In this work an integration of high-resolution meteo-marine forecast data with detailed ship powering and seakeeping computational algorithms is investigated in order to asses the potential for the attainable fuel savings by weather routing algorithms along relatively short routes (w.r.t. oceanic ones) as those in the Mediterranean Sea. The capability of high resolution models to predict the detailed space-time evolution of meteo-marine conditions at the Mediterranean basin scale is exploited in order to reliably forecast ship performances along Mediterranean routes. Based on this a computational framework applicable to weather routing algorithms is implemented and tested with the main goals of improving operational efficiency, by fuel savings, and of reducing the navigational risks connected to heavy weather at sea. The main elements of the proposed approach are: i) the construction of a detailed numerical model of a real ship; ii) the exploitation of in-service performance data recorded during real voyages of such a ship to tune its numerical model; iii) the use of high-resolution meteo-marine forecast and hindcast data for winds and complete directional wave spectra to assess the fuel saving potentialities of the implemented computational framework cited above. This last task is performed by exploiting forecast data coming from Ensemble Prediction Systems (EPS) applied to high resolution wind and wave forecasts. The obtained results are very interesting and encouraging to further develop the presented approaches. In particular a fuel saving potential ranging from few points of percentage till nearly 10% emerged from the two studied cases. Moreover the approach based on EPS reveled itself to be very useful as an investigation tool for the assessment of the reliability and stability of the fuel minimization with respect to forecast uncertainties.@en

The integrated use of modern seakeeping and powering computational techniques and state of the art meteo-marine forecasting and hindcasting resources has the potential of disclosing new ways to approach some relevant issues, such as for instance operations planning at sea, weather routing, in-service ship energy management and pollution control. Such an integrated approach could be profitably used during ship design for optimizing both hydrodynamic and powering characteristics too. In this paper the authors describe preliminary results of a study aimed at estimating the in-service optimal efficiency propulsion plant setting for a ship in real seaways conditions. To this aim numerical simulations of seakeeping and powering conditions of a ship along a real route in the Mediterranean sea have been performed. In the simulations detailed meteo-marine hindcasting data, consisting of wind data and complete directional waves spectra along the route, have been used. Strip theory has been applied for the seakeeping computation in order to evaluate the contribution of waves added resistance in realistic seaways. Such results have been then used in powering computation, to evaluate the dynamically evolving engine conditions in terms of fuel consumption. The results of such computations have been analyzed to evaluate the in-service optimization potentialities for the available setting of propulsion plant. Finally, heuristic hints are preliminarily suggested by the authors as a support for the use of scenario simulations with realistic meteo-marine data in the powering matching phases of the ship design process.@en

The influence of wave profile on ship righting arm is among the possible stability failure issues addressed by the recent activity at IMO. The present paper is mainly focused on the so called "pure loss of stability", a dangerous phenomenon that can occur for specific conditions in following seas. In the paper, the development of a computational tool is described, able to evaluate the influence of wave profile on ship metacentric height and righting arms, giving the possibility to investigate different ship geometries and loading conditions in relation with wave profiles in terms of different lengths and steepness. The tool is applied to several ship typologies and a special attention in the investigations is given to transversal metacentric height GM and to the maximum righting arm GZmax since, in some proposals, these are the parameters assumed as indicative while performing first and second level vulnerability analysis for pure loss of stability.

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Traditional engine-propeller matching techniques are mainly based on nondimensional parameters analysis: Thrust/advance coefficient or torque/advance coefficient ratio are the most used variables to assess the ship propulsion point or to match, at each selected ship speed, the selected propeller with the ship engine. The advantages of this robust and well established procedure (standard propeller open water measures only at some pitch ratios around the design configuration, availability of large databases and extrapolation laws) however, turn into the drawbacks for the inclusion of different constraints and objectives, further than the minimum fuel consumption, in the matching algorithm. On the other hand modern numerical tools and available hardware resources let to partially substitute, in the design stage, experimental campaigns and to collect large amount of information on propeller performances, including cavitation. In this sense numerical computations make out of date approaches just developed to overcome the deficiency of experimental measures. On the basis of these numerical data new algorithms for the engine-propeller matching can be developed capable of investigate different objectives and the influence of different constraints on the traditional optimum points.

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