RESISTANCE OPTIMIZATION OF DISPLACEMENT VESSELS ON THE BASIS OF PRINCIPAL PARAMETERS

The genetic algorithm (GA) has been used to optimize hullforms with re spect to their total resistance. The hulls are represented in a parame tric manner using a small number of variables, such as length, beam, a nd draft-as well as other geometric characteristics, including the len gth of parallel keel and draft at the bow and stern. Constraints may b e applied both to these variables and to other parameters. Results are shown for both monohulls and catamarans, in cases for which the const raints are largely inactive, for a large range of displaced volumes an d forward speeds. These illustrate the hulls generated in the extreme case in which resistance is the only factor of interest. An important characteristic of the results is the fact that the variations of the o ptimal principal dimensions are generally not continuous with respect to the speed, although the resistance itself is usually continuous. Th at is, it is possible that a small change in speed may demand an entir ely different optimal hullform.