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Re: construction without fasteners

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  • Chris Crandall
    ... I recommend against stainless--they are harder to use, and don t offer much in most applications for Michalak-style boats. But if you got em, you won t be
    Message 1 of 21 , Nov 1, 2007
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      Ray wrote:
      > True, but on the other hand, drywall screws are cheaper than stainless
      > and reusable as temporary fasteners, and even if you use stainless
      > screws, you still have to putty the heads to get a smooth hull.

      I recommend against stainless--they are harder to use, and don't offer
      much in most applications for Michalak-style boats. But if you got 'em,
      you won't be much harmed by their use.

      Drywall screws may be reusable, but they mangle up the wood a lot more
      than they need to, and fairing the holes is, in fact, quite a job.

      > Of the disadvantages of fasteners, he says:
      > 1/ Fasteners are expensive

      It's all relative. All the silicon bronze ring nails you'd need for,
      say, a Philsboat should cost you less than $18 at Jamestown Distributors
      (one pound of 3/4"). Cheaper if you use copper.


      > 2/ Fasteners often make the boat a little bit harder to fair

      Not really, considering the offset of fairing the marks made by either
      the temporary drywall screws, or even the clamps used in place of any
      fastening.

      > 3/ Over time fasteners may move a little, cracking the paint that
      > covers their heads and allow moisture to get in.

      The paint line can separate between the nail head and the surface of the
      wood, a very small amount. The swelling of the wood into the annular
      rings provides a seal equal to most paints--it's not really an issue.

      > 4/ A glued structure has a waterproof glue line between parts.
      > Fasteners penetrate the waterproof joins.

      This is sorta true, but not true if your fastener goes in while the glue
      is wet. And your fastener *should* be going in when the glue line is
      wet. Otherwise, what are you doing?


      > 5/ Fasteners can make repairs difficult - where fasteners are
      > eliminated from the structure and part of the boat can be cut, planed
      > or sawn without risk of damaging tools

      True enough, although bronze and copper are only a modest hindrance.


      > I'd never considered points 3 and 4, but they make sense to me.
      > Another issue is that a glue joint spreads stresses over the largest
      > possible area, whereas fasteners tend to concentrate stresses.

      This is actually not correct. Keep in mind that a ring nail spreads out
      stresses compared to a glue line. A glue line puts stresses in only one
      (or two) dimensions, whereas the fastener adds a second (or third)
      dimension. This can be a real boon, particularly when you're attaching
      a frame/bulkhead to the hull (which was the original situation that
      started this discussion).


      In short, in vessels designed with solid lumber/plywood joints,
      fasteners can be an *excellent* strategy. They are no replacement in
      joints designed for stitch-and-glue, but I don't think anyone was
      recommending it.

      -Chris
    • rhaldridge
      ... It s probably one of those personal things, but I didn t find it to be so. In other projects, when I used ring nails and screws, the holes were just as
      Message 2 of 21 , Nov 1, 2007
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        --- In Michalak@yahoogroups.com, Chris Crandall <crandall@...> wrote:
        >

        > Drywall screws may be reusable, but they mangle up the wood a lot more
        > than they need to, and fairing the holes is, in fact, quite a job.

        It's probably one of those personal things, but I didn't find it to be
        so. In other projects, when I used ring nails and screws, the holes
        were just as big, because nails and screws should be set below the
        surface, but the fairing putty tended to pop off sometimes because it
        didn't get much of a grip on the heads. The trick to fairing the
        empty screw holes, I find, is to use a low-density filler and mound it
        up a bit. It only takes a second with the orbital sander to cut them
        level.


        >
        > > Of the disadvantages of fasteners, he says:
        > > 1/ Fasteners are expensive
        >
        > It's all relative. All the silicon bronze ring nails you'd need for,
        > say, a Philsboat should cost you less than $18 at Jamestown
        Distributors
        > (one pound of 3/4"). Cheaper if you use copper.
        >
        >
        > > 2/ Fasteners often make the boat a little bit harder to fair
        >
        > Not really, considering the offset of fairing the marks made by either
        > the temporary drywall screws, or even the clamps used in place of any
        > fastening.
        >
        > > 3/ Over time fasteners may move a little, cracking the paint that
        > > covers their heads and allow moisture to get in.
        >
        > The paint line can separate between the nail head and the surface of
        the
        > wood, a very small amount. The swelling of the wood into the annular
        > rings provides a seal equal to most paints--it's not really an issue.
        >
        > > 4/ A glued structure has a waterproof glue line between parts.
        > > Fasteners penetrate the waterproof joins.
        >
        > This is sorta true, but not true if your fastener goes in while the
        glue
        > is wet. And your fastener *should* be going in when the glue line is
        > wet. Otherwise, what are you doing?
        >

        Hey, you're arguing with Michael Storer, not me, though I agree with
        him. But on that last part, the screw penetrates through the glue
        line, whenever you install it. Metal, having a different rate of
        expansion, is going to work back and forth, and eventually it's going
        to be easier for water to penetrate along a screw or ringnail,
        especially if underwater, than from the outside of a glueline. Also,
        above you mention "swelling of the wood"--which doesn't happen if no
        water penetrates-- as a positive aspect of fasteners. If there's
        enough moisture to swell the wood, sooner or later you'll get enough
        decay to loosen the fastener.


        >
        > > 5/ Fasteners can make repairs difficult - where fasteners are
        > > eliminated from the structure and part of the boat can be cut, planed
        > > or sawn without risk of damaging tools
        >
        > True enough, although bronze and copper are only a modest hindrance.
        >
        >
        > > I'd never considered points 3 and 4, but they make sense to me.
        > > Another issue is that a glue joint spreads stresses over the largest
        > > possible area, whereas fasteners tend to concentrate stresses.
        >
        > This is actually not correct. Keep in mind that a ring nail spreads
        out
        > stresses compared to a glue line. A glue line puts stresses in only
        one
        > (or two) dimensions, whereas the fastener adds a second (or third)
        > dimension.

        We'll have to disagree here. A fastener creates a point load. Just
        consider the area secured by the head of a nail or screw. It's minute
        compared to the area of a good wide glue joint. No matter how deeply
        it penetrates the framing member, it's still only holding the planking
        with its head. Remove the head and it's useless. Further, good
        engineering practice designs joints that are glued in at least two
        dimensions-- for example, the rub rail of my little cat is glued to
        the topside planking, and then the side deck glues down over the sheer
        clamp, the planking and the rub rail. Everything in that crucial
        joint is secure in at least two dimensions except for the side deck,
        but it's glued to a surface over two inches wide, and then glass taped
        to cover the end grain and protect the rub rail. Fasteners would add
        very little strength to that joint.

        Of course, some joints can't be glued in two dimensions. Storer says
        that, for example, rub rails not covered by the deck could be
        fastened. So there are certainly still joints that may need
        fastening. I'm probably going to use fasteners in the crossbeam to
        web connections of my little cat, just because it could be
        catastrophic if the glue line failed, (and probably because I lack
        confidence in my boatbuilding skills.)

        Consider that a ply boat built monocoque with epoxy is a composite
        structure. Ask any cutting edge naval architect if he backs up his
        high stress composite joints with fasteners and he'll look at you as
        if you just landed from Mars. Again, point loads. Carbon composite
        multihulls, which are probably the lightest and most highly stressed
        boats in existence, use carbon fiber set in epoxy to transfer the
        forces acting on crucial joints to the rest of the structure. As an
        example of this thinking, there was recently a discussion on a
        multihull group about forestay chainplates. Ian Farrier, the designer
        of the Corsair F boats, stated that he no longer recommended bolted-on
        chainplates, as composite chainplates made by wrapping glass or carbon
        fiber around a thimble and gluing the fiber to the interior topsides
        were stronger, cheaper, and would never leak or develop corrosion
        problems.

        Of course, all this is just my opinion. When boats were assembled
        from pieces of timber and caulked with oakum, there was no choice.
        You had to use fasteners. Maybe not any more. Michael Storer has
        been building small boats without fasteners for decades and claims
        he's never had one fall apart.

        On the other hand, if you're not using epoxy, fasteners are probably
        an excellent idea.

        Ray
      • Robb
        I still use stainless steel 1/4 crown staples. They hold nearly as well as screws and you can nail up a boat faster than you can even think about using nails
        Message 3 of 21 , Nov 1, 2007
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          I still use stainless steel 1/4 crown staples. They hold nearly as well as screws and you can nail up a boat faster than you can even think about using nails or screws. Robb



          ----- Original Message -----
          From: Chris Crandall
          To: No Reply
          Cc: Michalak@yahoogroups.com
          Sent: Thursday, November 01, 2007 11:42 AM
          Subject: [Michalak] Re: construction without fasteners


          Ray wrote:
          > True, but on the other hand, drywall screws are cheaper than stainless
          > and reusable as temporary fasteners, and even if you use stainless
          > screws, you still have to putty the heads to get a smooth hull.

          I recommend against stainless--they are harder to use, and don't offer
          much in most applications for Michalak-style boats. But if you got 'em,
          you won't be much harmed by their use.

          Drywall screws may be reusable, but they mangle up the wood a lot more
          than they need to, and fairing the holes is, in fact, quite a job.

          > Of the disadvantages of fasteners, he says:
          > 1/ Fasteners are expensive

          It's all relative. All the silicon bronze ring nails you'd need for,
          say, a Philsboat should cost you less than $18 at Jamestown Distributors
          (one pound of 3/4"). Cheaper if you use copper.

          > 2/ Fasteners often make the boat a little bit harder to fair

          Not really, considering the offset of fairing the marks made by either
          the temporary drywall screws, or even the clamps used in place of any
          fastening.

          > 3/ Over time fasteners may move a little, cracking the paint that
          > covers their heads and allow moisture to get in.

          The paint line can separate between the nail head and the surface of the
          wood, a very small amount. The swelling of the wood into the annular
          rings provides a seal equal to most paints--it's not really an issue.

          > 4/ A glued structure has a waterproof glue line between parts.
          > Fasteners penetrate the waterproof joins.

          This is sorta true, but not true if your fastener goes in while the glue
          is wet. And your fastener *should* be going in when the glue line is
          wet. Otherwise, what are you doing?

          > 5/ Fasteners can make repairs difficult - where fasteners are
          > eliminated from the structure and part of the boat can be cut, planed
          > or sawn without risk of damaging tools

          True enough, although bronze and copper are only a modest hindrance.

          > I'd never considered points 3 and 4, but they make sense to me.
          > Another issue is that a glue joint spreads stresses over the largest
          > possible area, whereas fasteners tend to concentrate stresses.

          This is actually not correct. Keep in mind that a ring nail spreads out
          stresses compared to a glue line. A glue line puts stresses in only one
          (or two) dimensions, whereas the fastener adds a second (or third)
          dimension. This can be a real boon, particularly when you're attaching
          a frame/bulkhead to the hull (which was the original situation that
          started this discussion).

          In short, in vessels designed with solid lumber/plywood joints,
          fasteners can be an *excellent* strategy. They are no replacement in
          joints designed for stitch-and-glue, but I don't think anyone was
          recommending it.

          -Chris





          [Non-text portions of this message have been removed]
        • vexatious2001
          ... as well as screws and you can nail up a boat faster than you can even think about using nails or screws. Robb ... I need to get me a air staple gun (and a
          Message 4 of 21 , Nov 1, 2007
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            --- In Michalak@yahoogroups.com, "Robb" <Robb@...> wrote:
            >
            > I still use stainless steel 1/4 crown staples. They hold nearly
            as well as screws and you can nail up a boat faster than you can
            even think about using nails or screws. Robb
            >
            >
            >
            >
            >
            >


            I need to get me a air staple gun (and a new compressor
            to replace the one I burned up) and try that some time.




            Max
          • Rob Rohde-Szudy
            I m with Max. No matter how good the glue is, I don t think it can ever replace a through fastener. It is immensely strong to use a metal piece that clamps the
            Message 5 of 21 , Nov 1, 2007
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              I'm with Max. No matter how good the glue is, I don't think it can ever replace a through fastener. It is immensely strong to use a metal piece that clamps the outside of one piece of wood all the way through to the opposite side of the other piece. Yes, epoxy joints usually break in the wood, which is good. Even better is having the wood itself reinforced with metal pins.

              Like Max, just my opinion. And like Max I always seem to have one.

              --Rob


              Re: construction without fasteners

              I vote for having the fasteners.

              You almost have to have them anyway during "glue-up,"
              and It's less work to use corrosion-resistant fasteners
              and leave them in, than to use drywall screws and then
              have to remove them and deal with the holes.

              Just my opinion.

              And I always have one.


              __________________________________________________
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              [Non-text portions of this message have been removed]
            • Dave Gray
              I m not totally sold on metal fasteners for all joint construction. Of late I ve been using bamboo skewers tipped with glue and driven into holes where screws
              Message 6 of 21 , Nov 2, 2007
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                I'm not totally sold on metal fasteners for all joint construction.
                Of late I've been using bamboo skewers tipped with glue and driven
                into holes where screws were used to help hold parts together
                temporarily until the glue dried. After the glue dries, the glue
                tipped skewers are driven into the holes. Later, the tops are clipped
                off, then knocked down flush to the surface with a small jack plane.
                Sure beats filling in over the tops of screws; and, for the cost of
                about eight stainless screws, you can buy a package of 100 of these
                skewers (50 larger diameter, 50 smaller diameter) at Wal-Mart that
                fit nicely into #8 and #10 screw holes.

                This approach works well on shear-stress joints. It may not be strong
                enough for a joint where there is a poor fit or where joint strength
                depends on one member being drawn up tightly to another under
                tension. I still use bronze nails to hold a flat bottom to a frame,
                for example.

                Dave Gray
                PolySail International



                --- In Michalak@yahoogroups.com, Rob Rohde-Szudy <robrohdeszudy@...>
                wrote:
                >
                >
                > I'm with Max. No matter how good the glue is, I don't think it can
                ever replace a through fastener. It is immensely strong to use a
                metal piece that clamps the outside of one piece of wood all the way
                through to the opposite side of the other piece. Yes, epoxy joints
                usually break in the wood, which is good. Even better is having the
                wood itself reinforced with metal pins.
                >
                > Like Max, just my opinion. And like Max I always seem to have one.
                >
                > --Rob
                >
                >
                > Re: construction without fasteners
                >
                > I vote for having the fasteners.
                >
                > You almost have to have them anyway during "glue-up,"
                > and It's less work to use corrosion-resistant fasteners
                > and leave them in, than to use drywall screws and then
                > have to remove them and deal with the holes.
                >
                > Just my opinion.
                >
                > And I always have one.
                >
                >
                > __________________________________________________
                > Do You Yahoo!?
                > Tired of spam? Yahoo! Mail has the best spam protection around
                > http://mail.yahoo.com
                >
                > [Non-text portions of this message have been removed]
                >
              • pecostx@comcast.net
                Just to be fecetious here, how about WAY back when they only used wooden pegs of different wood to swell up and fill the hole as fasteners? (hehehe) Geoff
                Message 7 of 21 , Nov 2, 2007
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                  Just to be fecetious here, how about WAY back when they only used wooden pegs of different wood to swell up and fill the hole as fasteners? (hehehe)
                  Geoff
                  (just having a little fun here. although very little.)

                  -------------- Original message --------------
                  From: "rhaldridge" <knobmaker@...>
                  --- In Michalak@yahoogroups.com, Chris Crandall <crandall@...> wrote:
                  >

                  > Drywall screws may be reusable, but they mangle up the wood a lot more
                  > than they need to, and fairing the holes is, in fact, quite a job.

                  It's probably one of those personal things, but I didn't find it to be
                  so. In other projects, when I used ring nails and screws, the holes
                  were just as big, because nails and screws should be set below the
                  surface, but the fairing putty tended to pop off sometimes because it
                  didn't get much of a grip on the heads. The trick to fairing the
                  empty screw holes, I find, is to use a low-density filler and mound it
                  up a bit. It only takes a second with the orbital sander to cut them
                  level.

                  >
                  > > Of the disadvantages of fasteners, he says:
                  > > 1/ Fasteners are expensive
                  >
                  > It's all relative. All the silicon bronze ring nails you'd need for,
                  > say, a Philsboat should cost you less than $18 at Jamestown
                  Distributors
                  > (one pound of 3/4"). Cheaper if you use copper.
                  >
                  >
                  > > 2/ Fasteners often make the boat a little bit harder to fair
                  >
                  > Not really, considering the offset of fairing the marks made by either
                  > the temporary drywall screws, or even the clamps used in place of any
                  > fastening.
                  >
                  > > 3/ Over time fasteners may move a little, cracking the paint that
                  > > covers their heads and allow moisture to get in.
                  >
                  > The paint line can separate between the nail head and the surface of
                  the
                  > wood, a very small amount. The swelling of the wood into the annular
                  > rings provides a seal equal to most paints--it's not really an issue.
                  >
                  > > 4/ A glued structure has a waterproof glue line between parts.
                  > > Fasteners penetrate the waterproof joins.
                  >
                  > This is sorta true, but not true if your fastener goes in while the
                  glue
                  > is wet. And your fastener *should* be going in when the glue line is
                  > wet. Otherwise, what are you doing?
                  >

                  Hey, you're arguing with Michael Storer, not me, though I agree with
                  him. But on that last part, the screw penetrates through the glue
                  line, whenever you install it. Metal, having a different rate of
                  expansion, is going to work back and forth, and eventually it's going
                  to be easier for water to penetrate along a screw or ringnail,
                  especially if underwater, than from the outside of a glueline. Also,
                  above you mention "swelling of the wood"--which doesn't happen if no
                  water penetrates-- as a positive aspect of fasteners. If there's
                  enough moisture to swell the wood, sooner or later you'll get enough
                  decay to loosen the fastener.

                  >
                  > > 5/ Fasteners can make repairs difficult - where fasteners are
                  > > eliminated from the structure and part of the boat can be cut, planed
                  > > or sawn without risk of damaging tools
                  >
                  > True enough, although bronze and copper are only a modest hindrance.
                  >
                  >
                  > > I'd never considered points 3 and 4, but they make sense to me.
                  > > Another issue is that a glue joint spreads stresses over the largest
                  > > possible area, whereas fasteners tend to concentrate stresses.
                  >
                  > This is actually not correct. Keep in mind that a ring nail spreads
                  out
                  > stresses compared to a glue line. A glue line puts stresses in only
                  one
                  > (or two) dimensions, whereas the fastener adds a second (or third)
                  > dimension.

                  We'll have to disagree here. A fastener creates a point load. Just
                  consider the area secured by the head of a nail or screw. It's minute
                  compared to the area of a good wide glue joint. No matter how deeply
                  it penetrates the framing member, it's still only holding the planking
                  with its head. Remove the head and it's useless. Further, good
                  engineering practice designs joints that are glued in at least two
                  dimensions-- for example, the rub rail of my little cat is glued to
                  the topside planking, and then the side deck glues down over the sheer
                  clamp, the planking and the rub rail. Everything in that crucial
                  joint is secure in at least two dimensions except for the side deck,
                  but it's glued to a surface over two inches wide, and then glass taped
                  to cover the end grain and protect the rub rail. Fasteners would add
                  very little strength to that joint.

                  Of course, some joints can't be glued in two dimensions. Storer says
                  that, for example, rub rails not covered by the deck could be
                  fastened. So there are certainly still joints that may need
                  fastening. I'm probably going to use fasteners in the crossbeam to
                  web connections of my little cat, just because it could be
                  catastrophic if the glue line failed, (and probably because I lack
                  confidence in my boatbuilding skills.)

                  Consider that a ply boat built monocoque with epoxy is a composite
                  structure. Ask any cutting edge naval architect if he backs up his
                  high stress composite joints with fasteners and he'll look at you as
                  if you just landed from Mars. Again, point loads. Carbon composite
                  multihulls, which are probably the lightest and most highly stressed
                  boats in existence, use carbon fiber set in epoxy to transfer the
                  forces acting on crucial joints to the rest of the structure. As an
                  example of this thinking, there was recently a discussion on a
                  multihull group about forestay chainplates. Ian Farrier, the designer
                  of the Corsair F boats, stated that he no longer recommended bolted-on
                  chainplates, as composite chainplates made by wrapping glass or carbon
                  fiber around a thimble and gluing the fiber to the interior topsides
                  were stronger, cheaper, and would never leak or develop corrosion
                  problems.

                  Of course, all this is just my opinion. When boats were assembled
                  from pieces of timber and caulked with oakum, there was no choice.
                  You had to use fasteners. Maybe not any more. Michael Storer has
                  been building small boats without fasteners for decades and claims
                  he's never had one fall apart.

                  On the other hand, if you're not using epoxy, fasteners are probably
                  an excellent idea.

                  Ray




                  [Non-text portions of this message have been removed]
                • Kenneth Grome
                  ... Do you mean like three years ago? http://www.naga-pelangi.de/Naga_2/album/may04SPF/page36.html http://www.naga-pelangi.de/Naga_2/album/may04SPF/page37.html
                  Message 8 of 21 , Nov 2, 2007
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                    > Just to be fecetious here, how about WAY back
                    > when they only used wooden pegs of different
                    > wood to swell up and fill the hole as fasteners?


                    Do you mean like three years ago?

                    http://www.naga-pelangi.de/Naga_2/album/may04SPF/page36.html
                    http://www.naga-pelangi.de/Naga_2/album/may04SPF/page37.html
                    http://www.naga-pelangi.de/Naga_2/album/may04SPF/page53.html
                    http://www.naga-pelangi.de/Naga_2/album/may04SPF/page62.html

                    Here's the main page of the site, it's an interesting record of the
                    construction of a very special boat. If you want to see how big boats
                    were built traditionally this is an exceptional example:

                    http://www.naga-pelangi.de/Naga_2/english/index_e.htm

                    Sincerely,
                    Ken Grome
                    Bagacay Boatworks
                    www.bagacayboatworks.com
                  • Chris Crandall
                    ... My comment was generic, not personal. The you was directed toward someone who is building a boat, and fastening plywood to a solid lumber frame without
                    Message 9 of 21 , Nov 2, 2007
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                      I wrote:

                      >> And your fastener *should* be going in when the glue line is
                      >> wet. Otherwise, what are you doing?


                      Ray writes:

                      > Hey, you're arguing with Michael Storer, not me, though I agree with
                      > him. But on that last part, the screw penetrates through the glue
                      > line, whenever you install it. Metal, having a different rate of
                      > expansion, is going to work back and forth, and eventually it's going
                      > to be easier for water to penetrate along a screw or ringnail,
                      > especially if underwater, than from the outside of a glueline. Also,
                      > above you mention "swelling of the wood"--which doesn't happen if no
                      > water penetrates-- as a positive aspect of fasteners. If there's
                      > enough moisture to swell the wood, sooner or later you'll get enough
                      > decay to loosen the fastener.

                      My comment was generic, not personal. The "you" was directed toward
                      someone who is building a boat, and fastening plywood to a solid lumber
                      frame without glue--"what is that person doing?" And the answer is
                      probably screwing up.

                      Wood does not require moisture to swell around an annular ring nail. It
                      is inherent in the qualities of most boatbuilding woods to swell around
                      the annular rings--all softwoods will do so (and who builds bulkheads of
                      Michalak boats without softwoods? People who are not sensible.).

                      > We'll have to disagree here. A fastener creates a point load. Just
                      > consider the area secured by the head of a nail or screw. It's minute
                      > compared to the area of a good wide glue joint. No matter how deeply
                      > it penetrates the framing member, it's still only holding the planking
                      > with its head. Remove the head and it's useless.

                      First off, you're exaggerating here. An annular nail has "gripping
                      power" along most of its shaft. You example/complaint only applies when
                      the plywood is so thin that it is thinner than the part of the nail near
                      the head with no rings. Second of all, no one was suggesting that one
                      would fail to use glue, the recommendation I was making was clearly *in
                      addition* to a glue line. Third, you're resisting the main point of the
                      argument--a nail offers compression (where the head is essential, as you
                      point out) *and* shear resistance, which is much, much more important,
                      and works absolutely fine in the absence of a head--the shaft alone
                      does the majority of the work.

                      > Consider that a ply boat built monocoque with epoxy is a composite
                      > structure. Ask any cutting edge naval architect if he backs up his
                      > high stress composite joints with fasteners and he'll look at you as
                      > if you just landed from Mars. Again, point loads.

                      You seem to be making a point in opposition to something, but I don't
                      know what. I wrote "They [fasteners] are no replacement in joints
                      designed for stitch-and-glue, but I don't think anyone was
                      recommending it." So apparently you're agreeing with me?
                    • rhaldridge
                      ... bulkheads of ... Perhaps you were referring to springback here-- the tendency of ruptured wood to return to its original shape. Most boatbuilders, when
                      Message 10 of 21 , Nov 2, 2007
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                        --- In Michalak@yahoogroups.com, Chris Crandall <crandall@...> wrote:

                        >
                        > Wood does not require moisture to swell around an annular ring nail. It
                        > is inherent in the qualities of most boatbuilding woods to swell around
                        > the annular rings--all softwoods will do so (and who builds
                        bulkheads of
                        > Michalak boats without softwoods? People who are not sensible.).

                        Perhaps you were referring to springback here-- the tendency of
                        ruptured wood to return to its original shape. Most boatbuilders,
                        when speaking of "swelling" would be referring to the tendency of wet
                        wood to swell, as in a carvel planked boat that must be kept wet to
                        swell the planks enough to tighten the caulking.

                        >
                        > > We'll have to disagree here. A fastener creates a point load. Just
                        > > consider the area secured by the head of a nail or screw. It's minute
                        > > compared to the area of a good wide glue joint. No matter how deeply
                        > > it penetrates the framing member, it's still only holding the planking
                        > > with its head. Remove the head and it's useless.
                        >
                        > First off, you're exaggerating here. An annular nail has "gripping
                        > power" along most of its shaft. You example/complaint only applies when
                        > the plywood is so thin that it is thinner than the part of the nail
                        near
                        > the head with no rings.

                        Okay, so let's nail two pieces of wood together with a headless
                        ringnail. It will have some resistance to being peeled apart, but not
                        enough that I couldn't pull it apart, given a few inches of leverage.
                        I've pulled a lot of ringnails out with vicegrips (I'm not a very
                        good boatbuilder) It's true it would have a lot of resistance to
                        shear, but it has none at all to torsion. A good glue joint does,
                        because it spreads its holding power over a larger area. And 1/4"
                        planking, common on small boats, has almost no resistance to peeling
                        forces, if secured by a headless nail.


                        Second of all, no one was suggesting that one
                        > would fail to use glue, the recommendation I was making was clearly *in
                        > addition* to a glue line.

                        The point I'm trying to get across is that in many instances, the
                        amount of security added by fasteners to a good glue joint is not
                        enough to be worth the trouble.


                        Third, you're resisting the main point of the
                        > argument--a nail offers compression (where the head is essential, as
                        you
                        > point out) *and* shear resistance, which is much, much more important,
                        > and works absolutely fine in the absence of a head--the shaft alone
                        > does the majority of the work.

                        Most screws and ringnails are used to secure planking to a framework.
                        Shear is not much of an issue under those circumstances. Long before
                        a nail could contribute to preventing shear forces from moving a
                        planking panel, almost all the glue lines holding the planking to the
                        frame would have to be broken. This seems to me a pretty good
                        illustration of why permanent fasteners are redundant in a ply-epoxy
                        boat.


                        >
                        > > Consider that a ply boat built monocoque with epoxy is a composite
                        > > structure. Ask any cutting edge naval architect if he backs up his
                        > > high stress composite joints with fasteners and he'll look at you as
                        > > if you just landed from Mars. Again, point loads.
                        >
                        > You seem to be making a point in opposition to something, but I don't
                        > know what.

                        I thought you were saying that epoxy-wood joints should be backed up
                        with fasteners. If a composite engineer wouldn't do it (point loads!)
                        why do you think it is a good idea?

                        I wrote "They [fasteners] are no replacement in joints
                        > designed for stitch-and-glue, but I don't think anyone was
                        > recommending it." So apparently you're agreeing with me?
                        >

                        It doesn't sound like it, does it? I'll try again. Your point seems
                        to be that permanent fasteners are a good idea, even in the presence
                        of a good glue joint. My point is that they add little actual
                        strength to a good glue joint, and may pose potential problems (point
                        loads, a path for water migration, complicating repairs, etc.), so why
                        use them?

                        Did you happen to look at the link I gave to Michael Storer's site?
                        He shows pictures of a Goat Island Skiff built many years ago without
                        fasteners. It's never been repainted and it looks like new.

                        To be fair, I'll probably never build a boat to that standard. The
                        GIS was painted with linear polyurethane, and my little cat is being
                        painted with house paint. He has glass both sides of every surface
                        and my cat is only glassed to the waterline on the outside. But I'm
                        not averse to learning from better boatbuilders than I'll ever be (a
                        category that, unfortunately, includes almost everyone.)

                        Michael Storer is a very good boatbuilder and his arguments seem
                        pretty good to me. If they don't to you, so what? In a hundred years
                        it won't make a bit of difference.

                        Ray
                      • Chris Crandall
                        Michalak@yahoogroups.com ... So, we agree. You ve qualified your poitn with in many instances and on that point, we agree. You ve not stated without
                        Message 11 of 21 , Nov 3, 2007
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                          Michalak@yahoogroups.com
                          Ray:

                          > The point I'm trying to get across is that in many instances, the
                          > amount of security added by fasteners to a good glue joint is not
                          > enough to be worth the trouble.


                          So, we agree. You've qualified your poitn with "in many instances" and
                          on that point, we agree. You've not stated without qualification,
                          implying that, in some instances, it is a good idea. And that is,
                          *exactly* my point. The particular case, which I've vbeen discussing
                          all along, and which the argument has had a tendency to stray from, is
                          the frame to planking joint, plywood to solid softwood lumber.


                          > Most screws and ringnails are used to secure planking to a framework.
                          > Shear is not much of an issue under those circumstances.

                          We'll have to disagree. A solid collision of a hull along the gunwales
                          will cause shear between frame and skin in a lot of circumstances, often
                          not in the place of location, but in a spot elsewhere, such as on the
                          other side of the boat.

                          > I thought you were saying that epoxy-wood joints should be backed up
                          > with fasteners. If a composite engineer wouldn't do it (point loads!)
                          > why do you think it is a good idea?

                          No, I was saying that *some* joints should be--the specific one that
                          started the discussion. It doesn't add much value to straw-man the argument.


                          > Did you happen to look at the link I gave to Michael Storer's site?

                          I've been there before, but not since this discussion.

                          > To be fair, I'll probably never build a boat to that standard. The
                          > GIS was painted with linear polyurethane, and my little cat is being
                          > painted with house paint. He has glass both sides of every surface
                          > and my cat is only glassed to the waterline on the outside. But I'm
                          > not averse to learning from better boatbuilders than I'll ever be (a
                          > category that, unfortunately, includes almost everyone.)

                          A double-epoxy/glass skinned boat is an entirely different animal from
                          the Michalak-style construction we (mostly) talk about in this forum.
                          The engineering is quite different, as Jacques Mertens has so generously
                          explained.
                          See http://www.bateau.com/ or any number of posts on rec.boats.building


                          > Michael Storer is a very good boatbuilder and his arguments seem
                          > pretty good to me. If they don't to you, so what? In a hundred years
                          > it won't make a bit of difference.

                          In 100 years GW Bush won't be President either, but it seems important
                          'round about now.

                          Cheers!

                          -Chris
                        • rhaldridge
                          ... often ... I m afraid I ll have to admit that I don t understand this. That sounds like a buckling load to me-- displacement would primarily be lateral,
                          Message 12 of 21 , Nov 3, 2007
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                            --- In Michalak@yahoogroups.com, Chris Crandall <crandall@...> wrote:
                            >
                            > Michalak@yahoogroups.com
                            > Ray:

                            >
                            > We'll have to disagree. A solid collision of a hull along the gunwales
                            > will cause shear between frame and skin in a lot of circumstances,
                            often
                            > not in the place of location, but in a spot elsewhere, such as on the
                            > other side of the boat.

                            I'm afraid I'll have to admit that I don't understand this. That
                            sounds like a buckling load to me-- displacement would primarily be
                            lateral, not in shear. In any case, if the loads are in fact in
                            shear, then for the fasteners to have any effect on keeping the
                            planking in place, a lot of glue lines will have to let go, and we're
                            back to the point load problem. A nail or screw resisting enough shear
                            to pop a lot of glue lines will be displaced to some extent, opening
                            up a path for water penetration.


                            >
                            > > I thought you were saying that epoxy-wood joints should be backed up
                            > > with fasteners. If a composite engineer wouldn't do it (point loads!)
                            > > why do you think it is a good idea?
                            >
                            > No, I was saying that *some* joints should be--the specific one that
                            > started the discussion. It doesn't add much value to straw-man the
                            argument.

                            Could you explain how this is a strawman argument? You've said that a
                            wood epoxy joint (planking to frame) should be backed up by fasteners.
                            Is it that you don't define that as a composite joint?



                            >
                            > A double-epoxy/glass skinned boat is an entirely different animal from
                            > the Michalak-style construction we (mostly) talk about in this forum.
                            > The engineering is quite different, as Jacques Mertens has so
                            generously
                            > explained.
                            > See http://www.bateau.com/ or any number of posts on rec.boats.building
                            >

                            Are you saying that fasteners are unnecessary in planking a
                            double-skinned boat? I wonder how your arguments as to shear forces
                            would differ in discussing such construction.


                            >
                            > > Michael Storer is a very good boatbuilder and his arguments seem
                            > > pretty good to me. If they don't to you, so what? In a hundred years
                            > > it won't make a bit of difference.
                            >
                            > In 100 years GW Bush won't be President either, but it seems important
                            > 'round about now.
                            >

                            I think you have just illuminated the difference between a trivial
                            problem and a serious problem.

                            Just to be clear, using fasteners (or not) in small boats falls into
                            the former category.

                            I'm going to have to let this go, I think. But if I end up floating
                            in the bay, clinging to the remnants of my fallen-apart cat, I'll
                            remember that you told me so.

                            Ray
                          • pgochnour@aol.com
                            Ray and Chris....great discussion..interesting and informative....hope you two will find another subject about which to disagree in the very near future...
                            Message 13 of 21 , Nov 4, 2007
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                              Ray and Chris....great discussion..interesting and informative....hope you
                              two will find another subject about which to disagree in the very near
                              future...

                              Tyson in Galveston


                              **************************************
                              See what's new
                              at http://www.aol.com


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                            • Chris Crandall
                              We re close, but with a few small areas of disagreement. I ll edit it down, and see if we end up on the same page. This exchange is critical. ... Ray: Could
                              Message 14 of 21 , Nov 5, 2007
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                                We're close, but with a few small areas of disagreement. I'll edit it
                                down, and see if we end up on the same page.


                                This exchange is critical.

                                Ray:
                                >>> I thought you were saying that epoxy-wood joints should be backed up
                                >>> with fasteners. If a composite engineer wouldn't do it (point loads!)
                                >>> why do you think it is a good idea?
                                Chris:
                                >> No, I was saying that *some* joints should be--the specific one that
                                >> started the discussion. It doesn't add much value to straw-man the
                                > argument.
                                Ray:> Could you explain how this is a strawman argument? You've said that a
                                > wood epoxy joint (planking to frame) should be backed up by fasteners.
                                > Is it that you don't define that as a composite joint?

                                A glued wood joint, even with epoxy, is not a composite joint.
                                Composite materials, in everyday boatbuilding parlance, almost always
                                refers to "fabric set in resin." A joint that is plywood to solid
                                lumber, using epoxy, is not a composite joint, it's just glued up.

                                In such a case, I recommend fasteners (and not just one!).

                                Now a joint that joins, say, a plywood bulkhead, without solid wood
                                framing around it, to a plywood hull, using thickened epoxy and a lay-up
                                of fiberglass or other epoxy-friendly fabric (usually with a spacer to
                                prevent the formation of a hard spot) would be a composite joint, and in
                                such a case, fasteners should be eschewed.

                                Chris:
                                >> A double-epoxy/glass skinned boat is an entirely different animal from
                                >> the Michalak-style construction we (mostly) talk about in this forum.
                                >> The engineering is quite different, as Jacques Mertens has so
                                >> generously explained. See http://www.bateau.com/

                                Ray:
                                > Are you saying that fasteners are unnecessary in planking a
                                > double-skinned boat? I wonder how your arguments as to shear forces
                                > would differ in discussing such construction.

                                I would say that, in *some* double-skinned boats, fasteners are
                                unnecessary. However, that is not how Michalak engineers his boats, or
                                at least any of the boats I've seen plans for or built.

                                > I'm going to have to let this go, I think. But if I end up floating
                                > in the bay, clinging to the remnants of my fallen-apart cat, I'll
                                > remember that you told me so.
                                > Ray

                                I think that it's unlikely that you'll experience catastrophic failure.
                                But I *have* experienced failure of such a joint, and I regret not using
                                a handful of nails to solve exactly this problem. The boat still is
                                usable, but the fix was harder than the solution would have been if I'd
                                used nails from the outset.

                                -Chris
                              • pecostx@comcast.net
                                I agree also. That poor horse has been beaten to death for a few days too many in my opinion and like Max I ve got mine. Geoff ... From: pgochnour@aol.com Ray
                                Message 15 of 21 , Nov 5, 2007
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                                  I agree also. That poor horse has been beaten to death for a few days too many in my opinion and like Max I've got mine.

                                  Geoff

                                  -------------- Original message --------------
                                  From: pgochnour@...
                                  Ray and Chris....great discussion..interesting and informative....hope you
                                  two will find another subject about which to disagree in the very near
                                  future...

                                  Tyson in Galveston

                                  **************************************
                                  See what's new
                                  at http://www.aol.com

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