Simple Yacht Hull Form using X-Topology

This tutorial goes through the process of creating a simple yacht hull.

1. Using a X-Topolology curve, create a centreline. In addition to the ends put three points on the keel line and two for the forefoot.

2. Apply the blend modifier to the two forefoot points. This will create a straight stem.

3. From the stem and using the X/Y plane, add deck line curve using four points.

4. Connect the centre and deck line curves together with a curve consisting of four control points.

5. Now add a midship section curve, change to a three dimensional view and using object snapping begin drawing a curve in the y/z plane from the centre line to the deck line.

6. Four points should be sufficient.

7. After drawing the curve, apply a location surface and set this to be an X-plane.

8. The curve will now show its true shape, constrained into two dimensions.

9. As the curves are being (practically) sketched, it is unlikely that the hull will have the right dimensions or ratios. At this point, with only four basic curves, the basic shape of the hull can be tidied up before adding the remaining curves. On the status bar, XT-Elastic can be set to curves so that any descendant curves will update as a ratio of an changes to points that reference a curve being edited.

10. Once the main curves have the right shape, turn the hull so that the visual amount of space between the centre line and deck line is maximised.

11. Add a diagonal curve halfway along the transom and mid ship section curves, finally attaching it to the stem section of the centre line curve. Include two control points, one each side of the midship section to allow control of the general fullness of the hull.

12. Add another curve above the last with a similar format of points. Make sure that when the curve is dynamically snapping to other curves, indicated by the links cursor.

13. Finally, add a third diagonal beneath the last two curves. Attach the forward end of this curve to the upper control point on the stem radius.

14. A section curve will be required at the forward quarter of the hull to reduce the aspect ratio of the surface patches and to provide an indication of hull shape. All of the control points on this curve will reference other curves and, therefore, will not have to be modified once added to the hull definition.

15. Apply an x-plane location surface to the newly added section curve.

16. Add a similar curve at the aft quarter and apply an x-plane locations surface.

17. The two sections, added previously, highlight the unfairness in the forward and aft quarters of the hull. Edit the three diagonal curves to resolve this. View the hull in there dimensions and edit the diagonals of the control points in the y/z plane.

18. Once all basic framework of curves are satifactorily defined, select all the curves.

19. Create the X-Topology Surface from the Right-Click menu. (Right-Click -> Multiple Selection -> Create XTSurface Group).

20. The hull surface will be generated, (using Gregory Bezier patches by default).

21. Select the generated hull surface and change its colour to dark blue.

22. The fairness of the hull can be checked by rendering the surface.

23. The fairness can also be checked by displaying surface curvature or reflextion lines.

24. Continue fairing the hull by modifying control points or adding more curves until the quality of the shape is satifactory.

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