Lines plan to 3d in Rhino - Long Keeled Problems

Discussion in 'Software' started by Velsia, Dec 4, 2021.

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  1. Velsia
    Joined: Oct 2008
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    Velsia Floater

    Hey,

    I always have trouble turning lines plans of long keeled boats into a 3d surface. Where the keel or deadwood reaches the turn of the bilge creates some issues.

    I have tried sweeping from 2 rails as well as lofting and curve networks. I am sure there must be a technique to it but I can't work out what it is.

    All input welcome.
     
  2. TANSL
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    TANSL Senior Member

    Make separate surfaces, one or more for the keel and one or more for the hull.
     
  3. DCockey
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    DCockey Senior Member

    If the keel is distinct from the "canoe" hull then TANSL's advice is probably the way to proceed. But it is difficult to offer any specific advice without an image of the lines or at least several photos of the boat.

    Also, several surfaces may be needed for the hull surface depending on the shape.
     
  4. Velsia
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    Velsia Floater

    Thanks very much for your input.

    I think this problem in particular arises where the keel meets the stern post and this turn in creates a strange shape in the bilge in that area.

    I did try to cut the shape at along the lines of the rabbit or inner edge of the garboard plank but this didn't work out too well.

    Attached is the lines plan of the boat in question and the current 3dm model if anyone is interested in having a look.

    I will give it go with the cuts in a different place.
     

    Attached Files:

  5. TANSL
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    TANSL Senior Member

  6. Velsia
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    Velsia Floater

    Really? I did the first time but edited the post so you could see them. Can you see them now?
     
  7. DCockey
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    DCockey Senior Member

    Lines and .3dm file are visible.
     
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  8. TANSL
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    TANSL Senior Member

    Yes, I can see then now. Thanks.
    Try to create the model, not by the cross sections, but by the water lines.
     
  9. Velsia
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    Velsia Floater

    Great. I will give that a go.

    You will see that I moved station 8 back a bit just to see if it would alleviate the problem.

    David - I see you are in the mid coast. This particular boat is too.
     
  10. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    Initial suggestions:

    The rabbet is a natural break in the surface. Model the keel, stem, sternpost, etc separately from the planking.

    Create the rabbet curve in 3D. Note that for much of the stem the rabbet has a constant offset from centerline. For the remainder of the rabbet curve Crv2View may be useful.

    Modify the station curves so they end on the rabbet.

    This looks like a drawing for publication, not the original design drawing. If so the table of offsets will be more accurate. I'll try to find time to post about my quick method for getting offsets into Rhino.

    Some questions:

    What will be the use of the digital model?

    How exactly does the digital model need to conform to the lines and offsets?

    How much experience do you have with boats and wooden boats? Did you immediately know what the rabbet is?

    What have you previously done with Rhino? Any boat design?
     
  11. DCockey
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    DCockey Senior Member

    What is the current name of the boat? Do you know a more precise location?
     
  12. Velsia
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    Velsia Floater

    • I will probably just use the model for my own study and cad practice. I want to make a righting curve for her (without having to do an inclination test) as I plan to rebuild/make new the rig amongst other things.
    • Not exactly but close enough, I doubt the boat is exactly to her design lines. I might for fun run the boat through the maxsurf vpp so it would be good to be reasonably accurate. I also want to make a half model with a cnc cutter so for my own piece of mind when I look at it, I would like it to be reasonably close.
    • I don't want to go into my life story online and I have a fair bit to learn but I know enough about boats to oversee 8 digit (usd) builds of yachts. I have played a part in a few restorations of wooden boats over the years and one new build. I have a good idea of what a rabbet is though I am not very good at cutting one physically!
    • I started using a different indexing system for my drawings 2 years ago and under that system, I have 105 different .3dms
    • The boat is in Sprucehead and called Rasputin. I own her with a friend and we sail her the around mussel ridge and penobscot engineless, drinking beer. Its about as much fun as you can have with your trousers on!
     
  13. pafurijaz
    Joined: Dec 2016
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    pafurijaz Senior Member

    Hi I made this hull with FreeCAD which I am trying to learn, the curves are not perfect, because I am still not very good at using FreeCAD at the moment, but with Rhino it will be easier to draw these curves, and you can make this hull in a simple way using the command surfaces from grids and another surface for the the bow with surfaces from edges. Find the Rhino model attached below, I hope this file helps you understand how to do it Test-Hull-from-drawings.png upload_2021-12-5_20-10-13.png
     

    Attached Files:

  14. Velsia
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    Velsia Floater

    Thanks very much for your help Pafurijaz. I can't get it to work on Rhino alone. I will give it a go through freecad
     

  15. pafurijaz
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    pafurijaz Senior Member

    As you wish, but I warn you that FreeCAD is much more complex to use than Rhino and is also a bit confusing than Rhino. 
Rhino has many commands that can help you get good results quickly, with FreeCAD this is not the case, you must already have a good basic knowledge of using parametric applications such as NX SolidEdge or SolidWorks, and it is not enough, you should also know the fundamentals of Nubrs surfaces and more. 
However, on the net you will find a lot of material to learn how to do small things.
     
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