**1. Introduction**

The increasing complexity of ships, the need of better performance and the introduction of new regulations, for example to protect the environment, call for an evolution of the design approach in the maritime field as well. The primary need to remain competitive in the international shipping arena concurs to develop an integrated approach, with superior attention during the design process to economic and environmental aspects along with the ship operational life [1–4]. This new awareness inevitably calls in turn for intensive design comparisons and trade-off analysis with a specific focus on the energy system. In this context also, the comparison between traditional and alternatives fuels plays an important role [5]. The new approach includes market and demand analysis, integrated economic and environmental considerations, efficiency and performance assessment mutually conversant in the ship design process. As possibly useful support in this direction, a formulation of a rational parametric analysis of the vessel over its life cycle has been developed and implemented in the traditional ship design process. In this way, different ship configurations or operational profiles can be deeply analyzed at an early design stage, when designers can still make decisions to change and improve the project [6].

The HOLISHIP European project (www.holiship.eu) addresses the issue of a comprehensive approach for ship design capable of meeting the future market needs. As part of the wide HOLISHIP project, an LCPA (Life Cycle Performance Assessment) tool [7], that combines the LCC (Life Cycle Costing) and LCA (Life Cycle Assessment), has been developed: the design tool permits, by a comparison framework, the valuation of various design alternatives. It allows a cost/benefit assessment over the ship life cycle considering, at the same phase, both design and operations. Different ship configurations or system layouts can be compared and analyzed in terms of building and operational cost, as well as environmental impact [8].

This paper aims to further develop operational and maintenance costs, defining, in particular, a structured and flexible tool to evaluate maintenance costs for different ship solutions. Based on real maintenance plans and maintenance tasks, overcoming the empiric formulations, this part would be implemented as an element of the main LCPA tool.

Section 2 of this paper provides a general overview of the LCPA tool developed during the HOLISHIP project; Section 3 describes the maintenance techniques commonly used; Section 4 describes step by step the maintenance prediction model developed during the research project; Section 5 provides a complete description of the reference vessel used for the application exercise; Section 6 contains the process to discuss about preferable solutions; Section 7 describes the obtained results; Section 8 provides the conclusions.
