,

Thanks for sharing your knowledge... Feel free to post your hummingbird document here on the board if you like.

BC

Thanks for the info. guys. Brenden, when you refer to gain I'm assuming that's the same as sensetivity. I'm going to take the boat out and work with all of the suggestions today. Thanks again, Carl

Greg, Thanks for helping us out, I know for a fact your an expert and expert advice is always welcome. Thanks again, Johnnie Crain

Brendan,

The document is already posted on our web site at: http://www.humminbird.com/generic2.asp?ID=412
Look for the “No Arches” link under “Fish Depictions”. There are other troubleshooting guides here as well that can apply to all depth sounders. Other manufacturers may call the same features and controls by other names but they are all basically the same.


Johnnie,

Thanks for the vote of confidence. I guess I’ve learned a little in my 22 years here at Humminbird but I don’t consider it enough to be called an expert. Lately though, I’ve been labeled an ‘expert’ trolling motor installer here as we have had to change over to all Minn Kota’s on our company boats. About the only thing I found I’m expert in is smashing my thumb with a hammer! Did a nice job of it too, all those pretty colors like black, blue and green… Oh yeah, the trolling motors work perfectly.

When I’m not busy smashing my fingers, I help where I can!


Greg Walters at Humminbird

Greg, I've installed a few trolling motors, but never used a hammer-LOL. A drill, nuts and bolts work well too! Good luck, JO)hnnie :p

Carl,

Yes, gain and sensitivity are one in the same.

Greg,

Thanks for posting the link.

BC

Thanks one and all for your help, because now I have a sonar unit that works, fish arches and all!! You gents have made my summer. Carl