Availability, reliability and economic sustainability of naval propulsion plants are key elements to cope with because maintenance costs represent a large slice of total operational expenses. Depending on the adopted strategy, impact of maintenance on overall expenses can remarkably vary; for example, letting an asset running up until breakdown can lead to unaffordable costs. As a matter of fact, a desideratum is to progress maintenance technology of ship propulsion systems from breakdown or preventive maintenance up to more effective condition-based maintenance approaches. The central idea in condition-based maintenance is to monitor the propulsion equipment by exploiting heterogeneous sensors, enabling diagnosis and, most of all, prognosis of the propulsion system's components and of their potential future failures. The success of condition-based maintenance clearly hinges on the capability of developing effective predictive models; for this purpose, effective use of machine learning methods is proposed in this article. In particular, authors take into consideration an application of condition-based maintenance to gas turbines used for vessel propulsion, where the performance and advantages of exploiting machine learning methods in modeling the degradation of the propulsion plant over time are tested. Experiments, conducted on data generated from a sophisticated simulator of a gas turbine, mounted on a Frigate characterized by a COmbined Diesel eLectric And Gas propulsion plant type, will allow to show the effectiveness of the proposed machine learning approaches and to benchmark them in a realistic maritime application.

Design and optimization of the propulsion system is a crucial task of the ship design\ud process. The behaviour of the propulsion system, in transient conditions as well as in steady\ud state, is greatly affected by the capability of the control system to manage the available power\ud and to achieve the desired performance in the shortest time.\ud The selection of a proper control scheme is a trade-off between different and conflicting\ud needs. Two of the opposites are: increasing the ship operability by adding more functions and\ud more controls; and reducing the control system development and installation time and cost.\ud In this paper, the rapid prototyping and testing procedure for the development of the\ud propulsion controller of the new Italian aircraft carrier Cavour is presented, using real-time\ud hardware-in-the-loop (RT-HIL) simulation. The procedure is based on a wide use of simulation\ud technology. First, a complete dynamical model of the ship propulsion plant was developed.\ud Then, batch simulation was used to develop the best possible control scheme. Finally, RT-HIL\ud simulation was used to debug the real controller software and to tune the controller parameters\ud before sea trials.\ud The application of the procedure led to a significant reduction in the development phase of\ud the controller design. Furthermore, the adoption of the RT-HIL technology greatly reduced the\ud time spent to tune the control system during the ship delivery phase

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This article focuses on the mathematical model of the pitch control mechanism for a marine controllable pitch propeller, with the aim of describing the dynamic behaviour of this kind of system and its influence on ship performance. Too great a load on the blades can result in high pressures in the actuating system, response delays and control system problems, which are ultimately responsible for most mechanism failures. The behaviour of the controllable pitch propeller actuating mechanism is considered in terms of blade position, oil pressures inside the controllable pitch propeller hub and magnitudes of the forces acting on the blades. In the proposed mathematical model, the forces acting on the propeller blade are evaluated taking into account the yaw motion of the ship, the propeller speed (including shaft accelerations and decelerations) and the turning of the blade during the pitch change. On the basis of the introduced procedure, a controllable pitch propeller numerical model as part of an overall propulsion and manoeuvrability simulator representing the dynamic behaviour of a twin-screw fast vessel is developed. The aim of this work is to represent the ship propulsion dynamics through time-domain simulation, based on which the designers can develop and test several design options, in order to avoid possible machinery overloads with their consequent failures and to obtain the best possible ship performances. In this aspect, the controllable pitch propeller model is an essential design tool.

The paper describes a mathematical model for the dynamics simulation of ship propulsion systems. The model, developed in a MATLAB-SIMULINK software environment, is structured in modular form; the various elements of the system are described as individuals blocks (hull, prime mover, gear, waterjet, etc.) and linked together to take their interactions into account. In this way it is possible to characterize the dynamic behaviour of both the single component and the whole propulsion plant. The model may be used to analyse the system response at off-design and transient conditions. In particular, the developed computer simulation code may be considered as a useful tool to facilitate the correct matching of the prime mover (diesel or gas turbine) to the propulsor (waterjet or propeller) in a wide range of operating conditions. The paper shows the application of the methodology to a cruise ferry used to validate the model results through a full-scale test campaign conducted by the authors during normal operation of the ship.

The design of a dynamic positioning (DP) system is a challenging task with several technical fields involved in the problem solution. Numerical simulation is a powerful tool to aid the designer during the system development and to speed up the design process. This paper presents the simulation methodology adopted to design and test the DP system for a vessel with a standard propulsion configuration. Simulation results and sea trial measurements are compared to illustrate the reliability of the proposed simulation platform.

A turbocharged diesel engine numerical model, suitable for real-time ship manoeuvre simulation, is presented in this paper. While some engine components (mainly the turbocharger, intercooler and manifolds) are modelled by a filling and emptying approach, the cylinder simulation is based on a set of five-dimensional numerical matrices (each matrix is generated by means of a more traditional thermodynamic model based on in-cylinder actual cycle). The new cylinder calculation approach strongly reduces the engine transient computation time, making it possible to transform the simulation model into a real-time executable application. As a case study, the simulation methodology is applied to a high speed four stroke turbocharged marine diesel engine, whose design and off design running data are available from the technical sheet. In order to verify the suitability of the proposed model in real-time simulation applications, a yacht propulsion plant simulator is developed. Numerical results in ship acceleration and deceleration manoeuvres are shown, reducing the simulation running time of 99% in comparison with the corresponding in-cylinder actual cycle engine model.

Heading and speed control for a patrol vessel is addressed by using simple PID regulators. The selection of the PID parameters for both controllers is accomplished by using decoupled linearized model of the original motion equations and LMIs as a design tool. The effectiveness of the resulting controllers is validated on the original dynamic equations and with the presence of external disturbances such as wind, waves, and current.