Fishfind help

Discussion in 'Fish Finder Review and Study' started by Dsage, Mar 28, 2008.

  1. Dsage

    Dsage Active Member

    Messages:
    2,137
    State:
    Topeka, Kansas
    I read a post a few months ago that had some good info on how to set up a fishfinder. A lot of nice topic were covered from reading the bottom. adjusting the noise, sensisitivity, turning the fish id off, ect. I was going to copy the link to it but I did not i guess. I spent a good part of last night looking for it on here again but I can not find it. I think it was in this section but I could be wrong. Hoping some one remembers the topic and can help me find it. Thanks
     
  2. Mr.T

    Mr.T New Member

    Messages:
    2,553
    State:
    MO

  3. Dsage

    Dsage Active Member

    Messages:
    2,137
    State:
    Topeka, Kansas
    That anwsered some of the things for me thanks.
     
  4. brother hilljack

    brother hilljack New Member

    Messages:
    7,305
    State:
    Shelbyville, TN
    There is so much info its hard to say, check the technology section or simply start the post again. I'm sure you'll find the answer.
     
  5. 4Low

    4Low New Member

    Messages:
    558
    State:
    Lonoke, AR
    I posted this one about 3 years ago. Let me know if you have any other questions......

    Maybe I can help answer a couple of questions...
    Soundwaves travel through water at a rate of 1495 meters/second, but only 331 m/sec through air (swim bladder)....therefore emitting an "arch" on the screen from the swim bladder "within" the fish due to the change in speed of the soundwaves (refraction/reflection) The change in speed of the soundwave from 1495-331 m/sec is huge, so an arch is shown. Scales and skin have absolutely nothing to do with the arch because sound travels through brain, liver, kidney, blood and muscle at a rate between 1510 and 1570 m/sec., meaning there is not enough of a propogation speed difference between that and water to create an arch on the screen. The swim bladder creates the arch. This is also the reason why bubbles from the motor can create so much artifact you can't see anything...why? Because the soundwaves leave the transducer at 1495 m/sec, hit the bubbles and slow to 331 m/sec. At 331, they are going so slow and are so close to the receiver, it picks them up before they go anywhere and you see nothing on the screen.
    Think of it like this:
    Your transducer is sending soundwaves through the water. These waves send returning echoes from everything they propogate through on the way to the bottom and back up again. Remember, only a FRACTION of the waves sent make it back, and the ones that do make it back are very much weaker than they were, so the RECEIVER and PROCESSOR are the most important parts...that's what you are spending the $$$$ for on a good graph. They have to receive, process and amplify the weak returns. These soundwaves are either absorbed, reflected or refracted while in the water. All structures the soundwaves propogate through will emit a signal, some stronger than others. This is why good graphs can differentiate between soft/hard bottoms, by measuring the amount of reflected signal the receiver picks up. A soft bottom will absorb more soundwaves than a hard bottom. The more soundwaves absorbed, the less reflected waves, the softer the bottom. Any hard structure in the water (wood, anchor, rockpile) will be shown on the graph due to reflection and refraction, along with soft ones like underwater grass and lilly pads. It's up to us to tweak the controls and use our brainpower to identify the difference between rockpiles, logjams, grassbeds and fish. Now for more physics....There are only so many "scan lines" traveling down. These are the amount of soundwaves traveling down within the cone. The more scan lines, the greater the line density, the better temporal resolution (left to right) and the better the graph. Then you have the length of the soundwave affecting the picture. Shorter soundwaves produce higher quality images at shallower depths (freshwater) because the waves are closer together but they attenuate (lose strength) faster as they go deeper. Longer wavelengths give better images deeper, (saltwater) but at shallow depths the waves are further apart thereby decreasing your axial resolution (top to bottom). Pixels only relate to the screen, not the transducer, so a higher pixel count only means better screen resolution. One other thing, if the transducer is not level when your boat is in the water, you will be misreading everything because the soundwaves will be emitted at an angle (making it read deeper than it really is) and even less soundwaves will make it back to be read due to refraction. Have I gotten too technical, probably...And I know there are a lot of people on here that know more about this than I do, but maybe I helped out a little bit.
     
  6. Dsage

    Dsage Active Member

    Messages:
    2,137
    State:
    Topeka, Kansas
    Thanks guys things are getting clearer for me now.
     
  7. kscathunter

    kscathunter New Member

    Messages:
    2,367
    State:
    Louisburg,
    well i finally got out to try my new fish finder (eagle cuda 168) and well it seemed to work ok up to 15-20 feet then it went down hill alot of crap thats not there started showing up and the bottom line dissapeared around 25-30 and around 30-40 i got broken line display. speed didnt make any difference. i mounted the transducer exactly like they said with the center line of the transduser level with the bottom of the boat. What could be wrong? i missplaced my manual so its no help till i find it. sence speed didnt effect the picture im wondering if the transducer angle may be the problem because i noticed the boat sitting low in the back.
     
  8. ChannelCatBen

    ChannelCatBen New Member

    Messages:
    179
    State:
    Minnesota
    I have the cuda 168, and it's new to me too. I'll have to check my owner's manual when I get home (I'm at work now), but the first thing I'd check is whether you have the bottom line set at auto or manual. If it's on manual, and you only have it set to read down to 30', then it would get funky once you get deeper.

    Like I said... I don't know. I'll check the manual when I get home.
     
  9. metalman

    metalman Well-Known Member

    Messages:
    3,447
    State:
    IN
    Name:
    Winston
    Brandon,
    I bet you could probably download the manual from their site until you find yours...W
     
  10. kscathunter

    kscathunter New Member

    Messages:
    2,367
    State:
    Louisburg,
    i found my manual and i think i was right im thinking its not pointing strait down because i wasnt getting full arches when i was getting them. so i guess ill angle it back some and see if that helps.:roll_eyes: