Author Topic: Creating a hull from a table of offsets  (Read 3223 times)

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Creating a hull from a table of offsets
« on: April 26, 2010, 08:39:01 AM »
There is no automated way to create a hull from a table of offsets. The steps to do it manually are:

1. Convert the table of offsets to points in Rhino. This is most easily done by converting the table of offsets to a simple text file. Point files must be in the form: x,y,z with no additional heading information at the top. The characters can be separated with a variety of characters and can be surrounded by quotation marks. In the Rhino Help file, search for “points, import from file.”

2. Read the file into Rhino. Create curves (e.g. stations) by connecting the points.

3. There are two options at this point:
    a. Quick, but difficult to create a fair surface: Loft the curves with Rhino’s Loft command. It helps if you do some extra work on the station curves, to make sure that they are all of the same degree and have the same number of control points.

    b. Slower, but easier to create a fair surface: In this approach, the station curves are used as a visual template. Create a surface (easiest way is to use one of the Hull Assistants) that is close to the desired shape. Define sections at the same locations as the sections generated from your original offset points. Edit the surface’s control points, so that the surface-based sections match the offset-generated sections.

The choice of the approach should be made based on what you intend to use the model for. If you’re simply using it for some quick renderings or some hydrostatic calculations, fairness is not terribly important, so the first approach is appropriate. If the model will ultimately be used to build the boat, the second approach should be used.