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Re: [bolger] scaling up a boat?

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  • Don Tyson
    so avoid building an elephant? ... doubles the volume. Surface ... the thickness (figure ... ago), so scantlings are ... elephant the same difference ... boat
    Message 1 of 23 , Mar 3, 2004
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      so avoid building an elephant?
      --- derbyrm@... <derbyrm@...> wrote:
      > Yes, and no.
      >
      > Note that adding 30% to the linear dimensions
      doubles the volume. Surface
      > area is 70% greater. Stiffness is some high power of
      the thickness (figure
      > the beam's moment of inertia, but that was 50 years
      ago), so scantlings are
      > ????
      >
      > Drop a kitten six feet and he grins, drop an
      elephant the same difference
      > and you have a mess to clean up.
      >
      > Roger
      > derbyrm at starband.net
      > http://derbyrm.mystarband.net
      >
      > ----- Original Message -----
      > From: "smithriverranger" <jasonstancil@...>
      > To: <bolger@yahoogroups.com>
      > Sent: Wednesday, March 03, 2004 5:27 PM
      > Subject: [bolger] scaling up a boat?
      >
      >
      > > Trying to get a grasp of how to exactly scale up a
      boat from
      > > existing plans.
      > > Say for a 30% enlargement would i just multiply
      everything by 1.3
      > > including the 12 inches between station lines?
      > > Been thinking of scaling up a nymph or a elegant
      punt if i don't
      > > build an oldshoe. I know i would need to beef up
      the framing a bit
      > > but that seems easy enough.
      > > Bought a really neat little contractor's
      calculator that does math
      > > in feet, inches, quarters, eights, sixteenths and
      > > thirtyseconds....it just got me thinking.
      > > Thanks, Jason Stancil
      >
      >
      >
      >
      > Bolger rules!!!
      > - no cursing, flaming, trolling, spamming, or
      flogging dead horses
      > - stay on topic, stay on thread, punctuate, no 'Ed,
      thanks, Fred' posts
      > - Pls add your comments at the TOP, SIGN your posts,
      and snip away
      > - Plans: Mr. Philip C. Bolger, P.O. Box 1209,
      Gloucester, MA, 01930, Fax: (978) 282-1349
      > - Unsubscribe: bolger-unsubscribe@yahoogroups.com
      > - Open discussion:
      bolger_coffee_lounge-subscribe@yahoogroups.com
      > Yahoo! Groups Links
      >
      >
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      >
      >
    • Peter Lenihan
      ... yup........especially white ones........:-) Peter Lenihan
      Message 2 of 23 , Mar 3, 2004
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        --- In bolger@yahoogroups.com, Don Tyson <tysond99@y...> wrote:
        > so avoid building an elephant?

        yup........especially white ones........:-)

        Peter Lenihan
      • smithriverranger
        I ve read about how the volume increases significantly with a slight increase in scale, but that s the point the current boat as drawn is too small. I m
        Message 3 of 23 , Mar 3, 2004
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          I've read about how the volume increases significantly with a slight
          increase in scale, but that's the point the current boat as drawn is
          too small. I'm talking about scaling up an 8' boat to 10'......no
          elephant here.
          Thanks for the input,
          Jason Stancil



          --- In bolger@yahoogroups.com, "Roger Derby" <derbyrm@s...> wrote:
          > Yes, and no.
          >
          > Note that adding 30% to the linear dimensions doubles the volume.
          Surface
          > area is 70% greater. Stiffness is some high power of the thickness
          (figure
          > the beam's moment of inertia, but that was 50 years ago), so
          scantlings are
          > ????
          >
          > Drop a kitten six feet and he grins, drop an elephant the same
          difference
          > and you have a mess to clean up.
          >
          > Roger
          > derbyrm at starband.net
          > http://derbyrm.mystarband.net
          >
          > ----- Original Message -----
          > From: "smithriverranger" <jasonstancil@h...>
          > To: <bolger@yahoogroups.com>
          > Sent: Wednesday, March 03, 2004 5:27 PM
          > Subject: [bolger] scaling up a boat?
          >
          >
          > > Trying to get a grasp of how to exactly scale up a boat from
          > > existing plans.
          > > Say for a 30% enlargement would i just multiply everything by 1.3
          > > including the 12 inches between station lines?
          > > Been thinking of scaling up a nymph or a elegant punt if i don't
          > > build an oldshoe. I know i would need to beef up the framing a
          bit
          > > but that seems easy enough.
          > > Bought a really neat little contractor's calculator that does
          math
          > > in feet, inches, quarters, eights, sixteenths and
          > > thirtyseconds....it just got me thinking.
          > > Thanks, Jason Stancil
        • Peter Lenihan
          ... slight ... is ... Jason, Maybe,just maybe,since you are refering to a very basic shape and only wish to add two feet to her length,then you might be able
          Message 4 of 23 , Mar 3, 2004
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            --- In bolger@yahoogroups.com, "smithriverranger" <jasonstancil@h...>
            wrote:
            > I've read about how the volume increases significantly with a
            slight
            > increase in scale, but that's the point the current boat as drawn
            is
            > too small. I'm talking about scaling up an 8' boat to 10'......no
            > elephant here.
            > Thanks for the input,
            > Jason Stancil

            Jason,
            Maybe,just maybe,since you are refering to a very basic shape and
            only wish to add two feet to her length,then you might be able to do
            just that without touching any of the other dimensions.
            This would,of course, require some extra waste in plywood and your
            willingness to"loft" the expanded side panels out to a length needed
            for a 10 foot version.Everything else,like the transom and frames
            would remain pretty much as is.
            Try it out,to the same scale as on the plans, with a model made
            out of some heavy construction paper(cardboard) and see if you like
            the looks ....adjust to taste :-)

            Sincerely,

            Peter Lenihan
          • craig o'donnell
            ... Up to 20% is typically OK, just move the stations further apart. Scows are a different case as are sharpies and you can scale up more. A scow is a scow
            Message 5 of 23 , Mar 4, 2004
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              >I've read about how the volume increases significantly with a slight
              >increase in scale, but that's the point the current boat as drawn is
              >too small. I'm talking about scaling up an 8' boat to 10'......no
              >elephant here.
              >Thanks for the input,
              >Jason Stancil

              Up to 20% is typically OK, just move the stations further apart. Scows are
              a different case as are sharpies and you can "scale up" more. A scow is a
              scow is a scow.
              --
              Craig O'Donnell
              Sinepuxent Ancestors & Boats
              <http://freepages.genealogy.rootsweb.com/~fassitt/>
              The Proa FAQ <http://boat-links.com/proafaq.html>
              The Cheap Pages <http://www.friend.ly.net/~dadadata/>
              Sailing Canoes, Polytarp Sails, Bamboo, Chinese Junks,
              American Proas, the Bolger Boat Honor Roll,
              Plywood Boats, Bamboo Rafts, &c.
              _________________________________

              -- Professor of Boatology -- Junkomologist
              -- Macintosh kinda guy
              Friend of Wanda the Wonder Cat, 1991-1997.
              _________________________________
            • cha62759@traverse.com
              I am building Howard Chappelle s 18 Camp Skiff . I have lofted the major lines and have the molds done and I am now struggling with the transom. How does one
              Message 6 of 23 , Mar 4, 2004
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                I am building Howard Chappelle's 18' "Camp Skiff". I have lofted the
                major lines and have the molds done and I am now struggling with the
                transom. How does one loft the side panels? or does your note only
                apply to previously expanded panels a la Bolger instant boats?
                Bob Chamberland

                --- In bolger@yahoogroups.com, "Peter Lenihan" <lestat@b...> wrote:
                > This would,of course, require some extra waste in plywood and your
                > willingness to"loft" the expanded side panels out to a length needed
                > for a 10 foot version.Everything else,like the transom and frames
                > would remain pretty much as is.

                > Peter Lenihan
              • Peter Lenihan
                ... Hi Bob, I was refering only to the expanded panels that Bolger usually shows for his plywood hulls. I m not familiar with Camp Skiff but if it is a
                Message 7 of 23 , Mar 4, 2004
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                  --- In bolger@yahoogroups.com, cha62759@t... wrote:
                  > I am building Howard Chappelle's 18' "Camp Skiff". I have lofted the
                  > major lines and have the molds done and I am now struggling with the
                  > transom. How does one loft the side panels? or does your note only
                  > apply to previously expanded panels a la Bolger instant boats?
                  > Bob Chamberland

                  Hi Bob,
                  I was refering only to the "expanded" panels that Bolger
                  usually shows for his plywood hulls.
                  I'm not familiar with "Camp Skiff" but if it is a Chappelle
                  work,does he call for the sides to be out of plywood or just planks?
                  The full lofting of side "panels" would involve,if I recall,laying
                  out on the loft floor all the stations and base line.Then using the
                  information provided in the table of off-sets,for each
                  frame/station/mold,you plot out the height of the chine and shear for
                  each.Once all your points are down,lay a fairing batten down and
                  strike a fair line.The resulting shape should be your"expanded" panel
                  shape.
                  Of course,if you have already lofted out the half breadths,then
                  you do not need to go back to the table of off-sets.Instead just pick
                  out the respective heights,for chine and shear,and transfer these to
                  their respective station lines layed out previously.
                  This will only work for flat,straight-sided,hulls.If the hull
                  is round,then you have to figure out the"chain girth" at each
                  station,divide this figure by the number of planks you intend on
                  using to get the correct shape of each plank so that the finished
                  boat does not have all its planks"frowning",ie;with the seams curving
                  downward,opposite to the sweep of the shearline.......
                  At any rate,I hope I have it right and haven't forgotten some
                  critical bit of information.Hopefully,someone who knows better will
                  jump in and correct my mistakes :-)

                  Sincerely,

                  Peter Lenihan
                • Bruce Hallman
                  ... This chain girth question has always confounded me, trying to figure out how to loft a lapstrake or planked boat. Peter, is it as simple as divide by
                  Message 8 of 23 , Mar 4, 2004
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                    --- Peter Lenihan wrote:
                    > If the hull is round,
                    > then you have to figure out the"chain
                    > girth" at each station, divide this figure
                    > by the number of planks you intend on
                    > using to get the correct shape of each plank
                    > so that the finished boat does not have all its
                    > planks"frowning",ie;with> the seams curving
                    > downward,opposite to the sweep of the
                    > shearline.......

                    This 'chain girth' question has always
                    confounded me, trying to figure out how
                    to loft a lapstrake or planked boat.

                    Peter, is it as simple as 'divide by the
                    number of planks'? Because that calculation
                    only gives you the width of each plank at
                    each station. [Not the distance of each edge
                    of the plank from the center line of the plank
                    at each station.]

                    In other words, it doesn't give you the
                    lengthwise curve of the plank, IE, is it
                    curved like a banana, and just how much?
                    Spiling, from one plank to the next,
                    I guess, gives that information.

                    That is unless, and this is where I get
                    confused, it appears that the lengthwise
                    curve of the plank could be 'read' through
                    the lofting of the 'diagonals' in the lofting
                    diagram. But I never figured that out.

                    Lofting the stations, halfbreaths and waterlines
                    makes sense to me, but lofting the diagonals
                    does not!
                  • John Bell
                    Rather than try to explain it, let me suggest you get a copy of Ian Oughtred s excellent book on lap ply construction. ... From: Bruce Hallman
                    Message 9 of 23 , Mar 4, 2004
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                      Rather than try to explain it, let me suggest you get a copy of Ian
                      Oughtred's excellent book on lap ply construction.

                      ----- Original Message -----
                      From: "Bruce Hallman" <bruce@...>
                      To: <bolger@yahoogroups.com>
                      Sent: Thursday, March 04, 2004 10:43 AM
                      Subject: Re: [bolger] Re: "Lofting" side panels


                      > --- Peter Lenihan wrote:
                      > > If the hull is round,
                      > > then you have to figure out the"chain
                      > > girth" at each station, divide this figure
                      > > by the number of planks you intend on
                      > > using to get the correct shape of each plank
                      > > so that the finished boat does not have all its
                      > > planks"frowning",ie;with> the seams curving
                      > > downward,opposite to the sweep of the
                      > > shearline.......
                      >
                      > This 'chain girth' question has always
                      > confounded me, trying to figure out how
                      > to loft a lapstrake or planked boat.
                      >
                      > Peter, is it as simple as 'divide by the
                      > number of planks'? Because that calculation
                      > only gives you the width of each plank at
                      > each station. [Not the distance of each edge
                      > of the plank from the center line of the plank
                      > at each station.]
                      >
                      > In other words, it doesn't give you the
                      > lengthwise curve of the plank, IE, is it
                      > curved like a banana, and just how much?
                      > Spiling, from one plank to the next,
                      > I guess, gives that information.
                      >
                      > That is unless, and this is where I get
                      > confused, it appears that the lengthwise
                      > curve of the plank could be 'read' through
                      > the lofting of the 'diagonals' in the lofting
                      > diagram. But I never figured that out.
                      >
                      > Lofting the stations, halfbreaths and waterlines
                      > makes sense to me, but lofting the diagonals
                      > does not!
                      >
                      >
                      >
                      >
                      > Bolger rules!!!
                      > - no cursing, flaming, trolling, spamming, or flogging dead horses
                      > - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
                      > - Pls add your comments at the TOP, SIGN your posts, and snip away
                      > - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
                      (978) 282-1349
                      > - Unsubscribe: bolger-unsubscribe@yahoogroups.com
                      > - Open discussion: bolger_coffee_lounge-subscribe@yahoogroups.com
                      > Yahoo! Groups Links
                      >
                      >
                      >
                      >
                      >
                    • pvanderwaart
                      My guess is that most boatbuilders will abandon the loftwork as soon as the frames have been fabricated and set up. At that point, it s no longer a matter of
                      Message 10 of 23 , Mar 4, 2004
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                        My guess is that most boatbuilders will abandon the loftwork as soon
                        as the frames have been fabricated and set up. At that point, it's no
                        longer a matter of what the designer had in mind, and more a matter
                        of what size and shape the frames actually are. In other words, the
                        shape would be taken from the frames, not from the planking. You
                        might try to get your hands on the WoodenBoat article on the building
                        of the Whittholz-designed Downeaster v-bottom powerboat. It shows how
                        to build a non-instant plywood boat about as well as anything.

                        I would set up the frames, rightside up, or upside down, as prefered.
                        To get the shape for the planking, I would take the shape from the
                        frames by making up a plank about 4" wide that is stiff enough and
                        pliable enough to make a fair curve. (e.g. 3/8" ply) It should be
                        long enough to go from stem to stern. Mount it temporarily along the
                        mid-point of the side plank. Then, at each frame, draw a line across
                        the 4" piece showing the angle at which the frame crosses it, and
                        measure the length from some mark to where the edge of the plank
                        needs to fall, both above and below.

                        Then to mark the planking, lay the marked piece on the stock. Extend
                        the lines marking where the frames will cross, and measure to where
                        the edge needs to fall. You can then draw a fair line along the
                        edge. ("Voila!," Peter might say.) I would leave an allowance for
                        find adjustment later.

                        This is basically the way a plank would be spiled for lap or carvel
                        construction. Perhaps you need a book? Chapelle's Boatbuilding or
                        Sewards' Boatbuilding Manual.

                        Peter
                      • David Romasco
                        Bruce, I, too, languished in ignorance for many years until I was shown the light ( Eureka! ) By Richard Cullison, who was teaching a lofting class at the
                        Message 11 of 23 , Mar 4, 2004
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                          Bruce,

                          I, too, languished in ignorance for many years until I was shown the light
                          ("Eureka!") By Richard Cullison, who was teaching a lofting class at the
                          Chesapeake Bay Maritime Museum (all three have my enthusiastic
                          recommendations, BTW).

                          The diagonals are arrived at by starting with the half-breadth lines and
                          taking the intersections of the diagonal line with each of the frames and
                          carrying that point over to the profile drawing, where the points are marked
                          on the frame stations. Spring a batten through those points and trace in
                          the line. Hey presto, and you've just drawn a diagonal! This line actually
                          helps define the three-dimensional nature of the lofting process, and you
                          can add as many as you like to further smooth the frames into line. The
                          process, once you get your arms around the function, is the magic that makes
                          lofting work.

                          Larry Pardey talks about adding waterlines and diagonals in his book about
                          traditional building methods (he goes a little overboard, but to be honest,
                          I get a severe case of inferiority neurosis every time I read one of his
                          books...).

                          David Romasco

                          _____

                          From: Bruce Hallman [mailto:bruce@...]
                          Sent: Thursday, March 04, 2004 10:43 AM
                          To: bolger@yahoogroups.com
                          Subject: Re: [bolger] Re: "Lofting" side panels


                          --- Peter Lenihan wrote:
                          > If the hull is round,
                          > then you have to figure out the"chain
                          > girth" at each station, divide this figure
                          > by the number of planks you intend on
                          > using to get the correct shape of each plank
                          > so that the finished boat does not have all its
                          > planks"frowning",ie;with> the seams curving
                          > downward,opposite to the sweep of the
                          > shearline.......

                          This 'chain girth' question has always
                          confounded me, trying to figure out how
                          to loft a lapstrake or planked boat.

                          Peter, is it as simple as 'divide by the
                          number of planks'? Because that calculation
                          only gives you the width of each plank at
                          each station. [Not the distance of each edge
                          of the plank from the center line of the plank
                          at each station.]

                          In other words, it doesn't give you the
                          lengthwise curve of the plank, IE, is it
                          curved like a banana, and just how much?
                          Spiling, from one plank to the next,
                          I guess, gives that information.

                          That is unless, and this is where I get
                          confused, it appears that the lengthwise
                          curve of the plank could be 'read' through
                          the lofting of the 'diagonals' in the lofting
                          diagram. But I never figured that out.

                          Lofting the stations, halfbreaths and waterlines
                          makes sense to me, but lofting the diagonals
                          does not!




                          Bolger rules!!!
                          - no cursing, flaming, trolling, spamming, or flogging dead horses
                          - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
                          - Pls add your comments at the TOP, SIGN your posts, and snip away
                          - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
                          (978) 282-1349
                          - Unsubscribe: bolger-unsubscribe@yahoogroups.com
                          - Open discussion: bolger_coffee_lounge-subscribe@yahoogroups.com



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                          [Non-text portions of this message have been removed]
                        • Peter Lenihan
                          ... Bruce,with a fairly typical hull shape(narrow and pointy at one end,fat and low in the middle,and slightly narrower and higher at the other end) you will
                          Message 12 of 23 , Mar 4, 2004
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                            --- In bolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
                            > Peter, is it as simple as 'divide by the
                            > number of planks'? Because that calculation
                            > only gives you the width of each plank at
                            > each station. [Not the distance of each edge
                            > of the plank from the center line of the plank
                            > at each station.]


                            Bruce,with a fairly typical hull shape(narrow and pointy at one
                            end,fat and low in the middle,and slightly narrower and higher at the
                            other end) you will indeed get different widths needed for each
                            plank.These widths need to be transfered onto your planking
                            stock,faired up with a batten,and trimmed to those lines.The look of
                            the plank before offering it up will appear somewhat skinny toward
                            the stern,swelling in the middle and slightly tappering toward the
                            stem.
                            Depending on how much shear is in the hull,alot of adjustment must be
                            done with the garboard plank to ensure you get the planks off on the
                            right foot.
                            You do not have to transfer your chain girth measurements to each and
                            every plank since,one you have established the number of planks you
                            will need(sometimes best determined once you know what size planks
                            are available) and establish the correct shape of your garboard
                            plank, it is just a simple matter of spiling the rest of your planks
                            up to the shear.
                            Some hull shapes,however,will require the use of stealer planks if
                            they have alot of shape to them(the hull,that is) since your plank
                            ends will begin to be tapered so much that they are too narrow to
                            drive a fastening into. Similarly,if you run your planking paralle to
                            the water line,you'll have to "cheat" a bit toward the ends with long
                            slivers of planking stock,just to meet the shear(or else have a very
                            wide shear strake and be prepared to waste a lot of wood).


                            > Lofting the stations, halfbreaths and waterlines
                            > makes sense to me, but lofting the diagonals
                            > does not!

                            Diagonals are beautiful for really tweeking ones lofting as they give
                            you yet another means of cross checking the fairness of your
                            previously laid down lines......very useful right in the turn of the
                            bilge!


                            If only I could remember correctly everything I was taught during a
                            course in lofting so many moons ago:-)

                            Sincerely,

                            Peter Lenihan
                          • Lincoln Ross
                            Keep in mind that the displacement would go up more than 100%! (Cube of 1.3 is about 2.2) Structural calculations probably not simple, tho I suppose you could
                            Message 13 of 23 , Mar 4, 2004
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                              Keep in mind that the displacement would go up more than 100%! (Cube of
                              1.3 is about 2.2)
                              Structural calculations probably not simple, tho I suppose you could
                              guesstimate. Panel expansions won't fit on plywood either, so you'll
                              probably use a lot more wood and maybe have more scarphs to do. Are you
                              sure you don't like the larger plans that are already available?
                              Windsprint, Featherwind (is that the name?) , and the Japanese Beach
                              cruiser come to mind, though I'm sure there are others. Bateau.com and
                              Michalak have some pramlike boats in a larger size range, too. But of
                              course, you'd probably be the only one around with an oversized Nymph.
                              I've seen an article somewhere by Bolger where he considers (and
                              rejects) a little cruiser based on a scale up of the Nymph.

                              >Jason Stancil wrote:
                              >Trying to get a grasp of how to exactly scale up a boat from
                              >existing plans.
                              >Say for a 30% enlargement would i just multiply everything by 1.3
                              >including the 12 inches between station lines?
                              >Been thinking of scaling up a nymph or a elegant punt if i don't
                              >build an oldshoe. I know i would need to beef up the framing a bit
                              >but that seems easy enough.
                              >Bought a really neat little contractor's calculator that does math
                              >in feet, inches, quarters, eights, sixteenths and
                              >thirtyseconds....it just got me thinking.
                              >Thanks, Jason Stancil
                              >
                              >
                              >
                              >
                              >___________________________________
                              >
                            • smithriverranger
                              ... You re on to me i m thinking about making a nymph micro cruiser. Can you remember where you saw that bolger article or how i can get my hands on it? More
                              Message 14 of 23 , Mar 4, 2004
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                                > I've seen an article somewhere by Bolger where he considers (and
                                > rejects) a little cruiser based on a scale up of the Nymph.

                                You're on to me i'm thinking about making a nymph micro cruiser. Can
                                you remember where you saw that bolger article or how i can get my
                                hands on it? More importantly do you remember why bolger rejected
                                the idea? I know i could just build a micro or old shoe, but i like
                                screwing around withthings a working with minimal amount of
                                directions....assuming i don't compromise safety or totally screw up
                                why the design originally worked in the first place.

                                > Structural calculations probably not simple, tho I suppose you
                                could guesstimate. Panel expansions won't fit on plywood either, so
                                you'll probably use a lot more wood and maybe have more scarphs to
                                do.

                                I'm in no hurry I just enjoy straining my brain on this kind of
                                stuff.....notice i'm not attempting anything "large"

                                Are you sure you don't like the larger plans that are already
                                available? Windsprint, Featherwind (is that the name?), and the
                                Japanese Beach cruiser come to mind, though I'm sure there are
                                others.

                                I like dory and pram hulls.....i've built a michalak boat and they
                                are well done but....for the most part i find them UGLY, but that's
                                me. What is the Japanese Beach Cruiser?

                                > course, you'd probably be the only one around with an oversized
                                Nymph.

                                Exactly!...just hope it'll float :)

                                Thanks for any info on that article,
                                Jason Stancil
                              • pvanderwaart
                                ... It was in MAIB. As I remember, he felt the design got too fussy, and the cuddy was not big enough for the intended use. Peter
                                Message 15 of 23 , Mar 4, 2004
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                                  > Can
                                  > you remember where you saw that bolger article or how i can get my
                                  > hands on it? More importantly do you remember why bolger rejected
                                  > the idea?

                                  It was in MAIB. As I remember, he felt the design got too fussy, and
                                  the cuddy was not big enough for the intended use.

                                  Peter
                                • cha62759@traverse.com
                                  My reading of the discussion is that you do not loft side panels. I understand the spiling process but was hoping perhaps that the accumulated knowledge of
                                  Message 16 of 23 , Mar 4, 2004
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                                    My reading of the discussion is that you do not "loft" side panels. I
                                    understand the spiling process but was hoping perhaps that the
                                    accumulated knowledge of this board could tell me how to draw and cut
                                    out one panel from information gained through lofting. I assume that
                                    Mr Bolger uses the computer to arrive at his panel extensions.

                                    The Chappelle camp skiff is a hard chine sharpy stink boat. Think
                                    "Redwing" which is derived from Mr Chappelle's design.

                                    The next question is, what computer program? Is there a relatively
                                    simple program which can take the lofted information and produce the
                                    panel extension?

                                    My last experience with this sort of problem led me to nailing a 4'x
                                    24" panel to the building molds and cutting to fit. This was a
                                    decidedly dicey proposition single handed.

                                    Bob Chamberland
                                  • cha62759@traverse.com
                                    Hi Peter, This process doesn t result in the expanded panels but rather in the elevation of the hull. It does not represent the curvature of the hull fore
                                    Message 17 of 23 , Mar 4, 2004
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                                      Hi Peter,
                                      This process doesn't result in the "expanded" panels" but rather in
                                      the "elevation" of the hull. It does not represent the curvature of
                                      the hull fore and aft.
                                      Bob Chamberland

                                      --- In bolger@yahoogroups.com, "Peter Lenihan" <lestat@b...> wrote:
                                      > Hi Bob,
                                      > I was refering only to the "expanded" panels that Bolger
                                      > usually shows for his plywood hulls.
                                      > I'm not familiar with "Camp Skiff" but if it is a Chappelle
                                      > work,does he call for the sides to be out of plywood or just planks?
                                      > The full lofting of side "panels" would involve,if I recall,laying
                                      > out on the loft floor all the stations and base line.Then using the
                                      > information provided in the table of off-sets,for each
                                      > frame/station/mold,you plot out the height of the chine and shear for
                                      > each.Once all your points are down,lay a fairing batten down and
                                      > strike a fair line.The resulting shape should be your"expanded" panel
                                      > shape.
                                      > Of course,if you have already lofted out the half breadths,then
                                      > you do not need to go back to the table of off-sets.Instead just pick
                                      > out the respective heights,for chine and shear,and transfer these to
                                      > their respective station lines layed out previously.
                                      > This will only work for flat,straight-sided,hulls.
                                    • Roger Derby
                                      For that sort of boat, Greg Carlson s Chine Hull Designer works very well. It s free and it generates the panel s expanded shapes.
                                      Message 18 of 23 , Mar 4, 2004
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                                        For that sort of boat, Greg Carlson's "Chine Hull Designer" works very well.
                                        It's free and it generates the panel's expanded shapes.
                                        http://www.carlsondesign.com/#Fun_Shareware

                                        It took me some thrashing around to figure out that there are no
                                        user-friendly error messages and that when the help files say six chines
                                        maximum, it means six chines maximum. (I was plotting out the lapstrakes
                                        for Chebacco and that wants seven "chines." I'm happy enough with the
                                        results I got by putting the hull in twice, once with a very broad sheer
                                        strake and once with a very broad garboard strake.)

                                        I decided that it wouldn't run on Win2K, but that was before I realized the
                                        six strake limit, so maybe it will. It works well on Win98SE which my other
                                        two computers use.

                                        It yields files which are ASCII text and can be input to other graphic
                                        programs or printed out and drawn by hand on the plywood. It allows you to
                                        specify the size of your plywood panels and shove the strakes around for
                                        efficient nesting. It also prints out pictures of the pieces.

                                        Roger
                                        derbyrm at starband.net
                                        http://derbyrm.mystarband.net


                                        ----- Original Message -----
                                        From: <cha62759@...>

                                        > The Chappelle camp skiff is a hard chine sharpy stink boat. Think
                                        > "Redwing" which is derived from Mr Chappelle's design.
                                        >
                                        > The next question is, what computer program? Is there a relatively
                                        > simple program which can take the lofted information and produce the
                                        > panel extension?
                                      • Mark
                                        Right. Not lofted but _expanded_ . Bolger doesn t need a computer for it, either. You can use the method described in Chappelle s Boat Building or get Greg
                                        Message 19 of 23 , Mar 4, 2004
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                                          Right. Not lofted but _expanded_ . Bolger doesn't need a computer for it, either. You can
                                          use the method described in Chappelle's 'Boat Building' or get Greg Carlson's free Chine
                                          Hull Designer program.
                                          http://www.carlsondesign.com/hulls.zip

                                          Another option, unless you are really interested in design work, is to send $65 to Karl
                                          Stambaugh for a thoroughly worked out version.
                                          Mark

                                          cha62759@... wrote:
                                          >
                                          > My reading of the discussion is that you do not "loft" side panels. I
                                          > understand the spiling process but was hoping perhaps that the
                                          > accumulated knowledge of this board could tell me how to draw and cut
                                          > out one panel from information gained through lofting. I assume that
                                          > Mr Bolger uses the computer to arrive at his panel extensions.
                                          >
                                          > The Chappelle camp skiff is a hard chine sharpy stink boat. Think
                                          > "Redwing" which is derived from Mr Chappelle's design.
                                          >
                                          > The next question is, what computer program? Is there a relatively
                                          > simple program which can take the lofted information and produce the
                                          > panel extension?
                                          >
                                          > My last experience with this sort of problem led me to nailing a 4'x
                                          > 24" panel to the building molds and cutting to fit. This was a
                                          > decidedly dicey proposition single handed.
                                          >
                                          > Bob Chamberland
                                        • Bruce Hallman
                                          Fundamentally, the way you determine the shape of flat plywood, which will curve correctly to fit the boat is to break down the surface shape into triangles.
                                          Message 20 of 23 , Mar 5, 2004
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                                            Fundamentally, the way you determine the
                                            shape of flat plywood, which will
                                            curve correctly to fit the boat is to
                                            break down the surface shape into
                                            triangles. I think that Sam Rabl first
                                            described this. See also:

                                            Jim Mickalak's article at =>

                                            http://marina.fortunecity.com/breakwater/274/2000/0101/

                                            If you dust off your memory of high school
                                            trigonometry, you can also do it relatively
                                            quickly using a spreadsheet.

                                            In essence, you know the shape of each quadrahedron
                                            with four corners being:
                                            station 1 chine,
                                            station 1 sheerline,
                                            station 2 chine,
                                            station 2 shearline.

                                            Connect corners diagonally to break it into triangles.
                                            Repeat....

                                            These triangles can then be 'unfolded' into a flat
                                            shape.
                                          • Lincoln Ross
                                            ... Probably MAIB (Messing Around in Boats, and I m sure a bit of web surfing will find the contact info), which I believe sells back issues. I bet if you
                                            Message 21 of 23 , Mar 5, 2004
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                                              See below:

                                              >Jason Stancil wrote:
                                              >snip
                                              >You're on to me i'm thinking about making a nymph micro cruiser. Can
                                              >you remember where you saw that bolger article or how i can get my
                                              >hands on it?
                                              >
                                              Probably MAIB (Messing Around in Boats, and I'm sure a bit of web
                                              surfing will find the contact info), which I believe sells back issues.
                                              I bet if you snail mail MAIB they can tell you which issue. Or there may
                                              be indexes on line someplace.

                                              >More importantly do you remember why bolger rejected
                                              >the idea?
                                              >
                                              I don't remember exactly. I seem to recall it might be ok but a boat
                                              designed for that size would be better.

                                              >I know i could just build a micro or old shoe, but i like
                                              >screwing around withthings a working with minimal amount of
                                              >directions....assuming i don't compromise safety or totally screw up
                                              >why the design originally worked in the first place.
                                              >
                                              >
                                              >
                                              > snip
                                              >
                                              >I like dory and pram hulls.....i've built a michalak boat and they
                                              >are well done but....for the most part i find them UGLY, but that's
                                              >me. What is the Japanese Beach Cruiser?
                                              >
                                              >
                                              Japanese Beach Cruiser is in Boats with an Open Mind. Quite pretty, and
                                              it's a pram. Maybe too many chines. I think about 12 feet long, as I
                                              recall. And I think Bolger has some other boats of that sort which might
                                              be worth looking into. Isn't there something called the Supermouse?
                                              (also a pram). One of the boats at bateau.com is a big pram, and not
                                              ugly, IMHO. It's not just you, a lot of Michalak boats are funny looking.

                                              > snip
                                              >
                                              >
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