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Re: Lug Sail loose-footed or not?

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  • David
    Chuck, This coming from a patternmaker... the most technical, finesse & precision oriented branch of woodbutchering???? Guys, I think maybe he s being IRONIC.
    Message 1 of 41 , Sep 1, 2006
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      Chuck,

      This coming from a patternmaker... the most technical, finesse &
      precision oriented branch of woodbutchering????

      Guys, I think maybe he's being IRONIC. Either that, or those epoxy
      fumes have finally begun to have an effect <G>

      Cheers & Theories,
      David Graybeal
      Portland, OR

      "Everything I need to know about woodworking, I learned in 7th grade
      Shop Class" - CL

      ********************

      --- In Michalak@yahoogroups.com, "Chuck Leinweber" <chuck@...> wrote:
      >
      >
      > Tsk, tsk, tsk. Tom. My point is that these very questions are
      irrelevant!
      > Only a commie pinko, pseudo intellectual, egg headed moron would
      think to
      > ask such a question! Compression? Tension? This is giving me a
      headache.
      > I gotta go find a hammer so I can bust something and epoxy it back
      together.
      > Chuck
      >
      >
      > Come on, Chuck - keep up with the rest of us. In John Wright's
      > post, No. 13348, he asks whether wood is as strong in tension as in
      > compression, and questions whether applying glass to one side
      > without applying it to the other would increase the strength.
      >
      > I replied that based on published data, wood is stronger in tension
      > than in compression (at least the clear test specimens are),
      > suggesting that supplementing the compression side would be more
      > advantageous than equally beefing up the tension side.
      >
      > Ken Grome indicated that he believed adding fiberglass to the
      > tension side was best, due to its tensile strength. I disagree,
      but
      > Ken has a lot more boatbuilding experience than I.
      >
      > I found the data in Gerr's book and offer it as additional
      > information for the readers.
      >
      > I'm not recommending any specific construction. I'm only trying to
      > answer the questions raised in this discussion.
      >
      > TJH
      >
      >
      >
      >
      > --- In Michalak@yahoogroups.com, "Chuck Leinweber" <chuck@> wrote:
      > >
      > >
      > > Wait just a cotton-pickin' minute! How practical is it to cover a
      > wood spar
      > > with fiberglass on only one side? The mast on my Caprice is
      cedar
      > covered
      > > with two layers of 12 oz 90/10 unidirectional glass set in
      epoxy.
      > As much
      > > trouble at that was to achieve, I can't imagine doing only one
      > side.
      > > Besides, Cedar was chosen for its light weight, not its tensile or
      > > compression strength. This is essentially a glass mast with a
      > light wood
      > > core. Doesn't that make more sense than counting the number of
      > angels that
      > > can dance on the head of a pin, I mean coating a fir spar on the
      > compression
      > > side only? ... sputter, ....sputter....
      > >
      > > Chuck
      > >
      > >
      > > I agree fully with your observations, John.
      > >
      > > Accordingly, I proposed that adding the fiberglass to
      > > the compression side (as opposed to adding it to the
      > > tension side) should maximize the section's strength,
      > > if the fiberglass is stronger in compression than the
      > > fir. But, the strength of fiberglass in compression
      > > remains undocumented (Gerr only publishes its tensile
      > > strength).
      > >
      > > On the other hand, Kenneth Grome's experience tells
      > > him that fiberglass is best placed on the tension
      > > side.
      > >
      > > I'd like to see this tested out.
      > >
      > > TJH
      > >
      > >
      > > --- john h wright <jhargrovewright2@> wrote:
      > >
      > > > Just a couple of observations based on the
      > > > "stiffness" below related to
      > > > spar construction.
      > > >
      > > > 1) The strength of wood is much less in compression
      > > > than in tension. That
      > > > would mean that wood in a bending failure is more
      > > > likely to initially be
      > > > caused by compression failure.
      > > >
      > > > 2) The fiberglass would all be located on the
      > > > extreme surface rather than
      > > > more on the interior of the spar and would be much
      > > > more effective per
      > > > unit of strength.
      > > >
      > > > 3) I would assume that the numbers are based on
      > > > clear dry fir and any
      > > > defect could make it somewhat weaker than this data
      > > > would indicate.
      > > >
      > > > John
      > > >
      > > > On Sun, 27 Aug 2006 13:21:40 -0000
      > > > "awellbalancedgun"
      > > > <awellbalancedgun@> writes:
      > > > I stumbled across these values last night while
      > > > looking up something
      > > > else:
      > > >
      > > > Dave Gerr in his "The Nature of Boats - Insights and
      > > > Esoterica for
      > > > the Nautically Obsessed" (A great book, by the way -
      > > > I highly
      > > > recommend it to anyone following this and the boom
      > > > construction/spar
      > > > stiffness threads) publishes the following values:
      > > >
      > > > E-glass set in polyester resin
      > > > --------------------------------
      > > > Tensile Strength = 15,000 psi
      > > > Stiffness (modulus of elasticity)= 1,400,000 psi
      > > >
      > > > Douglas Fir
      > > > ------------
      > > > Tensile Strength = 12,400 psi
      > > > Stiffness = 1,950,000 psi
      > > >
      > > > So, it looks like doug fir is stiffner, though not
      > > > as strong as E-
      > > > glass in polyester resin. E-glass set in epoxy might
      > > > not be all
      > > > that much different.
      > > >
      > > > He doesn't give values for compressive strength.
      > > >
      > > > This would be a great opportunity to do some actual
      > > > testing.
      > > >
      > > > TJH
      > > >
      > > > --- In Michalak@yahoogroups.com, Thomas Hamernik
      > > > <awellbalancedgun@> wrote:
      > > > >
      > > > > Adding anything to the compression side increases
      > > > the
      > > > > depth, and, as a result of the increased depth,
      > > > the
      > > > > stiffness.
      > > > >
      > > > > But, because the published values for wood suggest
      > > > > stronger tensile strength than compressive
      > > > strength,
      > > > > to take advantage of the tensile strength, the
      > > > > building up of a composite section should force
      > > > the
      > > > > neutral axis toward the compression side, thereby
      > > > > placing more of the wood in tension. One way of
      > > > doing
      > > > > this is to add a stiffer material on the
      > > > compression
      > > > > side.
      > > > >
      > > > > I don't have any good numbers for the mechanical
      > > > > properties of fiberglass in front of me, but I
      > > > believe
      > > > > that average values for normal glass suggest that
      > > > > glass fibers set in epoxy will have a higher
      > > > modulus
      > > > > of elasticity (stiffness) and higher compressive
      > > > > strength than most (if not all) species of wood.
      > > > (Ken
      > > > > – by chance do you know the MOE and strength
      > > > values
      > > > > typical of the fiberglass used for home-building?
      > > > I'd
      > > > > like to learn these, and we could confirm my
      > > > > suggestions with a few examples.).
      > > > >
      > > > > So, adding fiberglass (or steel, or wood having a
      > > > > higher modulus of elasticity and compressive
      > > > strength)
      > > > > to the compression side should result increase the
      > > > > capacity more so than if placed on the tension
      > > > side.
      > > > >
      > > > > It wouldn't surprise me, though, if fiberglass is
      > > > > stronger in tension than compression, as indicated
      > > > by
      > > > > Ken.
      > > > >
      > > > > Does this make sense?
      > > > >
      > > > > Tom
      > > > >
      > > > > --- Kenneth Grome <bagacayboatworks@> wrote:
      > > > >
      > > > > > > This suggests that adding fiberglass to the
      > > > > > > compression side might be of benefit.
      > > > > >
      > > > > > The strength of fiberglass is in tension, not in
      > > > > > compression. If you need more compressive
      > > > strength
      > > > > > you'll be better off laminating stronger wood to
      > > > the
      > > > > > compression side rather than by adding
      > > > fiberglass.
      > > > > >
      > > > > > Kenneth Grome
      > > > > > Bagacay Boatworks
      > > > > > Cebu City, Philippines
      > > > > > http://xbb.incebu.com
      > > > > >
      > > > > >
      > > > > >
      > > > > >
      > > > > >
      > > > > >
      > > > >
      > > > >
      > > > > __________________________________________________
      > > > > 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]
      > > >
      > > >
      > >
      > >
      > > __________________________________________________
      > > Do You Yahoo!?
      > > Tired of spam? Yahoo! Mail has the best spam protection around
      > > http://mail.yahoo.com
      > >
      > >
      > >
      > > Yahoo! Groups Links
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > > --
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      > > Checked by AVG Free Edition.
      > > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
      > 8/28/2006
      > >
      > >
      > > --
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      > > Checked by AVG Free Edition.
      > > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
      > 8/28/2006
      > >
      >
      >
      >
      >
      >
      >
      >
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
      >
      >
      >
      > --
      > No virus found in this incoming message.
      > Checked by AVG Free Edition.
      > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
      8/28/2006
      >
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      > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
      8/28/2006
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    • David
      Chuck, This coming from a patternmaker... the most technical, finesse & precision oriented branch of woodbutchering???? Guys, I think maybe he s being IRONIC.
      Message 41 of 41 , Sep 1, 2006
      • 0 Attachment
        Chuck,

        This coming from a patternmaker... the most technical, finesse &
        precision oriented branch of woodbutchering????

        Guys, I think maybe he's being IRONIC. Either that, or those epoxy
        fumes have finally begun to have an effect <G>

        Cheers & Theories,
        David Graybeal
        Portland, OR

        "Everything I need to know about woodworking, I learned in 7th grade
        Shop Class" - CL

        ********************

        --- In Michalak@yahoogroups.com, "Chuck Leinweber" <chuck@...> wrote:
        >
        >
        > Tsk, tsk, tsk. Tom. My point is that these very questions are
        irrelevant!
        > Only a commie pinko, pseudo intellectual, egg headed moron would
        think to
        > ask such a question! Compression? Tension? This is giving me a
        headache.
        > I gotta go find a hammer so I can bust something and epoxy it back
        together.
        > Chuck
        >
        >
        > Come on, Chuck - keep up with the rest of us. In John Wright's
        > post, No. 13348, he asks whether wood is as strong in tension as in
        > compression, and questions whether applying glass to one side
        > without applying it to the other would increase the strength.
        >
        > I replied that based on published data, wood is stronger in tension
        > than in compression (at least the clear test specimens are),
        > suggesting that supplementing the compression side would be more
        > advantageous than equally beefing up the tension side.
        >
        > Ken Grome indicated that he believed adding fiberglass to the
        > tension side was best, due to its tensile strength. I disagree,
        but
        > Ken has a lot more boatbuilding experience than I.
        >
        > I found the data in Gerr's book and offer it as additional
        > information for the readers.
        >
        > I'm not recommending any specific construction. I'm only trying to
        > answer the questions raised in this discussion.
        >
        > TJH
        >
        >
        >
        >
        > --- In Michalak@yahoogroups.com, "Chuck Leinweber" <chuck@> wrote:
        > >
        > >
        > > Wait just a cotton-pickin' minute! How practical is it to cover a
        > wood spar
        > > with fiberglass on only one side? The mast on my Caprice is
        cedar
        > covered
        > > with two layers of 12 oz 90/10 unidirectional glass set in
        epoxy.
        > As much
        > > trouble at that was to achieve, I can't imagine doing only one
        > side.
        > > Besides, Cedar was chosen for its light weight, not its tensile or
        > > compression strength. This is essentially a glass mast with a
        > light wood
        > > core. Doesn't that make more sense than counting the number of
        > angels that
        > > can dance on the head of a pin, I mean coating a fir spar on the
        > compression
        > > side only? ... sputter, ....sputter....
        > >
        > > Chuck
        > >
        > >
        > > I agree fully with your observations, John.
        > >
        > > Accordingly, I proposed that adding the fiberglass to
        > > the compression side (as opposed to adding it to the
        > > tension side) should maximize the section's strength,
        > > if the fiberglass is stronger in compression than the
        > > fir. But, the strength of fiberglass in compression
        > > remains undocumented (Gerr only publishes its tensile
        > > strength).
        > >
        > > On the other hand, Kenneth Grome's experience tells
        > > him that fiberglass is best placed on the tension
        > > side.
        > >
        > > I'd like to see this tested out.
        > >
        > > TJH
        > >
        > >
        > > --- john h wright <jhargrovewright2@> wrote:
        > >
        > > > Just a couple of observations based on the
        > > > "stiffness" below related to
        > > > spar construction.
        > > >
        > > > 1) The strength of wood is much less in compression
        > > > than in tension. That
        > > > would mean that wood in a bending failure is more
        > > > likely to initially be
        > > > caused by compression failure.
        > > >
        > > > 2) The fiberglass would all be located on the
        > > > extreme surface rather than
        > > > more on the interior of the spar and would be much
        > > > more effective per
        > > > unit of strength.
        > > >
        > > > 3) I would assume that the numbers are based on
        > > > clear dry fir and any
        > > > defect could make it somewhat weaker than this data
        > > > would indicate.
        > > >
        > > > John
        > > >
        > > > On Sun, 27 Aug 2006 13:21:40 -0000
        > > > "awellbalancedgun"
        > > > <awellbalancedgun@> writes:
        > > > I stumbled across these values last night while
        > > > looking up something
        > > > else:
        > > >
        > > > Dave Gerr in his "The Nature of Boats - Insights and
        > > > Esoterica for
        > > > the Nautically Obsessed" (A great book, by the way -
        > > > I highly
        > > > recommend it to anyone following this and the boom
        > > > construction/spar
        > > > stiffness threads) publishes the following values:
        > > >
        > > > E-glass set in polyester resin
        > > > --------------------------------
        > > > Tensile Strength = 15,000 psi
        > > > Stiffness (modulus of elasticity)= 1,400,000 psi
        > > >
        > > > Douglas Fir
        > > > ------------
        > > > Tensile Strength = 12,400 psi
        > > > Stiffness = 1,950,000 psi
        > > >
        > > > So, it looks like doug fir is stiffner, though not
        > > > as strong as E-
        > > > glass in polyester resin. E-glass set in epoxy might
        > > > not be all
        > > > that much different.
        > > >
        > > > He doesn't give values for compressive strength.
        > > >
        > > > This would be a great opportunity to do some actual
        > > > testing.
        > > >
        > > > TJH
        > > >
        > > > --- In Michalak@yahoogroups.com, Thomas Hamernik
        > > > <awellbalancedgun@> wrote:
        > > > >
        > > > > Adding anything to the compression side increases
        > > > the
        > > > > depth, and, as a result of the increased depth,
        > > > the
        > > > > stiffness.
        > > > >
        > > > > But, because the published values for wood suggest
        > > > > stronger tensile strength than compressive
        > > > strength,
        > > > > to take advantage of the tensile strength, the
        > > > > building up of a composite section should force
        > > > the
        > > > > neutral axis toward the compression side, thereby
        > > > > placing more of the wood in tension. One way of
        > > > doing
        > > > > this is to add a stiffer material on the
        > > > compression
        > > > > side.
        > > > >
        > > > > I don't have any good numbers for the mechanical
        > > > > properties of fiberglass in front of me, but I
        > > > believe
        > > > > that average values for normal glass suggest that
        > > > > glass fibers set in epoxy will have a higher
        > > > modulus
        > > > > of elasticity (stiffness) and higher compressive
        > > > > strength than most (if not all) species of wood.
        > > > (Ken
        > > > > – by chance do you know the MOE and strength
        > > > values
        > > > > typical of the fiberglass used for home-building?
        > > > I'd
        > > > > like to learn these, and we could confirm my
        > > > > suggestions with a few examples.).
        > > > >
        > > > > So, adding fiberglass (or steel, or wood having a
        > > > > higher modulus of elasticity and compressive
        > > > strength)
        > > > > to the compression side should result increase the
        > > > > capacity more so than if placed on the tension
        > > > side.
        > > > >
        > > > > It wouldn't surprise me, though, if fiberglass is
        > > > > stronger in tension than compression, as indicated
        > > > by
        > > > > Ken.
        > > > >
        > > > > Does this make sense?
        > > > >
        > > > > Tom
        > > > >
        > > > > --- Kenneth Grome <bagacayboatworks@> wrote:
        > > > >
        > > > > > > This suggests that adding fiberglass to the
        > > > > > > compression side might be of benefit.
        > > > > >
        > > > > > The strength of fiberglass is in tension, not in
        > > > > > compression. If you need more compressive
        > > > strength
        > > > > > you'll be better off laminating stronger wood to
        > > > the
        > > > > > compression side rather than by adding
        > > > fiberglass.
        > > > > >
        > > > > > Kenneth Grome
        > > > > > Bagacay Boatworks
        > > > > > Cebu City, Philippines
        > > > > > http://xbb.incebu.com
        > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > >
        > > > >
        > > > > __________________________________________________
        > > > > 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]
        > > >
        > > >
        > >
        > >
        > > __________________________________________________
        > > Do You Yahoo!?
        > > Tired of spam? Yahoo! Mail has the best spam protection around
        > > http://mail.yahoo.com
        > >
        > >
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        > >
        > >
        > >
        > >
        > >
        > > --
        > > No virus found in this incoming message.
        > > Checked by AVG Free Edition.
        > > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
        > 8/28/2006
        > >
        > >
        > > --
        > > No virus found in this outgoing message.
        > > Checked by AVG Free Edition.
        > > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
        > 8/28/2006
        > >
        >
        >
        >
        >
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
        >
        >
        >
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        > Checked by AVG Free Edition.
        > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
        8/28/2006
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        > Version: 7.1.405 / Virus Database: 268.11.6/429 - Release Date:
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