Dear Readers, I am pleased to present the fourth 2020 issue (No. 64) of the Scientific Journals of the Maritime University of Szczecin. This issue contains the research results and views of the authors of seven articles that are compiled into three subject groups: Civil Engineering and Transport; Mechanical Engineering; and Economics, Management and Quality Science. The Civil Engineering and Transport section begins with an article that examines the relationship between the occurrence of failures in selected types of buses and the time of their occurrence using the public transport of Lublin as an example. The second article presents the current state of research on the technical, legal and administrative problems that need to be solved in order for unmanned ships to be used widely by society. There are four papers in the Mechanical Engineering section. The first paper presents a numerical study of the hydrodynamic parameters of a modified hourglass-type FPSO (Floating Production, Storage and Offloading) ship with different geometric parameters. The second paper evaluates the atmospheric composition after degassing and ventilating a ship’s cargo tank after a washing process with reference to the entrance and its visual inspection The author of the third article presented methods of joining (welding and sealing) single-polymer composite materials in a hot air stream. The last study in this section determined the vibration- activity parameters of a hermetic harmonic drive to evaluate a gearbox in terms of its manufacturing quality and wear-related deterioration. The third section, Economics, Management and Quality Science, contains one article. The article synthetically presents the process of financing investments related to the construction and purchase of ships, presenting, among other things, the concept of shipbuilding cycles and the relationship between the shipbuilding industry and the shipping market. The articles presented demonstrate the authors’ continuing practical inspiration and contribute to interesting scientific inquiry. I am aware that the presented articles are only a modest expression of these ideas, but believe that they will provide a basis for reflection, discussion, and broader research. dr

The aim of this study was to examine the relationship between the occurrence of selected types of failures and the time and season of their occurrence in public transport buses in the city of Lublin. The analysis was carried out for buses operated in the Municipal Transport Company within the past 3 years. The chi-squared analysis showed that during operation, there are significant differences between the failures and the annual season, but there are no differences between the frequency of failures and the time of day.

Unmanned, remotely or autonomously ships are the fastest growing new technology in maritime transport in recent years. The design of unmanned vessels envisions clean, emission-free electric propulsion. The costs of building physical models and target vessels are high, but the expected benefits are generating increasing interest in such vessels. This article presents the current state of research in the field of unmanned ships and the technical, legal and administrative problems that need to be solved in order for these ships to be used by the general public.

This paper presents a numerical investigation of the hydrodynamic performance of a modified sandglass-type FPSO (Floating Production, Storage and Offloading) with different geometrical parameters. The influence of the roll damping plate on heave and pitch motions of the FPSO was studied in regular waves. To estimate the hydrodynamic performance and utilize the results on the design stage of the FPSO, the boundary element method (BEM) was used. Furthermore, the hydrodynamic performance of two cylindrical and sandglass-type FPSOs under the same conditions was compared in different waves. Five sandglass-type FPSOs with dissimilar inclination angles were utilized with the constant draft. The effects of different inclination angles, including various radii of water-plane part of the floating object on hydrodynamic responses and wave forces applied to the FPSO, were investigated, and presented here. Numerical results were compared against published experimental data of a sandglass-type model, and good agreement was achieved. Based on the simulation results, a conclusion that a sandglass-type FPSO with the inclination angle of 35 degrees proposes proper hydrodynamic performance in both heave and pitch motions for all ranges of wave frequencies was reached. In addition, as it was predicted, the effect of heading sea on a sandglass-type FPSO was significant compared to other wave directions. Finally, by adding a damper plate to the floor of the platform, its hydrodynamic performance is improved. For numerical analysis of the modified FPSO, three different damper sizes are used to investigate its effect on the reduction of the pitch motion amplitude in waves.

This paper discusses the problem of atmosphere composition assessment related to entrance and inspection of a vessel cargo tank after washing, gas-freeing and ventilation. A correct assessment of the atmosphere before an entrance into the cargo tank or other enclosed spaces is a basic condition for the possibility of safe crew working. An assessment of the flammability hazard, presence of toxic or dangerous gases for human, and the oxygen concentration should be completed. In this regard, the ship-owner should prepare adequate procedures before an entrance, during work, and in emergency situations. The officers responsible should perform an assessment onboard the vessel their decisions are crucial for the safety of successive operations. A proper assessment of oxygen concentration in the air into the cargo tank or an enclosed space after the measurement is one of the primary problems which should be properly interpreted. This concerns such situations when the measured oxygen concentration into the tank reaches the value over 22% and below 20.6% of volume (mole) contribution (v/v). Air temperature in the 5–25°C range may create additional threats. This manuscript clarifies the controversial information included in manuals concerning the safety of entrance into enclosed spaces on vessels and the ship-owners procedures concerning the safety precautions for preparing, entrance, protection, and work inside the cargo tanks.

I am pleased to present the fourth 2020 issue (No. 64) of the Scientific Journals of the Maritime University of Szczecin. This issue contains the research results and views of the authors of seven articles that are compiled into three subject groups: Civil Engineering and Transport; Mechanical Engineering; and Economics, Management and Quality Science. The Civil Engineering and Transport section begins with an article that examines the relationship between the occurrence of failures in selected types of buses and the time of their occurrence using the public transport of Lublin as an example. The second article presents the current state of research on the technical, legal and administrative problems that need to be solved in order for unmanned ships to be used widely by society. There are four papers in the Mechanical Engineering section. The first paper presents a numerical study of the hydrodynamic parameters of a modified hourglass-type FPSO (Floating Production, Storage and Offloading) ship with different geometric parameters. The second paper evaluates the atmospheric composition after degassing and ventilating a ship’s cargo tank after a washing process with reference to the entrance and its visual inspection The author of the third article presented methods of joining (welding and sealing) single-polymer composite materials in a hot air stream. The last study in this section determined the vibration- activity parameters of a hermetic harmonic drive to evaluate a gearbox in terms of its manufacturing quality and wear-related deterioration. The third section, Economics, Management and Quality Science, contains one article. The article synthetically presents the process of financing investments related to the construction and purchase of ships, presenting, among other things, the concept of shipbuilding cycles and the relationship between the shipbuilding industry and the shipping market. The articles presented demonstrate the authors’ continuing practical inspiration and contribute to interesting scientific inquiry. I am aware that the presented articles are only a modest expression of these ideas, but believe that they will provide a basis for reflection, discussion, and broader research.

This study was designed to determine the vibroactivity parameters of a hermetic harmonic drive. A specially-prepared test bench was used to measure the normal velocity of vibrations and acoustic pressure generated by the unit. Piezoelectric sensors were applied to measure the characteristic values on the body of the prototype. In selected sections of drive, we determined the effective values of acceleration ae and frequency f. For the same points, the effective values of vibration velocity Vc were determined for the corresponding frequencies. The findings presented in this paper enable the assessment of a toothed gear in terms of the quality of its workmanship and wear-related deterioration, which are very important due to the characteristic work of this special drive

The aim of the article is a synthetic presentation of the complex process of financing investments related to shipbuilding and purchase. The first part presents the concept of shipbuilding cycles and the relationship between the shipbuilding industry and the shipping market. The paper then reviews the concepts and literature related to the shipbuilding industry, shipbuilding financing, and ship purchase. Lastly, the current state of the shipbuilding market is described. The results of the analysis indicates possibilities of financing the purchase of new vessels including mortgage bonds.