Draw Lines plan without offset table

Discussion in 'Boat Design' started by Ghost Boy, Nov 18, 2019.

  1. Ghost Boy
    Joined: Oct 2019
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    Location: iNDIA

    Ghost Boy Junior Member

    Hello, I have to fill in the gap. I have some station in body plan. Here some station are missing. I have to draw the missing station. How can I do it?
     
  2. rnlock
    Joined: Aug 2016
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    Location: Massachusetts

    rnlock Junior Member

    If you have a CAD system, you could use a spline run through the points that you have now.

    You could also loft the stations you do have, at a large scale, and use a physical spline (say, a piece of thin PVC pipe or a straight stick) to interpolate.

    Neither of these will work if there's some kind of discontinuity.
     
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  3. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    @Ghost Boy, could you show us what you have. The answer to your question depends largely on the information you have and the accuracy you need to reach.
     
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  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You need at least two views to create a 3D representation. If what you have is on paper, take the lines from the profile and waterlines.
     
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  5. rnlock
    Joined: Aug 2016
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    rnlock Junior Member

    If you know where all the stations are, that ought to be enough without a second view. A lot of times, they're evenly spaced, aren't they? That would give you x,y and z for each point. The more views the merrier, though, especially if they're a bit off.
     
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  6. Ilan Voyager
    Joined: May 2004
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    Ilan Voyager Senior Member

    Ghost Boy I assume that you have no knowledge of technical drawing nor spline fairing of boats plans. If you had the knowledge you would not asking how to do in this forum, because for someone with the know how the answer is evident.
    So first download this free PDF book. There is a good chapter about reading plans, lofting and fairing, besides a lot of very useful infos about boatbuilding.
    Gougeon Brothers on Boat Construction book https://www.westsystem.com/wp-content/uploads/GougeonBook-061205-1.pdf
    I assume also that you are not familiar with boat building softwares nor CAD for the same reasons given supra.
    A good software needs a steep learning curve so you will be losing time as it's pretty easy to do it by hand on paper with simple cheap material found anywhere like a 50 cm stainless steel ruler with 1/2 millimeters marks so you'll have at least a 0.25 mm precision which is rather good, and battens, preferably of square section. A lot of materials are eligible. wood; plastic, plexiglass, aluminium, even the stainless steel ruler, etc...
    Read the chapter 16 page 165 (page 179 on the PDF) in detail and surely you will understand the method. In fact it's a lofting on paper, at a convenient scale 1/10 for example, for redrawing the missing lines and stations.
    And we are here to help you, after you have acquired the necessary knowledge.
     
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  7. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    That means you have two views.
     
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  8. rnlock
    Joined: Aug 2016
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    rnlock Junior Member

    No, it doesn't. All you have to know is how far apart the stations are, which doesn't require an actual view.
     
  9. gonzo
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    gonzo Senior Member

    It is the same. The view are simply the faired lines over the offset points. Any view gives two coordinates. The second view gives the third coordinate. The spacing between stations is the equivalent to a view.
     
  10. rnlock
    Joined: Aug 2016
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    rnlock Junior Member

    The spacing between stations may be equivalent to a view, but it's not a view and the original poster didn't say he didn't know the spacing. If the spacing is even, it's a single number I could write down on a piece of paper, no drawing required. If we know the distance between perpendiculars, that would serve also. Sometimes drawings have the intervals twice as long in the middle where there's not much going on. In that case, drawing with the assumption of even spaces would result in a kink in the lines, thus providing a clue to the greater spacing. Come to think of it, I wonder if that's the problem the OP has.
     

  11. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You can write down all the offsets on a piece of paper. What is your point? When lofting we take p0ints from either views or a table of offsets. It is indifferent.
     
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