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Re: [Michalak] Re: Twin Leeboards

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  • john colley
    We don t seem to be bothered with our centreboards ! Our boards are rarely straight down .Our yachts are ALWAYS Heeling.I cannot see where the problem is.  
    Message 1 of 28 , Mar 28, 2013
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      We don't seem to be bothered with our centreboards !
      Our boards are rarely straight "down".Our yachts are ALWAYS Heeling.I cannot see where the problem is.


       
      "There is magic in the feel of a paddle and the movement of a canoe, a magic compounded of distance, adventure, solitude, and peace."
      -Sigurd Olson


      ________________________________
      From: graeme <graeme19121984@...>
      To: Michalak@yahoogroups.com
      Sent: Thursday, 28 March 2013 3:32 PM
      Subject: [Michalak] Re: Twin Leeboards


       


      > --- In Michalak@yahoogroups.com, "jhargrovewright2@"
      > <jhargrovewright2@> wrote:
      > >
      > > Nels, I understand the theory and agree that a asymmetrical leeboard
      > > canted to windward should help a sailboat but is there any data to
      > > back that up, that you know of.

      Did you mean canted or toed-in?




      [Non-text portions of this message have been removed]
    • graeme
      You re talking about a canted board, ie. not being vertically upright in roll axis, leaning, heeling, flare, and etc, but was JIB talking about a different
      Message 2 of 28 , Mar 28, 2013
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        You're talking about a canted board, ie. not being vertically upright in roll axis, leaning, heeling, flare, and etc, but was JIB talking about a different performance angle altogether? Or maybe you're talking about a board being raked for 'n aft, no? I don't think JIB was talking about that. So was it board toe-in trying for better board/boat pointing in yaw axis, and better sheeting angle he had in mind?

        --- In Michalak@yahoogroups.com, john colley <Helliconia54@...> wrote:
        > We don't seem to be bothered with our centreboards !
        > Our boards are rarely straight "down".Our yachts are ALWAYS Heeling.I cannot see where the problem is.
      • jhargrovewright2@juno.com
        Correct I meant toed in, rather toed out....terminology/words are important! ... From: graeme To: Michalak@yahoogroups.com
        Message 3 of 28 , Mar 28, 2013
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          Correct I meant toed in, rather toed out....terminology/words are important!

          ---------- Original Message ----------
          From: "graeme" <graeme19121984@...>
          To: Michalak@yahoogroups.com
          Subject: [Michalak] Re: Twin Leeboards
          Date: Thu, 28 Mar 2013 04:32:03 -0000


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


          > --- In Michalak@yahoogroups.com, "jhargrovewright2@"
          > <jhargrovewright2@> wrote:
          > >
          > > Nels, I understand the theory and agree that a asymmetrical leeboard
          > > canted to windward should help a sailboat but is there any data to
          > > back that up, that you know of.

          Did you mean canted or toed-in?







          [Non-text portions of this message have been removed]
        • daniel brown
          can you explain how a leeboard canted to windward works better than a vertical one? To: Michalak@yahoogroups.com From: jhargrovewright2@juno.com Date: Thu, 28
          Message 4 of 28 , Mar 28, 2013
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            can you explain how a leeboard canted to windward works better than a vertical one?




            To: Michalak@yahoogroups.com
            From: jhargrovewright2@...
            Date: Thu, 28 Mar 2013 12:31:35 +0000
            Subject: Re: [Michalak] Re: Twin Leeboards





            Correct I meant toed in, rather toed out....terminology/words are important!

            ---------- Original Message ----------
            From: "graeme" <graeme19121984@...>
            To: Michalak@yahoogroups.com
            Subject: [Michalak] Re: Twin Leeboards
            Date: Thu, 28 Mar 2013 04:32:03 -0000

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

            > --- In Michalak@yahoogroups.com, "jhargrovewright2@"
            > <jhargrovewright2@> wrote:
            > >
            > > Nels, I understand the theory and agree that a asymmetrical leeboard
            > > canted to windward should help a sailboat but is there any data to
            > > back that up, that you know of.

            Did you mean canted or toed-in?

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






            [Non-text portions of this message have been removed]
          • jhargrovewright2@juno.com
            That was an incorrect word choice. I was thinking toe in or out of the board not canted . Sorry. JIB ... From: daniel brown To:
            Message 5 of 28 , Mar 28, 2013
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              That was an incorrect word choice. I was thinking toe in or out of the board not "canted". Sorry. JIB

              ---------- Original Message ----------
              From: daniel brown <dannyb9@...>
              To: "Michalak@yahoogroups.com" <michalak@yahoogroups.com>
              Subject: RE: [Michalak] Re: Twin Leeboards
              Date: Thu, 28 Mar 2013 18:51:49 +0000

              can you explain how a leeboard canted to windward works better than a vertical one?




              To: Michalak@yahoogroups.com
              From: jhargrovewright2@...
              Date: Thu, 28 Mar 2013 12:31:35 +0000
              Subject: Re: [Michalak] Re: Twin Leeboards





              Correct I meant toed in, rather toed out....terminology/words are important!

              ---------- Original Message ----------
              From: "graeme" <graeme19121984@...>
              To: Michalak@yahoogroups.com
              Subject: [Michalak] Re: Twin Leeboards
              Date: Thu, 28 Mar 2013 04:32:03 -0000

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

              > --- In Michalak@yahoogroups.com, "jhargrovewright2@"
              > <jhargrovewright2@> wrote:
              > >
              > > Nels, I understand the theory and agree that a asymmetrical leeboard
              > > canted to windward should help a sailboat but is there any data to
              > > back that up, that you know of.

              Did you mean canted or toed-in?

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






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



              ------------------------------------

              Yahoo! Groups Links




              [Non-text portions of this message have been removed]
            • graeme
              ... JIB, I wasn t sure but thought so. IIRC you were asking,,, if there s evidence for it being any good? Assymetrical boards and toe-in? Asymmetric gives
              Message 6 of 28 , Mar 29, 2013
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                --- In Michalak@yahoogroups.com, "jhargrovewright2@..." <jhargrovewright2@...> wrote:

                > Correct I meant toed in, rather toed out....terminology/words are
                > important!


                JIB, I wasn't sure but thought so. IIRC you were asking,,, if there's evidence for it being any good? Assymetrical boards and toe-in?

                Asymmetric gives better specific performance than symmetric. Only stunt planes and the like have symmetric sectioned wings. The others use asymmetric sections. There's all sorts of specific asymmetric profiles, but a simple to make ovoid section (arc of circle one side, flat the other) works ok. Asymmetry - as Jim M notes on occaision: sails with their camber one side might get up to a CL of 1.5 but symmetric boards might only manage CL 1.0 (CL = coefficient of lift).

                Toe-in? Yep, there's lots of evidence in theory and various practices for this improving boat performance - symmetrical dagger and centerboards leading edges angled and wedged to windward for each tack, hinged articulated keels or with trailing flaps to effectively reverse camber and get some 'toe-in', Dutch leeboard designs - the old style were tricked out for 0degrees running to 4 degrees of toe-in when beating by rake-variable cant-variable span-variable-twist, controlled by one rope - those are real interesting.

                Toe-in is good and worthwhile if performance really does matter, but it's easily over done. Racers do it, fishermen wanting to be first in with the days catch to catch a good price, hungry watermen striving for a commercial premium or to pass clear of grounding danger did it.

                Let's see if I don't get tangled up in asymmetric knots, with no guarantees. For beating to weather the overall leeway of the boat stays about the same whether the foil is toed-in or not. It might get a few degrees improvement in leeway is all. It stays about the same because the sum of the hull lateral resistance and the foil lateral resistance stays the same. Each source of lateral resistance still contributes the same individual amount to the combined total of leeway resistance. What toe-in changes is the pointing angle. The leeway angle may remain the same but the hull pointing angle can drop off the wind by the amount of angle that the foil is toed-in - and that, by reducing hull drag improves boat speed which may improve the amount of foil lift thereby maybe improving leeway angle again - a bit of a beneficial feedback spiral there - but the extra speed alone will improve vmg (distance made directly upwind over the ground). If you design board toe-in to vary continuously down from maximum when beating to zero angle running while raking the board back, as you do with a pivoting one anyway, then the board is optimised for lift/drag/speed at whatever point of sail. For some idea of what the Dutch boat wizards' leeboard idea is look at the continuously varying twist catering to varying apparent air speeds along a aeroplane propeller or a wind turbine blade and then pivot that blade off a sloping mount that also has a continuously varying caster angle!

                Another thing that toe-in is used for is to improve sheeting angles on boats with difficult sheeting solutions; relatively narrow boats for their rig for example. Toe-in by improving pointing angle - allowing the boat to point a bit more away from the wind and more in the direction it is actually travelling through the water - gives a wider range of sheeting angle adjustment to get more drive from the sail which improves speed which may improve etc, etc,,, which again improves vmg.

                Bookmarked these to grok long ago:

                Remember Barend's insight into simple pythagorean and trigonometrically derived relationship shortcut tables he showed were inherent in nearly all boats made of sheet material and could be used by anyone. His 101 peice on Dutch leeboards is a wonderful thing:

                http://www.duckworksmagazine.com/01/articles/leeboards/index.htm

                http://www.eiseendenhof.nl/Friese-Reunie/Fotoalbum%20Friese%20Regionale%20Reunie%20Heeg%202004/Zondag%208%20augustus/index.html

                http://www.eiseendenhof.nl/Friese-Reunie/Fotoalbum%20Friese%20Regionale%20Reunie%20Heeg%202004/Zondag%208%20augustus/index.html

                http://www.vaartips.nl/


                Graeme
              • jhargrovewright2@juno.com
                Graeme, I have been busy today....trying to get the dogs comfortable with their new home/facilities/yard.....so that I may start building boats again....after
                Message 7 of 28 , Mar 29, 2013
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                  Graeme, I have been busy today....trying to get the dogs comfortable with their new home/facilities/yard.....so that I may start building boats again....after almost two years of turmoil and struggle after the fire. 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 ". My 20' sailing canoe....that I will be building late summer will have two rather high aspect cambered leeboards. I will have to do some drawings to determine whether they will be weather or leeboards....toed in or toed out. I want to keep the leeboard and of course the pivot on the lee side out of the water when healing. Thanks for the Barend link.....I remember the article but needed the refresher....great insight and great presentation.
                  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
                  ---------- Original Message ----------
                  From: "graeme" <graeme19121984@...>
                  To: Michalak@yahoogroups.com
                  Subject: [Michalak] Re: Twin Leeboards
                  Date: Fri, 29 Mar 2013 16:15:23 -0000


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


                  --- In Michalak@yahoogroups.com, "jhargrovewright2@..." <jhargrovewright2@...> wrote:

                  > Correct I meant toed in, rather toed out....terminology/words are
                  > important!

                  JIB, I wasn't sure but thought so. IIRC you were asking,,, if there's evidence for it being any good? Assymetrical boards and toe-in?

                  Asymmetric gives better specific performance than symmetric. Only stunt planes and the like have symmetric sectioned wings. The others use asymmetric sections. There's all sorts of specific asymmetric profiles, but a simple to make ovoid section (arc of circle one side, flat the other) works ok. Asymmetry - as Jim M notes on occaision: sails with their camber one side might get up to a CL of 1.5 but symmetric boards might only manage CL 1.0 (CL = coefficient of lift).

                  Toe-in? Yep, there's lots of evidence in theory and various practices for this improving boat performance - symmetrical dagger and centerboards leading edges angled and wedged to windward for each tack, hinged articulated keels or with trailing flaps to effectively reverse camber and get some 'toe-in', Dutch leeboard designs - the old style were tricked out for 0degrees running to 4 degrees of toe-in when beating by rake-variable cant-variable span-variable-twist, controlled by one rope - those are real interesting.

                  Toe-in is good and worthwhile if performance really does matter, but it's easily over done. Racers do it, fishermen wanting to be first in with the days catch to catch a good price, hungry watermen striving for a commercial premium or to pass clear of grounding danger did it.

                  Let's see if I don't get tangled up in asymmetric knots, with no guarantees. For beating to weather the overall leeway of the boat stays about the same whether the foil is toed-in or not. It might get a few degrees improvement in leeway is all. It stays about the same because the sum of the hull lateral resistance and the foil lateral resistance stays the same. Each source of lateral resistance still contributes the same individual amount to the combined total of leeway resistance. What toe-in changes is the pointing angle. The leeway angle may remain the same but the hull pointing angle can drop off the wind by the amount of angle that the foil is toed-in - and that, by reducing hull drag improves boat speed which may improve the amount of foil lift thereby maybe improving leeway angle again - a bit of a beneficial feedback spiral there - but the extra speed alone will improve vmg (distance made directly upwind over the ground). If you design board toe-in to vary continuously down from maximum when beating to zero angle running while raking the board back, as you do with a pivoting one anyway, then the board is optimised for lift/drag/speed at whatever point of sail. For some idea of what the Dutch boat wizards' leeboard idea is look at the continuously varying twist catering to varying apparent air speeds along a aeroplane propeller or a wind turbine blade and then pivot that blade off a sloping mount that also has a continuously varying caster angle!

                  Another thing that toe-in is used for is to improve sheeting angles on boats with difficult sheeting solutions; relatively narrow boats for their rig for example. Toe-in by improving pointing angle - allowing the boat to point a bit more away from the wind and more in the direction it is actually travelling through the water - gives a wider range of sheeting angle adjustment to get more drive from the sail which improves speed which may improve etc, etc,,, which again improves vmg.

                  Bookmarked these to grok long ago:

                  Remember Barend's insight into simple pythagorean and trigonometrically derived relationship shortcut tables he showed were inherent in nearly all boats made of sheet material and could be used by anyone. His 101 peice on Dutch leeboards is a wonderful thing:

                  http://www.duckworksmagazine.com/01/articles/leeboards/index.htm

                  http://www.eiseendenhof.nl/Friese-Reunie/Fotoalbum%20Friese%20Regionale%20Reunie%20Heeg%202004/Zondag%208%20augustus/index.html

                  http://www.eiseendenhof.nl/Friese-Reunie/Fotoalbum%20Friese%20Regionale%20Reunie%20Heeg%202004/Zondag%208%20augustus/index.html

                  http://www.vaartips.nl/

                  Graeme







                  [Non-text portions of this message have been removed]
                • daniel brown
                  common practice when using two leeboards is to have the lee side board down in the water and the windward board up out of the water. whats the thinking
                  Message 8 of 28 , Mar 30, 2013
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                    common practice when using two 'leeboards' is to have the lee side board down in the water and the windward board up out of the water. whats the thinking behind keeping the lee board up and (presumably) the weather side board down?



                    To: Michalak@yahoogroups.com
                    From: jhargrovewright2@...
                    Date: Sat, 30 Mar 2013 02:40:51 +0000
                    Subject: Re: [Michalak] Re: Twin Leeboards





                    Graeme, I have been busy today....trying to get the dogs comfortable with their new home/facilities/yard.....so that I may start building boats again....after almost two years of turmoil and struggle after the fire. 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 ". My 20' sailing canoe....that I will be building late summer will have two rather high aspect cambered leeboards. I will have to do some drawings to determine whether they will be weather or leeboards....toed in or toed out. I want to keep the leeboard and of course the pivot on the lee side out of the water when healing. Thanks for the Barend link.....I remember the article but needed the refresher....great insight and great presentation.
                    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
                    ---------- Original Message ----------
                    From: "graeme" <graeme19121984@...>
                    To: Michalak@yahoogroups.com
                    Subject: [Michalak] Re: Twin Leeboards
                    Date: Fri, 29 Mar 2013 16:15:23 -0000

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

                    --- In Michalak@yahoogroups.com, "jhargrovewright2@..." <jhargrovewright2@...> wrote:

                    > Correct I meant toed in, rather toed out....terminology/words are
                    > important!

                    JIB, I wasn't sure but thought so. IIRC you were asking,,, if there's evidence for it being any good? Assymetrical boards and toe-in?

                    Asymmetric gives better specific performance than symmetric. Only stunt planes and the like have symmetric sectioned wings. The others use asymmetric sections. There's all sorts of specific asymmetric profiles, but a simple to make ovoid section (arc of circle one side, flat the other) works ok. Asymmetry - as Jim M notes on occaision: sails with their camber one side might get up to a CL of 1.5 but symmetric boards might only manage CL 1.0 (CL = coefficient of lift).

                    Toe-in? Yep, there's lots of evidence in theory and various practices for this improving boat performance - symmetrical dagger and centerboards leading edges angled and wedged to windward for each tack, hinged articulated keels or with trailing flaps to effectively reverse camber and get some 'toe-in', Dutch leeboard designs - the old style were tricked out for 0degrees running to 4 degrees of toe-in when beating by rake-variable cant-variable span-variable-twist, controlled by one rope - those are real interesting.

                    Toe-in is good and worthwhile if performance really does matter, but it's easily over done. Racers do it, fishermen wanting to be first in with the days catch to catch a good price, hungry watermen striving for a commercial premium or to pass clear of grounding danger did it.

                    Let's see if I don't get tangled up in asymmetric knots, with no guarantees. For beating to weather the overall leeway of the boat stays about the same whether the foil is toed-in or not. It might get a few degrees improvement in leeway is all. It stays about the same because the sum of the hull lateral resistance and the foil lateral resistance stays the same. Each source of lateral resistance still contributes the same individual amount to the combined total of leeway resistance. What toe-in changes is the pointing angle. The leeway angle may remain the same but the hull pointing angle can drop off the wind by the amount of angle that the foil is toed-in - and that, by reducing hull drag improves boat speed which may improve the amount of foil lift thereby maybe improving leeway angle again - a bit of a beneficial feedback spiral there - but the extra speed alone will improve vmg (distance made directly upwind over the ground). If you design board toe-in to vary continuously down from maximum when beating to zero angle running while raking the board back, as you do with a pivoting one anyway, then the board is optimised for lift/drag/speed at whatever point of sail. For some idea of what the Dutch boat wizards' leeboard idea is look at the continuously varying twist catering to varying apparent air speeds along a aeroplane propeller or a wind turbine blade and then pivot that blade off a sloping mount that also has a continuously varying caster angle!

                    Another thing that toe-in is used for is to improve sheeting angles on boats with difficult sheeting solutions; relatively narrow boats for their rig for example. Toe-in by improving pointing angle - allowing the boat to point a bit more away from the wind and more in the direction it is actually travelling through the water - gives a wider range of sheeting angle adjustment to get more drive from the sail which improves speed which may improve etc, etc,,, which again improves vmg.

                    Bookmarked these to grok long ago:

                    Remember Barend's insight into simple pythagorean and trigonometrically derived relationship shortcut tables he showed were inherent in nearly all boats made of sheet material and could be used by anyone. His 101 peice on Dutch leeboards is a wonderful thing:

                    http://www.duckworksmagazine.com/01/articles/leeboards/index.htm

                    http://www.eiseendenhof.nl/Friese-Reunie/Fotoalbum%20Friese%20Regionale%20Reunie%20Heeg%202004/Zondag%208%20augustus/index.html

                    http://www.eiseendenhof.nl/Friese-Reunie/Fotoalbum%20Friese%20Regionale%20Reunie%20Heeg%202004/Zondag%208%20augustus/index.html

                    http://www.vaartips.nl/

                    Graeme

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






                    [Non-text portions of this message have been removed]
                  • graeme
                    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
                    Message 9 of 28 , Mar 31, 2013
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                      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
                    • 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 10 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 11 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 12 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
                            >

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                            [Non-text portions of this message have been removed]
                          • graeme
                            50% smoke
                            Message 13 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 14 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 15 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 16 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 17 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 18 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 19 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 20 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 21 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 22 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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