The Automated Fairing of Ship Hull Lines Using Formal Optimisation Methods


Abstract: The problem of creating fair ship design curves is of major importance in Computer Aided Ship Design environment. The fairness of these curves is generally considered a subjective notion depending on the judgement of the designer (eg., visually pleasing, minimum variation of curvature, devoid of unnecessary bumps or wiggles, satisfying certain continuity requirements). Thus an automated fairing process based on objective criteria is clearly desirable. This paper presents an automated fairing algorithm for ship curves to satisfy objective geometric constraints. This procedure is based on the use of optimisation tools and cubic B-spline functions. The aim is to produce curves with a more gradual variation of curvature without deteriorating initial shapes. The optimisation based fairing procedure is applied to a variety of plane ship sections to demonstrate the capability and flexibility of the methodology. The resulting curves, with their corresponding curvature plots indicate that, provided that the designer can specify his objectives and constraints clearly, the procedure will generate fair ship definition curves within the constrained design space.

Keywords: Fairing, Optimisation, Ship Lines, Curvature, B-splines

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