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Re: [Michalak] Re: Twin Leeboards

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  • jhargrovewright2@juno.com
    Graeme..... I do not understand it at all yet, but, the guy seems to have studied it inside out....today s Duckworks Mag.
    Message 1 of 28 , Apr 1, 2013
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      Graeme..... I do not understand it at all yet, but, the guy seems to have studied it inside out....today's Duckworks Mag. http://www.duckworksmagazine.com/13/howto/propulsion/index.htm#.UVmryr4o5LM appears to be calculating a way for the underwater foils....specifically the leeboard....to produce propulsion.....???? I will not comment until I can understand....grok..
      JIB
      ---------- Original Message ----------
      From: "graeme" <graeme19121984@...>
      To: Michalak@yahoogroups.com
      Subject: [Michalak] Re: Twin Leeboards
      Date: Mon, 01 Apr 2013 06:49:07 -0000


      <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">


      It can take a lot of concentration to visualise how the angle of toe-in changes as those leeboards are appropriately raked from aft to fully down to suit the point of sail. Probably a model would help.

      One thing not shown there is that the mount faces slope sort of wedge or cam-like... think of a short wide solid cylinder - a thick round block. Ok? To make a leeboard mount that changes the relative toe-in through a 0 to 2 or 4deg angle with rotation up or down from being parallel with the boat longitudinal centreline slice the block in half to make two round blocks only slope the slice a little. When the two blocks are rotated relative to each other the two inner sloping mating faces then will cause the outer block faces to change angle. The blocks don't have to necessarily be round. The original Dutch way I believe is to have that "slope" shaped by carving it into the top of the leeboard mounting face - not a lot of trouble considering how well the rest of the board is similarly shaped by carving. I've seen drawings of the block type mounts though, one attached to the side and it's mate to the leeboard. The pin or shaft, like the hole for the shaft, goes through the lot in a straight line (board, blocks, side, plank) that in plan and elevation views is straight but of course in end elevation view (body plan) for the Dutch boat types it has an angle normal (90deg right angle) to the slope of the tumblehome plank.

      http://www.duckworksmagazine.com/02/articles/bbwadvii/index.htm

      http://www.duckworksbbs.com/media/books/barend/index.htm

      http://www.punterwerf.nl/

      http://www.duckworksmagazine.com/02/articles/bbwadvi/part6.htm

      Graeme

      --- In Michalak@yahoogroups.com, "jhargrovewright2@..." <jhargrovewright2@...> wrote:
      > Life is good.Thank you for re orienting me to the leeboard tow in/out and the canting of the Dutch boats. You linked to a great site http://www.duckworksmagazine.com/01/articles/leeboards/index.htm You and he have convinced me " boards must have camber, caster and toe-in ".
      > It took me a long time today to get through your post and the links. You have made me rethink the whole question. My canoe will be even better, thanks! JIB







      [Non-text portions of this message have been removed]
    • Anders Bjorklund
      Did you notice the date, John? On Mon, Apr 1, 2013 at 10:53 AM, jhargrovewright2@juno.com
      Message 2 of 28 , Apr 1, 2013
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        Did you notice the date, John?

        On Mon, Apr 1, 2013 at 10:53 AM, jhargrovewright2@... <
        jhargrovewright2@...> wrote:

        > Graeme..... I do not understand it at all yet, but, the guy seems to have
        > studied it inside out....today's Duckworks Mag.
        > http://www.duckworksmagazine.com/13/howto/propulsion/index.htm#.UVmryr4o5LMappears to be calculating a way for the underwater foils....specifically
        > the leeboard....to produce propulsion.....???? I will not comment until I
        > can understand....grok..
        > JIB
        >


        [Non-text portions of this message have been removed]
      • jhargrovewright2@juno.com
        Anders, I am not sure I understand the question....it is today s article in Duckworks Mag. Did you try the link? JIB ... From: Anders Bjorklund
        Message 3 of 28 , Apr 1, 2013
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          Anders, I am not sure I understand the question....it is today's article in Duckworks Mag. Did you try the link? JIB

          ---------- Original Message ----------
          From: Anders Bjorklund <andersbjorklund5@...>
          To: Michalak <Michalak@yahoogroups.com>
          Subject: Re: [Michalak] Re: Twin Leeboards
          Date: Mon, 1 Apr 2013 18:22:15 -0500


          <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
          Did you notice the date, John?

          On Mon, Apr 1, 2013 at 10:53 AM, jhargrovewright2@... <
          jhargrovewright2@...> wrote:

          > Graeme..... I do not understand it at all yet, but, the guy seems to have
          > studied it inside out....today's Duckworks Mag.
          > http://www.duckworksmagazine.com/13/howto/propulsion/index.htm#.UVmryr4o5LMappears to be calculating a way for the underwater foils....specifically
          > the leeboard....to produce propulsion.....???? I will not comment until I
          > can understand....grok..
          > JIB
          >

          [Non-text portions of this message have been removed]







          [Non-text portions of this message have been removed]
        • graeme
          50% smoke
          Message 4 of 28 , Apr 1, 2013
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            50% smoke

            --- In Michalak@yahoogroups.com, "jhargrovewright2@..."
            > Graeme..... I do not understand it at all yet, but, the guy seems to have studied it inside out....
          • Anders Bjorklund
            The date of today s Duckworks article? April 1? No one noticed? On Mon, Apr 1, 2013 at 8:53 PM, jhargrovewright2@juno.com
            Message 5 of 28 , Apr 1, 2013
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              The date of today's Duckworks article? April 1? No one noticed?


              On Mon, Apr 1, 2013 at 8:53 PM, jhargrovewright2@... <
              jhargrovewright2@...> wrote:

              > Anders, I am not sure I understand the question....it is today's article
              > in Duckworks Mag. Did you try the link? JIB


              [Non-text portions of this message have been removed]
            • graeme
              Ha !! It s April 2 already here obscured by the smoke haze fazed.
              Message 6 of 28 , Apr 1, 2013
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                Ha !! It's April 2 already here obscured by the smoke haze fazed.

                --- In Michalak@yahoogroups.com, Anders Bjorklund <andersbjorklund5@...> wrote:
                >
                > The date of today's Duckworks article? April 1? No one noticed?
              • jhargrovewright2@juno.com
                Anders, Thanks, you saved me some time. I was very busy yesterday so I printed it out so that I could read and study it....because I could not follow it. I
                Message 7 of 28 , Apr 2, 2013
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                  Anders, Thanks, you saved me some time. I was very busy yesterday so I printed it out so that I could read and study it....because I could not follow it. I can study something difficult much easier if it is on paper. I picked it up this morning while fresh, to read it...... and realized I HAD BEEN HAD! JOKE ON ME. On the yahoo proa group there are a couple of members that are very hard to follow and have a lot of education and training in aerodynamics, engineering......so I save it and print it out then read and re read until it makes sense..... Dyslexia is a curse and a blessing. JIB
                  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> The date of today's Duckworks article? April 1? No one noticed?

                  On Mon, Apr 1, 2013 at 8:53 PM, jhargrovewright2@... <
                  jhargrovewright2@...> wrote:

                  > Anders, I am not sure I understand the question....it is today's article
                  > in Duckworks Mag. Did you try the link? JIB

                  [Non-text portions of this message have been removed]



                  [Non-text portions of this message have been removed]
                • Tim Anderson
                  I had twin air-foiled lee boards on my PCB Black Skimmer, i used the pivots that Phil used on Black Gauntlet with 1 degree toe-in. I also added a bow dagger
                  Message 8 of 28 , Apr 4, 2013
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                    I had twin air-foiled lee boards on my PCB Black Skimmer, i used the pivots
                    that Phil used on Black Gauntlet with 1 degree toe-in. I also added a bow
                    dagger board for beating in shallow water. She pointed very high so long as
                    i sailed her as flat as possible. Tim P Anderson Swamp Dwelling Boat
                    Builder


                    [Non-text portions of this message have been removed]
                  • jhargrovewright2@juno.com
                    Tim Anderson... I admire the Black Skimmer and the information. What swamp do you reside in? Can you add any comments experience with the bow dagger board.
                    Message 9 of 28 , Apr 4, 2013
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                      Tim Anderson... I admire the Black Skimmer and the information. What swamp do you reside in? Can you add any comments experience with the bow dagger board. That is an unusual place for a foil and I wonder how and why Bolger came up with that arrangement. Any info would be appreciated. JIB

                      ---------- Original Message ----------
                      From: Tim Anderson <naturalist71261@...>
                      To: Michalak@yahoogroups.com
                      Subject: [Michalak] Re: Twin Leeboards
                      Date: Thu, 4 Apr 2013 15:47:55 -0500


                      <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
                      I had twin air-foiled lee boards on my PCB Black Skimmer, i used the pivots
                      that Phil used on Black Gauntlet with 1 degree toe-in. I also added a bow
                      dagger board for beating in shallow water. She pointed very high so long as
                      i sailed her as flat as possible. Tim P Anderson Swamp Dwelling Boat
                      Builder

                      [Non-text portions of this message have been removed]







                      [Non-text portions of this message have been removed]
                    • John Trussell
                      I had a Dovekie with a bow centerboard. It worked fine in shallow water. It somewhat offset the lee helm which developed when I reefed. However, if you are in
                      Message 10 of 28 , Apr 4, 2013
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                        I had a Dovekie with a bow centerboard. It worked fine in shallow water. It
                        somewhat offset the lee helm which developed when I reefed. However, if you
                        are in the habit of heading up in a puff, be aware that the bow centerboard
                        will resist heading up-best to ease the sheet.



                        JohnT



                        _____

                        From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On Behalf
                        Of jhargrovewright2@...
                        Sent: Thursday, April 04, 2013 6:18 PM
                        To: Michalak@yahoogroups.com
                        Subject: Re: [Michalak] Re: Twin Leeboards





                        Tim Anderson... I admire the Black Skimmer and the information. What swamp
                        do you reside in? Can you add any comments experience with the bow dagger
                        board. That is an unusual place for a foil and I wonder how and why Bolger
                        came up with that arrangement. Any info would be appreciated. JIB

                        ---------- Original Message ----------
                        From: Tim Anderson <naturalist71261@...
                        <mailto:naturalist71261%40gmail.com> >
                        To: Michalak@yahoogroups.com <mailto:Michalak%40yahoogroups.com>
                        Subject: [Michalak] Re: Twin Leeboards
                        Date: Thu, 4 Apr 2013 15:47:55 -0500

                        <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
                        "http://www.w3.org/TR/html4/strict.dtd">
                        I had twin air-foiled lee boards on my PCB Black Skimmer, i used the pivots
                        that Phil used on Black Gauntlet with 1 degree toe-in. I also added a bow
                        dagger board for beating in shallow water. She pointed very high so long as
                        i sailed her as flat as possible. Tim P Anderson Swamp Dwelling Boat
                        Builder

                        [Non-text portions of this message have been removed]

                        [Non-text portions of this message have been removed]





                        [Non-text portions of this message have been removed]
                      • prairiedog2332
                        Jim drew a design called Eisbox that had a bow centreboard installed in the free-flooding bow well as an option. There is a cartoon in the files section. The
                        Message 11 of 28 , Apr 5, 2013
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                          Jim drew a design called "Eisbox" that had a bow centreboard installed
                          in the free-flooding bow well as an option. There is a cartoon in the
                          files section.


                          The idea was to lower it enough in shallow water to help prevent lee
                          helm as the leeboard was raised. Very simple to add as you don't have to
                          worry about sealing the case since it is already inside the
                          free-flooding well, so it can be a very shallow rectangular box open at
                          the top. The board is in the shape of a quarter circle about 18" in
                          diameter. Just needs some weight added so it stays down and a control
                          line leads from a tab added to the aft end leading up to a turning block
                          at the bow and then back to the helm to raise it to the desired height
                          and locked into a jam cleat.


                          Eisbox has a 5 ft. deep leeboard so as it is raised in shallows will
                          quite likely introduce lee helm and spoil upwind capability. So as the
                          leeboard is raised you lower the bow board and hopefully maintain a
                          neutral balance at the helm by adjusting both boards as you go along.
                          The only thing is that you are restricted to 6" draft on Eisbox as it
                          has a skeg ahead of the inboard rudder to protect it - which Jim doesn't
                          like all that much - but the fellow who commissioned it insisted on as
                          he wanted the OB to be mounted on the centreline. It was intended to
                          motor more than sail in the purpose he wanted a boat for. He wanted to
                          motor out offshore to fish when the winds were normally too low to sail
                          and sail back home when the on-shore breeze arose in the afternoon.


                          So a fellow like JIB might be interested in this information if used in
                          hull with less draft than Eisbox and likes to sail in the shallows?

                          Nels


                          --- In Michalak@yahoogroups.com, "John Trussell" <jtrussell2@...> wrote:
                          >
                          > I had a Dovekie with a bow centerboard. It worked fine in shallow
                          water. It
                          > somewhat offset the lee helm which developed when I reefed. However,
                          if you
                          > are in the habit of heading up in a puff, be aware that the bow
                          centerboard
                          > will resist heading up-best to ease the sheet.
                          >
                          >
                          >
                          > JohnT
                          >
                          >
                          >




                          [Non-text portions of this message have been removed]
                        • jhargrovewright2@juno.com
                          Nels, I was not familiar with Eisbox. Interesting boat. I did not find any info on the bow centerboard but have thought about the effects/uses that it might
                          Message 12 of 28 , Apr 6, 2013
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                            Nels, I was not familiar with Eisbox. Interesting boat. I did not find any info on the bow centerboard but have thought about the effects/uses that it might have. I think I understand the purpose and function balancing the boat in shallow water....Clever. I prefer to set up my boats with significant weather helm and rely on the rudder for a good portion of the LR.... I am just as careful building the rudder as the leeboard. I may do a centerboard again but, that is not on the list yet... Thanks for the information. That bow centerboard device has long been a mystery to me. Thanks, you have expanded my understanding of the sailboat, again.,,, I do love to sail in shallow water. At the Texas200 a couple of years ago in my Laguna....I stood on the bow of the boat....in the shade of the forward sail and followed the Matagorda Bay shore in 6" to 1' water sneaking up on the fish and other creature of the shallows. Interesting was that in displacement mode in 5"-6" the boat created a significant breaking 1/4 wave following off the transom. I was running directly down wind (10 mph) and did not have the push needed to plane. JIB
                            --------------
                            <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> Jim drew a design called "Eisbox" that had a bow centreboard installed
                            in the free-flooding bow well as an option. There is a cartoon in the
                            files section.

                            The idea was to lower it enough in shallow water to help prevent lee
                            helm as the leeboard was raised. Very simple to add as you don't have to
                            worry about sealing the case since it is already inside the
                            free-flooding well, so it can be a very shallow rectangular box open at
                            the top. The board is in the shape of a quarter circle about 18" in
                            diameter. Just needs some weight added so it stays down and a control
                            line leads from a tab added to the aft end leading up to a turning block
                            at the bow and then back to the helm to raise it to the desired height
                            and locked into a jam cleat.

                            Eisbox has a 5 ft. deep leeboard so as it is raised in shallows will
                            quite likely introduce lee helm and spoil upwind capability. So as the
                            leeboard is raised you lower the bow board and hopefully maintain a
                            neutral balance at the helm by adjusting both boards as you go along.
                            The only thing is that you are restricted to 6" draft on Eisbox as it
                            has a skeg ahead of the inboard rudder to protect it - which Jim doesn't
                            like all that much - but the fellow who commissioned it insisted on as
                            he wanted the OB to be mounted on the centreline. It was intended to
                            motor more than sail in the purpose he wanted a boat for. He wanted to
                            motor out offshore to fish when the winds were normally too low to sail
                            and sail back home when the on-shore breeze arose in the afternoon.

                            So a fellow like JIB might be interested in this information if used in
                            hull with less draft than Eisbox and likes to sail in the shallows?

                            Nels

                            --- In Michalak@yahoogroups.com, "John Trussell" <jtrussell2@...> wrote:
                            >
                            > I had a Dovekie with a bow centerboard. It worked fine in shallow
                            water. It
                            > somewhat offset the lee helm which developed when I reefed. However,
                            if you
                            > are in the habit of heading up in a puff, be aware that the bow
                            centerboard
                            > will resist heading up-best to ease the sheet.
                            >
                            >
                            >
                            > JohnT
                            >
                            >
                            >

                            [Non-text portions of this message have been removed]



                            [Non-text portions of this message have been removed]
                          • prairiedog2332
                            As well as Dovekie and Black Skimmer Bolger added a bow board to his Whalewatcher for the same reasons - to help with helm balance. Bolger also tried to
                            Message 13 of 28 , Apr 6, 2013
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                              As well as Dovekie and Black Skimmer Bolger added a bow board to his
                              Whalewatcher for the same reasons - to help with helm balance.

                              Bolger also tried to develop a bow steering design, based I think on ice
                              boats? So a bow board you could adjust a bit to port or starboard would
                              probably be interesting like toed in or out with leeboards. I think the
                              control mechanisms quickly become complicated for the small gains in
                              performance. I think at planing speeds a bow board should be raised.

                              Nels
                              --- In Michalak@yahoogroups.com, "jhargrovewright2@..."
                              <jhargrovewright2@...> wrote:
                              >
                              > Nels, I was not familiar with Eisbox. Interesting boat. I did not
                              find any info on the bow centerboard but have thought about the
                              effects/uses that it might have. I think I understand the purpose and
                              function balancing the boat in shallow water....Clever. I prefer to
                              set up my boats with significant weather helm and rely on the rudder for
                              a good portion of the LR.... I am just as careful building the rudder
                              as the leeboard. I may do a centerboard again but, that is not on the
                              list yet... Thanks for the information. That bow centerboard device
                              has long been a mystery to me. Thanks, you have expanded my
                              understanding of the sailboat, again.,,, I do love to sail in shallow
                              water. At the Texas200 a couple of years ago in my Laguna....I stood on
                              the bow of the boat....in the shade of the forward sail and followed the
                              Matagorda Bay shore in 6" to 1' water sneaking up on the fish and other
                              creature of the shallows. Interesting was that in displacement mode in
                              5"-6" the boat created a significant breaking 1/4 wave following off the
                              transom. I was running directly down wind (10 mph) and did not have the
                              push needed to plane. JIB




                              [Non-text portions of this message have been removed]
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