A NEW METHOD FOR DEVELOPING HULL FORMS WITH SUPERIOR SEAKEEPING QUALITIES

A new method for analytical seakeeping optimisation is described in this paper. The method is based on a computercode which predicts seakeeping performance when the ship profile, the design waterline, the sectional area curve and the distribution along the ship of the centroid KB(x), of the crow sections are prescribed. The code can automatically generate variant hull forms differing from a parent in the main dimensions and in one or more parameters such as CW, LCF, LCB, KB distribution, CP etc. When appropriate ranges for the principal characteristics and parameters of the hull form under investigation are prescribed, a formal optimisation procedure is used to obtain the variant with the best seakeeping behaviour. The optimisation procedure uses as objective function the weighted average of a number of peak ship responses in regular waves for a number of ship speeds and headings and determines the optimum hull form using the Hooke and Jeeves Algorithm. The hull form of a reefer vessel was selected and optimised in head seas with respect to vertical accesseration and relative motion. Two-metre models of the parent and the optimised hull forms were subsequently built and tested for resistance, vertical ship response and added resistance.