Importing a Boundary Curve

For a typical project, the first step is to create the boundary curves, Profiles, Flat of Bottom, , either by importing data files or entering data points online.

When importing files (or specifying X coordinates internally) the user has the option of handling X values as one of the following; either Station numbers, Frame numbers or true X dimensions. The user can work with whichever is appropriate and this may vary between files and be changed at any time while working.

Set the X coordinate type

1. Select the User Parameters icon .

2. Select the Data Set page from the User Parameters dialog.

3. The files used in this example use true X distances.

4. Select the Distance button in the Section Numbering Part of the dialog.

5. Select OK to enable the options selected from the dialog.

   

   Figure 3:6. User Parameters Dialog - Data Set page.

Import data for a boundary curve

6. Select the create icon from the icon bar.

7. As the data is to be imported from a file, select the Curve Points page, select Stern Profile from the Type dropdown list and click the Import button.

   The user will then be presented with a file selection menu.

8. Select the file Stern.dat and click the Open button.

   When the points have been read from the data file, they are shown and can be modified from the grid. All points have been imported as ordinary (that is, there are no constraints specified for fitting a curve).

9. Change point number 7 to a Knuckle point by clicking on the blue grid cell and selecting Knuckle.

10. Change the second last point to a Tangent point.

11. Click the Create button after the points have been read from the data file.

    As an alternative the points could be input directly into the dialog.

    

Figure 3:7. Create Curve Dialog.

The method presents the data points to the user for manipulation as the current curve. The data points can be displayed in buttock view by first clicking the starboard view icon, , from the View toolbar, then displaying the points using the display points icon, . Lines does not automatically fit a curve to the data points so this should be done by clicking the prefit icon, .

The curve will look similar to that shown.

Figure 3:8. Buttock View, displaying the Stern Profile.

No more will be done on this curve. Therefore, to store it in the design, click the accept icon, , from the toolbar.

Within Lines, the curve that the user is working with at any given time (whether imported from a data file or interpolated from stored data) is referred to as the current curve. Before preceding to work with a subsequent curve the user must either accept existing current curve as above or quit by clicking the quit icon, , from the Edit toolbar.

The Stem Profile can now be imported by following the same procedure. As with the Stern Profile it is necessary to control the point type of some of the points. Therefore set the second and penultimate point types to Tangent to force straight lines in the curve.

Figure 3:9. Buttock View, displaying the fitted Stem Profile.

The Flat of Bottom (Bottom tangent line) and Flat of Side (Side tangent line) should now be imported. For this example these are also stored as boundary curves under the system names FOB and FOS respectively. For some projects it may be more appropriate to store these curves as Tangent or Knuckle lines, the choice is up to the user.

In this example, both curves require a straight section in the midbody region of the curve.

Apply the constraint using the Patch and Curve Editor

12. Import the curves (Fos.dat and Fob.dat) as for the profile curves, prefit and accept them without any changes.

13. Select the FOS and FOB items from the Boundary branch of the Curve Tree, click the Right Mouse button and select the Patch and Curve Editor button.

14. When the Patch and Curve Editor (PACE) dialog opens, select the Data Points checkbox for both curves. The window will look similar to that shown below:

    

Figure 3:10. Patch and Curve Editor - FOB and FOS.

Straighten the midbody section of the FOS

15. Select the first of the two lowest points by clicking on the point.

16. Extend the selection to include the second of the two lowest points by holding down the <Ctrl> key and clicking on the second point.

17. Select the Straighten button, .

    The curve will then look like that shown below:

    

Figure 3:11. FOS after straightening of middle section.

Perform a similar procedure for the FOB to produce the curve shown below.

Figure 3:12. FOB after straightening of middle section.

Accept these curves by clicking the Update button, , and then close the PACE.