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Re: [AtkinBoats] Re: Elon Jessup Plywood

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  • John B. Trussell
    There are a couple of variations of cross planking which might work for you. Woodenboat did a series of articles many years ago on a double planked flat
    Message 1 of 6 , Dec 21, 2005
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      There are a couple of variations of cross planking which might work for you.

      Woodenboat did a series of articles many years ago on a double planked flat
      bottom. The firdt layer was fastened to the keelson and chines with nails
      and marline between the planking and chines. Then a layer of muslin, bedded
      in roofing tar was aplied to the bottom and a second layer of planks
      (staggered to off set the seams on the first layer) was nailed to the
      chines, keelson, and clinch nailed to the first layer of planks.

      Pete Culler has suggested using splined bottom planking. He no doubt knew
      exactly what he was suggesting, but I.m not sure I understand it. The only
      detailed explanations I've seen of splining involve splined transoms. I
      infer (OK, I'm guessing) that you rip slots in the edges if the bottom
      planking stock and insert a woolden spline in the slots of adjoining planks.
      I've never been sure what to use for splines, but I think I would use
      plywood splies and one of the miracle goops like Sikaflex.

      Either of these approaches seems like a lot of work, but they promise the
      virtues of traditional cross planking with a reasonably leak proof bottom.

      Good luck.

      John T
      ----- Original Message -----
      From: "rljssn" <rljssn@...>
      To: <AtkinBoats@yahoogroups.com>
      Sent: Wednesday, December 21, 2005 4:44 PM
      Subject: [AtkinBoats] Re: Elon Jessup Plywood


      > In that issue (daisy skiff) how does he bed the bottom to the chines?
      > Lifecaulk perhaps? How do the side planks bed to the chines? The cold
      > molded bottom in solid wood is exactly what I was thinking of doing.
      > I really need to get ahold of that WB issue....
      > thanks,-Russell
      >
      >
      >
      > --- In AtkinBoats@yahoogroups.com, "cartacreations"
      > <cartacreations@y...> wrote:
      >>
      >> In WB 126 and 127 Harry Bryan details his building the skiff
      > Daisy. In it he shows an
      >> alternative method of cross planking a bottom with solid wood but
      > without caulking. He
      >> lays up two layers oh 3/8" thick cedar, beded to the chine and
      > epoxied to each other. The
      >> seams between planks are offset and epoxied tight as well. You get
      > the benefit of a solid
      >> wood bottom, built to the design specs, without the hassle of
      > caulking or having your
      >> boards come open when dry.
      >>
      >> The all ply bottom will require extra cross frames to help hold its
      > shape that I think look
      >> unattractive in an open boat of this type. I'd take a look at the
      > double cross planked
      >> bottom.
      >>
      >> dave
      >>
      >> --- In AtkinBoats@yahoogroups.com, "adharvey2" <adharvey@m...>
      > wrote:
      >> >
      >> > Russell, don't expect any help from the plans regarding plywood
      >> > scantlings. There's no mention whatsoever of plywood on the
      > sheets or
      >> > tables. The 3/4" bottom was just an inference on my part based on
      > the
      >> > relative lumber sizes. I've never actually tried making 3/4"
      > plywood
      >> > any shape it didn't want to be!
      >> > I'd like to keep the bottom frameless, but I'm starting to
      > wonder
      >> > if there's a good way to accomplish this with plywood. Cold
      > molding
      >> > may be the answer.
      >> > Andrew
      >> >
      >> >
      >> > --- In AtkinBoats@yahoogroups.com, "rljssn" <rljssn@y...> wrote:
      >> > >
      >> > > I have a MDO plywood boat and I think the stuff is pretty good
      > if you
      >> > > are careful about selection. There are different grades and the
      > one I
      >> > > have is 3/8" with only 3 ply's in it. It shows some voids too.
      > I would
      >> > > recommend the Crezon Signal brand with its more numerous inner
      > ply's
      >> > > and less voids. It is resin paper double sided so it makes for
      > a
      >> > > painted boat obviously. I (of course) want a bright interior.
      >> > >
      >> > > Hey, Ad Harvey... is that 3/4" bottom your idea or specified in
      > the
      >> > > scantlings as an alternative? I don't have the plans yet and
      > have not
      >> > > seen the alternative scantlings. If 3/4" I would be tempted to
      > cold
      >> > > mold the bottom with 2 layers of 1/4" 5 ply occume running at
      > 45
      >> > > degrees to the centerline and a final layer crossways for extra
      >> > > stiffness. Just an idea I had after reading Chapelle's
      > treatment on
      >> > > Ashcroft methods in his book. A good bit of extra work though.
      > Just as
      >> > > long as I don't have to run fiberglass reinforced fillets of
      > epoxy
      >> > > laden wood flour all over I'm happy. there is no double
      > curvature to
      >> > > help stiffen the composite so it may not work like I imagine.-
      > Russell
      >> > >
      >> >
      >>
      >
      >
      >
      >
      >
      >
      >
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      > polite.
      >
      > If you set out to build an Atkin boat, please do not modify the plans. If
      > you stray from the plans you do so at your own risk and Atkin & Co. will
      > take no responsibility for the performance of the resulting boat.
      >
      > The current Atkin boat plans catalog is online at
      > <http://www.atkinboatplans.com/>
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      > Yahoo! Groups Links
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      >
      >
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    • John Kohnen
      MDO is good stuff, the last makers of wooden runabouts in the US use (used? are they all gone?) MDO for lapstrake planking. But you ve got to get the good
      Message 2 of 6 , Dec 23, 2005
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        MDO is good stuff, the last makers of wooden runabouts in the US use
        (used? are they all gone?) MDO for lapstrake planking. But you've got to
        get the good stuff, the MDO you see at the home center can be very bad
        inside. :o( Simpson's Signal and Crezon are good grades:

        http://www.olypanel.com/sign_making/

        On Sat, 17 Dec 2005 11:44:57 -0800, rljssn wrote:

        > I have a MDO plywood boat and I think the stuff is pretty good if you
        > are careful about selection. There are different grades and the one I
        > have is 3/8" with only 3 ply's in it. It shows some voids too. I would
        > recommend the Crezon Signal brand with its more numerous inner ply's
        > and less voids. It is resin paper double sided so it makes for a
        > painted boat obviously. I (of course) want a bright interior.
        > ...

        --
        John <jkohnen@...>
        Correlation does not imply causation; except, of course, to your
        cat. <Craig O'Donnell>
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