Caulking windshield to deck

Discussion in 'Fiberglass/Wood/Gelcoat Repair' started by Nmor830, Jun 5, 2017.

  1. Nmor830

    Nmor830 Member

    Sep 12, 2016
    Channel Islands
    2008 340 Sundancer
    8.1l Mercruisers
    2008 340 Sundancer caulking between the deck and the windshield is crumbling. In researching different products 3m and others it seems there are a lot of mixed reviews. Wondering if anyone has done this and what was used and how well it is holding up.
  2. Air O'Nautical

    Air O'Nautical Active Member

    Feb 5, 2008
    Stamford CT "Ponus Yacht Club"
    1995 400EC. Raymarine E80,4kw dome, Garmin 235 gps,
    2013 7.4L Mercruiser Blue water.
    Hurth straight shaft 630's,
    Westerbeke 7.0 BCG
    I like 3M products never seen it crumble, as long as it's prepped properly.
    Could you be dealing with an additional, owner applied caulk that was placed over a waxed or dirty gel-coat??
  3. Escapade

    Escapade Member

    Jan 10, 2007
    Lake Michigan
    390 Sundancer 2005
    Twin 8.1's
    Clean with brush to remove the old caulk. 3M 4200 is available in calking tubes witch allows greater control when applying. I masked both SS on frame and the gel with 1/2" vinyl auto paint tape. Make certain to clean the area well with 3M Shape shooter . It will remove the wax and dirt.
  4. Nmor830

    Nmor830 Member

    Sep 12, 2016
    Channel Islands
    2008 340 Sundancer
    8.1l Mercruisers
    I believe this may be the original caulking material used by SR but can't be 100 % sure. Noticing all the sealed joints are looking old and cracking. The boat spent it's life in So. Calf. where it takes a good bit of UV abuse. Seems the 3M 4000 4200 is the material of choice which is probable what I'll use.
  5. Nmor830

    Nmor830 Member

    Sep 12, 2016
    Channel Islands
    2008 340 Sundancer
    8.1l Mercruisers
    Sounds like a good solution. Seems 3M is the material of choice.
    thank you
  6. JimFromMD

    JimFromMD Active Member

    Aug 9, 2010
    Annapolis, MD - Middle Chesapeake Bay
    2005 300DA, Garmin 740s w/Vision Charts and GMR18HD RADAR
    5.0MPI w/BIIs, Kohler 5E Generator.
    I used BoatLife Life Seal in white to do my windshield/deck joint two seasons ago... working great so far and still white. I used a cheap plastic caulk remover tool and plastic razor blades from HD to scrape out the dried caulk. Painters tape for cleaner edges would have been a good plan, but I didn't think of it.

    Also used LifeSeal to re-attach the vent covers and that held up for 4 seasons. The material was still white and flexible, just had to be redone because fenders occasionally push up against the covers when rafted with taller boats. It eventually starts to the covers loose at the aft corner.
    Manufacturer's site, but available at WM and many other places.
    Last edited: Jun 6, 2017
  7. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    The OEM's are using Sikasil-N Plus which is what I used to have the 400DA completely caulked.
    I had a long discussion with the Sika technical representative on what to use and they specified the Sikasil-N Plus; It went in and filled very smoothly and tooled out perfectly.
    I would not use 3M 4000, 4200, or 5000 as these are adhesives and not joint sealants. You will not be able to "tool" the joint and make it look good at all if you use these 3M products.

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