ii OPTIMIZATION OF SHIP HULL PARAMETERS BASED ON REGRESSION BASED RESISTANCE ANALYSIS

Abstract

This research represents a numerical optimization method based on regression resistance analysis for ship hull parameters. Two different ideas; non-linear optimization technique and ship hull resistance are used. The optimal hull form design enables the designer to include advance resistance performance predictions at early stage of design process, allowing a systematic evaluation of the resistance characteristics as a function of hull geometry. The resistances are calculated by well known regression based Holtrop, Hollenbach and Oortmerssen method. This in turn is linked to the non-linear optimization procedure of Sequential Quadratic Programming (SQP) technique. Non-linear optimization procedure is used because the relation between the ship hull resistance and the ship hull parameters are non linear. An optimal hull form is obtained through a series of iteration, subject to some design constraints. The optimizations were carried out by selecting a mathematical hull named Wigley at different speeds.In the first steps only the hull parameters such as length, length-breadth ratio, and breadth-draught ratio are optimized. In the second step the hull form parameters such as block coefficient, prismatic coefficient etc. are optimized by modifying water line shape and frame line shape. Finally both the hull parameters and hull form parameters are optimized. Optimization is carried out at a particular Froude number (Fn = 0.22). The resistance of the ship hull is taken as objective function and ship hull parameters such as length, breadth, draft etc. are taken as constraint that satisfying design constraint of SQP process. The optimized hull resistance is compared to the original ones and also the optimized ship hull parameters and form parameters.