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Re: [bolger] Hulls for lapstrake vs stitch and glue

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  • Roger Derby
    The moment of enlightenment for me came with a little sketch in the corner of one of the Chebacco drawings. The table of offsets defines a smooth hull. The
    Message 1 of 3 , Sep 25, 2005
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      The moment of enlightenment for me came with a little sketch in the corner
      of one of the Chebacco drawings. The table of offsets defines a smooth
      hull. The inside of the lapstrakes are tangent to the outside of this shape
      at their bottom edge. Their top edge, after beveling, is inside the defined
      hull shape.

      I laid out the strakes with Hulls and then added 3/4" to the top on the
      plywood before cutting them out. I left an inch or so at the bottom edge
      for error correction once they are hung on the molds. Tedious and maybe
      overkill, but I don't have much faith in my "lining off" skills.

      We'll know soon.

      Roger (still spreading epoxy and fiberglass on the strake blanks and
      sanding and sanding and sanding)
      derbyrm@...
      http://home.earthlink.net/~derbyrm

      ----- Original Message -----
      From: "Bruce Hallman" <bruce@...>


      > On 9/25/05, Rob Mouradian <r_mouradian@...> wrote:
      >> To interject a question here, if you input data from a table of offsets,
      >> do the
      >> expansions assume that the panels wll just butt up against each other, as
      >> you
      >> would want for stitch and glue? If so, how do you account for the
      >> over-lap of
      >> lapstrake construction?
      >
      > For my Cartoon 5 experiment, I actually had the flat edge of
      > each strake input as a surface. I didn't input all the data
      > from the table of offsets, but rather mostly just dragged the
      > lines around with a mouse. [using Hulls.exe]
      > Spot checking for reasonableness against the table
      > of offsets.
      >
      > I know it sounds tedious, but with practice is it quick. The
      > Hulls.exe data entry for Cartoon 5 took less than three hours.
      >
      > In truth, I suspect that the thickness of the strake is
      > inconsequential, as I used 1/8" luaun plywood.
      >
      > Also, as a though experiment, it has crossed my mind that the
      > strakes could be laid out without thought to the strake
      > overlap, and then the curvature could be adjusted by 'eye'.
      >
      > Imagine each strake with it's general 'banana' shape, you
      > could compensate by increasing the depth of the 'banana'
      > curve by one inch to allow for the increased curve caused
      > by the overlap.
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