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Re: [bolger] Micro Progress/lead hardness

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  • Sakari Aaltonen
    ... Which chart did you check? I checked the ones in Steward s Boatbuilding Manual and Gerr s The Nature of Boats . Both show stainless steel in *two*
    Message 1 of 19 , May 1, 2000
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      David Jost wrote:

      > I just checked the chart of metals/galvanic corrosion index. I will
      > stay with Stainless steel threaded rod instead of the bronze as
      > planned. too bad, I have a garage full of old bronze rod from a
      > neighbor that used to make the stuff at a foundry in Connecticut.
      > These bronze rods are at least 50 years old and were used to hold up
      > garden fencing at an oceanside garden in Harwich. They are still as
      > good as new after 50 years of horrendous salt encrusted air. The
      > table says that lead and bronze are not as compatible as stainless
      > and
      > lead. I hope that I can find 316 type stainless available.

      Which chart did you check? I checked the ones in Steward's
      "Boatbuilding Manual" and Gerr's "The Nature of Boats".
      Both show stainless steel in *two* places. This comes about
      because stainless steel has two states, active and passive.
      If it is in (steady) contact with oxygen (air or water), its
      state is passive and it is more compatible with lead than
      bronze. However, if there is no oxygen, like inside a keel,
      then stainless steel becomes active, and is much less compatible
      than bronze. That is, it will corrode (the keel lead will
      eat it, so to speak). This applies to type 316, too.


      Sakari Aaltonen
    • david
      David, Tradition and experience mediate against your choice. Bronze has been used successfully in keelbolts for centuries. Stainless steel has a checkered
      Message 2 of 19 , May 1, 2000
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        David,
        Tradition and experience mediate against your choice. Bronze has
        been used successfully in keelbolts for centuries. Stainless steel has
        a checkered history in this application. As I understand it, bronze is
        more "noble" than lead, and the lead keel will slowly waste away,
        very slowly, over decades (it's a lot of lead), in the presence of the
        small amount of bronze. The bronze rod will (in theory) not be
        affected. With stainless steel, the rod, buried in the keel and with no
        access to oxygen to maintain a stainless surface, will corrode rapidly
        over a few seasons. In any case, make sure that whatever keelbolts
        you use are easily removable for inspection and replacement, as
        wierd things happen to them, and losing your ballast can ruin your day,
        david

        David Jost wrote:

        > I just checked the chart of metals/galvanic corrosion index. I will
        > stay with Stainless steel threaded rod instead of the bronze as
        > planned. too bad, I have a garage full of old bronze rod from a
        > neighbor that used to make the stuff at a foundry in Connecticut.
        > These bronze rods are at least 50 years old and were used to hold up
        > garden fencing at an oceanside garden in Harwich. They are still as
        > good as new after 50 years of horrendous salt encrusted air. The
        > table says that lead and bronze are not as compatible as stainless
        > and
        > lead. I hope that I can find 316 type stainless available.
        > >
        >
        > > >
        > - In
        > > bolger@egroups.com, "David Jost" <djost@m...> wrote:
        > > > Peter,
        > > > I do not think that this is so much being pre-occupied, as
        > > being
        > > > careful. I think you have the correct idea in through bolting
        > the
        > > > keel and building it vertical. I can see only good things
        > > happening
        > > > for what amount to very little extra expense here. I will
        > install
        > > 3
        > > > bronze keel bolts that will run the length of the mold, and will
        > > > provied recesses for the external nuts. I think that the wood
        > > dowels
        > > > were a great idea! I think I will also continue to use the
        > exterior
        > > > sheething as well since I already have the material on hand.
        > > > How did you back up the nuts on the interior? And, What did
        > > you
        > > > use for caulking around the bolt holes?
        > > >
        > > > David Jost
        > > > " glorious in Boston today, "Firefly" now has two sides, 2
        > > frames,
        > > > and all spars and sails."
        >
        > ------------------------------------------------------------------------
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      • David Jost
        That certainly explains a lot! I will stick with bronze rod (since I already have quite a bit of it). I certainly can see why stainless would corrode under
        Message 3 of 19 , May 2, 2000
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          That certainly explains a lot! I will stick with bronze rod (since I
          already have quite a bit of it). I certainly can see why stainless
          would corrode under such circumstances. I would rather have the
          ballast corrode than the fastenings. I had an old Herreshoff day
          sailor that had bronze fastenings throughout. They were still in
          excellent condition despite 30 years of immersion in salt water. The
          keel on that boat was starting to corrode a bit, mainly due to the
          interaction of the copper bottom paint with the lead. This was
          shortly
          after the ban on paints with TFB in them. (I think that's the
          correct
          name)

          I now understand how stainless cannot be effective in an anaerobic
          environment. It needs to be exposed to the air to form its
          protective
          coating.

          Thanks for the input.
          David Jost
        • Bernie Wolfard
          I think the idea of dabbling in traditional boat building methods is the only valid reason for bolting a MICRO keel. There is a huge downside to this in that
          Message 4 of 19 , May 2, 2000
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            I think the idea of dabbling in "traditional" boat building
            methods
            is the only valid reason for bolting a MICRO keel. There is a huge
            downside to this in that it is generally considered a bad idea to
            drill holes in the bottom of a boat!
            As designed, a MICRO keel will pull the bottom off the boat before it
            lets go. This has been proved in personal experience as well in
            countless numbers of MICRO'S out there with keels attached as per
            plans. MICRO'S keel structure is a true composite, only different
            from high tech airplanes in that the composites interior foam is
            replaced with lead. It is as strong or stronger but with the mass
            make it a keel instead of a wing.
            That said, the idea of using ½" plywood on MICRO'S bottom is
            well
            founded. She will not be worst for the weight and be much strong,
            especially in taking the ground.

            --- In bolger@egroups.com, "David Jost" <djost@m...> wrote:
            > Peter,
            > I do not think that this is so much being pre-occupied, as
            being
            > careful. I think you have the correct idea in through bolting the
            > keel and building it vertical. I can see only good things
            happening
            > for what amount to very little extra expense here. I will install
            3
            > bronze keel bolts that will run the length of the mold, and will
            > provied recesses for the external nuts. I think that the wood
            dowels
            > were a great idea! I think I will also continue to use the exterior
            > sheething as well since I already have the material on hand.
            > How did you back up the nuts on the interior? And, What did
            you
            > use for caulking around the bolt holes?
            >
            > David Jost
            > " glorious in Boston today, "Firefly" now has two sides, 2
            frames,
            > and all spars and sails."
          • peter lenihan
            Hi Bernie, The huge downside which you refer to,is ONLY true if one forgets to plug/fill the holes one has drilled with something useful! :-D Warm Regards,
            Message 5 of 19 , May 2, 2000
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              Hi Bernie,
              The"huge downside"which you refer to,is ONLY true if one forgets
              to plug/fill the holes one has drilled with something useful! :-D
              Warm Regards,

              Peter Lenihan,itching to begin his seventh season with his MICRO
              which looks as beautiful and strong as the day she was launched,off
              the shores of the St.Lawrence......316 stainless keelbolts and
              all.....




              --- In bolger@egroups.com, "Bernie Wolfard" <berniew@n...> wrote:
              > I think the idea of dabbling in "traditional" boat building
              > methods
              > is the only valid reason for bolting a MICRO keel. There is a huge
              > downside to this in that it is generally considered a bad idea to
              > drill holes in the bottom of a boat!
              > As designed, a MICRO keel will pull the bottom off the boat before
              it
              > lets go. This has been proved in personal experience as well in
              > countless numbers of MICRO'S out there with keels attached as per
              > plans. MICRO'S keel structure is a true composite, only different
              > from high tech airplanes in that the composites interior foam is
              > replaced with lead. It is as strong or stronger but with the mass
              > make it a keel instead of a wing.
              > That said, the idea of using ½" plywood on MICRO'S bottom is
              > well
              > founded. She will not be worst for the weight and be much strong,
              > especially in taking the ground.
              >
              > --- In bolger@egroups.com, "David Jost" <djost@m...> wrote:
              > > Peter,
              > > I do not think that this is so much being pre-occupied, as
              > being
              > > careful. I think you have the correct idea in through bolting the
              > > keel and building it vertical. I can see only good things
              > happening
              > > for what amount to very little extra expense here. I will install
              > 3
              > > bronze keel bolts that will run the length of the mold, and will
              > > provied recesses for the external nuts. I think that the wood
              > dowels
              > > were a great idea! I think I will also continue to use the
              exterior
              > > sheething as well since I already have the material on hand.
              > > How did you back up the nuts on the interior? And, What did
              > you
              > > use for caulking around the bolt holes?
              > >
              > > David Jost
              > > " glorious in Boston today, "Firefly" now has two sides, 2
              > frames,
              > > and all spars and sails."
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