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    Sealant for trim tab mounting.

    Opinions on preferred sealant for mounting trim tab actuators below water line? Urethane i.e. 5200, 4200, or polysulfide? The PO used silicone sealant. One of the brass pipe nipples that pass through the transom split. A question I have is, could the silicone previously used contributed to this, corrosion stress? If so, I will pull the remaining three and re do them also. I am hesitant to use 5200, as I will have to disassemble at some point. Thoughts, suggestions? Thanks.
    '89 3888
    "RUM AWAY"

    #2
    5200 is the way to go IMO. If you need to remove it there are solvents sure as de-bond that will soften it.
    1997 Maxum 2400 SCR 5.7LX Bravo II

    Mike

    Comment


      #3
      3M 4200, it is a sealant/adheasive similar to 5200 but much easier to remove if needed, the screws hold the trim tabs on.
      Pat says: DO-IT-RIGHT THE FIRST TIME!

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

      Comment


        #4
        +1 on both of the previously mentioned sealants, either one would be a great choice IMO. Both are similar, 5200 may be more perminent but like Mike said it can be removed.
        maybe the nipple was of poor quality from the start??
        Dave
        Edmonds, WA
        "THE FIX"
        '93 2556
        Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
        Misc. projects thread
        https://www.baylinerownersclub.org/f...56-gctid789773

        Comment


          #5
          4200 and 5200 are quite different in their cured state. 4200 remains a little more flexible- I think this would make it superior for trim tab application. I have also used Boatlife Life Caulk for underwater applications with very good results. Make sure you remove ALL traces of silicone. Nothing sticks or bonds to silicone accept more silicone.
          Gibraltar, Mi.
          1986- 3870- Hino 175's
          1988 26' Shamrock/ Diesel
          14' Zodiac Bay Runner

          Comment


            #6
            the 3m 4200 is the sealant that I would recommend as it has every good property that any other sealant has, and has a quick 1hr skin time. it can also be removed a lot easier than the 5200.
            the 5200 can be used, but it is a sealant that should only be used when one wants to permanently mount/bed a fitting or substrate. the skin over time is 4hours in ideal conditions

            the 4000uv is total junk and should be pulled from the 3M line-up.... contrary to its UV rating, it will break down in the sun within 4 years, and when it does, it will become soft and crumbly and absorb water.... there is no good reason for it to exist with its short lifespan, when both the 4200 and the 5200 will outlast and out perform it many times over, and they are both uv stable..

            as for silicone, most people dont understand how to use it to get the best results, or what formulation of it to use.
            once its been used for bedding a fitting, when it becomes necessary to remove the fitting, ALL traces of the silicone needs to be removed from both surfaces before a new layer will perform as it is intended to... nothing will bond to cured silicone, NOT EVEN more silicone....
            its always best to use someting other than silicone, but if it is a high heat surface, or silicone is what you like to use, the dow corning 721 structural grade will adhere the best and will last forever.. its the same grade of silicone that glass fish tanks are glued together with..


            NU LIBERTE'
            Salem, OR

            1989 Bayliner 2556 Convertible
            5.7 OMC Cobra - 15.5x11 prop
            N2K equipped throughout..
            2014 Ram 3500 crew cab, 6.7 Cummins
            2007 M-3705 SLC weekend warrior, 5th wheel
            '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
            Heavy Equipment Repair and Specialty Welding

            Comment


              #7
              I have been using sikaflex 291 on both boats i have built. I put a complete new electric trim tab system with oversize tabs on my last boat and after 2 seasons on the ocean not a problem. Its good stuff too.
              Doug
              1995 2859 -extensively rebuilt/restored 2016/17
              496 big block - Bravo ll leg
              The Doghouse
              Prince George BC

              Comment


                #8
                Originally posted by sketch96 View Post
                I have been using sikaflex 291 on both boats i have built. I put a complete new electric trim tab system with oversize tabs on my last boat and after 2 seasons on the ocean not a problem. Its good stuff too.
                I agree the sikaflex is good stuff, but not as readily available or as well known in all areas as what the 3m sealant is.... and one still needs to know the proper formulation of sikaflex to use, as it can permanently glue stuff together like the 5200 does.

                one thing here about the "permanent" bond that needs to be clarified for some people... some will say that stuff attached with 5200 will come apart nearly as well as the 4200, but anyone who makes this claim didnt have the mating surfaces clean... a clean, residue free mating surface that has had 5200 cured to it, will be nearly impossible to have the 5200 removed from it without additional chemicals or power tools... but on the plus side, the old cured 3m product doesnt have to all be removed when rebonding, like when using silicone.


                NU LIBERTE'
                Salem, OR

                1989 Bayliner 2556 Convertible
                5.7 OMC Cobra - 15.5x11 prop
                N2K equipped throughout..
                2014 Ram 3500 crew cab, 6.7 Cummins
                2007 M-3705 SLC weekend warrior, 5th wheel
                '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
                Heavy Equipment Repair and Specialty Welding

                Comment


                  #9
                  Update: It appears that my identification of RTV silicone was incorrect. It appears that the previous sealant was 4200, or polysulfide. It cleaned up well, was semi-soft with a slight hydrocarbon odor.

                  I ended up using 5200 where the actuator attached to the transom, and where the bolts went through the mounting holes. I used 4200 from the inside to seal the pipe nipple through the transom.

                  Thanks for all the comments.
                  '89 3888
                  "RUM AWAY"

                  Comment


                    #10
                    The remnants of silicone should be mechanically removed, that's the only way to do it right.
                    I would use 5200 on it, there will be no problem removing it later.
                    Anything metal (like your bulkhead fitting) can be slightly heated with a heat gun so that it can be easily removed.
                    Alex
                    1997 2859, 7.4 MPI, Bravo II
                    1993 2452, 5.7 Bravo II - SOLD

                    Comment


                      #11
                      We boat yards use Sikaflex 291, which is the best product for this. 5200 is a waste and not necessary.
                      www.boatyardgm.com
                      www.pacificyachtimports.net
                      2002 Carver Voyager 57
                      "Making Waves"
                      3988 250 Hinos
                      "The Dark Side"
                      Alameda, California

                      Comment


                        #12
                        Not sure I'd consider it a waste. 5200 is a fantastic product, probably the most used by the average joe most likely because it can be found almost everywhere, no special trip needed to the marine supplier.
                        Dave
                        Edmonds, WA
                        "THE FIX"
                        '93 2556
                        Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                        Misc. projects thread
                        https://www.baylinerownersclub.org/f...56-gctid789773

                        Comment

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