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  1. #1
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    Jan 2016
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    Corbin,Ky.
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    SI and Boat Speed?

    When in search mode with SI what do you guys feel is good boat speed to use to get best reading?

    Thanks

  2. Member
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    Apr 2008
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    Lakeview,AR.
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    #2
    Between barely moving and 4 or 5 is the speed you will get the best detail provided you have adjusted the unit for optimum pic as well. My opinion is it depends on what is important to you at the time. If you are only looking for rocks or weeds or bottom hardness you can go faster and still accomplish your mission. If you want to see fish or other fine details keep the speed down. Bob
    Tell me where has a slow movin' once quick draw outlaw got to go

  3. Member Wayne P.'s Avatar
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    Jan 2010
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    #3
    If your transducer is installed so it can work for SI up to about 12 mph, it will. A Chart Speed set to 10 will do that.
    Wayne Purdum
    Charlottesville, Va.
    Helix 12 CHIRP MEGA+ SI G3N/G4N, Helix 15 CHIRP MEGA SI+ GPS G4N
    SOLIX 12 SI/G3, Helix 8 CHIRP MEGA SI+ G4N, Ultrex 80/LINK, MEGA360,
    MEGA LIVE, LIVE TL

  4. Humminbird Moderator SLYDoggie's Avatar
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    Aug 2015
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    Franklin TN & Tims Ford Lake
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    #4
    That totally depends on how your transducer is set and what kind of interference you get from bubbles coming across the bottom as well as bubbles coming off the motor. I have mine mounted on one of the "toons" on my Pontoon boat and can get up to about 8MPH before I start getting significant interference from bubbles coming off the "toons". I do a lot of trolling for stripers and typically do scouting for schools of fish at this speed. I do get a better image from the right than I do from the left as the motor is to the left of the transducer. The motor itself is definitely behind the transducer but I think it is probably bubbles coming off the "toon" on the opposite side as well as cavitation from the prop. As Wayne suggests, I do change my chart speed to 10. I typically troll at 2.2 MPH to 3 MPH and typically have my chart speed set to 8. I do this because I'm really only looking for fish and bait rather than bottom structure.
    ---> Regards, Steve Yarbrough (AKA: SLYDoggieTN on YouTube)
    • Apex 19/16/13, Mega 360, and Mega Live
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  5. Member Wayne P.'s Avatar
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    Jan 2010
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    #5
    If I want to do fast scanning, I use another transducer to get farther below the hull bottom that cavitation doesn't interfere with the images.

    Wayne Purdum
    Charlottesville, Va.
    Helix 12 CHIRP MEGA+ SI G3N/G4N, Helix 15 CHIRP MEGA SI+ GPS G4N
    SOLIX 12 SI/G3, Helix 8 CHIRP MEGA SI+ G4N, Ultrex 80/LINK, MEGA360,
    MEGA LIVE, LIVE TL

  6. Member
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    Jan 2016
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    Corbin,Ky.
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    410
    #6
    Thanks for the info guys. I am coming from Garmin units that had SI capabilities but never took time to learn how to use and read. I going to start learning how to use SI finally now.

  7. Member
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    Jun 2008
    Location
    Whitehall Wisconsin
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    491
    #7
    As usually I do not look for pretty pictures just fish I will always have my scroll speed much faster then boat speed as this will elongate fish making them easier to see. Once I find fish then I will swing back around bring chart speed back to match boat speed and look at the details. With my set up I can get SI readings even on plane, as expected it only gives a rough idea of what is there it will pick out weed edges and large objects at speed and bottom changes.

  8. Member
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    Nov 2004
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    Columbus, Indiana
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    #8
    My transducer is mounted to the bottom of the holeshot plate on my jackplate. At normal position, 4-5mph is best. If I want to fast scan, I can drop the plate all the way and I can get over 9mph with a pretty clear picture. It all depends on how the water comes off the back of your hull.

  9. Member
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    Jun 2006
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    DeLand, FL
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    #9
    I ended up getting a second transducer with a Y cable because of all the bubbles from my trim tabs. I get good SI up to 10-12 mph now
    Alweld 1856 Stick Steer with 70 Yamaha
    Dual Power Pole Blades/ Helix 10 MSI
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    USAF Ret

  10. Member
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    Sep 2020
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    Port Saint Lucie/Florida
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    #10
    I run 3 to 4 mph at 60 feet in each direction and get awesome images on my Helix 10 MSI G3N