Parametric design and multiobjective optimization of SWATH

Abstract

More specific at this thesis chapter 1 is generally about CAD/CAE systems for ship design. It is described how are used , what they can do and there is a description about the software exploited in the present thesis.

Chapter 2 is relevant with optimization and how it works. It analyses the optimization problem , separates the single from the multi objective optimization and describes the genetic algorithms.

Chapter 3 talks about multi-hull ships at general and especially Swaths. It quotes the aspects the design parameters the history of Swath. In addition it describes the comparison of them with conventional ships and present the newly built Swath.

Chapter 4 contains the case study of the Swath design and optimization(AQ3) and it is obvious the core of the thesis. It is widely acknowledged that at present times an economic option is very attractive to the public, especially if we talk about passenger and car ships. So regarding to this, the optimization was made in order to minimize every aspect of resistance. As a result some designs were found for every need. Either the best model for a high speed that serves the public at summers or the best model at a relatively low speed that that serves at a non commercial period, or a optimized model for a combination of the above. All these accompanied with the strict regulations and safety rules. All of these developments create a new (almost chaotic) patch that both the existing and new built ships have to respond to. It is generally admitted that these requirements change entirely the way we think about shipping in general and the challenge is big and often a handicap and burden for the operability and profitability of the owning and managing company. This creates a new need for innovative, safer and more efficient designs that will not mitigate the economic performance, sustainability and competitiveness of each concept. Initially though these designs are not easily acceptable by shipyards and need additional capital expenditure.

They key in making them a sustainable option is reduce the Operating Expenditures (OPEX) and maintenance costs, as well increase the availability and reliability of the product in order to achieve a balance. This balance will subsequently trigger new orders and investments towards this direction and in a long run a two Tier market, of upscale innovative ships and more conventional ones, with the last struggling to face the competition both in commercial and operating terms. It is the technology leap that will illustrate the potential of the new designs and establish them as actual and realistic solutions.

The present diploma thesis concludes with chapter 5 that describes a brief summary and outline of the work undertaken, providing some design directives for future, tender concepts as well as an outline of the Swath optimization (global and less detailed one). The contribution of the Thesis in Swath design is outlined and some perspectives for future work are underlined.

Finally appendix A and appendix B contains two small case studies. The first one is about an optimization of tri-hull with the same displacement of AQ3. The main matter is to minimize the waves produced by the hulls behind the main hull. The second one is an optimization of a tetra-hull with a diamond shape again trying to minimize the waves of the hulls behind the main hull, and hence the total resistance.