Hull Fairing in Rhino

[Jecobin]

Hi, I use AutoCAD to create my lines drawing of a hull, but I would like to use Rhino to fair the hull and then return to AutoCAD to complete my drawing.

Can anyone tell me if Rhino can be used to fair hull lines without having any add-on such as orca3D. If Rhino is able to fair a hull without any add-on could anyone give me a few pointers in the right direction.

John

[Raggi_Thor]

Rhino is very good at building fair, smooth surfaces.
You can import lines from AutoCAD and fair those before you make a loose loft for example, and then "nudge" the control points to make the volume and shape close enough to the original lines.
"Dynamic sections" in Orca is very useful.
Manual sections takes maybe 12 seconds or so
(Select, Section, click, direction, type distance between sections or something like that).

Some useful info from Rhinocentre.nl:
http://il.youtube.com/watch?v=cMdBZu...eature=related

He, He, right now I found this one also, for automatic sections,
http://wiki.mcneel.com/labs/archcut

The whole concept of fairing is built on the assumption that something is not fair or incorrect in the first place. Analyzing curves you can quickly see what control points that should be "nudged" (moved a little) to minimize curvature without changing the overall shape. Fairing a large surface with many control points is often more time consuming (for me) than building a new one based on smoother curves.

[Jecobin]

Thanks for your reply Ragnar. I dont have Orca and will try with Rhino only. Many thanks.

[DavidJ]

I work at a professional yacht design office and the main hull guy is very very good a making beautiful fair hulls in Rhino. We have the Rhino Marine plugins and use them all the time for initial hydrostatic numbers. However, all of the fairing and lines plan production is done using native Rhino tools. We also then export to Acad to make drawings. The "contour" command is the tool that creates an array of sections as Raggi_Thor described.

Hull fairing is an art although it is an art that can be learned. Practice practice practice. Nudging control points. Build and rebuilt surfaces. Inspect the curvature graph of your curves for unwanted direction changes. Use the environment map and/or zebra to spot surface irregularities. Pay close attention to your isocurves when you create a surface. And of course use the smallest number of control points in your curves and surfaces that get the shape you want. Then practice practice practice.

[Jecobin]

Hi David, That's really very interesting reading and I appreciate your time to reply to my question. You have answered it perfectly and given me a good few hints and tips to work with. I noticed when visiting Ragnar's links that there are some good looking tutorial's on CD that can be purchased from the US. I think I will invest in them as they are directed at boat design and will more than likely be a great help in get started with Rhino and the area's that you have mentioned. Once again many thanks for your help.

[Paul Kotzebue]

Excellent advice from DavidJ.

Here is a link with a PDF showing how I faired a sailboat hull in Rhino:

www.pkboatplans.com/NA_Notebook.html

[Jecobin]

Hi Paul, Thank you for replying to my question. I just read through your PDF file and its really very helpful work. It’s just what I needed to get started in learning fairing techniques. I appreciate your help and many thanks. This will save me a lot of time.

[bhnautika]

The problem with using contours or archcut is that they are not dynamic in so far as they have to be re done after changes are made to the surface. The method I use is to create a surface with a simple control mesh with the centre line sitting on a zero plane. On that centre line plane I draw a grid of the sections, waterlines etc. Then in the appropriate view (sections in side view) I go to “record history” then to “curve from objects” then “project to surface” follow the prompts first selecting your grid line the then surface. This should give you section lines on the surface that change when the surface is moved also if you un tick “lock children” in the history box you can select the section lines you have created and change their colour and importantly turn on the curve graph. Also you can do a “record history” and mirror the hull surface you have created and it changes automatically, you can select that surface and turn on the surface analyse to get a global view.

[Raggi_Thor]

Thanks, that was a really useful tip!
Good

[Jecobin]

Thanks for the advice and help bhnautika. I dont understand all that you said yet but after trying this for a while I hope I shall. At least I know where to start. I appreciate all the help you guy's are giving.