This paper presents the results of a study aimed at improving the accuracy of the recently published SATUFER method for estimating the dilution level of lubricating oil with diesel oil. It used the measured value of oil kinematic viscosity and known reference values of kinematic viscosity at the same temperature for fresh lubricating oil and diesel oil fed to the engine. This method was based on the REFUTAS algorithm for the analytical determination of the viscosity of a mixture with known mass shares and viscosities of the components. The correction factor K used in the formula estimating the concentration of diesel in the lubricating oil was Pareto optimized in the range 0.0–1.0 to minimize the value of the maximum absolute fitting error, δmax, and maximize the coefficient of determination, R2 , determined for the function estimating the degree of dilution of the lubricating oil with diesel relative to a known reference value. The analysis used a dataset of kinematic viscosity values for blends of SAE 30 or SAE 40 viscosity grade lubricating oil with B7 diesel oil at concentrations of 0, 1, 2, 5, 10, 20, 30, 40, 50, 75, and 100% m/m diesel oil in the blend at temperatures of 40, 50, 60, 70, 80, 90, and 100 °C. For each mixture, an estimated dilution level was calculated using the SATUFER method, and the result was presented with a known reference value. The results of the analysis for the assumptions presented in this article indicated that the initial value of the K-factor for further analysis was K = 0.53 instead of the initial value of K = 0.80 adopted in the REFUTAS method, which was the basis for the proposed and developed SATUFER method.

The seakeeping performance of ships is a critical factor in ship design, influencing both safety and efficiency. This paper examines the effect of two stern shapes (i.e., transom and canoe) on the response of the heave and pitch motions of a ship. The original U-shaped stern is redesigned into a curved shape by adjusting the longitudinal and transverse control points of the hull. The curvature starting point is positioned at 0.04L from the stern perpendicular toward the bow. After designing and constructing the modified model, the response amplitude operator (RAO) of the heave and pitch motions for regular waves in a towing tank test is analyzed under three different speeds and six wave frequencies. The results reveal that the transom stern shows slightly higher heave RAO values than the canoe stern, while demonstrating improved performance in pitch motion. Overall, the canoe stern exhibits a 5–15% reduction in total motion response compared with the transom stern.

The coastal zone is a very dynamic area, hence the need to monitor changes occurring within it. The aim of this study was to use video monitoring along the Polish coast of the Baltic Sea to analyze changes in beach width depending on the hydrodynamic conditions prevailing in the analyzed period. The research was conducted from October 20, 2022, to July 31, 2023. Snapshot images were collected in Jarosławiec. The measurement of beach inundation in the collected images was made using the FIJI is just ImageJ program, designed for image analysis. This research included the analysis of three issues: (1) change in beach width (2) statistical analysis of hydrological data and (3) correlation between beach width and hydrological parameters. Analyses showed that the greatest beach inundation occurs in winter and spring. The height of a significant wave was usually equal or less than 2 m. The dominant direction of waves was west. Most often, the maximum sea level during storms reached from 510 to 540 cm.

This article presents a preliminary method for selecting a standard bulk carrier intended for the loading and transportation of polymetallic nodules in the Clarion–Clipperton zone. The selection process is driven by key operational parameters, including the ship’s deadweight tonnage (DWT), the number of required bulk carriers, the loading time, and the annual fuel consumption. The mathematical models are developed for each parameter as a function of DWT, and a composite objective function is formulated to balance these criteria. The optimization task is performed using the Solver add-in within Excel. The results indicate that bulk carriers with a DWT between 12,000 and 24,000 tons are suitably aligned with the selected parameters, with optimal values depending on the prioritization of operational factors. Accordingly, handysize bulk carriers may be considered appropriate for the transportation of nodules from the Clarion–Clipperton zone to the discharge port.

This paper presents the electromagnetic design and evaluation of a low-voltage permanent magnet-assisted synchronous reluctance motor (PMaSynRM) intended for a compact underwater thruster in USV applications. The study addresses a propulsion motor required to operate at 3000 rpm and 0.6 N m under a maximum direct-current (DC) supply voltage of 14 V, with a rated phase current of 15 A (peak) and a short-time overload capability of 30 A (peak). Following a review of electrical machine topologies used in compact underwater propulsion, PMaSynRM is adopted as the target machine topology for a constrained low-voltage thruster drive. The design procedure focused on the electromagnetic sizing of a 24-slot, 4-pole machine under strict voltage and geometric limitations, including the selection of the main dimensions, winding configuration and rotor structure. A finite element analysis (FEA) was then used to evaluate magnetic saturation, shaft torque, torque ripple, efficiency and loss distribution under rated and overload conditions. The results show that the designed machine meets the required operating point, while the application of a stator skew reduces torque ripple with only a slight reduction in average torque. The highest efficiency is obtained in the vicinity of the rated operating region, whereas the overload operation is limited by increased magnetic saturation. At a rated current, copper losses dominate the loss balance, while core and excess losses remain significantly lower. The results indicate that PMaSynRM is a viable design option for compact low-voltage underwater thruster drives subject to strict voltage and space constraints.

Physical risk factors on ships are physical hazards arising from the working environment that threaten the health and safety of seafarers, and the assessment of the risks arising from these hazards is very important for sustainable maritime transportation. With this in mind, this study aims to analyze physical risk factors such as noise, thermal comfort conditions, static electricity, vibration, pressure, lighting conditions, weather conditions, and radiation on ships with the AHP and Fine-Kinney methods. According to the findings of this research, slippery floors, radiation, and noise are the most common physical risk factors that personnel working in the ship environment are exposed to. As a result of the weighting made by the analytical hierarchy process (AHP) method, the effect of these factors on occupational health and safety is found to be higher than that of other factors. Risk scoring performed with the Fine-Kinney method revealed that these factors were mostly at risk levels that “require precautions” or “require urgent intervention.” The findings show that physical risk factors affect not only employee health but also operational efficiency and long-term maritime safety. In this context, it is of great importance for ship operators to prioritize and evaluate these risks for the goal of sustainable and safe maritime transportation. In addition, the obtained findings provide important data for improving ship design processes, ergonomically reorganizing working conditions, and systematically monitoring risks.

This cross-sectional observational study evaluated the prevalence and determinants of metabolic syndrome (MetS) among 1432 seafarers aboard 76 trade vessels in the Red Sea. Data collection involved onboard examinations and remote or email-based protocols, encompassing anthropometric, biochemical, and lifestyle assessments. The prevalence of MetS was 27.8%, with higher rates among officers (33.5%) than among ratings (24.8%). Central obesity (81.3%) and elevated blood pressure (72.4%) were the most common components. Multivariate analysis identified age of 40 years or older, officer rank, and physical inactivity as significant predictors. Based on these findings, a novel three-phase maritime health framework is proposed, integrating digital screening, artificial intelligence (AI)-driven risk stratification, and continuous telemedicine monitoring. This model addresses operational challenges in surveillance compliance and aligns with the shipping sector’s digital transformation, providing a predictive and preventive approach to chronic disease management at sea.

Maritime autonomous surface ships (MASS) introduce operational paradigms for which no standard GUI designs or established operator roles currently exist. Conventional usability testing (UT) methods involving users are predominantly qualitative, limiting the precision of evaluations. While experienced system designers can partially compensate for this limitation, in the contexts of MASS—where operational conditions and operator roles are unprecedented—their experience offers less guidance. This underscores the need for UT methods that can efficiently support makers in developing and adapting schemata that remain well aligned with those of MASS operators. Leveraging recent advances in eye-tracking, this paper presents a conceptual UT method—a maker–user schemata alignment analysis—designed to support the research and development of GUI design for MASS. A proof-of-concept demonstration using scripted interactions illustrates how the method can reveal differences between makers’ and users’ schemata and quantify the extent of these divergences. The conceptual demonstration suggests the potential of the proposed method in providing both qualitative and quantitative assessments of maker–user schemata alignment, establishing a foundation for rigorous, human-centered evaluation frameworks as operational MASS systems are developed.

The risk management process in an organization consists of several stages, during which various methods, techniques, and tools are used. Their selection depends on the specifics of the company and the possibility of their application, given the current space-time conditions and the possession of specific resources. The most popular tools are SWOT analysis, brainstorming, and methods of studying the environment, etc. Sometimes, however, in a more complicated situation in an organization relating to the occurrence of risk, these methods may prove insufficient. They can be supported by solutions based on the Haddon model, which is based on several important factors discussed in detail in three dimensions: before a given event (risk), during its duration, and after the event. The main objective of this paper is to discuss the Haddon matrix tool that can be used in the risk management process at the stage of both risk identification and response. The paper also focuses on the practical application of the Haddon matrix for frequently occurring risks in an organization. Moreover, the application of the Haddon matrix for one of the risks occurring in a selected production company is presented.

This study evaluates the quantitative effects of laser cladding technology on the refurbishment of valve cages and exhaust valves in a Deutz TBD645 internal combustion engine. Laser powder cladding with Inconel 625 alloy is applied to GGG40 cast iron, and process parameters are optimized to minimize Fe dilution. The method enables low dilution, a homogeneous crack-free microstructure, reproducible valve seat geometry, and stable surface roughness after machining. Quantitative results indicate that laser cladding reduces unit repair costs by 70–80%, while total overhaul expenses decrease by 40–60%. For exhaust valve refurbishment, yearly savings of EUR 125,000–200,000 are achievable for fleets repairing 50–80 components per year. Despite process costs of EUR 250–383/kg, economic benefits remain strongly positive due to reduced downtime and extended component lifetime. The results confirm that laser cladding is an effective method for marine engine overhauls, delivering measurable economic benefits and supporting circular economy objectives in line with IMO 2030 and EU Green Deal targets.

This article presents simulation scenarios that enable a reduction in the rolling surface wear of independently rotating wheels of a four-axle traction vehicle on a curved track with a small radius of curvature. Based on current knowledge, a simulation model of a light four-axle traction vehicle with independently rotating wheels driven by asynchronous AC traction motors is constructed. Kalker’s nonlinear theory is used to describe the contact between the wheels and the rails. The operation of the electric traction motors is controlled using the PWM method. The influence of the stiffness of the first-stage suspension in the vehicle on the wear of individual wheels of the vehicle model is analyzed. It is shown that it is possible to simulate the magnitude of the driving torques acting on individual wheels of the vehicle model, ensuring the reduction of the wear process of the rolling surface of the vehicle wheels on a curved track. Information on the magnitude of these torques could be used to control the movement of the real vehicle

Dear Readers, you hold in your hands the last issue of the quarterly in 2025 (No. 84), concluding another year of our publishing activity. The articles collected in it address contemporary and diverse research issues, reflecting contemporary technological, organisational, legal and environmental challenges, and demonstrating the interdisciplinary nature of the research carried out, relevant to both science and business practices. The current issue features papers on safety and reliability, including risk analyses of hydrogen infrastructure, state-of-the-art radiation monitoring systems using machine learning methods and human reliability issues in industrial maintenance. Articles in the field of mechanical and materials engineering are also an important part of the issue, presenting tests on structural components and the evaluation of the properties of aluminium alloys for marine applications. Transport, logistics and legal issues are also prominently featured, including paid parking zones, pedestrian safety, the reliability of supply chains operating under uncertainty and the transport of dangerous goods in light of international maritime law regulations. Additionally, this issue discusses studies on offshore wind energy development in Poland and modern control algorithms for ship generators. As we close the year 2025, I would like to wish you a splendid 2026, prosperity in your research and professional plans, satisfaction with the challenges you face and further scientific success in the coming year. I hope that this issue will inspire further research and scholarly discussion. I would like to thank the authors and reviewers for their contribution to the high level of the publication. With regards, Editor-in-Chief dr inż. Paweł Prajzendanc

Analyzing available literature, both scientific and commercial, the lack of a simple and quick methodology for determining the dimensions of sailing yachts might be noticed. This method could be used to accelerate the optimal design of modern sailing yachts. When a sailing yacht is designed, many factors need to be taken into consideration, e.g., autonomy, number of crew members, limitations of road transportation, construction and operating costs, yacht speed, and safety of navigation (stability and seaworthiness). Based on the analysis of these criteria, the main dimensions of the yacht need to be determined. In order to quickly select the most optimal type of yacht that will meet the expectations of the customer, several or a dozen variants of the yacht size should be made. Approximate functions are necessary to quickly determine the calculated coefficients depending on the length of the waterline of the hull. The dimensions of the sailing yacht and its coefficients have a decisive influence on the speed of the yacht. The methodological approach used in this article is to use a quick and easy-to-use regression method to present an analysis of the design dimensions and coefficients of a classic sailing yacht. Sailing yachts’ data of 35 similar yachts built between 2010 and 2019 were collected. The overall length range from 6.93 to 21.8 m and the obtained results, without loss of accuracy, are interpolated within the range. The main contribution of this article is to develop simple regression equations to calculate the main dimensions and coefficients of a sailing yacht in many variants without unnecessary delay. These can be used by yacht designers and other people interested in yacht design.

This paper presents a numerical approach to evaluating ship waterplane hydrostatic parameters. The analysis focuses mainly on determining the longitudinal moment of inertia, computed relative to both the aft perpendicular and the midship section. This study is performed for a 9000 DWT general cargo ship with a design draught of 7.5 m. The results show small differences in the longitudinal moment of inertia (IL), which subsequently affect the moment-to-change trim (MTC). However, the study demonstrates that these differences, resulting from the selected point of origin, have a negligible impact on trim calculations. Despite minor mathematical discrepancies, their overall effect is insignificant, with IL deviations within ±0.1%, confirming that these variations do not influence practical trim calculations.

The subject of this paper is to discuss and analyze the noise-induced hazards on ships. For this purpose, factors such as noise levels in different accommodations during various engine operations, methods of protecting crews from the harmful effects of noise, and the impact of noise on health and work are examined. Noise level tests are conducted at different locations on the vessel using a sound meter. Subsequently, a statistical analysis of the obtained results is carried out and the main statistical characteristics are determined and interpreted. The conducted research demonstrates in which rooms the standards are met, where they are exceeded, and in which areas hearing protection should be used. The results could be utilized in future research on occupational health and safety