Holistic Ship Design Optimization - Merchant and Naval Ships

Apostolos D. Papanikolaou (National Technical University of Athens)

The design of ships is a complex endeavor requiring the successful coordination of many disciplines, of both technical and non-technical nature, and of individual experts to arrive at valuable design solutions. Inherently coupled with the design process is design optimization, namely the selection of the best solution out of many feasible ones on the basis of a criterion, or rather a set of criteria. Such evaluation criteria are the shipbuilding cost or the required freight rate for merchant ships or more complex ones that include, besides economy, ship performance in terms of safety, comfort, survivability in intact and damage condition and eco-friendliness. A systemic approach to ship design may consider the ship as a complex system integrating a variety of subsystems and their components.

The use of Multi-Objective Genetic Algorithms(MOGA), combined with gradient based search techniques in micro-scale exploration and with a utility functions technique for the design evaluation, is advanced in the present paper as a generic type optimization technique for generating and identifying optimized designs through effective exploration of the large-scale, nonlinear design space and a multitude of evaluation criteria occurring in ship design. Several applications of this generic, multi-objective ship design optimization approach by use of NTUA-SDL’s design software system, integrating the naval architectural software package NAPA, the optimization software modeFRONTIER and various application software tools. Five different configurations were considered and a total of 21,500 designs were examined in the present study. Those five alternative configurations were selected to allow validating the characteristics of the reference design, as well as identifying possible improvements through analysis of the respective Pareto frontiers. It was shown that multi-objective mathematical optimization approaches are very valuable tools and greatly enhance the quality of ship design, even if applied to vessel concepts already optimized by traditional methods. The design developed and optimization methodology may be a useful tool for the designer in the preliminary design stage, facilitating the elaboration of a large number of design alternatives quickly and with little effort. The designer may explore this possibility to investigate the effect of crucial decisions on the vessel’s operating performance before proceeding to the detailed design stage. The design methodology may also be effectively used in feasibility studies, providing assistance for the determination on a rational basis of the most suitable vessel size, transport capacity, speed, and other operating characteristics for a selected service.