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  1. #1
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    Sealing transom holes

    I have an old aluminum boat that has 14 holes in the lower right corner of the transom from the various transducers that have been mounted. I'm replacing the transom wood and had sealed it nicely with epoxy. Two or three holes are actually below the wood and had screws with sealant plugging them. I've gone to the trouble to carefully sealed the wood, even drilled out all 12 of the through holes 1/16" oversize and sealed the hole ID. I am reluctant to fill that many holes with screws into the wood.

    Do I seal the extra holes with marine tex?

    Seal the holes with 5200?

    Do I install new screws with 5200?

    Is there a better way to seal them without welding?

    Thanks in advance.

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    #2
    Welding would be ideal but I'd guess marine tex would work just fine. I've used it a bunch on glass boats with good results. Someone may chime in with a better solution but if I were doing it I'd use marine tex.
    Derek McCarty

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    #3
    Thanks. Any experience regarding the longevity of a marine tex patch on aluminum?

    I did patch a small hole near the bow with marine tex about 1.5 years ago but that is truly the extent of my experience patching aluminum. I don't really know how long it'll last. I have used marine tex on a fiberglass hull for 10+ years with no change, but that is literally a different animal.

    I would weld it but the only person I've found to do it is an expensive mobile welder. The boat is nearly 40 years old. Besides not wanting to put too much into it, some of the holes are a bit irregular like some galvanic corrosion has occurred. 40 years with dissimilar metal in contact could do that. I'm half afraid to take a TIG torch to it for fear that it just blows out.

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    #4
    The wood slides down between two sheets of aluminum 1.5" apart. If I take the wood out and weld the holes and end up with a glob of metal on the inside, there's no way to grind it down to make the wood fit. If I leave the wood in place and maybe slide in a backer plate, I may burn off the epoxy sealer. Plus, getting the backer plate in there will be difficult. Welding has several significant challenges.

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    #5
    You could also do sealed rivets with 5200 on them... Just a thought.

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    #6
    Are you planning on mounting any transducers in that spot? You could always cover the holes with a piece of starboard and mount your transduce to the board!

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    #7
    Google “dangar patch transom”. He has a youtube video showing how he patches multiple holes in an aluminum boat. I guess its one way to go.
    Last edited by Avanti; 01-12-2022 at 02:14 PM.

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    #8
    Quote Originally Posted by Avanti View Post
    Google “dangar patch transom”. He has a youtube video showing how he patches multiple holes in an aluminum boat. I guess its one way to go.
    I did and that's what I am going to do to patch a 1" hole that the previous owner bored through the transom for a transducer. I had just left it in place until now. You are right, I could do the same for all of these little holes and just drill new ones for my transducer. I ran my cable over transom, not through it. I can take a photo before and after so that a prospective buyer can know that I didn't patch a baseball size hole.

    I was hoping someone had some long term experience with marine tex on aluminum. As mentioned, I know it will last on fiberglass and wouldn't hesitate with fiberglass.

  9. Member
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    #9
    I filled all small holes with 5200 then added a piece of starboard over the top and sealed with 5200 as well.been a few years zero issues so far.
    jerrysroadservice@gmail.com
    2017 Lund Pro V Bass 1875

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    #10

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    #11
    I filled all small holes with 5200 then added a piece of starboard over the top and sealed with 5200 as well.been a few years zero issues so far.
    This is what I did too, and it works great for moving, adjusting, replacing transducers.

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    #12
    Thanks all for the input. I'm going with Marine tex and if it starts to leak, I'll attach a Star board to cover the holes. I know that the SI transducer location works so I'll use the same holes. I don't see myself doing any upgrades on this boat.

    I used a scotch Brite wheel on an angle grinder on the outside to bare metal and a sst brush on the inside. Pressed it into the holes really well and spread it over the area like bondo and sanded smooth. If it fails soon I'll report back.

    I did do some research on UHMW and found that it doesn't do really well with UV rays. Star board contains additives to protect against UV rays.