Loading ...
Sorry, an error occurred while loading the content.

Dug out masts such as the file of Johanna's mast

Expand Messages
  • shaunbarrymcmillan
    I have been collecting information as is available on the forum. I have reviewed the dimensions and construction details of the mast from Johanna and the
    Message 1 of 21 , Jan 1, 2008
    • 0 Attachment
      I have been collecting information as is available on the forum. I
      have reviewed the dimensions and construction details of the mast
      from Johanna and the related file. But I have some concerns I would
      like to address because, if these problems have been addressed, that
      technique is a great way to build a lighter stick.

      My questions are:

      (1) Since the mast is a dug out grown stick-will it check? and if it
      checks what happens to the 20% wall thickness?

      (2) I would suppose you would use epoxy to glue the halves back
      together because of the ability of epoxy to tolerate gaps-but is this
      necessarily so? Epoxy does have issues with UV which would be more
      problematic in the tropics. Would traditional, non-epoxy glues work.
      If you use epoxy you would have to be quick because of the cure time.

      (3) If you glass the mast that would work -again - unless it checks.

      (4) If not glassing with the fiber then what- varnish or oil?

      Fair Winds and Fair Tides - Shaun McMillan
    • arne_kverneland_norway
      Stavanger, 20080101. Hi Shaun, HNY! That was quick – don t tell me you have already read the article I uploaded to FILES just a few minutes ago?? I suggest
      Message 2 of 21 , Jan 1, 2008
      • 0 Attachment
        Stavanger, 20080101.

        Hi Shaun, HNY!
        That was quick – don't tell me you have already read the article I
        uploaded to FILES just a few minutes ago?? I suggest you take a
        closer look there, and you will at least have a few questions
        answered.

        Just about checking:
        I cannot speak for all the masts in the world, but when we tied the
        2 halves together during the curing process (.. 3 masts so far...),
        we have had no problem with checking.

        Arne


        --- In junkrig@yahoogroups.com, "shaunbarrymcmillan"
        <shaunbarrymcmillan@...> wrote:
        >
        > I have been collecting information as is available on the forum. I
        > have reviewed the dimensions and construction details of the mast
        > from Johanna and the related file. But I have some concerns I
        would
        > like to address because, if these problems have been addressed,
        that
        > technique is a great way to build a lighter stick.
        >
        > My questions are:
        >
        > (1) Since the mast is a dug out grown stick-will it check? and if
        it
        > checks what happens to the 20% wall thickness?
        >
        > (2) I would suppose you would use epoxy to glue the halves back
        > together because of the ability of epoxy to tolerate gaps-but is
        this
        > necessarily so? Epoxy does have issues with UV which would be more
        > problematic in the tropics. Would traditional, non-epoxy glues
        work.
        > If you use epoxy you would have to be quick because of the cure
        time.
        >
        > (3) If you glass the mast that would work -again - unless it
        checks.
        >
        > (4) If not glassing with the fiber then what- varnish or oil?
        >
        > Fair Winds and Fair Tides - Shaun McMillan
        >
      • May and Lex Hodgkinson
        Hi and happy new year. Passepatu s masts are solid grown spruce as per Mcleods specs and were originally coated in linseed oil and dressed with a mixture of
        Message 3 of 21 , Jan 2, 2008
        • 0 Attachment
          Hi and happy new year.
          Passepatu's masts are solid grown spruce as per Mcleods specs and were
          originally coated in linseed oil and dressed with a mixture of linseed and
          petroleum jelly ("vaselene"). I have redressed them about 3 or 4 times since
          then over the past 15 years or so and the timber is still in good condition,
          with any shakes in the timber being sealed from water. I also coat the
          parrels in the vaseline mixture and these also help dress the timber, and
          although the sails do get a bit "oily" in way of the masts this has not been
          a problem, I also coat the halyards and other running rigging, this tends to
          reduce hardening due to UV and makes things run freely and also keeps the
          hands soft!
          Sounds strange but it works and is not expensive.
          Cheers
          Lex

          On 02/01/2008, shaunbarrymcmillan <shaunbarrymcmillan@...> wrote:
          >
          > I have been collecting information as is available on the forum. I
          > have reviewed the dimensions and construction details of the mast
          > from Johanna and the related file. But I have some concerns I would
          > like to address because, if these problems have been addressed, that
          > technique is a great way to build a lighter stick.
          >
          > My questions are:
          >
          > (1) Since the mast is a dug out grown stick-will it check? and if it
          > checks what happens to the 20% wall thickness?
          >
          > (2) I would suppose you would use epoxy to glue the halves back
          > together because of the ability of epoxy to tolerate gaps-but is this
          > necessarily so? Epoxy does have issues with UV which would be more
          > problematic in the tropics. Would traditional, non-epoxy glues work.
          > If you use epoxy you would have to be quick because of the cure time.
          >
          > (3) If you glass the mast that would work -again - unless it checks.
          >
          > (4) If not glassing with the fiber then what- varnish or oil?
          >
          > Fair Winds and Fair Tides - Shaun McMillan
          >
          >
          >


          [Non-text portions of this message have been removed]
        • Tim Dunn
          I have read that you should never use epoxy to make a wooden mast, but rather that you should always use brown (resorcinol) glue. If I wanted to make a wooden
          Message 4 of 21 , Feb 2, 2008
          • 0 Attachment
            I have read that you should never use epoxy to make a wooden mast, but
            rather that you should always use brown (resorcinol) glue. If I
            wanted to make a wooden hollow mast, I think I'd make a "birdsmouth"
            mast. If you google that you will find exact instructions.

            I am leaning towards vinylestyer, e-glass +45-45, and carbon fiber
            unidirectional. I have a description of how to make a mast this way at
            http://www.dunnanddunnrealtors.com/Catamaran.html .
          • skarv2006
            ... Hi Tim. Was there mentioned reasons for not using epoxy?. I understand that there are many types of epoxy. Some are hard, some are not so hard. I have also
            Message 5 of 21 , Feb 2, 2008
            • 0 Attachment
              --- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@...> wrote:
              >
              > I have read that you should never use epoxy to make a wooden mast, but
              > rather that you should always use brown (resorcinol) glue. If I
              > wanted to make a wooden hollow mast, I think I'd make a "birdsmouth"
              > mast. If you google that you will find exact instructions.
              >
              > I am leaning towards vinylestyer, e-glass +45-45, and carbon fiber
              > unidirectional. I have a description of how to make a mast this way at
              > http://www.dunnanddunnrealtors.com/Catamaran.html .
              >

              Hi Tim.
              Was there mentioned reasons for not using epoxy?.
              I understand that there are many types of epoxy. Some are hard, some
              are not so hard.
              I have also heared that epoxy should not be used to glue big
              dimensions of wood.
              Are there any expert on glueing out there who can guide us?

              Victor
            • arne_kverneland_norway
              Stavanger, 20080202 Hi Tim Even if you have read that about epoxy, I think it should be taken with a tiny grain of salt. It may well depend on HOW the mast has
              Message 6 of 21 , Feb 2, 2008
              • 0 Attachment
                Stavanger, 20080202

                Hi Tim
                Even if you have read that about epoxy, I think it should be taken
                with a tiny grain of salt. It may well depend on HOW the mast has
                been laminated.

                A dug out mast like those I have had made for Malena (1995) and
                Johanna (2001) have no scarf joints in them, only the two full-
                length joints (epoxy) where the two dug-out halves were re-
                assembled. Now, on Malena her first mast was solid and had huge
                natural splits running several metres, and that didn't seem to
                affect the strength at all. From that experience I guess (..just
                guess...) that the shear load is not that high, so any water-
                resistant glue will do in the length-wise joints.

                However, if you are building up a mast from staves, more often than
                not you will have to make a number of scarf joints. These will be
                the critical parts, I'm afraid. I don't know which is best of
                resorcinol or epoxy, but I am convinced that the scarf joints just
                have to be PERFECT fits – and nice and looong. Any amateur should
                make e few practice runs before starting on the mast.

                I learned a good year ago that JESTER II lost her mast in moderate
                conditions the summer 2006, I think it was (diam=18.14cm hollow,
                professionally built). The failure appeared to be in one of those
                scarf joints. The colour of the joints suggested that resorcinol had
                been used in the full-length joints, while for the scarf joint
                something else had been used.

                The idea of making e-glass masts is of course tempting, but I fear
                that I would lose a lot of time and money in the learning process...

                Good luck!

                Arne


                --- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@...> wrote:
                >
                > I have read that you should never use epoxy to make a wooden mast,
                but
                > rather that you should always use brown (resorcinol) glue. If I
                > wanted to make a wooden hollow mast, I think I'd make
                a "birdsmouth"
                > mast. If you google that you will find exact instructions.
                >
                > I am leaning towards vinylestyer, e-glass +45-45, and carbon fiber
                > unidirectional. I have a description of how to make a mast this
                way at
                > http://www.dunnanddunnrealtors.com/Catamaran.html .
                >
              • sae140
                ... way at ... Hi Victor - I m certainly no expert on epoxy, but know first-hand that some epoxy glues can be very brittle when set, and some remain relatively
                Message 7 of 21 , Feb 3, 2008
                • 0 Attachment
                  --- In junkrig@yahoogroups.com, "skarv2006" <skarv2006@...> wrote:
                  >
                  > --- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@> wrote:
                  > >
                  > > I have read that you should never use epoxy to make a wooden mast, but
                  > > rather that you should always use brown (resorcinol) glue. If I
                  > > wanted to make a wooden hollow mast, I think I'd make a "birdsmouth"
                  > > mast. If you google that you will find exact instructions.
                  > >
                  > > I am leaning towards vinylestyer, e-glass +45-45, and carbon fiber
                  > > unidirectional. I have a description of how to make a mast this
                  way at
                  > > http://www.dunnanddunnrealtors.com/Catamaran.html .
                  > >
                  >
                  > Hi Tim.
                  > Was there mentioned reasons for not using epoxy?.
                  > I understand that there are many types of epoxy. Some are hard, some
                  > are not so hard.
                  > I have also heared that epoxy should not be used to glue big
                  > dimensions of wood.
                  > Are there any expert on glueing out there who can guide us?
                  >
                  > Victor
                  >

                  Hi Victor - I'm certainly no expert on epoxy, but know first-hand that
                  some epoxy glues can be very brittle when set, and some remain
                  relatively flexible. I much prefer using the latter for all marine
                  uses: wood and grp lay-up. Some vendors advertise the epoxy's cured
                  characteristics and some don't.

                  I'd be happy using flexible epoxy on all kinds of wood, including new
                  teak which is normally considered troublesome due to it's surface oil
                  - I simply wipe down those surfaces to be glued with acetone or
                  thinners immediately prior to applying the glue.

                  Colin
                • skarv2006
                  ... Hi Colin. Just as I thought. It is possible to find Epoxies that are a little flexible. What type do you use?, or would you use to make masts?. Victor
                  Message 8 of 21 , Feb 3, 2008
                  • 0 Attachment
                    --- In junkrig@yahoogroups.com, "sae140" <colinpowell@...> wrote:

                    >
                    > Hi Victor - I'm certainly no expert on epoxy, but know first-hand that
                    > some epoxy glues can be very brittle when set, and some remain
                    > relatively flexible. I much prefer using the latter for all marine
                    > uses: wood and grp lay-up. Some vendors advertise the epoxy's cured
                    > characteristics and some don't.
                    >
                    > I'd be happy using flexible epoxy on all kinds of wood, including new
                    > teak which is normally considered troublesome due to it's surface oil
                    > - I simply wipe down those surfaces to be glued with acetone or
                    > thinners immediately prior to applying the glue.
                    >
                    > Colin
                    >
                    Hi Colin.
                    Just as I thought. It is possible to find Epoxies that are a little
                    flexible.
                    What type do you use?, or would you use to make masts?.

                    Victor
                  • Tim Dunn
                    Hi, Victor I don t know if the claim that resorcinol is better than epoxy for mast-making is true or not, but I thought I d mention it so that any one planning
                    Message 9 of 21 , Feb 3, 2008
                    • 0 Attachment
                      Hi, Victor

                      I don't know if the claim that resorcinol is better than epoxy for
                      mast-making is true or not, but I thought I'd mention it so that any
                      one planning to make a glued wooden mast could look into it. Some
                      claim that not only is UV bad for epoxy, but that heat is also bad
                      for it. It is well known that UV is bad for epoxy, so epoxy exposed
                      to the sun should definitely be painted white or otherwise protected
                      from UV.

                      The claim that resorcinol is better than epoxy for masts is something
                      that I read on the forums at www.woodenboat.com/ , which seem to be
                      off-line at the moment. Speaking of off-line, I notice that your site
                      is off-line. I am sure that I am not the only "junkie" looking
                      forward to seeing it return.

                      TD

                      > Hi Tim.
                      > Was there mentioned reasons for not using epoxy?.
                      > I understand that there are many types of epoxy. Some are hard, some
                      > are not so hard.
                      > I have also heared that epoxy should not be used to glue big
                      > dimensions of wood.
                      > Are there any expert on glueing out there who can guide us?
                      >
                      > Victor
                      >
                    • De Clarke
                      I ve made a slight upgrade to my mast calculator page. It now makes a rough guess at the benefit of reefing, for the mast size and conditions you ve
                      Message 10 of 21 , Feb 3, 2008
                      • 0 Attachment
                        I've made a slight upgrade to my mast calculator page. It now makes
                        a rough guess at the benefit of reefing, for the mast size and conditions
                        you've specified; so you can see how much safety margin you get with
                        one panel reefed, two panels reefed, etc. If I have not done something
                        mathematically stupid, the effect of reefing is enormous as one is not
                        only reducing sail area but effective height (lever arm).

                        2 panels down is something like 50 percent of the force of full hoist,
                        if I am right about this. That's actually rather encouraging; it
                        suggests that a large safety margin is obtainable while still carrying
                        2/3 of one's sail area. Hooray for junk rigs and instant reefing :-)

                        this leaves me still struggling with the correct attitude to take to
                        mast strength vs sail area.

                        If we consider that a junk rig carries its entire wardrobe bent on at all
                        times, then full hoist all around is the equivalent of flying your big
                        genny and spinny and everything else you can find in the sail locker, on
                        a marconi rig; something you would never do in anything but soft light
                        air. So the implication is that junk rigs should expect to sail most
                        of the time with one or more panels reefed particularly on the main
                        and possibly also the fore. And the mast need not be sized for a full
                        hoist to stand up to, say, 30 kts full aback.

                        But the knock-on implication is that we should be particularly interested
                        in the performance of our sails with 1 or 2 panels reefed (and usually we
                        see inferior sail shape as we start to reef down, or that is my experience
                        with Taz anyway, the yard starts to twist off as there is too much halyard
                        above it); *or* we should perhaps look into other ways of flying more sail
                        in lighter air, and scale the rig to normal conditions so that a full hoist
                        can be carried more of the time. For example the "junk rig water sail"
                        concept is one way to add more sail area in light air, or most of us
                        could theoretically hoist an asymmetrical spinny (gennaker) or even a
                        golly, for the cost of storing a bundle of light para cloth below somewhere.

                        I find myself envying the square rig skipper who could "send up a top
                        mast" and adjust the overall height of the rig underway! Water sails are
                        very pretty but the best air is usually aloft. And that brings us back to
                        tall junk rigs which don't use a full hoist except on exceptionally light
                        days...

                        Sorry if this is a bit rambling; I've got too many boat projects on my
                        mind and keep switching trains of thought from one to another.

                        de

                        --
                        .............................................................................
                        :De Clarke, Software Engineer UCO/Lick Observatory, UCSC:
                        :S/V Taz, Newcastle Marina, Nanaimo BC :
                        :Mail: de@... | Your planet's immune system is trying to get rid :
                        :Web: www.svtaz.org | of you. --Kurt Vonnegut :
                      • Tim Dunn
                        Hi, Arne I don t have an opinion of my own in the epoxy vs. resorcinol controversy. I am just mentioning that the controversy exists. I learned to fiberglass
                        Message 11 of 21 , Feb 3, 2008
                        • 0 Attachment
                          Hi, Arne

                          I don't have an opinion of my own in the epoxy vs. resorcinol
                          controversy. I am just mentioning that the controversy exists.

                          I learned to fiberglass at a boatbuilder's shop long ago. It is
                          absurdly easy, at least with polyester resin. I think it is much
                          harder to bake a cake or make a loaf of bread. You just mix resin
                          with hardener, pour it on the fabric, and work it to get the air
                          bubbles out of the laminate, (for example by rolling a metal rolling
                          tool made for the purpose over the laminate.) I am going to have a
                          vacuum setup, so rolling won't be necessary except for making joins of
                          larger parts, but then I am starting on a larger laminating project.

                          (You do use resin premixed for the season with the correct amount of
                          promoter (usually cobalt based,) and the amount of MEKP used does
                          depend on the temperature-you get this information from the resin
                          manufacturer. You want fresh resin, as it has a relatively brief shelf
                          life.)

                          Vinylester is stronger and blister-resistant, but apparently the same
                          to work with as polyester, so I am not worried. The e-glass should be
                          used for the +45-45 oriented fabric, to resist wringing (torsional)
                          strains, but carbon fiber at 0 degrees (unidirectional fabric laid the
                          long way,) should be used to resist bending. Vinylester resin is
                          strong enough that it doesn't matter if your layup is a bit rich or
                          not, as it is just as strong from the extra thickness if it is resin
                          rich, as it would be if the resin amount were just right. Squishing
                          out the extra resin makes it lighter when using vinylester, but not
                          stronger.

                          TD

                          > Even if you have read that about epoxy, I think it should be taken
                          > with a tiny grain of salt. It may well depend on HOW the mast has
                          > been laminated.
                          >
                          Any amateur should

                          > I learned a good year ago that JESTER II lost her mast in moderate
                          > conditions the summer 2006, I think it was (diam=18.14cm hollow,
                          > professionally built). The failure appeared to be in one of those
                          > scarf joints. The colour of the joints suggested that resorcinol had
                          > been used in the full-length joints, while for the scarf joint
                          > something else had been used.
                          >
                          > The idea of making e-glass masts is of course tempting, but I fear
                          > that I would lose a lot of time and money in the learning process...
                          >
                          > Good luck!
                          >
                          > Arne
                          >
                          >
                          > --- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@> wrote:
                          > >
                          > > I have read that you should never use epoxy to make a wooden mast,
                          > but
                          > > rather that you should always use brown (resorcinol) glue. If I
                          > > wanted to make a wooden hollow mast, I think I'd make
                          > a "birdsmouth"
                          > > mast. If you google that you will find exact instructions.
                          > >
                          > > I am leaning towards vinylestyer, e-glass +45-45, and carbon fiber
                          > > unidirectional. I have a description of how to make a mast this
                          > way at
                          > > http://www.dunnanddunnrealtors.com/Catamaran.html .
                          > >
                          >
                        • Tim Dunn
                          Hi, De I have long been in the habit of looking at the heeling moment by calculating the reefed area and height of the reefed CE. Now that I am working on
                          Message 12 of 21 , Feb 3, 2008
                          • 0 Attachment
                            Hi, De

                            I have long been in the habit of looking at the heeling moment by
                            calculating the reefed area and height of the reefed CE. Now that I
                            am working on catamaran designs, this has become critical, as you use
                            math rather than instinct to reef them. (The lack of heeling leaves
                            you with no clue as to how hard pressed you are.) The formula for
                            wind pressure is P = .004 x(v squared) where P = pounds per sq. ft.
                            and v is in statue (not knots) miles per hour.

                            Using the above information, I multiply a given pounds per square foot
                            x the height of center of effort (the center of the sails, at each
                            reefed amount of sail area,) to get the foot pounds of heeling force.
                            I assume this is what is behind your calculations, and yes, it is
                            indeed dramatic how much reefing reduces the foot pounds.

                            Of course, the increase in wind pressure is dramatic as the wind
                            speeds increase, as well. 16 mph has, for example, twice the wind
                            pressure as 11 mph, and 22 mph has four times the wind pressure of 11
                            mph. Of course the same is just as true in metric units, that is,
                            twice the speed = 4 times the pressure.

                            Anyway, thanks for your calculator!

                            TD
                          • De Clarke
                            ... yes I have sailed on a cat once and found it quite unnerving -- you ll know when you should have reefed cos you ll be upside down ... yes, same basic
                            Message 13 of 21 , Feb 3, 2008
                            • 0 Attachment
                              Tim Dunn (steelsil2@...) wrote:
                              >
                              > math rather than instinct to reef them. (The lack of heeling leaves
                              > you with no clue as to how hard pressed you are.) The formula for

                              yes I have sailed on a cat once and found it quite unnerving --
                              "you'll know when you should have reefed 'cos you'll be upside down"
                              :-) OK, an exaggeration, but it was bizarre having no feedback.

                              > I assume this is what is behind your calculations, and yes, it is
                              > indeed dramatic how much reefing reduces the foot pounds.

                              yes, same basic formulae.

                              > Anyway, thanks for your calculator!

                              you're quite welcome. I still wish I had a reliable formula for
                              stress on the mizzen boomkin, but haven't had the time to pursue
                              it. it's an ugly problem with compound vectors... life is short,
                              and I think it will just be a case of "find a strong bit of pipe
                              and hope for the best."

                              de

                              --
                              .............................................................................
                              :De Clarke, Software Engineer UCO/Lick Observatory, UCSC:
                              :S/V Taz, Newcastle Marina, Nanaimo BC :
                              :Mail: de@... | Your planet's immune system is trying to get rid :
                              :Web: www.svtaz.org | of you. --Kurt Vonnegut :
                            • Sven
                              Hi, when I browsed the junkrig2 photos section I found this: http://ph.groups.yahoo.com/group/junkrig2/photos/browse/15d4 Is this a appropriate method to build
                              Message 14 of 21 , Feb 4, 2008
                              • 0 Attachment
                                Hi,
                                when I browsed the junkrig2 photos section I found
                                this:
                                http://ph.groups.yahoo.com/group/junkrig2/photos/browse/15d4


                                Is this a appropriate method to build a hollow mast?
                                The gaps between the batteńs seems to be rather
                                big.

                                fair winds
                                Sven

                                --- Tim Dunn <steelsil2@...> schrieb:

                                > I have read that you should never use epoxy to make
                                > a wooden mast, but
                                > rather that you should always use brown (resorcinol)
                                > glue. If I
                                > wanted to make a wooden hollow mast, I think I'd
                                > make a "birdsmouth"
                                > mast. If you google that you will find exact
                                > instructions.
                                >
                                > I am leaning towards vinylestyer, e-glass +45-45,
                                > and carbon fiber
                                > unidirectional. I have a description of how to make
                                > a mast this way at
                                > http://www.dunnanddunnrealtors.com/Catamaran.html .
                                >
                                >
                                >



                                Heute schon einen Blick in die Zukunft von E-Mails wagen? Versuchen Sie´s mit dem neuen Yahoo! Mail. www.yahoo.de/mail
                              • skarv2006
                                ... Hi Tim. You are right about UV, and heat, but the Epoxy should be protected as you say. Lots of Wood-Epoxy boats have been built, so I don t believe that
                                Message 15 of 21 , Feb 4, 2008
                                • 0 Attachment
                                  --- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@...> wrote:
                                  >
                                  > Hi, Victor
                                  >
                                  > I don't know if the claim that resorcinol is better than epoxy for
                                  > mast-making is true or not, but I thought I'd mention it so that any
                                  > one planning to make a glued wooden mast could look into it. Some
                                  > claim that not only is UV bad for epoxy, but that heat is also bad
                                  > for it. It is well known that UV is bad for epoxy, so epoxy exposed
                                  > to the sun should definitely be painted white or otherwise protected
                                  > from UV.
                                  >
                                  > The claim that resorcinol is better than epoxy for masts is something
                                  > that I read on the forums at www.woodenboat.com/ , which seem to be
                                  > off-line at the moment. Speaking of off-line, I notice that your site
                                  > is off-line. I am sure that I am not the only "junkie" looking
                                  > forward to seeing it return.
                                  >
                                  > TD

                                  Hi Tim.
                                  You are right about UV, and heat, but the Epoxy should be protected as
                                  you say. Lots of Wood-Epoxy boats have been built, so I don't believe
                                  that epoxy in a mast will give trouble if it is properly protected.
                                  Here at 60 deg North, we have hardly any sun, or heat to be afraid of
                                  anyway Ha ha.
                                  Regarding my home site.
                                  Maybe I could put my article about Junk-Rig into a file on the
                                  yahoo-group?

                                  Victor
                                • Paul T. Howard
                                  Ah, Catamaran sailing!! Having circumnavigated the world in a junk rigged monohull, as well as having owned gaff cutter and bermuda rigged monohulls, I am well
                                  Message 16 of 21 , Feb 4, 2008
                                  • 0 Attachment
                                    Ah, Catamaran sailing!!
                                    Having circumnavigated the world in a junk rigged monohull, as well as having owned gaff cutter and bermuda rigged monohulls, I am well aware of when to reef monohulls.
                                    I have also sailed our 38 foot catamaran around the north side of Iceland, crossing the Arctic Circle, as well as having sailed her round Cape Horn at the southern end of the world.
                                    Catamarans do let you know when they are hard pressed and want to be reefed.
                                    It is easier to ignore as you are not being tipped out of the cockpit as with a monohull.
                                    But the signs for conservative long distance sailors are definitely there to be learned.
                                    You can let a cat run on at high speeds, but there will be costs in terms of spoiled gear.
                                    My son-in-law was heard to mutter, "Just when the boat really gets going, HE wants to reef." Referring to me.
                                    When the lee bow begins to dig in it is definitely past time to reef.

                                    I also judge when to reef the catamaran by the motion. When I am being jostled about more than I like, it is time to slow the boat to displacement speeds.
                                    With practice, as in all things, you can judge when double reefing the mainsail does not so much slow the catamaran, but makes it more manageable and comfortable.
                                    Paul

                                    De Clarke <de@...> wrote: Tim Dunn (steelsil2@...) wrote:
                                    >
                                    > math rather than instinct to reef them. (The lack of heeling leaves
                                    > you with no clue as to how hard pressed you are.) The formula for

                                    yes I have sailed on a cat once and found it quite unnerving --
                                    "you'll know when you should have reefed 'cos you'll be upside down"
                                    :-) OK, an exaggeration, but it was bizarre having no feedback.

                                    > I assume this is what is behind your calculations, and yes, it is
                                    > indeed dramatic how much reefing reduces the foot pounds.

                                    yes, same basic formulae.

                                    > Anyway, thanks for your calculator!

                                    you're quite welcome. I still wish I had a reliable formula for
                                    stress on the mizzen boomkin, but haven't had the time to pursue
                                    it. it's an ugly problem with compound vectors... life is short,
                                    and I think it will just be a case of "find a strong bit of pipe
                                    and hope for the best."

                                    de

                                    --
                                    .............................................................................
                                    :De Clarke, Software Engineer UCO/Lick Observatory, UCSC:
                                    :S/V Taz, Newcastle Marina, Nanaimo BC :
                                    :Mail: de@... | Your planet's immune system is trying to get rid :
                                    :Web: www.svtaz.org | of you. --Kurt Vonnegut :






                                    ---------------------------------
                                    Instant message from any web browser! Try the new Yahoo! Canada Messenger for the Web BETA

                                    [Non-text portions of this message have been removed]
                                  • sae140
                                    ... Hi Victor, I once bought some cheap stuff - the brand was 151 - it smelled strongly of burnt oil as it cured and it set like glass. It shattered with a
                                    Message 17 of 21 , Feb 4, 2008
                                    • 0 Attachment
                                      --- In junkrig@yahoogroups.com, "skarv2006" <skarv2006@...> wrote:
                                      >
                                      > --- In junkrig@yahoogroups.com, "sae140" <colinpowell@> wrote:
                                      >
                                      > >
                                      > > Hi Victor - I'm certainly no expert on epoxy, but know first-hand that
                                      > > some epoxy glues can be very brittle when set, and some remain
                                      > > relatively flexible. I much prefer using the latter for all marine
                                      > > uses: wood and grp lay-up. Some vendors advertise the epoxy's cured
                                      > > characteristics and some don't.
                                      > >
                                      > > I'd be happy using flexible epoxy on all kinds of wood, including new
                                      > > teak which is normally considered troublesome due to it's surface oil
                                      > > - I simply wipe down those surfaces to be glued with acetone or
                                      > > thinners immediately prior to applying the glue.
                                      > >
                                      > > Colin
                                      > >
                                      > Hi Colin.
                                      > Just as I thought. It is possible to find Epoxies that are a little
                                      > flexible.
                                      > What type do you use?, or would you use to make masts?.
                                      >
                                      > Victor
                                      >


                                      Hi Victor,

                                      I once bought some cheap stuff - the brand was '151' - it smelled
                                      strongly of burnt oil as it cured and it set like glass. It shattered
                                      with a modest hammer-blow, so it went straight in the bin.

                                      One company I can fully recommend is ABL Stevens:
                                      http://www.resin-supplies.co.uk/Pricelist.htm

                                      I use their General Purpose Epoxy Laminating Resin, which is a 2:1 mix
                                      *by weight*. That's very nearly 2:1 by volume, but not quite - so
                                      I've made up a set of calibrated mixing pots from clear disposable
                                      plastic tumbler/beakers: put one beaker inside another, then carefully
                                      weigh out the hardener and mark the outside beaker with tape or a gem
                                      marker, then carefully add 2x weight of resin, and mark it again.
                                      Then retain the marked beaker and just pop a fresh beaker into it for
                                      each new mix. Speeds up the process, and no need for any further
                                      weighing !

                                      The guy at ABL Stevens is very helpful, and if the hardener should go
                                      'off' with age, he will supply more on request. There's no need to buy
                                      the resin as well, if you have some left over. The shelf-life of the
                                      hardener is around 12 months, but I'm finding that this can be doubled
                                      if it's kept in an airtight container, in the fridge. The resin itself
                                      has no expiry date, afaik.

                                      I bought a couple of packs of West Systems epoxy last year but haven't
                                      used it yet, so can't comment on how good that brand is. But it's
                                      more expensive than the stuff from ABL Stevens.

                                      Stevens also offers UV-stabilised epoxy, so I guess a thin coat of
                                      this could be applied over the regular stuff to protect it from
                                      sunlight for those who live in hot, sunny places. I don't think
                                      Britain qualifies as having a UV problem !!

                                      Polyester is much cheaper than epoxy, and although it's good stuff for
                                      binding a grp lay-up together, as an adhesive it's nowhere near as
                                      good as epoxy, so personally I wouldn't use it to bond 2 pieces of
                                      wood together, nor for any repair work.

                                      Colin
                                    • skarv2006
                                      ... Hi Colin Yes. I think it is important to read and learn a little about the different types before choosing one. I have only experianse with West-Epoxy, and
                                      Message 18 of 21 , Feb 4, 2008
                                      • 0 Attachment
                                        --- In junkrig@yahoogroups.com, "sae140" <colinpowell@...> wrote:

                                        > Hi Victor,
                                        >
                                        > I once bought some cheap stuff - the brand was '151' - it smelled
                                        > strongly of burnt oil as it cured and it set like glass. It shattered
                                        > with a modest hammer-blow, so it went straight in the bin.
                                        >
                                        > One company I can fully recommend is ABL Stevens:
                                        > http://www.resin-supplies.co.uk/Pricelist.htm
                                        >
                                        > I use their General Purpose Epoxy Laminating Resin, which is a 2:1 mix
                                        > *by weight*. That's very nearly 2:1 by volume, but not quite - so
                                        > I've made up a set of calibrated mixing pots from clear disposable
                                        > plastic tumbler/beakers: put one beaker inside another, then carefully
                                        > weigh out the hardener and mark the outside beaker with tape or a gem
                                        > marker, then carefully add 2x weight of resin, and mark it again.
                                        > Then retain the marked beaker and just pop a fresh beaker into it for
                                        > each new mix. Speeds up the process, and no need for any further
                                        > weighing !
                                        >
                                        > The guy at ABL Stevens is very helpful, and if the hardener should go
                                        > 'off' with age, he will supply more on request. There's no need to buy
                                        > the resin as well, if you have some left over. The shelf-life of the
                                        > hardener is around 12 months, but I'm finding that this can be doubled
                                        > if it's kept in an airtight container, in the fridge. The resin itself
                                        > has no expiry date, afaik.
                                        >
                                        > I bought a couple of packs of West Systems epoxy last year but haven't
                                        > used it yet, so can't comment on how good that brand is. But it's
                                        > more expensive than the stuff from ABL Stevens.
                                        >
                                        > Stevens also offers UV-stabilised epoxy, so I guess a thin coat of
                                        > this could be applied over the regular stuff to protect it from
                                        > sunlight for those who live in hot, sunny places. I don't think
                                        > Britain qualifies as having a UV problem !!
                                        >
                                        > Polyester is much cheaper than epoxy, and although it's good stuff for
                                        > binding a grp lay-up together, as an adhesive it's nowhere near as
                                        > good as epoxy, so personally I wouldn't use it to bond 2 pieces of
                                        > wood together, nor for any repair work.
                                        >
                                        > Colin
                                        >
                                        Hi Colin
                                        Yes. I think it is important to read and learn a little about the
                                        different types before choosing one. I have only experianse with
                                        West-Epoxy, and that type are quite hard. When I rebuilt my saloon
                                        table, wich can also be used in the cockpit, I used a one-komponent
                                        polyuretane glue. It is not as strong as epoxy, but easy to use, and
                                        good enough for non-struktural purposes.

                                        Victor
                                      • sae140
                                        ... Hi Victor - although I haven t used the stuff myself, I ve heard good reports about polyurethane glue. As with epoxy, there are several brands -
                                        Message 19 of 21 , Feb 5, 2008
                                        • 0 Attachment
                                          --- In junkrig@yahoogroups.com, "skarv2006" <skarv2006@...> wrote:
                                          >

                                          > Hi Colin
                                          > Yes. I think it is important to read and learn a little about the
                                          > different types before choosing one. I have only experianse with
                                          > West-Epoxy, and that type are quite hard. When I rebuilt my saloon
                                          > table, wich can also be used in the cockpit, I used a one-komponent
                                          > polyuretane glue. It is not as strong as epoxy, but easy to use, and
                                          > good enough for non-struktural purposes.
                                          >
                                          > Victor
                                          >

                                          Hi Victor - although I haven't used the stuff myself, I've heard good
                                          reports about polyurethane glue. As with epoxy, there are several
                                          brands - presumably with different properties. I remember Ted Stone
                                          telling me about some polyurethane glue testing he did (with a lump
                                          hammer !). Unfortunately I can't remember the brand name.

                                          If you're reading this Ted - could you script a few words outlining
                                          the outcome of the big hammer test ?

                                          Colin
                                        • Debbie
                                          - Hi Tim, I guess I ll jump in on this thread, I have been building and gluing for twenty years and have spoken to the technical dept.s of most of the well
                                          Message 20 of 21 , Feb 9, 2008
                                          • 0 Attachment
                                            - Hi Tim,
                                            I guess I'll jump in on this thread, I have been building and
                                            gluing for twenty years and have spoken to the technical dept.s of
                                            most of the well known glue companies out there, something thats easy
                                            to do and they love to talk. In theory resorcinol would be better
                                            how ever it must have a perfect mating of the two surfaces or else a
                                            great deal of pressure; you want a glue line of 1-3 mil and the
                                            presure helps to get you there. Both are difficult to do on anything
                                            the size and complexity of a multi-stave mast. Resorcinal is also
                                            the only truely Type 1 waterproof glue out there. Masts used to be
                                            built with what amounts to Elmers glue and did just fine as long as
                                            they stayed dry. Epoxy is waterproof enough and gap filling and does
                                            not need a lot of presure and so in the real world is just as good.
                                            The tensile strength of all of these glues are higher that the woods
                                            we commonly build masts of as well. As is usually the case (within
                                            reason)the best material or technique is the one you are most
                                            familiar with. Mike Lyons


                                            -- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@...> wrote:
                                            >
                                            > Hi, Arne
                                            >
                                            > I don't have an opinion of my own in the epoxy vs. resorcinol
                                            > controversy. I am just mentioning that the controversy exists.
                                            >
                                            > I learned to fiberglass at a boatbuilder's shop long ago. It is
                                            > absurdly easy, at least with polyester resin. I think it is much
                                            > harder to bake a cake or make a loaf of bread. You just mix resin
                                            > with hardener, pour it on the fabric, and work it to get the air
                                            > bubbles out of the laminate, (for example by rolling a metal rolling
                                            > tool made for the purpose over the laminate.) I am going to have a
                                            > vacuum setup, so rolling won't be necessary except for making joins
                                            of
                                            > larger parts, but then I am starting on a larger laminating
                                            project.
                                            >
                                            > (You do use resin premixed for the season with the correct amount of
                                            > promoter (usually cobalt based,) and the amount of MEKP used does
                                            > depend on the temperature-you get this information from the resin
                                            > manufacturer. You want fresh resin, as it has a relatively brief
                                            shelf
                                            > life.)
                                            >
                                            > Vinylester is stronger and blister-resistant, but apparently the
                                            same
                                            > to work with as polyester, so I am not worried. The e-glass should
                                            be
                                            > used for the +45-45 oriented fabric, to resist wringing (torsional)
                                            > strains, but carbon fiber at 0 degrees (unidirectional fabric laid
                                            the
                                            > long way,) should be used to resist bending. Vinylester resin is
                                            > strong enough that it doesn't matter if your layup is a bit rich or
                                            > not, as it is just as strong from the extra thickness if it is resin
                                            > rich, as it would be if the resin amount were just right. Squishing
                                            > out the extra resin makes it lighter when using vinylester, but not
                                            > stronger.
                                            >
                                            > TD
                                            >
                                            > > Even if you have read that about epoxy, I think it should be
                                            taken
                                            > > with a tiny grain of salt. It may well depend on HOW the mast has
                                            > > been laminated.
                                            > >
                                            > Any amateur should
                                            >
                                            > > I learned a good year ago that JESTER II lost her mast in
                                            moderate
                                            > > conditions the summer 2006, I think it was (diam=18.14cm hollow,
                                            > > professionally built). The failure appeared to be in one of those
                                            > > scarf joints. The colour of the joints suggested that resorcinol
                                            had
                                            > > been used in the full-length joints, while for the scarf joint
                                            > > something else had been used.
                                            > >
                                            > > The idea of making e-glass masts is of course tempting, but I
                                            fear
                                            > > that I would lose a lot of time and money in the learning
                                            process...
                                            > >
                                            > > Good luck!
                                            > >
                                            > > Arne
                                            > >
                                            > >
                                            > > --- In junkrig@yahoogroups.com, "Tim Dunn" <steelsil2@> wrote:
                                            > > >
                                            > > > I have read that you should never use epoxy to make a wooden
                                            mast,
                                            > > but
                                            > > > rather that you should always use brown (resorcinol) glue. If I
                                            > > > wanted to make a wooden hollow mast, I think I'd make
                                            > > a "birdsmouth"
                                            > > > mast. If you google that you will find exact instructions.
                                            > > >
                                            > > > I am leaning towards vinylestyer, e-glass +45-45, and carbon
                                            fiber
                                            > > > unidirectional. I have a description of how to make a mast
                                            this
                                            > > way at
                                            > > > http://www.dunnanddunnrealtors.com/Catamaran.html .
                                            > > >
                                            > >
                                            >
                                          • Don Taylor
                                            Mike: What about the new moisture-cured urethane glues? E.g. LePage s PL Premium. They have good gap filling properties, they are water-proof, cheaper than
                                            Message 21 of 21 , Feb 9, 2008
                                            • 0 Attachment
                                              Mike:

                                              What about the new moisture-cured urethane glues? E.g. LePage's PL
                                              Premium.

                                              They have good gap filling properties, they are water-proof, cheaper
                                              than epoxies, single part, paintable and readily available from building
                                              supply stores.

                                              Don.
                                            Your message has been successfully submitted and would be delivered to recipients shortly.