Humminbird 797

Discussion in 'Fish Finder Review and Study' started by screamnclickersc, Mar 31, 2008.

  1. screamnclickersc

    screamnclickersc New Member

    Messages:
    755
    State:
    S.C.
    I know this question is very popular w/ this unit,so how do I keep from losing the bottom around 18-20mph?The depth will stay on the display,but the bottom is distorted.I dropped the transducer about 1/2" lower into the water but had the same results.Aslo I had to make a shield to cover the transducer to keep the spray out the boat.
     

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  2. SkipEye

    SkipEye Well-Known Member

    Messages:
    7,525
    State:
    Winfield, MO
    Name:
    Darryl
    I initially had problems holding bottom over 12 mph. Your issue is with location or depth of your transducer. It seems on most aluminum hulls, especially the flatter 3 degree hulls you need the bottom of your bracket almost flush with the bottom of the transom.

    I actually ended up doing a dual transducer setup going into a Humminbird Y cable (AS SIDB Y), the 2d sonar high-speed puck is an (XNT 9 20). It handles the regular sonar imaging and is much smaller in profile. The side imaging puck only handles the side imaging function now. No switches required, both are on all the time. Side imaging is a slow speed operation anyway.

    I now go full throttle 34 mph without losing lock on the bottom (digital readout). The sonar image will still start breaking up on you though.

    As far as your massive roostertail, get rid of the shield. You'll see a BIG square hole in your bracket-to-transducer mount area. Tape the bottom of it up and fill it with Black silicone. Let it setup for a day, take the tape off and no more roostertail. Well, a little but not much. The square hole is the root of your problem.

    Hope it helps!
     

  3. blackwaterkatz

    blackwaterkatz Active Member

    Messages:
    3,659
    State:
    Andrews, SC
    Jimmy, did you get your unit working ok? I mounted mine on my fiberglass center console boat, with about 1/2 of the transducer below the bottom, clear of anything that might disturb the water flow, and it reads just fine up to max speed, about 35-39 mph. I just used electrical tape to cover the opening at the transducer, but will probably fill it with silicone before I go out again. Just got to use the thing today for the first time.