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Reading a fish finder for dummies??

Discussion in 'The Lounge' started by KSUFLASH, Jun 22, 2004.


    KSUFLASH respect our rivers please

    Hey guys, now that I have a fairly nice Eagle Fishmark 480, I am wanting to learn to read and comprehend what the finder is showing me. I used to turn on the little fish symbol feature and just watch little fishes pop up on the screen. I get the feeling this feature is lying at times, and it might not be a fish, but rather something else in the water. I have a few questions.

    1. If I am not moving, would I seen any fish arches on the finder when anchored?

    2. With all the bells and whistles on my finder, what are the typical sensitivity settings you guys use?

    I have used fish finders for only about 2 years now. I pretty much don't know how to really read what they are telling me when I have it set to show me the actual echo returned, aka the arches, rather than the fish id feature. I am almost tempted to take the boat out with no fishing gear, and just put around and try to teach myself this sonar thing. I have read a few things online, but when I get on the water, I forget it all.

    My finder is a really nice unit, nice big screen, and the resolution it shows is excellent. Now if I could just figure out what is what.


  2. Lundy

    Lundy Staff Member

    Hi flash,

    Welcome to the 21st century.

    What did you do prior to having a fish finder, stick your head under the water and look? :D

    Arches dipicting a fish on your screen are created by movement of either the fish or your boat. The arches are created as a fish comes into the outside edge of your signal cone. The return signal strength is at the weakest at the outside of the cone. As the fish swims more to the center of your cone, or your boat drifts across a stationary fish, the returm signal increases in strength creating the top heavy section of the classic arch. As the fish continues swiming through to the outer edge of the cone the signal strength decreases and the back leg of the arch is created.

    The actually have the all elusive classic arch show up everything must be just right. The fish must move through the signal cone at a fairly high speed, and maintain that speed from beginning to end. If it were to enter the cone edge and swim to the middle, while you were anchored, and then stop, your screen would show a contineous flat horizontal line.

    I worry less about arches and more about any return showing above, or right on bottom and the intensity (grey scale) of those returns. Arches are pretty to look at, but really don't mean a whole lot.

    I would suggest that you visit the Lowrance web site. They have some great information in there.

    Doctor had also posted some great stuff on reading a depth finder on the OLD site. I don't know if he's posted it here yet or not. It's probably available on his site as well.

    see ya,
  3. KSUFlash,

    I never believed in my electronics as much until I started fishing Lake Erie. The combination of fishing in the clear water and also using an underwater camera has made a believer out of me. The more I fish up there the more I become familiar with my Lowrance electronics. It's easier to get the hang of up there since you have clearer water and can use the underwater camera. If you know of anyone that has an underwater camera go with them and then relate what you see on your finder to what you see on your screen. If you don't have that luxury sometimes you gotta fall back to the old, tie something heavy like a 1oz sinker on there and then drop it down and feel/see what your seeing on your finder. Then ask yourself, Am I pulling up weeds, does my sinker stop abruptly, does it feel like a mushy bottom, does it feel rocky, does it feel like wood?

    The thing I look for mostly on my depth finder is something structurally different on the bottom or contour changes. Weed patches, beds, humps, and baitfish schools. Chance are if you run across a school of baitfish it will look like a black cloud that is suspended.

    I'll stop rambling now, let me know if I can help in any way.
  4. Corey and Doc Lange both wrote some good guidelines a while back on GFO. Contact them and have a copy sent to you. Read all you can then get out on the water. DON"T fool around in water less than 15 feet deep as your cone coverage will be better and allow you a better opportunity to view fish and other objects in deeper water. If you get into twenty to twenty five fow you will see enough of the bottom structure for it to make sense. You will also see the suspended fish. Take your time and let the unit do it's thing set on automatic (default), that way all you have to do is watch the screen. When you feel comfortable regarding reading the screen in auto, switch to a 2 to 1 zoom split screen and again get to know how to correlate the images. Try this method drifting or motoring slowly as well as anchored. Last of all, crank up the sensitivity and see what it does. I don't find it necessary to increase the sensity unless I'm fairly certain the fish are laying on the bottom and even then it is tough to recognize them.
    Another great aid is to have someone that knows how to read the screen help you when on the water.
    Last of all, leave the rods out of the boat. Dedicate yourself to a learning session then enjoy your new gizmo.
  5. Corey

    Corey OGF Team-Charter Member

    Remember also, and this is something many anglers don't understand about their electronics, the the depth shown on your screen is the distance from the transducer to the shallowest point in the area displayed. If the bottom drops off in that area you will have a "dead spot", where there may be fish that you don't see. When moving parallel along breaklines this can cause to you miss seeing many fish. You can see any fish that are on such structure by moving perpendicularly to the breakline, letting the edge of the cone travel up the slope of the contour, then moving out and repeating the perpendicular approach, stitching the breakline, in-and-out, in-and-out, etc.. Get rid of the fish pictures. Manufacturers of fishing electronics try to make units that can be bought, off-the-shelf, installed and used by the average angler, with little or no technical knowledge, and deliver as much information as possible. There is no way however, for these units to differentiate between air bubbles, leaves or other suspended objects, a layer where water density changes due to stratification, and fish. They will show you a fish picture whenever the signal bounces off of anything between the transducer and the bottom. Using your unit in manual mode, properly adjusted for water depths and conditions, will give you information that you can interpret, after gaining some experience, to give you a better idea of what is actually down there. Sensitivity is one of the things that confuses some anglers. Many think that by increasing the sensitivity they will be able to see more and better. This isn't always the case. Take Saugeye for an example; they are a bottom relating fish and often lie so tight to the bottom that they are very hard to see. With the sensitivity turned up you will be able to see more and smaller baitfish, the dense water layer at the thermocline, etc.,m but the strength of the signal will cause a fish that is on the bottom to "blend" with the bottom, showing merely a small bump, with no separation or internal Grayline. By decreasing your sensitivity setting you will lose the ability to see smaller objects like small baitfish but you will be more likely to see a separation of fish from the bottom. Using your Zoom function also helps in seeing fish that are glued to the bottom. When in the Zoom mode each pixel on your readout screen represents less of the water column, therefore providing more detail and better separation.
  6. Fish4Fun

    Fish4Fun Relaxing.

    this will be a great topic as i just started using my fishfinder this yr as well. on knox i have not been paying much attention to the little fish id as i have been watching for sunken logs and changes in the bottom have found some things now i need to get a unit with gps were you can mark the spots sounds all to complecated.
  7. catking

    catking Banned

    All the hocus pocus, black magic, voo doo bull aint gonna help ya catch fish Ben :rolleyes: It starts with SKILL :cool: .............DA KING !!! :D

    KSUFLASH respect our rivers please

    It takes skill to catch catfish? :D :eek:

  9. Doctor

    Doctor CJ Cat Attack Pack

    Time on the water is your best teacher, also if it is crystal clear and you can see the bottom it will show you a lot also, good idea from TritonBill on the use of a camera.

    I learned to read them by fishing on Norris lake where the water is really clear, for both Cats and Stripers, trust me I spent a lot of time fishing for stupid rocks that I thought were fish.

    Use the unit in automatic mode till you get the feel of how the unit preforms, once you feel comfortable with it then switch it to manual mode, you can do so much more with the unit, also take the time to sit down and read the manuel there is a wealth of information in that book. I have the older Lowrance 350 great unit, during it's time it was the best of the best, really doesn't compare to the newer units of today, the newer ones today have better memory, better resolution and so much more cool stuff, but I can mark a fish running down the river turn around and catch that fish so I'm very comfortable with my unit, at some point in time I'll upgrade. For now I stick with what I'm comfortable with. Donnie and Larry just bought new units and I was amazed at all the stuff that is integrated into them. The night vision mode is very easy on the eyes, and the mapping units are amazing and very accurate.

    Biggest thing is trust what the unit is telling you, get rid of the fishy symbols as the unit is telling you what it thinks it see's plus it takes a lot of power to create those symbols.

    Hard bottoms will show a thick greyline as the signal goes down bounces off and comes back fast, soft bottoms will show a thin greyline as the signal gets lost in the mud and takes it a while to get back to the depth finder.
    Run your tracking speed wide open on the unit, the more information you can recieve the better. Everything on the right side of the screen is the newest information, if the unit has a built-in flasher mode I would have that on also as it will show you realtime information plus what is directly under the boat.

    You can set the sensitivity by going into like 20 foot of water and dropping a 1/4oz jig below the transducer, let it hit the bottom and pick it up and drop it back down, you should be able to bump up the sensitivity till you can see that jig go up and down on the screen, that will get you real close to the ballpark of having the correct setting, in the automatic mode it may filter it out or miss it totally so manual mode would be the choice for this set-up.

    Each and everytime you go to launch the boat check the position of the transducer on the back, these things get bumped up or down during transportation so each trip I just make sure it is in the correct position as I undo the straps, I also wipe it down cause dust or mud will collect and it is amazing what kind of readings you get with dust or mud on the eyes of a unit.

    Sensitvity settings should be somewhere in the 65%-85% range depending on the units power, more power the less you have to crank up the sensitivity. the units work very well in 10- 50 foot of water, actually the deeper the water the better separation between fish and structure, now I fish mainly for Flatheads so these guys will blend in with the bottom structure so sometimes it is hard to pick them up, but there are tricks to the trade.

    At the present time I'm only a few weeks away from turning in an article to Captain Rogers about sonar interpetation, it has taken me six months to develop this thing but it is mainly a picture tutorial which I think will really help people out when they go to use there depth finders.

    Hope this helps you out again time on the water is the best teacher, or get somebody on board your boat that can shorten the learning curve for you, good luck and hope your rod tips get slammed down hard............Doc
  10. O.K., now I have a question. With my Garmin, I always kept the sensitivity around 70%, give or take. Now with my Lowrance X125, I have to keep it well under 40% or the screen is filled with clutter. If I put to 70%, the entire screen is black. Why the difference?
  11. Doctor

    Doctor CJ Cat Attack Pack

    It maybe your contrast of the unit, you sure it's sensitivity 40% the screen should be white with very little information, 70% should be ideal marking a good bottom plus baitfish and fish.....Doc
  12. Yeah, I'm sure it's sensitivity. I mess with it almost every time out. It really threw me off the first time out. It seems best at around 35%. :confused: It needs to go back to Lowrance anyway, so I'm going to ask them when I call.
  13. Doctor

    Doctor CJ Cat Attack Pack

    I would agree, hey maybe somebody wired a board in wrong but what you describe doesn't sound right....Doc
  14. Well, I called and asked Lowrance. The guy I talked to was confused as we are. The one thing we came up with was a possible algea bloom, which is possible. I've never turned it up too far since that first time, so I'll try it this week.
  15. I would put a chain on it so you don't drop in the water first!!!!!!!!!
  16. Stampede

    Stampede The Fish Feeder

    I've got a lowrance x87 on the trollin motor.When you see fish on the screen,how do you relate where the fish is.How much area does the cone cover.What i mean is,how do you tell if the fish is under you,to the right or left.I also have a lowrance x47 on the stern.The graphics aren't as good but it show's more fish symbols.Back to the x87,when i use the auto,i don't see very good archs and i see a lot of clutter to where the whole screen is almost dark.Should i adjust the sensitivity to a lower number.I've sat on the lake and played with it and still can't make heads or tails of it.I use the fish i.d. mostly and for depths,but i'd like to know it better.

    KSUFLASH respect our rivers please

    and i thought I was the only one left on the lake that was still a bit confused about reading those fish finders. Glad I am not alone... :D :D

  18. mrfishohio

    mrfishohio Recovering Fishaholic

    Fish archs !! This unit makes me crazy at times, but then sometimes I'm real happy. I may actually have a defective transducer that leaks water into it because I get funny readings sometimes. My sensitivity usually has to be pretty high..98% or 100%. What to do is to crank it up until you begin to see some debris in the water....little specks, then turn it down a % or 2. I get better readings on this unit with the surface clutter off & the interferance(noise) off too. Maybe it's because I'mrunning a dual frequency transducer, I'm going to change it over to a 200 only someday. In clear water it works better, I've noticed a reduction when the river is muddy. Then I get over hard bottoms(rock formations) and it's like the pictures in the book :confused:

  19. mrfishohio

    mrfishohio Recovering Fishaholic

    Here's a hard bottom picture...