Knowing the process of generating exhaust emissions and the determination of influential parameters are important factors in improving two-stroke slow-speed marine engines, particularly for further reductions in fuel consumption and stringent regulations on the limitation of nitrogen oxide emissions. In this article, a model of a marine low-speed two-stroke diesel engine has been developed. Experimental and numerical analyses of the nitrogen monoxide formations were carried out. When measuring the concentration of nitrogen oxides in the exhaust emissions, the amount of nitrogen dioxide (NO₂) is usually measured, because nitrogen monoxide is very unstable, and due to the large amount of oxygen in the exhaust gases, it is rapidly converted into nitrogen dioxide and its amount is included in the total emission of nitrogen oxides. In this paper, the most significant parameters for the formation of nitrogen monoxide have been determined. Model validation was performed based on measured combustion pressures, engine power, and concentrations of nitrogen oxides at 50% and 75% of maximum continuous engine load. The possibilities of fuel consumption optimization and reduction in nitrogen monoxide emissions by correcting the injection timing and changing the compression ratio were examined. An engine model was developed, based on measured combustion pressures and scavenging air flow, to be used on board by marine engineers for rapid analyses and determining changes in the concentration of nitrogen oxides in exhaust emissions. The amount of nitrogen oxide in exhaust emissions is influenced by the relevant features described in this paper: fuel injection timing and engine compression ratio. The presented methodology provides a basis for further research about the simultaneous impact of changing the injection timing and compression ratio, exhaust valve opening and closing times, as well as the impact of multiple fuel injection to reduce consumption and maintain exhaust emissions within the permissible limits.

Due to growing environmental concerns and stringent emissions regulations, optimizing the fuel consumption of marine propulsion systems is crucial. This work deals with the potential in an LNG ship propulsion system to reduce fuel consumption through controlled load distribution between engines in Dual-Fuel Diesel Electric (DFDE) plant. Based on cyclical data acquisition measured onboard and using an optimization model, this study evaluates different load distribution strategies between setups according to the optimization model results and automatic (equal) operation to determine their effectiveness in improving fuel efficiency. The analysis includes scenarios with different fuel types, including LNG, MDO and HFO, at different engine loads. The results indicate that load distribution adjustment based on the optimization model results significantly improves fuel efficiency compared to conventional methods of uniform load distribution controlled by power management systems in almost all load intervals. This research contributes to the maritime industry by demonstrating that strategic load management can achieve significant fuel savings and reduce environmental impact, which is in line with global sustainability goals. This work not only provides a framework for the implementation of more efficient energy management systems on LNG vessels, but also sets a benchmark for future innovations in maritime energy optimization as well as in the view of exhaust emission reduction.

Marine propulsion shafting systems are exposed to torsional vibrations originating from excitations in their prime movers and propellers. It is essential to analyse their steady state response in the earliest stage of ship design. The paper describes the implementation of SimulationX software based upon simulation modelling for these calculations. This software can be used either by the design office of the shipyard or by the classification society for verification within the plan approval phase. Some specifics of the input data preparation are briefly discussed. In addition, the simulation results depend on the modelling approach chosen. For these reasons, the real two-stroke Diesel engine ship propulsion system was chosen and several different models were implemented for system modelling. SimulationX calculation results are compared with those of two well-known and field-proven programs that use an analytical approach. Finally, the results are compared with the measurements performed on the actual newly built ship. Discussion reviews the selected SimulationX model, and its verification and validation in the case of engine cylinders with normal ignition.

The implementation of a system for the acquisition, transferring and processing of data essential for marine engine diagnostics is the basis of condition maintenance. Determining the most influential operating parameters, and conducting monitoring, analysis and taking action based on expert knowledge prevents downtime due to possible malfunctions. Timely corrections and replacements of worn parts based on condition diagnostics enable maintenance planning, which reduces the frequency of maintenance and the accumulation of unnecessary spare parts in warehouses. For research purposes, a system for remote data collection from electronically controlled marine engines was developed and applied. The system was installed on a four-stroke high-speed propulsion engine from a ferry, and the operating parameters of the engine were monitored during regular sailing in order to detect irregularities and possible failures at an early stage. The measurement system monitored the parameters obtained through the electronic engine control module via the J1939 protocol, and in this paper, the following relevant engine parameters were analyzed: engine speed, boost pressure, fuel consumption and engine load at the current speed. The analysis included the creation of trend diagrams to present the distribution of the minimum, median and maximum values of each parameter of all the measurements performed. This study also examined the simulation of the faults of the high-speed four-stroke marine engine model. By utilizing sensor data from critical system components, this research investigated different scenarios. The analysis aimed to elucidate the impact of these faults on engine performance. Based on the analyses of the relevant operating parameters of the engine, diagnostics were carried out.

Maritime traffic complexity (MTC) is a term that has gained increased importance in the last decade in the maritime safety domain. It is a concept for understanding navigational safety and operational challenges in congested maritime environments. Although research interest in MTC has grown, it is a concept that remains fragmented, with various interpretations of definitions, indicators, and modeling approaches present in the literature. This study presents a comprehensive literature review and bibliometric analysis to synthesize the current state of research on MTC as a scientific construct and clarify its conceptual foundations from an analytical perspective. In accordance with PRISMA guidelines and systematic literature review (SLR) methodology, relevant studies were identified and screened across major scientific databases. A detailed analysis was conducted on 40 scientific publications. The findings indicate that most existing MTC models rely mainly on Automatic Identification System (AIS) data and corresponding derived metrics. MTC is primarily assessed through geometric vessel–vessel interactions, relative motion parameters, and collision-risk indicators. Bibliometric analysis demonstrates a rapid increase in scientific interest in this topic since 2015, with research concentrated in several leading journals. The study identifies a significant methodological limitation in current frameworks, which often overlook the heterogeneity of marine traffic, environmental conditions, vessel reliability, and human factors. Therefore, this study highlights the need for a more comprehensive MTC evaluation framework that incorporates operational, geographical constraint-based, environmental, and behavioral variables alongside traditional AIS-based metrics.

Due to growing environmental concerns and stringent emissions regulations, optimizing the fuel consumption of marine propulsion systems is crucial. This work deals with the potential in an LNG ship propulsion system to reduce fuel consumption through controlled load distribution between engines in Dual Fuel Diesel Electric (DFDE) plant. Based on cyclical data acquisitioning measured on board and using an optimization model, the study evaluates different load distribution strategies between set up according to the optimization model results and automatic (equal) operation to determine their effectiveness in improving fuel efficiency. The analysis includes scenarios with different fuel types, including LNG, MDO and HFO, at different engine loads. The results indicate that load distribution adjustment based on the optimization model results significantly improves fuel efficiency compared to conventional methods of uniform load distribution controlled by power management systems almost in all load intervals. This research contributes to the maritime industry by demonstrating that strategic load management can achieve significant fuel savings and reduce environmental impact, which is in line with global sustainability goals. This work not only provides a framework for the implementation of more efficient energy management systems on LNG vessels, but also sets a benchmark for future innovations in maritime energy optimization as well as in the view of exhaust emission reduction.