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Thread: Replacing gasket on Lewmar Hatch

  1. #1
    Contributing Member III
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    Replacing gasket on Lewmar Hatch

    Hi all,

    Finally getting around to this repair. Thanks for the post by rick and the video by Christian. They were very useful. The PO used silicon to bed and seal and we are spending much time just cleaning the old stuff. We have the bulk off but there are remnants that will take hours to scrape off completely.

    It occurred to me to soak the hatch (just the metal part) in mineral spirits for several days to soften the silicon and then use a dish scouring pad to get the soft mess off.

    Before doing so, I'd thought I'd ask for advice. Will soaking help? Can soaking hurt the metal? Any other tips?

    Thanks in advance.

  2. #2
    Principal Partner footrope's Avatar
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    Try a brass wire wheel either with a drill or even in a Dremel. Use a light touch with the drill and wheel. A little practice and you won't hurt the frame. Finish up with light sanding and wipe with acetone or spirits. I do this routine with all my aluminum frames. This even works on gelcoat contaminated with silicone.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    Somebody once said "It's an old boat and therefore resistant to change."

  3. #3
    Principal Partner markvone's Avatar
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    I second what Craig suggested.

    Everything I've read says that silicone comes off best with mechanical methods. I tried a couple of special silicone removal liquids with no results. I got some cheap, small stainless wire wheels on ebay for my dremel and used those and coarse sandpaper to scrape/sand most of the silicone from a previous repair off. Since my hatches are solid cast aluminum and the area in question was already partially raw aluminum, I could sand pretty hard and got most of the silicone off. For extruded aluminum frames I would be more gentle and try and save the anodizing/coating if possible.

    Mark
    Mark & Ronnie Vinette
    E36RH #21 GLIDE
    Annapolis, MD

  4. #4
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    I used gasoline and mineral spirits to soften it up and clean it up. It seemed to make the job a little easier. Although I think mine were the original Lewmar sealant, not sure if that was silicone based.
    Last edited by Timsb; 12-07-2017 at 08:23 PM.
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  5. #5
    Moderator Christian Williams's Avatar
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    You can try most solvents--diesel fuel, WD 40, PB Blaster, DeBond--it won't hurt the frame.

    But if it is silicone, gotta scrape it off mechanically. And nothing will stick to any residue.

    (What will hurt our yacht anodized aluminum is many hardware-store versions of aluminum "polish", which amounts to oven cleaner. CAr guys use it to prepare for polishing. We have to read label and make sure it doesn;t say "not for anodized aluminum."
    Thelonious II, E381 hull 513 (1984) Universal 5432
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  6. #6
    Principal Partner footrope's Avatar
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    Did I mention that using a wire wheel is so much FASTer than scraping or soaking?
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    Somebody once said "It's an old boat and therefore resistant to change."

  7. #7
    Contributing Member III
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    Thanks for all the replies. Great ideas.

    I'm not sure it is silicone. The PO used silicone in lots of places so I just assumed that I was dealing with silicone given how hard it was to remove. But now I'm thinking it was probably original equipment.

    Either way, I have a dremel. If I can find a soft steel/hard plastic attachment brush, I'll try that. Although we are not pressed for time, no point in doing things the hard way.

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