Waterline Endings and Frame Feet

In order to generate Waterline Endings and Frame Feet, an End Surface is created. This is a true mathematical surface onto which existing or new waterlines are merged. New sections fitted using this method will also intersect the end surface. An end surface can be generated at both the stem and stern.

There are two approaches which can be used to generate waterline endings, depending on whether or not the radius at each waterline height is known in advance. If this is not known, then the main steps involved in waterline endings are:

• Create a half siding curve (See Creating a Half Siding Curve)

• Fit Waterlines to the half siding (See Fitting Waterlines to the Half Siding)

• Generate the radii curve from the half siding and fitted waterlines (See Creating the Radii Curve from the Half Siding)

• Create an eccentricity curve (optional) (See Creating the Eccentricity Curve)

• Create the end surface (See Creating the End Surface)

• Create the transition curve (optional, but recommended) (See Create the Transition Curve)

• Update waterlines (See Updating Waterlines)

If radii values are known, then the radii curve can be created manually and steps 4-7 are carried out. (See User Defined Radii Curve)

When waterlines are updated, each waterline is truncated at its intersection with the transition curve. The end surface is intersected at the waterline height and a new curve piece is inserted between the truncated waterline and the ending, such that the new piece is as fair as possible whilst maintaining continuity with the truncated waterline and the ending (see ). The point at which each waterline is tangential to the end surface is used to generate a tangent curve (Stem or Stern) (See Modifying the Tangent Curve). Once an end surface is defined, new sections and waterlines can be fitted through it (See Fitting New Waterlines and Sections).

Figure 3:80. Waterline Endings Construction.

It is possible to omit the transition curve if the waterlines are already fair and only the ending is to be altered. In this case, if the tangent curve exists, then the existing waterline is truncated at the tangent point. The waterline ending, derived by intersecting the end surface, is attached to the truncated waterline at the tangent point. Note that the tangent point must lie on the existing waterline and on the end surface for this method to succeed. If the tangent curve does not exist, then the existing waterline is truncated at its intersection with the end surface. The waterline ending, derived by intersecting the end surface, is attached to the truncated waterline, up to the intersection point. Note that the existing waterline must intersect the end surface for this method to succeed. Furthermore, the intersection point must already be fair, otherwise the waterline will contain a discontinuity.