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Re: Fast Motorsailer mods

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  • Ryan Cermak
    ... deal ... notes ... mag? ... the ... is ... Yes, I did tell Phil (in a fax) about the mods we wanted to make but at the time he said that they didn t have
    Message 1 of 4 , Oct 1, 2004
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      --- In bolger@yahoogroups.com, "Nels" <arvent@h...> wrote:
      > Good for you two. I will be following your progress with a great
      deal
      > of interest. Take lots of photos for the visual folks, and make
      notes
      > for us cerebral types;-) Maybe do an article or two for Duckworks
      mag?
      >
      > Have you run all your proposed changes past the Boss? NO I mean
      the
      > OTHER BOSS - Susanne:-)
      >
      > I am sure they would have no objections, to any of the changes, it
      is
      > just that they may have some even better ideas.
      >
      > All the best, Nels

      Yes, I did tell Phil (in a fax) about the mods we wanted to make but
      at the time he said that they didn't have the time to do them due to
      other ongoing projects. At that time he didn't say anything about
      better ideas but did send me 2 pages about sail plan mods that
      someone over in Germany had done. Since we aren't too interested in
      the sail part of motorsailer we are not getting the extra plan pages
      for those.

      Based on the fact that the hull is fairly straight sided and doesn't
      curve too much, I don't think it will be too hard to add in the
      extra length right in the middle to keep the center of gravity
      moment near the same.

      Part of my job when I was in the Air Force as a Boom Operator was
      computing the CG of the KC-135's that I was flying on. In those
      planes we had about 39" from forward to aft center of gravity limits
      that we had to stay within.

      Find the center of gravity, split the hull there, move the two
      halves three to five feet apart, add in an extra frame (or two),
      cover with plywood, tape and epoxy the seams.

      I know it will be more complicated than that, but that should be the
      basic process.

      Ryan
    • Howard Stephenson
      Not trying to put you off, Ryan, but here is another consideration: without increasing scantlings (thicker ply on the bottom?), will the boat be strong enough
      Message 2 of 4 , Oct 1, 2004
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        Not trying to put you off, Ryan, but here is another consideration:
        without increasing scantlings (thicker ply on the bottom?), will the
        boat be strong enough with the extra section added? Five ft. is a lot
        in a boat this size. Think of the forces at work when the hull is
        supported in the middle by a wave, particularly if that wave is
        moving at 20Kt or so. The trouble with flat sheets of plywood is that
        they are not as rigid as sheets that are curved. There might not be a
        problem unless you are using a large engine. PCB would have the
        answers.

        --- In bolger@yahoogroups.com, "Ryan Cermak" <RCermak@t...> wrote:

        > Find the center of gravity, split the hull there, move the two
        > halves three to five feet apart, add in an extra frame (or two),
        > cover with plywood, tape and epoxy the seams.

        You need to think about (and possibly calculate) whether the hull
        will trim correctly, at rest and while planing. You will be changing
        the weight, the buoyancy and the dimensions of the planing surface.
        With aircraft, I don't suppose you need to worry too much about
        hydrostatics, or the hydrodynamics of planing surfaces either, except
        with seaplanes or flying-boats.

        Howard
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