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Thread: INFO: [Graphs/Depthfinders] Calculating cone diameters

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    Arrow INFO: [Graphs/Depthfinders] Calculating cone diameters


    I have a simple Excel spreadsheet that will calculate the cone diameter for your graph/depth finder for a given cone angle and depth. For anyone needing this, send me a PM. Forumula included if you want to roll your own.

    Formula: 2*d*TAN((Pi/180)*(ConeAngle/2)) where d=depth and Pi =3.14


    Quick Calcs for cone diameter:
    ======================================
    12° Cone Angle > 1/5th of depth (Depth/5 )
    For example, at 100' depth, you would 'see' approximately 20' of bottom surface area

    20° Cone Angle > 1/3rd of depth (Depth/3)

    35° Cone Angle > Depth x .6
    ======================================

    Hope this helps someone. If anyone finds a mistake, please let me know.

    BleuGhill
    Last edited by BleuGhill; 01-07-2008 at 09:23 PM. Reason: change icon

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    Default hmmm

    Go to a tangent table. Select the your cone (tangent) angle and get the tangent of the cone angle. Multiply this number (tangent) by the depth. This calculation will render viewable area diameter.

    That was easy.

    Yep. I know. It is an isosceles triangle. But it's pretty close to the right answer.

    tangent table link. Check it out.

    http://www.science-projects.com/TangentTable.htm
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    Canepole,

    How would you calculate the viewable area diameter of a 20/50 transducer? Im pretty sure that's what I have.

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    Default Now why didn't I think of that.....



    ..but I think I'll just write the 'quick calcs' on a piece of duct tape and stick it on my graph ha ha. I'm afraid a big ol' table won't fit in my boat!

    BleuGhill

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    Quote Originally Posted by CrappieHound
    Canepole,

    How would you calculate the viewable area diameter of a 20/50 transducer? Im pretty sure that's what I have.
    depth*tan(10°)=viewable area radius for 20° transducer

    depth*tan(25°)=viewable area radius for 50° transducer

    multiply radius by 2 to get the diameter
    Keith
    2008 NWR Bash Crappie Champion
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    Do you gents do that math in your head? I do alot of things in my head too but I'm sure you wouldn't believe what all it is, LOL. I'm convinced my high school math teacher didn't know crap about fishing, lol.
    Quit Wish'in and Let's Go Fish'in
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    501-844-5418 --- [email protected]

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    What you really want to know is how close you (or your boat) are to objects on your screen, right? Easiest way to find that out is to put a half-ounce or large weight on your line and mark your line at 10, 15 or 20-feet with a permanent marker. Then lower the weight to a known depth and slowly (slow enough that your line remains vertical) move your line towards your transducer while watching your screen. When your weight begins showing up on your graph the distance your line is from your transducer is the distance (horizontally) all objects at that depth are when they first come on your screen from the same direction. If your transducer is not pointing straight down then that distance will vary depending on which side of the transducer an object is on.

    Keep in mind that increasing your sensitivity can effectively increase your cone angle because objects that are on the periphery of your graph's view may show up at higher sensitivity settings and not show up at lower settings.
    FISH ON!
    Jerry Blake

    www.BLAKETOURS.com

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    Default Whoa!


    Haha...hold on folks!

    Didn't mean to turn fishin' into high-tech ciphering, and now I hate myself for posting this! Can I holler 'slips'?

    I always went around in a cross-eyed daze wondering just how much the transducer was actually 'seeing' under my boat - and figured some new folks might find some use in a quick way to get a close estimate. So I offered up two ways:

    1. Quick calculation that they could write on their hat or on a piece of tape - based on the depth. I didn't include every cone angle obviously.

    2. For folks with Excel on their 'puter, they could basically copy/paste the formula and get it chugging.

    Good tip Jerry! I'm gonna try it!

    (...backin' outta here....slowly...)

    BleuGhill

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    Quote Originally Posted by CrappieHound
    Canepole,

    How would you calculate the viewable area diameter of a 20/50 transducer? Im pretty sure that's what I have.
    Pan Man formula are correct. I just too lazy to multiply by 2...:D Look up the tangent in the tangent table or use your engineering calculator.
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    Thanks PanMan, CanePole. That is very interesting. I'm actually seeing more of the bottom than I previously thought. Now I will have to tackle the JerryB problem.

    Good things to ponder in the off season.

    CH

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