Programs to model hydro in?

Discussion in 'Hydrodynamics and Aerodynamics' started by Shrimpkin, Nov 30, 2015.

  1. Shrimpkin
    Joined: Nov 2015
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    Shrimpkin Junior Member

    I have been tinkering with a few different designs that I build in Google Sketchup. I am wondering if there are any programs than can import a 3d DXF file and run a hydrostatic test on it.
     
  2. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Allow me to analyze your DXF file to see if my ARQN program can use it to perform these calculations. ARQN works with AutoCAD, so DXF files should not be a problem.
     
  3. Shrimpkin
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    Shrimpkin Junior Member

    Try this attachment, units are in inches. Also, I am guessing by the nature of the name that hydro-static testing involves a stationary object and hydrodynamic testing involves the way it functions when moving?
     

    Attached Files:

  4. TANSL
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    TANSL Senior Member

    Unfortunately the model is built by means of polyface meshes and with that object I can not do anything. If you could define your model with NURBS surfaces or ruled surfaces, I could easily get hydrostatic values.
    You are right when you speak of hydrostatic and hydrodynamic test. Dynamic studies require much more sophisticated and expensive programs.
     
  5. Shrimpkin
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    Shrimpkin Junior Member

    Is there a way to use NURBS to define sharp edges like I have in my poly model or are you limited to smooth curves?
     
  6. TANSL
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    TANSL Senior Member

    Youl should use different surfaces to the sides, bottom, transom, etc
     
  7. Shrimpkin
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    Shrimpkin Junior Member

    I am not sure if you are familiar with Sketchup, but won't anything I build in sketchup be output as a polyface mesh?
     
  8. TANSL
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    TANSL Senior Member

    I do not know Sketchup.
    I could make a new model of your boat based on your DXF file, and calculate hydrostatic, but do not know if it would be helpful to you. What format is your software able to read?
     
  9. Shrimpkin
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    Shrimpkin Junior Member

    I'd rather not make you do all that work ;). I'll work with freeship and see if I can learn it and then come back and get more info on how to use it for hydrostatics, etc. I think I found a decent tutorial online that will help me get the hard corners like in my drawing.
     
  10. TANSL
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    TANSL Senior Member

    Hard corners are difficult to achieve with any modeling program. You can get them by accumulating many points and forcing the surface to adapt to them and, therefore, models produced are difficult to handle.
    Instead of looking for a single surface with those hard corners, it is preferable to construct various surfaces intersecting precisely in those corners. For example, you could use sheer and chine lines to define a surface that relies on them.
     
  11. Shrimpkin
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    Shrimpkin Junior Member

    Not sure what sheer and chine lines are. I did some work in freeship though and, while it's not exactly what I drew in Sketchup, it's very similar. Should I export it as something particular from Freeship or just attach the freeship save file if I wanted you to look at it?
     
  12. W9GFO
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    W9GFO Senior Member

    There are free plugins for SketchUp that will allow you to export as different types of dxfs.

    I wouldn't use SketchUp for designing. Since you have been using FreeShip I would focus on developing your design in that. Are there hydrostatic calculations that you need that FreeShip can't do?

    If needed you can export from FreeShip to obj or stl, then import to SketchUp. Best thing to do is export to obj then open that obj in Netfabb, scale it, repair it, then export as stl - then import that into SketchUp.
     
  13. Shrimpkin
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    Shrimpkin Junior Member

    I guess I need to just delve into the manual with Freeship if it does all that stuff for me. It's just MUCH easier for me to model something in Sketchup than in Freeship because I have been using Sketchup for years now.

    Maybe you guys could tell me what you think of my current model and some things that I can do to improve not only on the design but in the way I draw (anything you guys have to suggest really).
     

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  14. W9GFO
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    W9GFO Senior Member

    You needed to have a transom to seal up the leak points below the waterline so that the hydrostatics could work.

    I added a transom and changed the draft in the project settings.
     

    Attached Files:


  15. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    I hope this sequence of pictures to help you understand what I mean.
     

    Attached Files:

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