It is my great honour to introduce the latest 56 (128) issue of Scientific Journals of the Maritime University of Szczecin. The current issues contains the latest research in the field of marine technology, transport and logistics. The introductory paper entitled “Practical approach to calculating the hydrodynamic oscillating loads of a ship propeller under non-uniform wake field” has been written by the world-class expert in fluid mechanics, Prof. Hassan Ghassemi, professor of marine engineering at the Amirkabir University of Technology. The article presents selected issues related to hydrodynamic modelling of screw propellers. The publication was prepared in connection with our implementation of the project funded by the Ministry of Science and Higher Education of the Republic of Poland from the fund for science-popularising activities (grant No. 790/P-DUN/2016). The author’s remuneration and costs of publication were covered by the Rector of the Maritime University of Szczecin from funds for international cooperation. I hope that the relevance of the publication will contribute to its attractiveness to all readers interested in optimising the vessel power systems. The Marine Technology and Innovation section gathers articles devoted to the studies of austenitic-ferritic steel on cavitation erosion, modelling of brass/steel ingot structures, determining the properties of composites with glass-recycled polyester additives and assessing the quality of welding. In the section on Navigation and Maritime Transport, articles are devoted to communication using the R-Mode receiver for medium frequency signals and analysing the fairway capacity impacted by LNG carrier transit. The Transport Engineering section includes articles on marine emergency management digital platforms and analysing the risk of operating fishing vessels with regard to the possibility of damaging underwater cables. We are almost at the end of another publishing year which bears the fruit of higher bibliometric indices, denoting the increasing quality of the quarterly. The annual journal citation chart in the Web of Science Core Collection presented in Figure 1 indicates a growing recognition of research results published in the Scientific Journals of the Maritime University of Szczecin. According to Web of Science statistics for 1132 articles indexed in the Core Collection database, the average citation of each article is 0.45. This is a very good result, bearing in mind that out of the 507 citations, 388 (76%) citations have been generated from January 1, 2015 (as of 05.12.2018). In addition, it is worth emphasising that on September 25 we received a message from the Scientific Journals Evaluation Team of the Index Copernicus International saying that – based on the information submitted in our journal’s questionnaire – Index Copernicus experts have calculated the Index Copernicus Value (ICV) for 2017: ICV 1017 = 100.00. The ICV for 2017 is shown on the full list of indexed journals at the ICI Journals Master List 2017. The values of the indicator from the previous three years were respectively ICV 2014 = 79.38, ICV 2015 = 87.49 and ICV 2016 = 90.35 (Journals Master List, 2018). The above indicators show that the quarterly is constantly improving its prestige (Chybowski 2016a; 2016b; 2017). I can also say with full confidence that during the four years of my duties as editor-in-chief the assumptions that I set and promised to fulfil to the former Rector of the Maritime University of Szczecin, Prof. Stanisław Gucma – to whom I am grateful for the trust granted to me then, have been achieved. I would like to express my thanks to the authors – we would not be publishing without their contribution and could not achieve such high and constantly rising bibliometric indicators. Moreover, I would like to highlight that the constant improvement of our journal’s publishing quality is a result of hard work of the editorial team, members of the Scientific Board, reviewers and university authorities through their policy supporting the development of our quarterly. I would like to thank all of those persons. I believe that our journal is on the right track to joining the group of publications included in the Journal Citation Reports and being finally noted in the Impact Factor® Index, which is a realistic goal for the next 2–5 years with the right strategy. I would like to use this opportunity to encourage authors from all over the world to publish the results of their research in the Scientific Journals of the Maritime University of Szczecin. All readers are welcome to visit our refreshed website. Going to http://scientific-journals.eu/ grants access to the electronic version of the current issue and archival volumes of the journal.

Propellers usually operate in the ship’s stern, where the inflow of the non-uniform wake generates oscillating loads and changes the hydrodynamic performance. Therefore, determination of the forces on propellers and hydrodynamic performance due to a non-uniform wake field are the challenging problems for naval architects and hydrodynamists. The main objectives of the present study are to assess the hydrodynamic performance for a single blade and all the blades. The propeller is a B-series propeller under non-uniform wake field behind the Seiun-Maru (hereafter SM) ship hull. A practical approach is employed to calculate the hydrodynamic oscillating loads of the ship propeller under a non-uniform wake field. Results of the computations on the propeller behind the SM ship, due to a non-uniform wake field, are presented and analyzed using classical mathematical methods over a single cycle. The results show that a variation of thrust with the discussed parameters is the same as that shown for torque, also the blade-frequency of the total force, thrust and torque is an increasing function of radial sections, whereas these parameters decrease with increasing radial blade sections.

Building Information Modelling (BIM) technology is briefly reviewed in this paper in order to demonstrate the potential application of this methodology in the shipbuilding industry. A properly-created BIM model is a valuable tool for the designers and future users of a given investment. BIM models improve the design and execution process and serve as a tool to maintain and manage any asset. The purpose of this article is to propose to use BIM technology in other construction industries, including the shipbuilding industry. A properly-constructed BIM model of a ship can be used both by the shipyard, as well as by the ship owner or target users. The information contained in the BIM model of the ship can be used to optimize the execution phase in the shipyard, as well as provide valuable assistance to the user of the unit during its operation.

Cavitation is a one of many wear mechanisms which are related to the flow of liquid. It is one of the most destructive wear methods for stainless materials. The local changes in the pressure of the liquid stream related to the flow across the metal component cause straightening of the surface area, as well as its erosion and the formation of pits on the surface layer. The erosion value of cavitation is related to the material’s microstructure, the geometry of the element, the phase composition of the material and the surface roughness. In this paper the investigation of the cavitation process for duplex stainless steel has been performed. Samples examined in the first stages of the experiments were not significantly changed, but after a long time the hardness increase was very visible. The result of the cavitation was also cracking along the interphase boundaries, which resulted in the chipping of the material. One of the most important results was a description of the change in the wear mechanisms and its intensity during the cavitation exposure time. At first plastic micro deformation of the material’s surface occurred, then the plastic deformation increased significantly and after some time this resulted in erosion of the material and interfacial boundary decohesion; these two effects increased simultaneously. The last of the mechanisms was mechanical destabilization of the austenite, but the clear result of the mechanical destabilization of the austenite was only observed in the last sample. Martensitic transformation of the material changed the material’s mechanical properties, but for the stainless steels this resulted in electrochemical corrosion of the material, especially through the formation of an electrochemical potential between austenite and martensite.

Polyester-glass composites are widely used in many industries, in various types of constructions, including dynamically loaded ones. This article examines the influence of the content of a glass-polyester recycled additive on the strength properties of layered composites. The recyclate was polyester-glass waste, which was pre-crushed and then milled into the appropriate fractions. Manual laminating technology was used to make the materials. The composite materials were made with a waste content of 0%, 10%, 20% and granulations of ≥ 1.2 mm and ≥ 3 mm. Samples for testing were prepared in accordance with the PN-EN ISO 179-1: 2010E standard (Plastics – Charpy Impact Assessment – Part 1: Non-instrumental impact test). Impact tests of the samples were performed using the Charpy method with the Zwick Roell RKP450 swinging hammer. The test results showed that the addition of polyester-glass recyclate, its content %, and its granulation size, have an impact on the composite resistance to loads in dynamic tests.

The authors of this article have been looking for new parameters and dynamic characteristics which can be applied to the non-destructive testing of welded joints. All the characteristics have been based on the recorded data generated during the vibration tests of welded joints both with and without failures. This article has dealt with the methods of assessing welded joints using either 2D or 3D time-frequency dynamic characteristics. The calculation procedure that was used for analyzing the simultaneous changes of the response modules, registered by acceleration sensors, has been presented. The vibration amplitudes were transformed into a function of time and frequency (simultaneously) and presented over 2D or 3D time-frequency characteristics. The analyses of the characteristics were performed for a plate without a welded joint, for a plate with a non-defective welded joint and for a plate with a defective welded joint caused by edge bonding. Having analyzed and registered the 2D or 3D time-frequency dynamic characteristics it could be noticed that by presenting the responses, analyzed simultaneously against time and frequency, allowed for the evaluation of whether the examined system maintained non-linearity and, at the same time, allowed for the quality of the welded joint to be indirectly assessed. The proposed measurement parameters of the quality of a welded joint can be defined as a dispersion of the colors from the obtained characteristics. The faults (and the vibration nonlinearity) of the welded joints will be bigger if the dispersion is greater.

Metallographic studies performed on a cross-section of static steel ingot allow the observation of the following morphological zones: a) columnar grains (treated as austenite single crystals), b) zone of the columnar into equiaxed grains transformation (CET), and c) equiaxed grains at the ingot axis. These zones are reproduced theoretically by the numerical simulation. The simulation is based on the calculation of both the temperature field in a solidifying large steel ingot and the thermal gradient field obtained for the same boundary conditions. In particular, a new, innovative method based on the mathematical treatment applied to different functions resulting from both the aforementioned fields, are used in the structural predictions. The method developed, firstly for the massive steel ingot, has subsequently been applied to theoretically predict the structural zones in continuously cast brass ingots. In the case of continuously cast brass ingots three different morphologies were revealed experimentally: a) columnar structures, b) equiaxed structures preceded by the CET (sharp transition), and c) single crystals situated axially. The above model for the structural zones prediction is useful in plastic deformation design for: a) steel forging ingots assigned for the crankshafts applied to the ship engines, and b) continuously cast brass ingots assigned for special applications in the shipbuilding industry.

Signals from Global Navigation Satellite Systems are the primary source for Position, Navigation and Time (PNT) information onboard any vessel today. As these signals are prone to interference, a maritime backup system is needed to provide reliable PNT data, R(anging)-Mode is such a system. It utilizes existing maritime radio beacons or base stations of the Automatic Identification System (AIS) by adding ranging components to the legacy signals. The first modified radio beacons transmit medium frequency (MF) R-Mode signals in northern Germany. This paper has described the current state of the authors’ research and development activities at the receiver level for MF R-Mode signals. The receiver platform has been introduced, which was based on off-theshelf components and the implemented algorithms for distance estimation have been explained. Furthermore, the results of the first ranging measurements have been presented, which have shown the general suitability of the R-Mode technology as a source for maritime positioning and timing data.

Liquefied natural gas (LNG), as one of the main sources of clean energy, has witnessed great growth in marine transportation in recent years. Due to the potential catastrophic consequences in case of a vessel traffic accident, the guidelines of the design of an LNG Port and the regulation of traffic management require that a mobile safety zone be set up for the transit of an LNG carrier, that is, a moving safety area around the carrier that excludes other ship traffic. To study the impact of a safety zone on channel capacity, this paper has presented a mathematical model to calculate the impact ratio of a large LNG ship on channel capacity considering different speeds and sailing modes. As a case study, an approach channel to a new LNG port that was developed in Yueqing bay, Zhejiang province, East China, has been analyzed during the concept design of the port with the aim of receiving ships with a capacity of 145,000 m3. Based on the model, the impact ratio on the whole channel and the segmented channel when a carrier arrives at and leaves the berth has been calculated. The methodology can support the job of port design and vessel traffic management to improve the capacity, efficiency and safety of a waterway.

This paper presents human and operational factors related to risk assessment during the operations of crude oil, petroleum products, and liquefied gas transfer between ships, called Ship to Ship (STS) operations. The lessons learned from accidents during STS when both ships are underway show that the most frequent accidents occur due to ship handling errors. Several influencing factors have already been identified, however there is still a need to investigate the human factor. Both human and operational factors are interrelated as the operational factors influence the human stress level. This paper identifies the stressors related to the external pressures imposed on the ship’s staff, which can be limited to improve safety. The preliminary study of the influence of particular elements of human factors, e.g., personality traits and stress levels, on the probability of ship handling error is presented.

With the development of tourism in the inland waters, various types of accidents in the waters have posed a great threat to human life, property, and the environment. This has caused concern in all circles of society. According to water tourism safety issues, and relying on Internet technology, shipping safety, and public safety management theory, this paper has proposed the concept and design plan of an Internet + maritime emergency management platform. This platform includes functions such as the intelligent perception of a ship’s navigation status, the scientific selection of a maritime emergency rescue site, the emergency rescue scene, the online dynamic management of maritime emergency resources, and the online production of a maritime emergency rescue plan. The design scheme has been used in the platform’s development. This paper has taken the application of the Internet + maritime emergency management platform for the Liujiaxia reservoir in the Gansu Province of China as an example. The results showed that the design of the platform that has been proposed in this paper is reasonable and that it can provide scientific, fast and accurate decision information for emergency command in the Liujiaxia reservoir and improve the effective control of the accident site as well as the use of resources.

Accidental damage to underwater cables caused by ship traffic seems to be a current problem. According to the statistics more than 44 percent of such damage is caused by fishing vessels. The reason for the next 14 percent is damage from ships’ anchors. The construction of the underwater installation risk model was based on the determination of the density of the traffic in the area where the installation is located. There are several models used to assess the risk of underwater cable damage requiring the implementation of data on the density of traffic of fishing vessels. For this purpose, they usually use AIS (Automatic Identification System) data or statistical data on traffic density in the areas called fishing squares. The aim of this article was to compare traffic data that was based on two independent systems AIS and VMS (Vessel Monitoring System) and verify the reliability of them. The research was carried out in the area of the Slupsk Bank where an underwater cable has been damaged several times. The authors have demonstrated the need to verify the data from both systems in order to obtain reliable information about fishing vessels.