Apostolos Papanikolaou

Holistic ship design optimization

Ship design 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. A systemic approach to ship design may consider the ship as a complex system integrating a variety of subsystems and their components, for example, subsystems for cargo storage and handling, energy/power generation and ship propulsion, accommodation of crew/passengers and ship navigation. Independently, considering that ship design should actually address the whole ships life-cycle, it may be split into various stages that are traditionally composed of the concept/preliminary design, the contractual and detailed design, the ship construction/fabrication process, ship operation for an economic life and scrapping/recycling. It is evident that an optimal ship is the outcome of a holistic optimization of the entire, above-defined ship system over her whole life-cycle. But even the simplest component of the above-defined optimization problem, namely the first phase (conceptual/preliminary design), is complex enough to require to be simplified (reduced) in practice. Inherent to ship design optimization are also the conflicting requirements resulting from the design constraints and optimization criteria (merit or objective functions), reflecting the interests of the various ship design stake holders. The present paper provides a brief introduction to the holistic approach to ship design optimization, defines the generic ship design optimization problem and demonstrates its solution by use of advanced optimization techniques for the computer-aided generation, exploration and selection of optimal designs. It discusses proposed methods on the basis of some typical ship design optimization problems with multiple objectives, leading to improved and partly innovative designs with increased cargo carrying capacity, increased safety and survivability, reduced required powering and improved environmental protection. The application of the proposed methods to the integrated ship system for life-cycle optimization problem remains a challenging but straightforward task for the years to come.

Methods and Tools

Risk-based ship design demands advanced tools to accomplish the safety assessment of a given design. In this chapter, the background theory for the development and examples of application of related risk-based tools and of assessment procedures will be given. These tools and methods facilitate the analysis of the initiation and of the consequences of a variety of hazards, like system failure, collision, grounding, structural failure, fire, flooding and loss of intact stability. Finally tools for the simulation and analysis of evacuation, mustering & rescue procedures will be presented.

On integral-equation-methods for the evaluation of motions and loads of arbitrary bodies in waves

SummaryThe paper deals with the hydrodynamic interaction problem of an arbitrarily shaped body and a train of regular surface waves. The body is assumed rigid and performing small amplitude oscillations or being fixed in or below the free-surface of an ideal fluid. Applying Greens theorems of potential theory the boundary-value-problem formulated is reduced to the solution of Fredholm integral equations of the second kind. The numerical procedure employed is based on a discretization of the body surface by triangular or quadrilateral patches, an efficient evaluation of the influence matrices and the solution of a resulting set of linear algebraic equations. Sample calculations are presented and compared with those of other authors and methods.übersichtDie vorliegende Arbeit befa\t sich mit dem hydrodynamischen Wechselwirkungsproblem eines Körpers beliebiger Form und eines regelmÄ\igen Wellenzuges von OberflÄchenwellen. Der angenommene Starrkörper soll Oszillationen kleiner Amplitude ausführen oder festgehalten werden an oder nahe unter der freien OberflÄche einer idealen Flüssigkeit. Das formulierte potentialtheoretische Randwertproblem wird mit Hilfe der Greenschen SÄtze auf die Lösung von Fredholmschen Integralgleichungen zweiter Art zurückgeführt. Das eingesetzte numerische Lösungsverfahren basiert auf einer Diskretisierung der KörperoberflÄche durch ebene Viereck- oder Dreieckselemente, einer effektiven Bestimmung der Einflu\matrizen und der Lösung von sich ergebenden linearen algebraischen Gleichungssystemen. Beispielrechnungen werden dargestellt und mit Ergebnissen anderer Autoren und von Methoden verglichen.

Optimization of Arrangements of Ro-Ro Passenger Ships with Genetic Algorithms

Abstract A formal multi-objective optimization procedure based on genetic algorithms is applied for the internal compartmentation of Ro-Ro ferries. Attained Subdivision Index, lane meters and steel weight are considered as object functions. Case studies for a typical Ro-Ro ferry yield realistic results and show that the optimization procedure can handle realistic design problems.

On the development of the new harmonised damage stability regulations for dry cargo and passenger ships

Abstract This paper outlines the methodological background and presents a summary of the main results of a series of undertaken international, IMO-led studies, on the harmonisation of the new probabilistic, risk-based regulations with the currently in-force regulatory provisions for assessing the damage stability of dry cargo and passenger ships. It reviews the historical development of the new regulations, to be applied to all new buildings on January 1, 2009, and the anticipated impact of the new rules on the design and indirect operation of various subcategories of dry cargo and passenger ships. It identifies certain loopholes in the existing regulations that appear cured by the new ones, though certain compromises adopted in the development of the new regulations, particularly those related to large passenger ships’ survivability, have left some open issues to be addressed in the near future.

Updated vertical extent of collision damage

The probabilistic distribution of the vertical extent of collision damage is an important and somewhat controversial component of the proposed IMO harmonized damage stability regulations for cargo and passenger ships. The only pre-existing vertical distribution, currently used in the international cargo ship regulations, was based on a very simplified presumption of bow heights. This paper investigates the development of this damage extent distribution based on three independent methodologies; actual casualty measurements, world fleet bow height statistics, and collision simulation modeling. The results from the three methods are compared, and a proposed distribution for the new harmonized regulations is presented.

GOALDS - goal based damage ship stability and safety standards

The new probabilistic damaged stability regulations for dry cargo and passenger ships (SOLAS 2009), which entered into force on January 1, 2009, represent a major step forward in achieving an improved safety standard through the rationalisation and harmonization of damaged stability requirements. There are, however, serious concerns regarding the adopted formulation for the calculation of the survival probability of passenger ships, particularly for ROPAX and large cruise vessels. The present paper outlines the objectives, the methodology of work and main results of the EU-funded FP7 project GOALDS (Goal Based Damaged Stability, 2009-2012), which aims to address the above shortcomings by state-of-the-art scientific methods and by formulating a rational, goal-based regulatory framework, properly accounting for the damage stability properties of passenger ships and the risk of people onboard.

Casualty analysis of Aframax tankers

The paper presents detailed results of a comprehensive analysis pertaining to Aframax tanker incidents and accidents that occurred in the last 26 years. The thorough review of the captured accident database information and the analysis of the historical records provided essential qualitative and quantitative information on a variety of parameters relevant to risk-based methodologies, namely the degree of severity and frequencies of accidents broken down into the pre-1990 and post-1990 periods, the spilled tonne rates and the impact of hull design and of ships age, particularly on non-accidental structural failure accidents and geography of worldwide oil spills. The generated information enables conclusions on Aframax tanker accidents and of tankers in general to be drawn, for further exploitation in risk based design, operation and regulations.

Second-order theory and calculations of motions and loads of arbitrarily shaped 3D bodies in waves

Abstract This paper deals with the development of a complete second-order theory for the evaluation of motions and loads of arbitrarily shaped 3D bodies in waves at finite water depth. The developed second-order potential theory leads to the solution of integral equations for the evaluation of second-order potentials and corresponding second-order pressures, forces, motions, etc. The developed algorithm for the treatment of the second-order inhomogeneity of the free-surface boundary condition allows the application of the related computer program to bodies of arbitrary shape, in contrast to previous theories applicable only to axisymmetric bodies. The paper includes typical numerical results for the second-order motions and loads for various bodies of both axisymmetric and nonaxisymmetric shape.

Energy efficiency parametric design tool in the framework of holistic ship design optimization

Recent International Maritime Organization (IMO) decisions with respect to measures to reduce the emissions from maritime greenhouse gases (GHGs) suggest that the collaboration of all major stakeholders of shipbuilding and ship operations is required to address this complex techno-economical and highly political problem efficiently. This calls eventually for the development of proper design, operational knowledge, and assessment tools for the energy-efficient design and operation of ships, as suggested by the Second IMO GHG Study (2009). This type of coordination of the efforts of many maritime stakeholders, with often conflicting professional interests but ultimately commonly aiming at optimal ship design and operation solutions, has been addressed within a methodology developed in the EU-funded Logistics-Based (LOGBASED) Design Project (2004–2007). Based on the knowledge base developed within this project, a new parametric design software tool (PDT) has been developed by the National Technical University of Athens, Ship Design Laboratory (NTUA-SDL), for implementing an energy efficiency design and management procedure. The PDT is an integral part of an earlier developed holistic ship design optimization approach by NTUA-SDL that addresses the multi-objective ship design optimization problem. It provides Pareto-optimum solutions and a complete mapping of the design space in a comprehensive way for the final assessment and decision by all the involved stakeholders. The application of the tool to the design of a large oil tanker and alternatively to container ships is elaborated in the presented paper.