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The term "Sections" refers to planar curves such as stations, buttocks, and waterlines, that are computed as the intersection of a plane with one or more surfaces. Orca3D uses Rhino's contour command to compute the curves. The Section curves are just like any other Rhino curves, except that they "know" that they were derived from a surface, and if you use Orca3D's real-time section updating, they will update as the surface is modified. If you select a Section and look at its properties, next to Object Type it will display "Orca3D section."

Orca3D provides an interface to quickly define a list of station, buttock, waterline, diagonal, cant, and incline locations. This list is maintained and stored with your model, and sections will be computed at these locations through the surface(s) that you have selected.

When you define sections, they are associated with one or more surfaces. They will only be computed through the surfaces that you select when you begin the command. If you wish to have sections through a different set of surfaces, simply select those surfaces, run the Orcasections command again, and click OK.

Important Points to Remember

1. Because the Section curves will change if the surface is changed, you should copy any of them that you want to use for a different part of your drawing.

2. Because Sections are associated with a surface, they cannot be directly edited or deleted. They will only change shape if the underlying surface is modified, and the only method of deleting a Section curve is to remove it from the section list in the Sections dialog.

3. If you mirror a surface that has sections defined, but you do not select the Orca3D sections as objects to be mirrored, the mirrored surface will not have Orca3D sections. In order to see Orca3D Sections on the mirrored surface, you must select the mirrored surface along with the original surface, and update the Sections (right-click on the Sections icon).

4. If you mirror Orca3D sections, either by themselves or along with their parent surface, the mirrored sections will be Rhino curve object, and not Orca3D sections. They can be moved, edited, and deleted like any other Rhino curves, and will not update as the surface is modified.