hydrostatic in rhino 3

Discussion in 'Software' started by Ahmed Wahab, Dec 23, 2007.

  1. Ahmed Wahab
    Joined: May 2007
    Posts: 26
    Likes: 1, Points: 3, Legacy Rep: 15
    Location: Egypt

    Ahmed Wahab Junior Member

    I designed a hull in rhino 3.The WL is 9.8 m,When I check hydrostatic it gives me WL is 13.7 m !!!and I think also the rest of the calculations are wrong.
    I deleted the model several times and restarted again But the same result !!
    If you have any idea what I'm doing wrong
    Regards
     
  2. Grant Nelson
    Joined: Feb 2005
    Posts: 210
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    Location: Netherlands

    Grant Nelson Senior Member

    Hi Ahmed, its always handy if you include the file so we can see what your are doing. I assume you are using the hydrostatics command under analyse. I tried it out, and it works fine for me. Perhaps you can check your waterline - by default its the cPlane - if your boat is below the cPlane, then its going to give a waterline length closer to the maximum hull length (and a displacement equal to the entire volume of the hull...
    Hope this helps
    Grant
     
  3. Ahmed Wahab
    Joined: May 2007
    Posts: 26
    Likes: 1, Points: 3, Legacy Rep: 15
    Location: Egypt

    Ahmed Wahab Junior Member

    I will try to attach the file tonight.But I'm sure the WL is the 0 in the cplan!
    Thanks for help
     
  4. Ahmed Wahab
    Joined: May 2007
    Posts: 26
    Likes: 1, Points: 3, Legacy Rep: 15
    Location: Egypt

    Ahmed Wahab Junior Member

    hydrostatic in rhino 3

    This is the file which is done with rhino 3.
    It's just an inial hull to check the hydrostatic.
    I would apreciate your comments !
    Regards
     

    Attached Files:

    • 9.8m.3dm
      9.8m.3dm
      File size:
      93.2 KB
      Views:
      804
  5. Grant Nelson
    Joined: Feb 2005
    Posts: 210
    Likes: 12, Points: 0, Legacy Rep: 163
    Location: Netherlands

    Grant Nelson Senior Member

    After an Xmas dinner, all my blood is in my stomach, and so I can not say exactly why, but if you set the option 'symetric' after you start the hydrostatic command, to Yes, then you boat is 9.8meters... just as we assumed it was. Have a nice holiday period,
    Grant
     
  6. terhohalme
    Joined: Jun 2003
    Posts: 512
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    Location: Kotka, Finland

    terhohalme BEng Boat Technology

    Rise the body 0.001 m and hydrostatics will work. If the body has several corners exactly at origin, rhino's hyrdostatics can do errors.

    Here are my results after 1 mm rising:
    Volume Displacement = 5.15971
    Center of Buoyancy = 4.7028, -6.88549e-016, -0.210555
    Wetted Surface Area = 18.6501
    Waterline Length = 9.79552
    Maximum Waterline Beam = 2.2674
    Water Plane Area = 15.2934
    Center of Floatation = 4.36588, -4.84571e-016,0

    Sounds reasonable. RhinoMarine found it similar.

    ps. your model had two stems, deleted one.

    Terho
     
    Last edited: Dec 26, 2007
  7. Ahmed Wahab
    Joined: May 2007
    Posts: 26
    Likes: 1, Points: 3, Legacy Rep: 15
    Location: Egypt

    Ahmed Wahab Junior Member

    Thanks alot !!!!
    It works great and I got the same result.

    another question please
    Is there large deviation sometimes between the hydrostatic in rhino& rhinomarine

    regards
     

  8. terhohalme
    Joined: Jun 2003
    Posts: 512
    Likes: 40, Points: 28, Legacy Rep: 506
    Location: Kotka, Finland

    terhohalme BEng Boat Technology

    Rhino's hydrostatics is only for quick checking and can give unexpected results. Rhinomarine modules are for real yacht design work. Look at:

    http://www.rhinomarine3d.com/
     
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