How to Create Lines From A Simple Drawing

Discussion in 'Boat Design' started by Southern Cross, Feb 3, 2014.

  1. Southern Cross
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    Southern Cross Senior Member

    George Olson was a surf board shaper and eyeballed the lines on the Olson 30, according to several people that knew him well. So there are no plans. I want to build a scale model. We have scale models that were made professionally of all our boats. This will be a hobby project for me.

    So, how can I come up with accurate lines to reproduce the hull shape based on the drawing I have and an actual Olson 30?

    Thanks in advance.
     

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  2. DCockey
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    DCockey Senior Member

    If you want to create an accurate set of lines without a table of offsets you will first need to measure a boat, commonly referred to as "taking the lines off". Methods for doing so are described in Boats, a Manual for Their Documentation which can be downloaded free at http://www.museumsmallcraft.org/publications.html
     
  3. rwatson
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    rwatson Senior Member

    Davids contribution is a valuable one.

    The problem you will have with using a drawing, is that the waterlines are not able to be calculated from just an outline of the elevation.

    For example, the shape of the sheer line ( where the deck meets the hull ) is easy to calculate. Its height above the bottom of the keel, and the distance in from the centreline is easy to calculate from a scale drawing with a set of dividers or drawing compass.

    However, take any water line - say the hull 1 metre below the deck.

    You know there is hull there, but you dont know how far from the centreline it is, so you have to guess that.

    The actual shape of the hull may not be important in model, you may be able to approximate close enough. If it has to float and sail, then the shape becomes more critical.

    To accurately calculate the shape of a hull, and its 'stations', you really need this sort of information.
     

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  4. TANSL
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    TANSL Senior Member

    Southern Cross,If were talking about calculations for stability and seaworthiness of the ship, I would say that with the information you have, it is impossible to obtain a correct forms. But when it comes to make a scale model of the boat, with the longitudinal profile and the main deck lines, it is posible to create a body lines drawing and no one will realize they are not the original ship. If you send me the information, I can try to create some forms that seem sufficiently satisfactory and, from these, get the cross sections you need or any other information.
     
  5. FAST FRED
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    FAST FRED Senior Member

    Both MIT in Camebridge Mass.and The Mystic Museum in CT have very good marine archives.

    Perhaps you could simply purchase the lines plans , and table of offsets for construction?
     
  6. Southern Cross
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    Southern Cross Senior Member

    Thank you all very much.

    Thanks Tansl for your offer. I'll give it a go myself in Hullform and if no luck I take you up.

    I will check with MIT and Mystic but I am pretty certain plans don't exist.

    My boat is on a trailer so I will try using the above method for taking measurements. I thought of using a laser measuring device at preselected points on the hull - 12 sections or so, 12 lines. But how to plug that data into a CAD program? I'm sure there is a way.

    At one point I thought of bending wires to 12 sections of the contour of the hull then photographing them against a board, then importing those as reference in a CAD program.

    Thanks again.
     
  7. DCockey
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    DCockey Senior Member

    Using measured data to create a set of lines in suitable CAD software is very do-able.

    What software? How familiar are you with the software? How familiar are you with drawing lines and lofting?
     
  8. Southern Cross
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    Southern Cross Senior Member

    I have only used Maya in the past. Otherwise, I have no experience at all in lofting etc.
     
  9. TANSL
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    TANSL Senior Member

    Southern Cross,after obtaining the measurements of the 12 sections, by laser meter, it is very easy to pass them to a CAD program and get a smoothed forms. I use AutoCAD, for these things, and from there I can export files of any type compatible with other applications. Again I express my willingness to help you in whatever you need.
    If needed, I can make a diagram of how to take measurements.
     
  10. DCockey
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    DCockey Senior Member

    Sounds like you should have someone like TANSL generate a set of lines for you after you make the measurements, unless you want to devote many hours to learning how to do it.
     
  11. Southern Cross
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    Southern Cross Senior Member

    David, sounds right.

    Tansl. I'll take you up on that offer. Any particular kind of laser measures? What about this? http://youtu.be/lqEMHTusDyk
     
  12. Westfield 11
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    Westfield 11 Senior Member

    Quick and Dirty Method
    To find a point on the hull, drop a plumb bob to find the distance from the CL of the keel and use a clear hose filled with colored water to get the elevation above the baseline, or your laser. Plot it on graph paper or fullsize on the wall or floor, enough points and you can fair them to get close enough sections. Relatively easy with a flared hull, more complicated with tumblehome.
     
  13. Skyak
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    Skyak Senior Member

    A few years ago Autocad had a site that allowed you to upload a bunch of pictures and their software would create a 3D model output. If the pictures contained a reference object of known size the model could be to scale. It worked surprisingly well. That was the beta. Now they have a product that is part of their subscription service.

    http://usa.autodesk.com/adsk/servlet/pc/index?id=11390028&siteID=123112

    I never did a boat but I always wanted to. The software needs to identify points to triangulate so you would need to scribble on your boat with a dry erase pen but based on the results I had with human heads with the beta software your boat would be super easy to model. The Beta not lonly created the 3D model, it also created the surface texture bitmap which of course can be edited.
     
  14. Southern Cross
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    Southern Cross Senior Member

    That's really interesting. Photos with dry erase is pretty easy to do.
     

  15. DCockey
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    DCockey Senior Member

    You are talking about one version of photogrammetry sometimes referred to as SfM+MVS. I experimented with the free AutoCAD software and more recently have been using PhotoScan to measure boats. SfM+MVS photogrammetry generally does not work will with clean fiberglass boats because a random visual texture is required. It does work well on wood boats with exposed wood grain and painted boats with worn/dirty paint.

    For purposes of getting enough information to develop a set of lines for display model making manual measurements is probably quicker and simpler to learn.
     
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