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Batychron is a flexible underwater bell patented by the Gdynia Maritime University as a device used in hydro-technics engineering for underwater transport and diving while maintaining the safety of human life. This study aims to present the methods and results of strength tests and the conducted analysis of the selection of the most appropriate method of joining thermoplastic polyurethane film (TPU) and polypropylene belts for underwater use to obtain a device with a specific buoyancy force. A universal testing machine with a hydraulic drive was used for the tests. Various methods of joining polypropylene belts were tested to select the most favourable in terms of strength properties. For this purpose, two types of materials were selected: the TE324 polyester belt and the TS501_50 style belt. Various connection methods have been used: without seams; zig-zag stitch, straight cross; cross stitch, straight longitudinal; cross stitch, straight transverse, in order to select a joint with the highest strength parameters. In addition, the tensile strength of individual types of belts was tested. The methods of joining the TPU film were verified. The obtained results allowed us to determine that the strongest bond of TE324 material is a straight, longitudinal cross stitch. This is related to the load distribution in the belts tested in laboratory conditions, but also reflected in their practical application. Thanks to the results obtained, it was possible to select the optimal methods of joining (connection) and the construction of Batychron. [ABSTRACT FROM AUTHOR]

Various endeavors are undertaken by the maritime industry, academia, and policy-makers to reduce greenhouse gas emissions. These include the search for feasible technologies that could be used onboard merchant vessels and are propelled by international legal and social initiatives. To this end, this study aimed to critically analyze the research trends pertaining to the active methods of reducing the negative environmental impact of shipping. The research is focused on alternative fuels and renewable energy systems with respect to the related policy-making and existing legal framework. Therefore, a bibliometric approach was applied to a sample of 234 scientific papers indexed in the SCI-EXPANDED in Clarivate Analytics Web of Science Core Collection. The results indicate that the scientific efforts were made more on alternative fuels, while renewable energy sources only recently became a popular research subject. Moreover, the environmental benefits of prospective technologies are more investigated than their financial aspects. The research effort on alternative maritime fuels was made in parallel with the legal one, both aiming to combat global climate change and magnifying each other. [ABSTRACT FROM AUTHOR]

A recent publication of two independently performed studies investigating a very similar topic of green shipping, applying very similar methods (bibliometric analysis) on very similar data sets (scientific databases) provides an opportunity for an unbiased analysis of what factors can impact the outcome of one's research. This discussion paper reviews and compares the two following papers: • Ampah, J.D., Yusuf, A.A., Afrane, S., Jin, C., Liu, H., 2021. Reviewing two decades of cleaner alternative marine fuels: Towards IMO's decarbonization of the maritime transport sector. J. Clean. Prod. 320, 128871. https://doi.org/10.1016/j.jclepro.2021.128871 • Kołakowski, P., Gil, M., Wróbel, K., Ho, Y., 2021. State of play in technology and legal framework of alternative marine fuels and renewable energy systems: a bibliometric analysis. Marit. Policy Manag. https://doi.org/10.1080/03088839.2021.1969460 This paper aims to conclude on the insights arising from both papers concerning their different methodological peculiarities. • Commentary on two independent bibliometric studies on alternative fuels for shipping. • Similarities and differences of both studies discussed. • Current commentary offers key insights into the use of bibliometric analysis. [ABSTRACT FROM AUTHOR]