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Old Nasty Black Adhesive in Rub Rail Staining Hull

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  • Old Nasty Black Adhesive in Rub Rail Staining Hull


    The factory black adhesive under the rub rail has been staining my hull for a while now (10 plus years):

    Click image for larger version  Name:	rubrail1.jpg Views:	0 Size:	72.1 KB ID:	33672

    Click image for larger version  Name:	rubrail2.jpg Views:	0 Size:	52.4 KB ID:	33673

    Click image for larger version  Name:	image3.jpg Views:	0 Size:	52.7 KB ID:	33675

    When I had the boat out during my repower in 2019, I scrubbed the black adhesive to get the surface as clean I could to where it was not staining my finger when I ran it on the surface. But after some time, it started back up.

    The boat will be blocked up at the boat yard for a new coat of anti fouling paint next week, so I would like to address this the best I can without removing the rub rail. Any ideas on how to do this? I noticed that some of the black adhesive has come off already:

    Click image for larger version  Name:	image4.jpg Views:	0 Size:	47.8 KB ID:	33674

    Thank you, and happy holidays!
    Attached Files
    Last edited by Damon; 12-24-2021, 10:42 AM.
    1990 Shamrock Mackinaw
    Mercruiser 383 Stroker MPI
    VD 72C 1.52:1 ACME 14.5x14.25 4B .150 cup

  • #2
    After scrubbing with a strong detergent and a rub down with lacquer thinner I would run a thin bead of a sealant of your choice where the rail meets the hull. After the sealant is set give the rail two or three coats of your favorite wax.

    regards Holty


    • crhodes
      crhodes commented
      Editing a comment
      Agree. Might add 1) cut old sealant away if protruding below the rub rail (as shown in picture an 2) after cleaning, wipe down with acetone to get all residual oils off, then use the caulk.

  • #3
    I don't believe the factory used adhesive. Rub rail was screwed thru the cap and hull into a thin wood backing. The wood doesn't last very long. If you could find out what the adhesive is, it would be easier to eliminate it.
    1988 26' cuddy
    1975 20' open
    16' Sandpiper
    14' Certified Fiberglass


    • #4
      That looks something like Sikaflex which is a great sealant but cant take UV. Or maybe something else. Might just be easier to remove sealant as mentioned and redo.
      '78 20ft Cuddy
      Mercruiser 350 FWC preVortec w/Carb


      • #5
        Got them black streaks on my gelding too. Used Mothers Marine Black Streak Remover. Then l stripped all the wax off using white vinegar. Wash hull with dawn after, rinsed really really good then used a new fangled ceramic coatings l got from work for cars. Don’t remember the name but there are products out there for gelcoat. Used boat for two years in salt and 3 years sitting on the hard.. The streaks would wash right off with a fiberglass soap and water with very little effort. I sold the boat the 6th year in the spring, washed it before l put her up for sale, could see it needed to be redone by the 5th year but she cleaned up well.
        Was told the streaks come from oxidation between the different materials under the rub rail. So l don’t think sealing would be a good idea. But that is just my .02$
        Just wishin', and hopen', and dreamin'