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This paper presents an analysis of the acceleration of a fast boat using a simulation model. Mathematical equations of ship motion dynamics with two types of propeller capabilities are developed using MATLAB and Simulink as simulation tools. The equations are extended to include the acting thrust, resistance, propeller’s performance curves, and the PID governor curve for the acceleration manoeuvre. The application models the dynamic differential equations representing the vessel dynamics in one degree of freedom. MATLAB code was used to develop the ship acceleration as a multibody system. Modules of hydrodynamic forces, resistance, moments, and propeller performances were implemented to simulate the ship manoeuvring process. A comparison of the results for the boat’s propulsion performance with two different propellers and the characteristics of the PID governor, which controls the fuel dose in the gas turbines, was carried out. We present a summary including a comparative analysis of the results for the boat dynamics with and without the PID governor. The results obtained here confirm significant discrepancies between the results of numerical simulations with and without the PID governor.

In the process of designing a marine propeller, hydroelasticity effects are neglected in most cases, due to the negligible influence of the blade’s deformation on its hydrodynamic characteristics. However, there are cases where the impact of hydroelasticity is crucial, for example in the case of high skew-back propellers or heavy-loaded composite propellers. Furthermore, the importance of composite propellers is growing due to their wide range of application, for instance in naval ships and unmanned vehicles. Although structural models and two-way fluid-structure interactions are implemented in most commercial CFD solvers, their relevance to the design process is severely limited due to the high computational cost for a single iteration. An effective solution would therefore be to implement a two-way fluid-structure interaction model in the lifting surface software, which is commonly accepted as a design tool due to its relatively low computational time and its applicability to multi-criteria optimisation. This paper presents the results of hydrodynamic analyses of an elastic propeller carried out using in-house software based on the lifting surface flow model, and extended with the FEM model for the blade structure. The results are compared with experimental measurements and computational analyses with the commercial RANS solver STAR-CCM+.

There has been a rapidly growing interest in the use of composite and polymer materials for the construction of marine propellers for over 20 years. The main advantages of these materials are a reduction in the weight of the propeller, increased efficiency due to the hydroelasticity effect, a reduction of the hydroacoustic signature, and a cost reduction for serial production. This paper presents an overview of diagnostic methods that can be applied at the design level and during the operation of marine propellers made of polymeric materials. Non-invasive contact and non-contact-based diagnostic techniques for evaluating the technical state of the propeller are reviewed, and the advantages and disadvantages of qualitative and quantitative methods are identified. Operational diagnostic procedures for propellers are areessential for the safety of vessels at sea. Finally, the structure of a diagnostic system is proposed. It combined diagnosis process with the genesis of damage and the prognosis of the technical condition, i.e. production and in-service diagnostics.

The study presents the evaluation and comparative analysis of engine shaft line performance in maritime transport ships of the same type. During its operation, a technical system performs functions for which it was designed. It goes through different states. Dynamic state changes of a rotational system can be identified by means of its vibration measurement. For this purpose, a research was carried out which involved recording vibrations of the analysed rotational systems. The recordings were used for calculating selected characteristics in the time-domain, where one of the most unique is the value of the normalized mutual correlation function. On the basis of the concentration values, the characteristics which unambiguously determine the ability state were selected for further studies. Then an identification method for rotational system non-coaxiality was proposed. The method involves using fuzzy clustering. According to this method the values of input signal characteristics were used to formulate fuzzy clusters of system ability and inability states. The method can be used for identifying the current state of the system. The study presents the results of the application of this method in engine turbine shaft lines of minesweepers, with the rotational system selected as an example. It needs to be noted that the efficiency of identifying the operating state of the system with this method is higher than with other methods described in the literature by authors who deal with this issue. The research results have a significant impact on the evaluation of mechanical properties of the studied objects and directly affect operational states of mechanical systems, including those installed in minesweepers, thus determining their reliability.

The paper presents examples of vibration performances of the naval propulsion systems. It describes the methodology of preparation for measurement, used gauges and their restrictions. The necessity of synchronous measurements had been justified. The work contains also samples of analysis, to facilitate the reader with the components of amplitude-frequency spectra of naval propulsion systems. An overview of the existing normative documents had been presented. At the same time limitations of applying of them during technical monitoring of marine propulsion systems had been presented.

ABSTRACTThe paper presents an analysis of the dynamics of the shaft line of landing ship manoeuvre during grounding at a landing area. The work characterises the specific features of shallow water interactions on the propeller operation. There is a characteristic structure of the ship's propulsion system. Potential operational hazards arising from the problem of grounding and descent from shore shoals of a landing ship have also been identified. A model of sandy water interaction on propellers’ torque was proposed for the dynamic calculations of shafts’ loads. The results of the simulation of torsional vibrations on the shoal area are presented as well.

ABSTRACTThis article presents the possibility of evaluating the technical condition of common rail fuel systems injectors using the vibration method. The other most successful methods of diagnosing the common rail injectors were described. Marine diesel engine common rail injection installations had been characterised. Results of tests obtained during vibration measurements were presented as well. The results confirm the possibility of determining the technical condition of modern diesel engines injectors without the need of engine stopping. The results are especially important for marine engines without indicating cocks or thermoelements allowing measurements of exhaust gases temperature on each cylinder.

The paper presents operational problems in diagnosing the propulsion system of motor-sail yachts. The advantages and operational problems are presented in the paper and the specificity of use of the propulsion systems. It is shown here solutions to meet the requirements of the marine environment. There are shown exemplary damages resulting from operational errors of crew use. It is proposed program of sea trials, which further operation would be an indispensable diagnostic tool supporting the reliability and safety of the yacht at sea.

Naval propulsion systems are characterized by a high degree of complexity within a single system and a large variation between the solutions applied to individual vessels. In this situation, issues relating to the comprehensive diagnostic is a serious problem. Diagnostics models are useful to made the this problem easier. It should be emphasized that it is impossible to develop a universal model correct for all types of vessels. The paper presents general guidelines for the creation of diagnostic models. The results of first stage of studies on diagnostic model covers unit equipped with a twin-engine twin-shaft drive system had been presented.Introduction Changes of technical state of the machine occur as a result of its response to changes in the energy emitted by them. If qualitative and quantitative parameters of this energy are known diagnostician after proper analysis is able to determine the technical condition of the machine. It can be concluded that the technical diagnostics is a test of object response to the impact of energy causing change of its technical condition [9]. As far as the destruction of the object model is concerned we find that the degree of wear of the machine is proportional to the energy dissipated from it.

In this paper an analysis of the stress state of the hull of the ship Kormoran II loaded by non-contact mine explosion were performed. An empirical description of the pressure wave from the non-contact TNT explosion loads reported by authors such as RH Cole T. L. Geers and K.S. Hunter was used. The way of modeling the pressure wave using the acoustic medium implemented CAE programs was shown. The paper presents the results of pressure distribution on the hull of the ship Kormoran II at selected time points from TNT explosion under the keel of the ship. The paper presents detailed results of the stress state in the selected nodes, for example on the frame of main motor construction.

The paper presents a model of dynamics of six-cylinder inline diesel engine executed in the Matlab software. The basic equations necessary to describe the forces acting during the engine operation was presented. Application of some simplifications allowed to present proposal of a mathematical model of the engine, which allows analysis of changes of forces in the crank-piston system, depending on the technical condition of the fuel system elements. Operational experience indicate that one of the most common cause of failure of the fuel system is reduced fuel charge supplied by a defective fuel injection pump. Calculations of gas forces had been replaced by the implementation into the model indication charts recorded from tests on a engine test stand. Simulation results were presented as a result of FFT spectra of modeled tangential forces.

A correctly designed machine is characteristic of low vibration values. However wear processes occur during its operation. They are accompanied by a lack of balance of its rotating parts and elements, which results in non-coaxiality of shafts. For this reason energy and dynamic load resulting from machine vibrations grows. In this case cause and effect are mutually connected by feedback, that inevitably leads to occurrence of a failure. This paper presents results of investigations carried out on the basis of vibration analysis of propulsion systems installed on 207P minesweepers. In view of specific features of their operation it is very important to ensure high level of reliability for them. For this reason was done an attempt to develop a method intended for identifying non-coaxiality of shaft line systems of engines propelling the ships. 16 characteristic features of recorded vibration signals were selected. As any of them has not satisfied criteria assigned to features which unambiguously determine state of reliability of shaft line systems, the investigations have been continued and as a result a novel method for non-coaxiality identification was proposed. The method consists in determining unserviceability clusters and assumes that characteristic features are of a concentrated character. This way a non-coaxiality of main engine shaft lines of 207P minesweepers could be detected. This paper presents the proposed method and results of its application to the case in question.

The paper presents problems of modeling the ships hull loaded by the shock wave associated with non-contact underwater explosion. These problems are mainly due to the rapidness of the phenomena and the need of taking into consideration that processes go on at the border of different centers (water medium-ships hull-air). The article presents analysis for describing the parameters of shock wave as well as preliminary results of virtual tests of the steel hull subjected to an impulse load.

Minehunters are subjected to specific sea loads due to waving and dynamical impacts associated with underwater explosion. Sea waving can be sufficiently exactly modeled by means of statistical methods. Much more problems arise from modeling impacts due to underwater explosion. Knowledge of a character of impulse loading which affects ship shaft line can make it possible to identify potential failures by means of on-line vibration measuring systems. The problem of influence of sea mine explosion on hull structure is complex and belongs to more difficult issues of ship dynamics. Underwater explosion is meant as a violent upset of balance of a given system due to detonation of explosives in water environment. A paper presents a proposal of identification of a degree of hazard the ships hull forced from underwater explosion. A theoretical analysis was made of influence of changes of hull structure in vicinity of hull. The main problem of naval vessels is a lack of dynamical requirements of stiffness of the hull. Modeled signals and hull structure were recognized within sensitive symptoms of three sub models: model of hull structure, model of impact and model of propulsion system. All sub models allow testing forces and their responses in vibration spectrum using SIMULINK software and FEM models.

Ship shock tests have been conducted for shock qualification of hull integrity and proper operation systems and subsystems. The ship shock trial identifies design and construction and it also validates shock hardening criteria. The main problem is that ship shock trials are costly. Numerical modeling and simulation, using FEM, may provide information to look into the details of fluid model, dynamic characteristics of ship hull and its internal component. The ship shock modeling and simulation has been performed and the predicted results were compared with ship shock test data made into sea trials. The preliminary studies of shock analysis approach are presented and the important parameters are discussed

Ship shock tests have been conducted for shock qualification of hull integrity and proper operation systems and subsystems. The ship shock trial identifies design and construction and it also validates shock hardening criteria. The main problem is that ship shock trials are costly. Numerical modeling and simulation, using FEM, may provide information to look into the details of fluid model, dynamic characteristics of ship hull and its internal component. The ship shock modeling and simulation has been performed and the predicted results were compared with ship shock test data made into sea trials. The preliminary studies of shock analysis approach is presented and the important parameters are discussed.