Maintenance/repair and production-oriented life cycle cost/earning model for ship structural optimisation during conceptual design stage

The aim of this paper is to investigate the effect of the change in structural weight due to optimisation experiments on life cycle cost and earning elements using the life cycle cost/earning model, which was developed for structure optimisation. The relation between structural variables and relevant cost/earning elements are explored and discussed in detail. The developed model is restricted to the relevant life cycle cost and earning elements, namely production cost, periodic maintenance cost, fuel oil cost, operational earning and dismantling earning. Therefore it is important to emphasise here that the cost/earning figure calculated through the developed methodology will not be a full life cycle cost/earning value for a subject vessel, but will be the relevant life cycle cost/earning value. As one of the main focuses of this paper is the maintenance/repair issue, the data was collected from a number of ship operators and was solely used for the purpose of regression analysis. An illustrative example for a chemical tanker is provided to show the applicability of the proposed approac

A hybrid approach for multi-objective combinatorial optimisation problems in ship design and shipping

Numerous real-world problems relating to ship design and shipping are characterised by combinatorially explosive alternatives as well as multiple conflicting objectives and are denoted as multi-objective combinatorial optimisation (MOCO) problems. The main problem is that the solution space is very large and therefore the set of feasible solutions cannot be enumerated one by one. Current approaches to solve these problems are multi-objective metaheuristics techniques, which fall in two categories: population-based search and trajectory-based search. This paper gives an overall view for the MOCO problems in ship design and shipping where considerable emphasis is put on evolutionary computation and the evaluation of trade-off solutions. A two-stage hybrid approach is proposed for solving a particular MOCO problem in ship design, subdivision arrangement of a ROPAX vessel. In the first stage, a multi-objective genetic algorithm method is employed to approximate the set of pareto-optimal solutions through an evolutionary optimisation process. In the subsequent stage, a higher-level decision-making approach is adopted to rank these solutions from best to worst and to determine the best solution in a deterministic environment with a single decision maker

Risk assessment of loss of life for fishing vessels in fuzzy environment

Describes a risk assessment of loss of life for fishing vessels in fuzzy environment

Integrated multiple attributive decision support system for producibility evaluation in ship design

Ship design today can be viewed as an ad hoc process. It must be considered in the context of integration with other design development activities, such as production, costing, quality control, and so forth. Otherwise, it is possible for the designer to design a ship that is difficult to produce, requires high material or labor cost, or contains some design flaws that the production engineers have to correct or send back for redesigning before production can be done. Any adjustment required after the design stage will result in a penalty of extra time or cost. Deficiencies in the design of a ship will influence the succeeding stages of production. In addition to designing a ship that fulfills producibility requirements, it is also desirable to design a ship that satisfies risk, performance, cost, and customer requirements criteria. More recently, environmental concerns, safety, passenger comfort, and life-cycle issues are becoming essential parts of the current shipbuilding industry. Therefore, "design for X paradigm" should also be considered during the ship design stages. An integrated multiple attributive decision support system for producibility evaluation in ship design (PRODEVIS) is developed to use by industry and researchers in evaluating the producibility of competing ship designs and design features during the early stages of ship design by taking into account cost, performance, risk, and "design for X paradigm" attributes. This developed approach is a fuzzy multiple attributive group decision-making methodology where feasible design alternatives are conducted by a ship production simulation technique. In this approach, an attribute-based aggregation technique for a heterogeneous group of experts is employed and used for dealing with fuzzy opinion aggregation for the subjective attributes of the ship design evaluation problem. The developed methodology is illustrated with a case study

An integrated multi-objective optimisation and fuzzy multi-attributive group decision-making technique for subdivision arrangment of Ro-Ro vessels

This paper focuses on developing a new multiple criteria decision-making (MCDM) methodology for subdivision arrangement of Ro-Ro vessels, which integrates the multi-objective optimisation with a fuzzy multi-attributive group decision-making (FMAGDM) technique. The study concentrates on the task of finding and then evaluating (or ranking) the finite number of pareto-optimal design alternatives (PODAs). A genetic algorithm based multi-objective optimisation technique, namely MOGA, is employed for optimisation purpose in terms of chosen design parameters such as damage stability, survivability, and cargo capacity. MOGA is the methodology where the solution space is searched for a set of PODAs, from which experts can express their opinions and choose the best PODA. The subjectiveness and imprecision of the ranking process is modelled as linear trapezoidal fuzzy numbers by means of linguistic terms. An attribute based aggregation technique for homogeneous and heterogeneous groups of experts is employed and used for dealing with the fuzzy opinion aggregation. Finally, a real case study on the subdivision arrangement of a Ro-Ro vessel is conducted to illustrate the effectiveness of the approach

Evaluating the potential economic and societal impacts of slow steaming when used as the primary tool towards greenhouse gas emissions reduction

A qualitative systematic literature review was conducted to evaluate the potential economic and societal impacts of slow steaming, when used as the primary means of reducing greenhouse gas emissions from shipping. The vast majority of studies were focused on the economic cost-effectiveness or the effect on transport cost when using slow-steaming as a means of reducing fuel consumption in shipping. Additionally, a certain number of these studies employed modelling, by using a limited number of vessels and associated routes to identify the effects of slow-steaming. The literature resulted in reasonable agreement that a reduction of the transportation costs follows a reduction in speed mainly coming from the reduced costs for fuel, with which it is correlated. Other factors, which were observed to increase costs, such as operational costs of the vessels, had a less dominant effect. The literature pointed in many occasions that costs reduction from the implementation of slow-steaming were unequally distributed across the maritime stakeholders. Shipping companies were the main beneficiaries of important cost reductions, but these “savings” were not always passed on to the shippers’ side