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    Marelon Thru Hulls

    Specifically the 93 OEM series. Seems like a good product. I saw some of Mainsails destructive testing and they lasted to 800+ pounds of load before breaking. I'm thinking of replacing all the thru hulls in the forward part of the boat with marelon, and trying to track down a plastic AC strainer and just eliminate that part of the bonding system. If my engine intakes are bad, Forespar has a 93 series with a garden hose attachment for flushing. It looks pretty tight. Thoughts? I had planned to replace the ball valves on stems with real seacocks anyways when I hauled. They are coming out anyways because they were moving on the backing plates and needed to be reworked.

    Thanks!
    . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

    #2
    It seems counterintuitive, but may, in fact, be the right answer. What about long term degradation? My experience with the plastics out in the weather is they eventually Show crazing and/or become brittle. Without some serious education, if I were to be looking to buy your boat, my reaction would be “oh, hell no!” Are there any of the upper tier builders using them?
    P/C Pete
    Edmonds Yacht Club (Commodore 1993)
    1988 3818 "GLAUBEN”
    Hino EH700 175 Onan MDKD Genset
    MMSI 367770440

    Comment


    • Cool_Beans
      Cool_Beans commented
      Editing a comment
      Oyster, Swan, Baltic, Morris, Catalina, Wellcraft, Boston Whaler, Hinkley, etc. I'll post a link to the valves.

    • Pcpete
      Pcpete commented
      Editing a comment
      Interesting. I took a look at their website yesterday. I guess I’m stuck in the “thru hull fittings should be bronze or stainless” rut.

    #3
    I agree the marelon thru-hulls are a good way to go...I use them for drain lines, but not on the macerator outlet.
    they are less than half the weight of stainless or bronze, cheaper, and can last just as long if they are installed properly.

    ive seen "budget" bronze and stainless thru hulls that were machined too thin after being cast, and broke off as they were being installed and tightened down.
    so if one wants to use the metal thru-hulls, I would be very careful of the quality of the cheap ones you can find on ebay... just because they look like good quality, doesnt mean they are, and just because one manufacture makes a mistake in their machining once in awhile, doesnt mean they all do all the time... I like budget priced parts, as long as the quality is there.


    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


      #4
      If it's below the water line you want bronze, marelon is a good option for above water line thru hulls.
      1997 Maxum 2400 SCR 5.7LX Bravo II

      Mike

      Comment


        #5
        Originally posted by Nauti_Mike View Post
        If it's below the water line you want bronze, marelon is a good option for above water line thru hulls.
        Marelon is is rated for underwater use and is quite common. Real Marelon is nothing like the plastic thru hills used above the waterline on our boats. These thru hulls exceed ISO and ABYC standards for underwater thru hulls.
        1999 3788, Cummins 270 "Freedom"
        2013 Boston Whaler 130 SS
        Anacortes, WA

        Comment


        • Nauti_Mike
          Nauti_Mike commented
          Editing a comment
          Understood but what I stated is my position.

        #6
        https://www.defender.com/product.jsp?id=199316

        These things are far from budget. But they come complete as a rated assembly, ready to install. They are supposed to be rebuildable in the boat as well...they come with a plug in the handle to insert in the thru-hull. I may just go for it and see if there are any regrets later, hehe.
        . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

        Comment


          #7
          I installed all new SS thru hulls, any from the engine bulkhead back under water tied tied into the bonding system.
          As a note, all wiring on my 3870 has been replaced with upsized wire.
          reason for re-wiring was the boat was sunk in the harbor prior to my purchase from the insurance company for $1300.
          Last edited by boatworkfl; 02-21-2020, 06:55 AM.
          Pat says: DO-IT-RIGHT THE FIRST TIME!

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

          Comment


            #8
            Marelon thru hull & seacocks are quite normal on many sailboats, including higher end ones. I had several on our last boat and the only real worry was the handles breaking, The new ones from Forespar are supposedly improved quite a bit in several regards

            Here is a link to a thread with a good discussion and some testing results ( older and updated)
            https://forums.sailboatowners.com/th....136999/page-3

            Even with bronze you need to be careful (apparently) as not all bronze is created equal.
            Althea -- 2000 3988 270 Cummins, Hull Extension
            Semiahmoo, WA

            Comment


              #9
              Originally posted by jimbo88 View Post
              Marelon thru hull & seacocks are quite normal on many sailboats, including higher end ones. I had several on our last boat and the only real worry was the handles breaking, The new ones from Forespar are supposedly improved quite a bit in several regards

              Here is a link to a thread with a good discussion and some testing results ( older and updated)
              https://forums.sailboatowners.com/th....136999/page-3

              Even with bronze you need to be careful (apparently) as not all bronze is created equal.
              I only recommend marine grade bronze seacocks, no brass!
              There is a difference between a bronze valve and a seacock!
              Last edited by boatworkfl; 02-14-2020, 06:16 AM.
              Pat says: DO-IT-RIGHT THE FIRST TIME!

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

              Comment


                #10
                Originally posted by boatworkfl View Post

                I only recommend marine grade bronze seacocks, no brass!
                I have a friend who owned a large boat repair business for almost 40 years. I specifically asked him about using Marelon. He said that the only issue he's ever seen in all the years he's been in the business was the shaft breaking on the original Marelon valves. He said the later valve design is fine and the thru-hulls have always been excellent. He would not hesitate using Marelon in a boat.

                He cautioned that it needs to be Marelon, and not generic plastic.
                1999 3788, Cummins 270 "Freedom"
                2013 Boston Whaler 130 SS
                Anacortes, WA

                Comment


                  #11
                  So I bought a 3/4" for the head intake and a 1" for the A/C (I'll neck down to the strainer). These are really cool looking and beefy pieces of modern engineering! I might pony up and replace my engine intakes with the 1 1/4" seacocks with built in hose fittings for flushing. I can post pics if anyone is interested.
                  . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

                  Comment


                  • builderdude
                    builderdude commented
                    Editing a comment
                    Yes please, pics are worth a thousand words 👍🏼

                  #12
                  Okey dokey Builderdude, since you asked!

                  I ordered a 3/4" for my head intake and a 1" for the AC intake. The mushrooms and fittings are under sized (not full flow, like Groco) which is why I went with 1" for the AC intake. The style Defender sells comes with separate straight or 90 degree fittings. The entire assembly was $110. Pics attached are the 1" Series 93 Seacock. It's an impressive piece of modern engineering. Instructions state the ABYC 500+ lbs load rating can be developed with just the mushroom which is special designed for this seacock. But, it has bosses molded in for 1/4"-20 thru bolts if you wanted to install them. There is a plug in the handle that will fit into and seal the mushroom from outside. It can be disassembled and cleaned in the boat. Handle is extra beefy. No regrets so far! I'll have them installed by next week.
                  Attached Files
                  . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

                  Comment


                  • builderdude
                    builderdude commented
                    Editing a comment
                    Thanks dude👍🏼

                  #13
                  Interesting, looks like if a shut off is desired it’s simply added in the stack. None of my through hulls are below the waterline (except the head intake) which is factory bronze. I went with stainless on the rest. How do theses compare cost wise?
                  Dave
                  Edmonds, WA
                  "THE FIX"
                  '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                  (.030 over-Vortec top end-part closed cooled)
                  The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                  Misc. projects thread
                  https://www.baylinerownersclub.org/f...56-gctid789773

                  Comment


                    #14
                    Originally posted by builderdude View Post
                    Interesting, looks like if a shut off is desired it’s simply added in the stack. None of my through hulls are below the waterline (except the head intake) which is factory bronze. I went with stainless on the rest. How do theses compare cost wise?
                    What do you mean a shut-off? The ball valve portion is built in.
                    . . .It places the lotion in the Basket. . .and that basket happens to be in a 1987 Bayliner 3870 w/ Hino 175's

                    Comment


                      #15
                      Originally posted by Cool_Beans View Post

                      What do you mean a shut-off? The ball valve portion is built in.
                      Looks like the ball valve portion is one of three sections (center) with gaskets on either end all held together with the 4 screws.
                      Click image for larger version

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                      Dave
                      Edmonds, WA
                      "THE FIX"
                      '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                      (.030 over-Vortec top end-part closed cooled)
                      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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