Hull analysis plugin for Rhino

Discussion in 'Software' started by Karsten, Feb 18, 2015.

  1. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    After I received lots of encouraging comments for my free Rhino hull balance script I decided to develop a bit of a toolbox for the yacht designer.

    So far I have a plugin under development which calculates the following values:

    • Displaced volume
    • Waterline length and width
    • LCB
    • VCB
    • Cp
    • Cross section area curve

    I will also add hull length and width. Link to a demo video is below. I would very much appreciate any comments and requests for additional features.

    https://www.youtube.com/watch?v=ypvCEGhU81Q&feature=youtu.be
     
    1 person likes this.
  2. TANSL
    Joined: Sep 2011
    Posts: 6,244
    Likes: 302, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    The first thing I want is to congratulate you for what you are doing, as I did in the other thread that you have open.
    You must continue calculating things because, unfortunately, if you calculate only 5 of the 8 parameters necessary, people will not use your plugin.
    As for your other thread where you calculate the balance of the boat: I suppose to do it, previously, had calculated all the values shown in the current thread.
     
    Last edited: Feb 20, 2015
  3. SukiSolo
    Joined: Dec 2012
    Posts: 1,270
    Likes: 25, Points: 0, Legacy Rep: 271
    Location: Hampshire UK

    SukiSolo Senior Member

    Good work Karsten. Personally I find the Curve of Areas a particularly useful piece of information, to help aid things, so this would be most helpful to me. I do extract the information but it seems a bit 'longhand' currently.

    Thanks for posting and good luck with the project, much appreciated.
     
  4. Alik
    Joined: Jul 2003
    Posts: 2,911
    Likes: 242, Points: 73, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    Section area curve was available from RhinoMarine plug-in; I am quite sure Orca does it. So good exercise, but what's the point?
     
  5. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    I calculated a few more values. An example is shown below. The data is just an example and I'm aware that it is a pretty extreme boat. The units depend on the model units. The plugin is also able to analyse asymmetric hulls.

    My idea is to create a toolbox which makes yacht design in Rhino faster and simpler. I'm aware of Orca3D but I don't personally have it. I think RhinoMarine has been discontinued. At the moment this is just for my personal enjoyment but if others are interested I might share the plugin in some way.

    Once this plugin is working I would like to combine it with my hull balance script so that the results shown below can be calculated in a range of heel angles (for example 0 - 45 degrees in 3 degree steps). I'm planning to export the results as a CSV file so that the results can be plotted in Excel.

    Hull length = 12000 mm
    Hull width = 3005.080078125 mm
    Canoe body draft = 375 mm
    Waterline length = 11071.8098414454 mm
    Waterline width = 2430.96501953221 mm

    Displaced volume = 4301652481.25428 mm3
    Cp = 0.533277598453803
    Cb = 0.426193406426212
    Displacement / LWL^3 = 0.00316941761649015
    LCB = 6183.22508207987 mm
    LCB / LWL = 0.557418765560104
    VCB = -145.47989816832 mm
    Wetted surface area = 19463760.5445615 mm2

    Max section area = 728556.71153826 mm2
    Max section area coefficient = 0.799196155364348

    Waterpane area = 17244089.6895899 mm2
    Centre of flotation = 6593.02334405709 mm
    CF / LWL = 0.595478376026408
    Waterpane coeficcient = 0.640682623499249
     
  6. TANSL
    Joined: Sep 2011
    Posts: 6,244
    Likes: 302, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Has merit what you're doing. Courage and move on.
    One way to check that some calculations are serious to evaluate the accuracy in the calculation of the wet surface. It is one of the toughest values calculated correctly.
    Should also calculate the moments of inertia of the float. I think, with that, you could say that your app is worth to design boats.
     
  7. DCockey
    Joined: Oct 2009
    Posts: 4,743
    Likes: 334, Points: 83, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    RhinoMarine was discontinued in 2009. Orca3D is the successor to RhinoMarine.
     
  8. Dr34m3r
    Joined: Mar 2012
    Posts: 148
    Likes: 3, Points: 18, Legacy Rep: 10
    Location: Europe

    Dr34m3r Senior Member

    keep going ! what is the point ? Point is , he love to do it :)
     
  9. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    I'm happy to present the latest version of my toolbox. I added a new tool which allows to calculate the righting moment curve and pretty much any other parameter in a range of heel angles. Video is here:

    https://www.youtube.com/watch?v=z4pIhILMaIo

    To see the new tool in action you can forward to about 3 minutes.
     
  10. TANSL
    Joined: Sep 2011
    Posts: 6,244
    Likes: 302, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I have not the slightest intention of being negative but rather, trying to help. Some thoughts:
    • Have you taken into account when calculating the righting moment that displacement should be the same in each of the heeling?
    • The righting moment curve thoughts about having a value less than zero when the heel is zero. This is only possible if the initial position of the ship has a certain list.
    • The boat, while heeling, will also acquire variables trims.
    Perhaps I was not able to correctly interpret the video.
     
  11. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    Hi Tansl
    Thanks for your questions. You are not negative at all.

    The displacement is the same for all hulls created. The hull surface is automatically moved in the z- direction until the displacement matches the input value. This iteration is stopped when the error is less than 1%.

    In the video I used the 'Line' plot function in Excel. The righting moment at zero heel is plotted at x = 1. Therefore it looks like the curve is not going through x = 0 and y = 0. If you use the 'Scatter' plot in Excel the curve is plotted correctly. Nevertheless the righting moment at zero heel often shows an extremely small value due to rounding.

    The plug-in calculates the righting moment in length^4 (volume times lever arm). If you use Millimeters as the length unit the values get very big. To calculate a righting moment in kg * m you would have to multiply the plug-in results by the water density.

    The hull surfaces are automatically rotated around the lateral y- axis until the longitudinal position of the centre of buoyancy matches the x position of the centre of gravity. Again this is done via iterations and the typical error is approximately 1.5 mm for a 14 m long hull.

    Hope this answers your questions.
     
  12. TANSL
    Joined: Sep 2011
    Posts: 6,244
    Likes: 302, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    That answers my questions, of course it does, and from what I understood, I'm surprised how correctly calculate your procedure. Congratulations. I think this is fast becoming a very very good solution for naval architecture.
    Sorry if my questions have been seem trivial, but I believed important to check these things to calibrate your application.
    BTW, would it be possible to have a beta, or test release to tinker with it?.
     
  13. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    The plug-in is completed for now. It is available as a free download here:

    http://www.food4rhino.com/project/na-toolbox?ufh

    The zip file contains the plug-in file (for Rhino 5 only), icons to make custom buttons and installation instructions. Enjoy and let me know if you find any issues.
     
  14. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    A new free version of the plug-in is available for download via the Food for Rhino link in the post above. The new version makes it possible to analyse multihulls and classic V planing hulls. Previously the results for hulls with immersed transoms were not very accurate due to the step in the section area curve. The new version allows to specify a section close to the transom to fix this issue.

    I have also released a pro version which has all the features of the free version. Additionally it is possible to calculate all hydrostatic properties in a range of heel angles. This is ideal for calculating the righting moment curve and finding the heel angle at minimum wetted surface area.

    Additionally it is possible to assign mass data to Rhino materials. The data is stored in the material notes box. Existing notes are moved to the end. Each material can have a density, area mass and point mass.

    To calculate the combined mass and centre of gravity of multiple objects the plug-in automatically detects if the object is a solid, surface or point. Volumes will be multiplied by the density, areas by the area mass and point objects will have point masses applied. The NA toolbox is therefore ideal for tracking masses as well as hydrostatic analysis. A video is here:

    https://www.youtube.com/watch?v=xThneyncheo

    The pro version can be purchased here:

    http://www.kj-engineering.com.au/shop/hull-analysis-1-detail
     

  15. DCockey
    Joined: Oct 2009
    Posts: 4,743
    Likes: 334, Points: 83, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Does the toolbox use the traditional integration of sections for calculating hydrostatics, or does it use the volumetric integration functions available in Rhino?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.