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Transom Mounting Transducer

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    Transom Mounting Transducer

    The original PO's Fish Finder transducer was bad when we purchased the boat last year (pic of boat on trailer). It broke from its mount (2nd pic of current status), and I am now ready to replace it for our new Raymarine Unit. Intend to pull the old bracket tomorrow, and then sand the area and fill the holes with some epoxy, providing I don't see it gush water and have any transom issue (none expected)..

    Questions - 1. Will 3M marine epoxy be OK to fill the old holes, and 2. will that location be OK for the new transducer? Am thinking it is a bit close to the strake & TAB and perhaps it should go a bit more (2-3") to the left as seen in the pic (one which shows the original transducer still attached).

    I was going to use 5200 to fill the holes, but thinking the epoxy would be a better/more permanent fill, then sanded & covered with a touchup of bottom paint. Good with tools, but no experience installing transducers.

    TIA ----

    Attached Files
    1998 BL Ciera 2655 Sunbridge LX (Special Edition)
    "Sea Flights"
    5.7L 2bbl w/Thunderbolt Ignition
    Alpha I Gen II Sterndrive with raw water cooling
    MFG Extra's - A/C, Fresh Water Engine Flush port, HWH and Windlass
    Docks @ Punta Gorda, Florida

    #2
    Move the transducer further to the center and off of the bunker.
    Pat says: DO-IT-RIGHT THE FIRST TIME!

    Bayliner 3870 "ALASKA33)
    Twin 350 GM power
    Located in Seward, AK
    Retired marine surveyor

    Comment


      #3
      Originally posted by boatworkfl View Post
      Move the transducer further to the center and off of the bunker.
      That's what I was thinking Pat. It doesn't go on that trailer anymore as it was used to deliver it to the ramp by the boatyard that sold it to us. I was thinking about halfway between the old one and the outdrive as I've read it needs to be at least 6" from the prop/outdrive. Sound about right you think?
      1998 BL Ciera 2655 Sunbridge LX (Special Edition)
      "Sea Flights"
      5.7L 2bbl w/Thunderbolt Ignition
      Alpha I Gen II Sterndrive with raw water cooling
      MFG Extra's - A/C, Fresh Water Engine Flush port, HWH and Windlass
      Docks @ Punta Gorda, Florida

      Comment


      • boatworkfl
        boatworkfl commented
        Editing a comment
        The performance from the transducer will be better further inboard, but not too close to the keel.
        Air bubbles are the issue.

      #4
      The transducer should've come with documentation explaining what to avoid when selecting a location. Make sure there's nothing underneath the boat forward of where you put the transducer. Things like scoops or thru-hulls. Though if it's more than about 5 ft forward it should be ok. And you're right that it looks a little too close to the strake.

      The procedure I was told (and what I did) was to drill holes larger and deeper than the mounting screws. Fill those holes entirely with epoxy and let it set. Then drill holes slightly smaller than the screws into the epoxy. Slather a bit of 3M 5200 or 4200 or 4000 around the holes and go ahead and screw the transducer mount in place. The idea is that if the 4200 doesn't completely seal a screw hole, the epoxy will act as a second barrier protecting the interior of the transom and any core material from water ingress.

      For filling the old holes I used epoxy. Didn't need to sand or touch it up since I attached a piece of starboard as a transducer mounting board so I wouldn't have to drill any more holes into my transom (I upgraded to a sidescan unit so I needed to attach two new transducers). The board hides the old holes, so I just needed them waterproofed. The starboard also allows me to loosen the screws to readjust the transducer mount without worrying about applying more 4200.
      1994 2556, 350 MAG MPI Horizon, Bravo 2

      Comment


        #5
        Originally posted by Solandri View Post
        The transducer should've come with documentation explaining what to avoid when selecting a location. Make sure there's nothing underneath the boat forward of where you put the transducer. Things like scoops or thru-hulls. Though if it's more than about 5 ft forward it should be ok. And you're right that it looks a little too close to the strake.

        The procedure I was told (and what I did) was to drill holes larger and deeper than the mounting screws. Fill those holes entirely with epoxy and let it set. Then drill holes slightly smaller than the screws into the epoxy. Slather a bit of 3M 5200 or 4200 or 4000 around the holes and go ahead and screw the transducer mount in place. The idea is that if the 4200 doesn't completely seal a screw hole, the epoxy will act as a second barrier protecting the interior of the transom and any core material from water ingress.

        For filling the old holes I used epoxy. Didn't need to sand or touch it up since I attached a piece of starboard as a transducer mounting board so I wouldn't have to drill any more holes into my transom (I upgraded to a sidescan unit so I needed to attach two new transducers). The board hides the old holes, so I just needed them waterproofed. The starboard also allows me to loosen the screws to readjust the transducer mount without worrying about applying more 4200.
        Great info. Thanks. Hadn't thought about the starboard idea. I like it and it solves the adjustment issue. I was thinking that the MFG directions to "adjust" after installation would mean running without a good sealant in the holes or between the bracket which was not sitting well with me.
        1998 BL Ciera 2655 Sunbridge LX (Special Edition)
        "Sea Flights"
        5.7L 2bbl w/Thunderbolt Ignition
        Alpha I Gen II Sterndrive with raw water cooling
        MFG Extra's - A/C, Fresh Water Engine Flush port, HWH and Windlass
        Docks @ Punta Gorda, Florida

        Comment

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