hull offset .off format

Discussion in 'Sailboats' started by water addict, Apr 30, 2023.

  1. water addict
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    water addict Naval Architect

    does anyone have documentation of the format of the hull offsets file .off?
    I know it is a simple text file, but have not been able to find any documentation on the format.
     
  2. TANSL
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    TANSL Senior Member

  3. water addict
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    water addict Naval Architect

    Open what file?
     
  4. TANSL
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    TANSL Senior Member

  5. water addict
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    water addict Naval Architect

    of course I can.
    I want a description of the format so I can create my own files, not just open some random .off file.
     
  6. TANSL
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    TANSL Senior Member

    Well, if you can open a file you will be able to see how it is formatted.
    What format do you mean if not?
     
  7. water addict
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    water addict Naval Architect

    It is a text file without comments. A bunch of numbers, without description. Do you have a document describing the format ?
     
  8. TANSL
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    TANSL Senior Member

    No, I don't have it and I don't know the .off files.
    Being a "simple text file" I suppose you can give it the format you want and, later, read it by applying the format you created.
    Excuse me if I'm talking nonsense and I'm wasting your time. I really don't understand why you have problems with a "simple text file".
     
  9. water addict
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    water addict Naval Architect

    The offset files are the x,y,z coordinates of the hull surface. There are other complications as well, like the description of the sheer line, keel and rudder, centerboards, daggerboards, etc. Those coordinates are ordered, you cannot just willy-nilly read them, they have to be formatted so the ORC and ORR vpp can read them properly, you can't just dump the coordinates however you want in a text file and expect them to work.
     
  10. TANSL
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    TANSL Senior Member

    I have not asked you "willy-nilly read" anything. Just scan the contents of the files and try to figure out what each number means.
    If it is about surfaces, it is probably not about coordinates of its points but about other parameters.
    What application is generating these .off files?
     
  11. baeckmo
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    baeckmo Hydrodynamics

    I think the .off file coordinates start with x=0 (ie zero) at the forward perpendicular, and consists of something like 20 y+z coordinates per station (depending on complexity of shape), numbered from the keel and up. As TANSL said, if you have an example file available, it should be reasonably straight forward to understand how it is structured.

    F.i. if there is a non-regular step in the x-series, with obvious changes in the y-z coordinates, that might be the attachement point of a keel or a fin. I'd also expect some additional code in the beginning (not looking like an x-position) that may indicate whether it is a chine section or rounded, and some indication at the end, saying "EOF" or similar.
     
  12. water addict
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    water addict Naval Architect

    No sh** sherlock. If I knew what every possible input parameter was, I could decipher it after days of trial and error maybe. I was trying to cut out that process and see if anyone has documentation of the file format. Why don't you bugger off if you don't know anything about it.
     
  13. TANSL
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    TANSL Senior Member

    I believed, and still believe, that I could help you. I am sorry that you have decided that I am not capable of doing it. Good luck, and be patient if you're going to do it yourself.
     
    BlueBell likes this.
  14. water addict
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    water addict Naval Architect

    Your offer to help consists of "Just scan the contents of the files and try to figure out what each number means."

    Brilliant.
     

  15. Rumars
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    Rumars Senior Member

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