A Parametric Approach for Initial Hull Form Modeling Using NURBS Representation

Abstract

An approach to initial hull form modeling using the concept of parametric generation and manipulation is introduced. The parametric approach is to directly control geometric features or to describe hydrostatic performance of a hull by utilizing naval architecture parameters that uniquely and unambiguously define a hull form. The Non Uniform Rational B-spline (NURBS) representation, which is the most common type of a hull form modeling in use, is combined with the parametric approach to represent a hull form. From a planar net of control points of a NURBS surface, a hull form satisfying the given requirements is automatically generated. The generation of the hull form is accomplished by subdividing the hull into five zones: stem, entrance, midbody, run, and stern, maintaining the continuity between adjacent zones. A library of pre-defined stems and sterns is provided to help a rapid and efficient design. Modification of the initial hull form can be accomplished by manipulating the set of NURBS control points that influences the designated part of the hull form. Refinement for precise hull form and variation to similar hull forms are easily carried out within any hull form distortion system. This proposed modeling approach is useful for an initial hull form design from scratch with minimal user requirements; therefore, it can be an effective tool for the initial design of a hull form when a suitable parent model is unavailable.