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Re: [junkrig] Re: leeboards and seaworthiness

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  • Gary PIck
    Hi Annie, Just wanted to say hello, your first book is one of the main reasons for my decision to go junkrig.I have been living a similar lifstyle except on
    Message 1 of 8 , Aug 13, 2007
      Hi Annie, Just wanted to say hello, your first book is one of the main
      reasons for my decision to go junkrig.I have been living a similar
      lifstyle except on land...I'm an old Hippy:-)
      Gary
      On Tue, 2007-08-14 at 11:53 +1200, Annie Hill wrote:
      > I'm interested in this debate and we need to be sure just what we are
      > discussing.
      >
      > I've met Jim Melcher, who owns 'Alerte', the Bolger boat in question,
      > which he sailed across the Atlantic. He told me he did it with some
      > trepidation and would not have taken her offshore in HIGH latitudes.
      >
      > There is also a difference in risks between a boat that has a
      > potential
      > easily to capsize and a boat that is not self-righting. A ballast
      > keel
      > not only reduces a vessel's chance of capsizing in the first place,
      > it
      > also, in theory, ensures that the boat rights itself if this should
      > happen.
      >
      > Form stability can reduce an unballasted vessel's chance of
      > capsizing.
      > Cunning cabin design can ensure that an unballasted boat is unstable
      > upside down. Bolger has worked on these ideas. There are keel boats
      > around that are stable inverted; there a leeboard designs around that
      > are form stable the right way up and unstable the wrong way up. You
      > pays your money and you takes your choice.
      >
      > However, I completely endorse the idea of doing lots of reading - not
      > only the text books, but also the classic cruising yarns, which will
      > include such tales at Joshua Slocum and his junk-rigged boat, Captain
      > Voss's 'Tilikum' and rather more conventional boats such as WA
      > Robinson's 'Svaap' or Peter and Anne Pye's 'Moonraker'.
      >
      > However, it would all be too boring if everyone were to build and
      > sail
      > the same type of boat.
      >
      > Annie
      >
      > [Non-text portions of this message have been removed]
      >
      >
      >
      >
      >
    • Annie Hill
      I m interested in this debate and we need to be sure just what we are discussing. I ve met Jim Melcher, who owns Alerte , the Bolger boat in question, which
      Message 2 of 8 , Aug 13, 2007
        I'm interested in this debate and we need to be sure just what we are
        discussing.

        I've met Jim Melcher, who owns 'Alerte', the Bolger boat in question,
        which he sailed across the Atlantic. He told me he did it with some
        trepidation and would not have taken her offshore in HIGH latitudes.

        There is also a difference in risks between a boat that has a potential
        easily to capsize and a boat that is not self-righting. A ballast keel
        not only reduces a vessel's chance of capsizing in the first place, it
        also, in theory, ensures that the boat rights itself if this should happen.

        Form stability can reduce an unballasted vessel's chance of capsizing.
        Cunning cabin design can ensure that an unballasted boat is unstable
        upside down. Bolger has worked on these ideas. There are keel boats
        around that are stable inverted; there a leeboard designs around that
        are form stable the right way up and unstable the wrong way up. You
        pays your money and you takes your choice.

        However, I completely endorse the idea of doing lots of reading - not
        only the text books, but also the classic cruising yarns, which will
        include such tales at Joshua Slocum and his junk-rigged boat, Captain
        Voss's 'Tilikum' and rather more conventional boats such as WA
        Robinson's 'Svaap' or Peter and Anne Pye's 'Moonraker'.

        However, it would all be too boring if everyone were to build and sail
        the same type of boat.

        Annie


        [Non-text portions of this message have been removed]
      • ANDREW AIREY
        You can hardly get more classic than Voyaging on a small income and my own copy is getting very dog eared. My own area of interest is in sailing
        Message 3 of 8 , Aug 14, 2007
          You can hardly get more classic than 'Voyaging on a
          small income'and my own copy is getting very dog
          eared. My own area of interest is in sailing
          barges,mostly.it must be said,for canal/river
          use.However,because there are isolated systems,then
          one has to address the question of seaworthiness and
          coastal capability.I was on a 97 yr old,50ft Ijsselaak
          off the Brittany coast last week,but since we had
          light following winds to and from Paimpol we used the
          sails for stability,and motorsailed all the way.She
          did roll a bit coming back,with a lumpy sea coming in
          on the port quarter from the previous nights force
          6,but nothing to get alarmed about.The skipper,who is
          nearly as old as the barge(85) says that she sails on
          her ear when sailing properly (7knots in a force 5 or
          9 in a force 6.although he wouldn't take her out in
          that - she did that on the Ijsselmeer when she was
          being demonstrated)Phil Bolger said the same about his
          'Weston Martyr' design,although I would have thought
          he would have used detachable leeboards on that
          one.since that was our local practise,rather than the
          bilgeboard actually incorporated.We didn't use the
          leeboards at all on my trip though,except once for
          manoevering in harbour.But sailing barges.with
          leeboards,were used all over the north sea coasts of
          England and Holland,so they must have had something
          going for them.
          cheers
          Andy Airey

          Send instant messages to your online friends http://uk.messenger.yahoo.com
        • Gil
          Hello, I have a 32ft. steel double-ender, on which I would like to use a steel round tapered mast. Here is that I found:
          Message 4 of 8 , Aug 14, 2007
            Hello,

            I have a 32ft. steel double-ender, on which I would like to use a steel
            round tapered mast.

            Here is that I found:

            http://utilitymetals.com/lighting_poles/tapered_capacity.htm

            There are two 35' poles there I am looking into.
            There would be maybe 30' above deck, maybe 2-3 ft. less (cut from the
            top).

            To the people who are more math-inclined that I am, would this be of
            sufficient strength, assuming a 500sq. ft. sail?

            Thanks,

            Gil.


            [Non-text portions of this message have been removed]
          • De Clarke
            ... note the hand-hole shown in the drawing on this page: http://utilitymetals.com/lighting_poles/round_tapered.htm it would bother me to have a large opening
            Message 5 of 8 , Aug 14, 2007
              >> http://utilitymetals.com/lighting_poles/tapered_capacity.htm

              note the hand-hole shown in the drawing on this page:

              http://utilitymetals.com/lighting_poles/round_tapered.htm

              it would bother me to have a large opening in the butt end
              of the mast. but anyway... they don't mention wall thickness,
              instead rating their poles by their ability to carry a
              loaded cantilever bracket of given dimension/weight near
              the tapered end.

              we could assume they are made of 1/8 steel plate (I think the
              weight seems about right, no?)

              the 2 35 ft poles are 9.1 inches and 8.5 inches at base
              tapering to 4.2 and 3.6 inches respectively.

              let's run them through the unstayed mast calculator...

              1) 8.5 inches, 30 feet of cantilever beam (partners to cap)
              assuming 5 ft of bury which may be optimistic. what if
              you got caught aback in 30 kts?

              MAST HEIGHT (ft) 30
              DIAM (inches) 8.5
              SOLID? no
              WALL THICKN (inches) .125
              WIND SPEED (kts) 30
              SAIL AREA (sq ft) 500
              FORCE 1829.74
              MOMENT 27446.10
              I 28.8417
              STRESS (psi) 48532.20

              For reference: the yield strength of

              * doug fir is from 7250-12,000 psi
              * T6 hardened aluminium is 31,000 psi
              * mild steel is 37,000 psi
              * Corten steel is about 40 percent better
              than mild or approx 52,800 psi
              * carbon fibre 10-layer epoxy composite may
              be as high as 96,000 psi

              They (pole mfr) are claiming 55,000 psi yield strength for the
              shaft, which seems a bit optimistic to me... it must be
              hardened in some way, 'cos mild steel is usually rated at
              35,000 to 37,000 psi. hardened is good, but means you probably
              can't do any welding on it w/o losing the hardening (note that
              lamp standards are bolted not welded together, from stock
              interchangeable parts). I personally find 48,000 psi to be a
              tad too close to 55,000 psi, but that is for a 30 knot gust
              with the whole sail flying dead across the wind.

              if you assume you will always get sail down before the
              wind goes past 25 kts, it's a lot more encouraging at
              STRESS (psi) 33703.00 (encouraging for steel hardened
              as they claim, anyway).

              how about the larger diam?

              MAST HEIGHT (ft) 30
              DIAM (inches) 9.1
              SOLID? no
              WALL THICKN (inches) .125
              WIND SPEED (kts) 30
              SAIL AREA (sq ft) 500
              FORCE 1829.74
              MOMENT 27446.10
              I 35.4942
              STRESS (psi) 42219.70

              That's a bit more reassuring.

              the 25 kt figure here would be
              STRESS (psi) 29319.20 -- pretty comfortable, unless
              you're building suspension bridges.

              feel free to try it for yourself...

              http://spg.ucolick.org/cgi-bin/Tcl/MastModel.cgi



              de



              ............................................................................
              :De Clarke, Software Engineer UCO/Lick Observatory, UCSC:
              :Mail: de@... | Your planet's immune system is trying to get rid :
              :Web: www.ucolick.org | of you. --Kurt Vonnegut :
              :1024D/B9C9E76E | F892 5F17 8E0A F095 05CD EE8B D169 EDAA B9C9 E76E:
            • skarv2006
              Hi De Clarke Some comments on the figures that goes into the mast calculations. 1/8 is very light. At deck level there is always danger of making a dent in
              Message 6 of 8 , Aug 16, 2007
                Hi De Clarke

                Some comments on the figures that goes into the mast calculations.
                1/8" is very light. At deck level there is always danger of making
                a dent in the mast!.

                Victor

                --- In junkrig@yahoogroups.com, De Clarke <de@...> wrote:
                >
                >
                > >> http://utilitymetals.com/lighting_poles/tapered_capacity.htm
                >
                > note the hand-hole shown in the drawing on this page:
                >
                > http://utilitymetals.com/lighting_poles/round_tapered.htm
                >
                > it would bother me to have a large opening in the butt end
                > of the mast. but anyway... they don't mention wall thickness,
                > instead rating their poles by their ability to carry a
                > loaded cantilever bracket of given dimension/weight near
                > the tapered end.
                >
                > we could assume they are made of 1/8 steel plate (I think the
                > weight seems about right, no?)
                >
                > the 2 35 ft poles are 9.1 inches and 8.5 inches at base
                > tapering to 4.2 and 3.6 inches respectively.
                >
                > let's run them through the unstayed mast calculator...
                >
                > 1) 8.5 inches, 30 feet of cantilever beam (partners to cap)
                > assuming 5 ft of bury which may be optimistic. what if
                > you got caught aback in 30 kts?
                >
                > MAST HEIGHT (ft) 30
                > DIAM (inches) 8.5
                > SOLID? no
                > WALL THICKN (inches) .125
                > WIND SPEED (kts) 30
                > SAIL AREA (sq ft) 500
                > FORCE 1829.74
                > MOMENT 27446.10
                > I 28.8417
                > STRESS (psi) 48532.20
                >
                > For reference: the yield strength of
                >
                > * doug fir is from 7250-12,000 psi
                > * T6 hardened aluminium is 31,000 psi
                > * mild steel is 37,000 psi
                > * Corten steel is about 40 percent better
                > than mild or approx 52,800 psi
                > * carbon fibre 10-layer epoxy composite may
                > be as high as 96,000 psi
                >
                > They (pole mfr) are claiming 55,000 psi yield strength for the
                > shaft, which seems a bit optimistic to me... it must be
                > hardened in some way, 'cos mild steel is usually rated at
                > 35,000 to 37,000 psi. hardened is good, but means you probably
                > can't do any welding on it w/o losing the hardening (note that
                > lamp standards are bolted not welded together, from stock
                > interchangeable parts). I personally find 48,000 psi to be a
                > tad too close to 55,000 psi, but that is for a 30 knot gust
                > with the whole sail flying dead across the wind.
                >
                > if you assume you will always get sail down before the
                > wind goes past 25 kts, it's a lot more encouraging at
                > STRESS (psi) 33703.00 (encouraging for steel hardened
                > as they claim, anyway).
                >
                > how about the larger diam?
                >
                > MAST HEIGHT (ft) 30
                > DIAM (inches) 9.1
                > SOLID? no
                > WALL THICKN (inches) .125
                > WIND SPEED (kts) 30
                > SAIL AREA (sq ft) 500
                > FORCE 1829.74
                > MOMENT 27446.10
                > I 35.4942
                > STRESS (psi) 42219.70
                >
                > That's a bit more reassuring.
                >
                > the 25 kt figure here would be
                > STRESS (psi) 29319.20 -- pretty comfortable, unless
                > you're building suspension bridges.
                >
                > feel free to try it for yourself...
                >
                > http://spg.ucolick.org/cgi-bin/Tcl/MastModel.cgi
                >
                >
                >
                > de
                >
                >
                >
                >
                ............................................................................
                > :De Clarke, Software Engineer UCO/Lick
                Observatory, UCSC:
                > :Mail: de@... | Your planet's immune system is trying to get rid :
                > :Web: www.ucolick.org | of you. --Kurt Vonnegut :
                > :1024D/B9C9E76E | F892 5F17 8E0A F095 05CD EE8B D169 EDAA
                B9C9 E76E:
                >
              • De Clarke
                ... yes, I agree. but given the weight for height of the poles mentioned by the original poster, it s hard for me to imagine they are much heavier than 1/8...
                Message 7 of 8 , Aug 16, 2007
                  skarv2006 (skarv2006@...) wrote:
                  > Hi De Clarke
                  >
                  > Some comments on the figures that goes into the mast calculations.
                  > 1/8" is very light. At deck level there is always danger of making
                  > a dent in the mast!.

                  yes, I agree. but given the weight for height of the poles mentioned
                  by the original poster, it's hard for me to imagine they are much
                  heavier than 1/8... correct me if I'm wrong here, I didn't do the
                  math for the volume of steel, just guesstimating.

                  de

                  --
                  .............................................................................
                  :De Clarke, Software Engineer UCO/Lick Observatory, UCSC:
                  :Mail: de@... | Your planet's immune system is trying to get rid :
                  :Web: www.ucolick.org | of you. --Kurt Vonnegut :
                  :1024D/B9C9E76E | F892 5F17 8E0A F095 05CD EE8B D169 EDAA B9C9 E76E:
                • Gil
                  ... Hello, Thanks for the calculation. The manufacturer indeed confirmed 1/8. I guess I ll have to go with the 9.1 base one.. Sincerely, Gil. --
                  Message 8 of 8 , Aug 17, 2007
                    On Thu, 2007-08-16 at 23:02 -0700, De Clarke wrote:
                    > skarv2006 (skarv2006@...) wrote:
                    > > Hi De Clarke
                    > >
                    > > Some comments on the figures that goes into the mast calculations.
                    > > 1/8" is very light. At deck level there is always danger of making
                    > > a dent in the mast!.
                    >
                    > yes, I agree. but given the weight for height of the poles mentioned
                    > by the original poster, it's hard for me to imagine they are much
                    > heavier than 1/8... correct me if I'm wrong here, I didn't do the
                    > math for the volume of steel, just guesstimating.
                    >
                    > de
                    >

                    Hello,

                    Thanks for the calculation. The manufacturer indeed confirmed 1/8.
                    I guess I'll have to go with the 9.1'' base one..

                    Sincerely,

                    Gil.
                    --
                    http://islandlimited.net
                    http://planenews.com
                    PGP Key: http://keskydee.com/gil.asc
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