Create Angle Curves

After fairing the localized Plines, by projecting and merging, then refitting the sections, it may be necessary to introduce angle curves to give more control. The user can convert selected Plines to Tangent curves, using the accept dialog, then create angle curves for the section to 3D curve intersection angles. These angle curves can then be faired and the section re-fitted.

Angle curves are associated with Knuckle and Tangent curves and are defined for a particular line-set. They are created as follows.

Create Angle curves

1. In the 2D Construction dialog select the Angle page, select the curve type by choosing either the Tangent or Knuckle Radio button.

2. Pick the individual curve from the list for which the angle curve is required, then from the View panel select the set of orthogonal curves (Section, Waterline, Buttock) with which the angle is to be calculated.

3. To automatically generate the curve, select the Automatic Radio button and click the Create button.

   This will create a 2D curve, whose axes are "curve position" and "angle" which can be fitted and faired in the usual manner. Angle curves are stored in the Cline directory, their names are derived from their associated surface curve and line-set. See the CREATE ANGLE command, in Command Reference

Depending on the shape and location of the 3D curve in relation to the sections, the angle curves may have extreme changes of shape. The user should not radically change the curve in order to fair it as this can produce extreme changes to the sections.

For some angle curves the user may find it better to fit a spline using the PREFIT /CENTRIPTAL option, , which gives a more controlled fit.

You may wish to create angle curves for existing control curves that means, knuckle and tangent curves. In this case is not necessary to create any Clines in these areas.

You may wish to create angle curves for existing boundary curves for example, FOB, FOS This can be achieved by copying the curve in question to a tangent or knuckle curve. This can be achieved by selecting the curve in the Curve Tree, clicking the Right Mouse button and selecting Copy from the popup menu. The Copy Curve dialog then appears (see Figure 3:25 below) Select Tangent as the To curve type and select a name.

Figure 3:25. Copy Curve Dialog.

An angle curve can be created as described above. However, users should note that if the FOB and FOS curves are correctly defined then an implicit angle curve exists in this region and the user need not provide a specific one.

The user should then fit additional sections in critical regions such as the stem and stern. These can be spaced every 0.1 meters or even 0.05 meters to accurately assess the fairness.