Prefit provides a means of keyboard entry of existing offset data for use in the generation of a three dimensional surface. The surface generated by Prefit may be saved as a Maxsurf design file. Offset data may also be loaded from a text file or copied from a spreadsheet.
You may find it easier to use the fitting functions provided in the Markers menu in Maxsurf rather than using the standalone version of Prefit.
Using Prefit is a three-stage process, entering the bow and stern shapes, fitting the transverse splines, and fitting the surface.