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Re: Flat / curved ?

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  • doug6949
    The greatest volume you can enclose for a particular surface area will be in the shape of a circle. Thus, round bottom boats minimize the amount of skin
    Message 1 of 10 , Jun 2, 2004
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      The greatest volume you can enclose for a particular surface area will
      be in the shape of a circle. Thus, round bottom boats minimize the
      amount of skin friction. Additionally, they minimize turbulance if
      designed correctly.

      Flat bottomed hulls have higher initial stability. They don't roll as
      much. Most important, they are easier to build. And least important,
      from Bolger's point of view, they tend to be ugly.

      Doug

      --- In bolger@yahoogroups.com, "alternateuser2001"
      <alternateuser2001@y...> wrote:
      >
      > Hi there ,
      >
      > 'Got a question for you all - can anyone explain to me why
      > the 'classic' boats all have a 'curved' underside ... While the
      boats from
      > Mr.Bolger (and other modern boats) often have a much more "flatt"
      > one ??
    • alternateuser2001
      Thank you very much !! Wow ! that cleared up a LOT , for me that is - the whole hull-form issue s much more clear now . And how logical it is, when you
      Message 2 of 10 , Jun 2, 2004
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        Thank you very much !! Wow ! that cleared up a LOT , for me that is -
        the whole "hull-form" issue 's much more clear now . And how logical
        it is, when you think of it; what would move the easiest through
        water - a square block or a needle ?! (why didn't I think of
        that ...;)Thanks!

        But that leaves me with the question: for a sort-of "narrow-like-
        shanty-boat", the flatt hull ( 'box-style' they call it
        at 'cimplicityboats') like f.o. off Bolger's Tennessee , isn't a good
        idea ,because this boat isn't going to plane over the water...??
      • pvanderwaart
        There are many complicating factors, and many different ideas. Boat shape questions do not have single answers. The weight of the boat is an important factor.
        Message 3 of 10 , Jun 2, 2004
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          There are many complicating factors, and many different ideas. Boat
          shape questions do not have single answers.

          The weight of the boat is an important factor. The lighter a boat is,
          the flatter the bottom will be. A light boat can't push a rounded
          shape deep enough into the water. Tenessee is very light for her
          size. Bolger uses a very flat bottom so the boat does not go deep in
          the water. It only has to push a little surface water aside as it
          moves along. (And it is an easy shape to build.)

          A shanty boat built on a barge-like shape will have a flat bottom
          because it is easy to build and will float in shallow water. It will
          never go anywere fast, so the shape does not have to be very
          boatlike. The flat bottom will also rock the least.

          Peter

          --- In bolger@yahoogroups.com, "alternateuser2001"
          <alternateuser2001@y...> wrote:
          >
          > Thank you very much !! Wow ! that cleared up a LOT , for me that
          is -
          > the whole "hull-form" issue 's much more clear now . And how
          logical
          > it is, when you think of it; what would move the easiest through
          > water - a square block or a needle ?! (why didn't I think of
          > that ...;)Thanks!
          >
          > But that leaves me with the question: for a sort-of "narrow-like-
          > shanty-boat", the flatt hull ( 'box-style' they call it
          > at 'cimplicityboats') like f.o. off Bolger's Tennessee , isn't a
          good
          > idea ,because this boat isn't going to plane over the water...??
        • alternateuser2001
          Thanks people ... that s a LOT of info, a lot to think about as well. I m off to make some planns and sketches ! Thanks again . Sincere greetings, M.Hulleman
          Message 4 of 10 , Jun 2, 2004
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            Thanks people ...
            that 's a LOT of info, a lot to think about as well.
            I'm off to make some planns and sketches !

            Thanks again .


            Sincere greetings,

            M.Hulleman
          • craig o'donnell
            ... But there are also Dutch boats with flat bottoms! -- Craig O Donnell Sinepuxent Ancestors & Boats The
            Message 5 of 10 , Jun 2, 2004
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              >If anyone would be so kind as to explain this a little I would be
              >very gratefull for that.
              >Also my earlier offer; to be willing to search for anything "Dutch-
              >related" still stands, ok ?!
              >
              >Sincere greetings,
              >
              >M.Hulleman

              But there are also Dutch boats with flat bottoms!
              --
              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.
              _________________________________
            • craig o'donnell
              ... If a boat is going to go very slow, then the barge shape: or scow shape is no problem. When scow shapes are very large they are very efficient load
              Message 6 of 10 , Jun 2, 2004
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                >But that leaves me with the question: for a sort-of "narrow-like-
                >shanty-boat", the flatt hull ( 'box-style' they call it
                >at 'cimplicityboats') like f.o. off Bolger's Tennessee , isn't a good
                >idea ,because this boat isn't going to plane over the water...??

                If a boat is going to go very slow, then the "barge shape: or "scow shape"
                is no problem. When scow shapes are very large they are very efficient load
                carriers. Keep the transom out of the water. In the case of the scow keep
                both transoms out of the water.

                There is another reason for flat bottom boats. In the USA, many small
                working boats were "crossplanked" that is the boards on the bottom were
                nailed across. This makes for an easily built, cheap and very strong hull.
                Sometimes there is a little "V" to the bottom but the principle remains the
                same.

                Cheap and strong is what the fishermen wanted.


                --
                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.
                _________________________________
              • Roger Derby
                One other issue with flat surfaces -- they oil can. By introducing a curve (aka arch) the stresses do not reverse and the material/structure lasts longer.
                Message 7 of 10 , Jun 2, 2004
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                  One other issue with flat surfaces -- they "oil can." By introducing a
                  curve (aka arch) the stresses do not reverse and the material/structure
                  lasts longer.

                  Roger
                  derbyrm@...
                  derbyrm.mystarband.net/default.htm

                  ----- Original Message -----
                  From: "pvanderwaart" <pvanderwaart@...>
                  >
                  > There are many complicating factors, and many different ideas. Boat
                  > shape questions do not have single answers.
                  >
                  > The weight of the boat is an important factor. The lighter a boat is,
                  > the flatter the bottom will be. A light boat can't push a rounded
                  > shape deep enough into the water. Tenessee is very light for her
                  > size. Bolger uses a very flat bottom so the boat does not go deep in
                  > the water. It only has to push a little surface water aside as it
                  > moves along. (And it is an easy shape to build.)
                  >
                  > A shanty boat built on a barge-like shape will have a flat bottom
                  > because it is easy to build and will float in shallow water. It will
                  > never go anywere fast, so the shape does not have to be very
                  > boatlike. The flat bottom will also rock the least.
                  >
                  > Peter
                • grant corson
                  One good reason would be a softer ride, no pounding, however if you are building a slow moving flat bottomed boat you wont need to be concerned too much about
                  Message 8 of 10 , Jun 2, 2004
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                    One good reason would be a softer ride, no pounding, however if you are
                    building a slow moving flat bottomed boat you wont need to be concerned too
                    much about it....
                    Grant
                    on 6/2/04 5:49 PM, alternateuser2001 at alternateuser2001@... wrote:

                    >
                    > Hi there ,
                    >
                    > 'Got a question for you all - can anyone explain to me why
                    > the 'classic' boats all have a 'curved' underside (aiii...what a
                    > terrible terminology to USE , dutchman ...and that to a boatbuilding
                    > group ... Go wash your mouth with some soap !! ) While the boats from
                    > Mr.Bolger (and other modern boats) often have a much more "flatt"
                    > one ??
                    > I DO know that it would be much better to take up some sort a course
                    > in 'elementary shipbuilding' or something like that, and I will in
                    > due time...but I just was curious .
                    > Allready I know (by studying the texts and articles from this great
                    > site (!) that my own little "shanty-boat' / 'narrow-boat' is gonna
                    > get a flatbottom - she will be going very slowly through very calm
                    > water, with allmost no deep water at all ... So that will do just
                    > fine then .
                    >
                    > If anyone would be so kind as to explain this a little I would be
                    > very gratefull for that.
                    > Also my earlier offer; to be willing to search for anything "Dutch-
                    > related" still stands, ok ?!
                    >
                    > Sincere greetings,
                    >
                    > M.Hulleman
                    >
                    >
                    >
                    >
                    > Bolger rules!!!
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                    > - 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
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