The mathematical definition and fairing of hull lines presents several advantages as:
a) Speed-up of the hydrostatic calculations, which are possible since the preliminary phases of hull definition;
b) Easy change of main dimensions and local/global shape with immediate evaluation of the modifications in the points relevant for stability and hydrodynamic evaluation.
c) Automatization of the production process through the codes for nesting and numerical control of cutting/welding machines.
After fifteen years of industrial applications the practical results are, however, not yet satisfactory. In this paper the authors present a new methodological approach based on the definition of hull surface by means of the so-called longitudinal control lines.
