Offset Tables And Lines Drawings

Discussion in 'Boatbuilding' started by BASIL J WALL, Feb 20, 2012.

  1. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    The offsets for the waterlines and buttocks are typically used to draw the section at each station along with the any other offests at the particular station. The applicable waterline offsets are typically used in drawing the stem/keel/sternpost/transom.
  2. PerCorell
    Joined: Jan 2005
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    Location: Denmark

    PerCorell Junior Member

    When you see a drawing of the one side of the hull there are sections, paralell lines all allon the drawing. These are the sections seen from the side. Each offcaurse look different seen from front of the hull, there they are ribs and often splines showing a row of cuts in the 3D model of the hull. They invented offset tables in the 17's century.
    From side view, each rib looks the same, they are strait lines, just with different length -- later you can put this into a simple spreadsheet or even calculate it with a string as they originaly did. So id you point to a particular rib, forget alout all the others and look from front instead of the side you can read each rib and copy it from the xy measures describing a 2D spline.
    If you make a catalog of each sections X.Y place describing a continous line, you have a table of offsets, see from the beginning you looked at paralell sections down a 3D boat hull model then what is good about it, computers newer was the caurse of foults they can't anything but do it right. People can, and esp. if they don't realy know, what they speak about.

    Still with efficient design software and a CAD world that been surviving since it started the computer revolution, your internet, there are all sorts of math, ready made to just use, to unfold those spline surface, you get in a 3D program, by connecting all the sections, into a 3D form. Offcaurse there are a price but that is not bad measures, never that. But in real life, there are no realy good way to make that hull from one piect, so you make it from long panels, -- the same that you unfold from the 3D model offcaurse will deliver that, if you weld all panels along the boat together, on a jig made from other sections also taken from same 3D model ... to do it perfect, you make two hulls, one smaller offset true, within the other. So between the two, you have the volume, where some sort of frame system, make the ribs. I suggest 3dh there, ---- you allready have the 3d model so you can unfold the panels from the same model, that show you the advanced 3d volumes, where you display the ribs. --- in a 3d rendering after you had a small app. generate them as closed volumes, as without the real 3D model, you can't render them and check them by the image.

  3. cthippo
    Joined: Sep 2010
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    Location: Bellingham WA

    cthippo Senior Member

    I design them in Freeship and use the output offsets to make the stations on the strongback.
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