Resistance Optimization of Displacement Vessels on the Basis of Principal Parameters

Abstract

The genetic algorithm (GA) has been used to optimize hullforms with respect to their total resistance. The hulls are represented in a parametric manner using a small number of variables, such as length, beam, and draft—as well as other geometric characteristics, including the length of parallel keel and draft at the bow and stern. Constraints may be applied both to these variables and to other parameters. Results are shown for both monohulls and catamarans, in cases for which the constraints are largely inactive, for a large range of displaced volumes and 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 optimal principal dimensions are generally not continuous with respect to the speed, although the resistance itself is usually continuous. That is, it is possible that a small change in speed may demand an entirely different optimal hullform.