Creating and editing the defining curves

The end surface is completely defined by the following elements (shown in Figure 3:87 in Overview):

• Profile curve

• Radii curve

• Eccentricity curve (optional)

• End surface type regions

The radii and eccentricity curves define the distribution of radius and eccentricity along the length of the profile curve.

The vertical axis represents the length (that means, girth-wise measurement) of the profile curve. If you edit the profile curve, you will see the length of this axis changing. There are dotted lines drawn between points on the profile curve and corresponding points on the vertical axis to make the relationship between them clearer.

The vertical axis is divided into regions by small red dots (markers) corresponding to some of the dotted lines coming from the profile curve. A marker corresponds to either the end of the curve, or a point where the tangent to the profile curve is vertical. It is at these latter markers that the type of the end surface is allowed to change.

A region of end surface can be one of two types:

• Elliptical/circular in a waterline (that means, horizontal) plane (waterline type, indicated by a yellow region on the vertical axis).

• Elliptical/circular in a plane that is normal to the profile curve (normal type, indicated by a green region on the vertical axis)

Change the end surface type of a particular region

1. Right-click on it and select the new type (this will appear as the only available option) from the popup menu.

The horizontal axis represents the radius or eccentricity value at a point along the profile. The radius value represents the length of the semi-minor axis of the elliptical arc formed by slicing through the end surface at this point on the profile (either parallel to a waterline plane or a normal plane). The eccentricity value is the ratio of the major semi-axis to the minor semi-axis. Therefore, the meaning of eccentricity values is:

If no eccentricity curve exists, the value of eccentricity is taken to be unity everywhere.

There are 2 approaches to creating the defining curves:

• Manually, by digitizing data points.

• Automatically, using the half siding approach.

These approaches are described in the following sub-sections.