Scientific Journal of Maritime Research - Pomorstvo

Investigating the Effects of Cargo Weight and its Distribution on the Dynamic Performance of a High-Speed Planing Hull

Mohammad Gandomkar — 2024-06-28

The aim of this article is to evaluate the effects of cargo relative weight and its distribution along the boat’s length in addition to the relative water wavelength on the dynamic performance of a high-speed planing hull. Here, the dynamic performance is measured by the intensity of the boat’s heave and pitch motions. The Zarnick’s strip theory, which divides the vessel’s hull into equal lateral sections, is used to study the applied forces on the vessel, and a MATLAB code is provided based on it. It is demonstrated that increasing the cargo weight and its distribution result in more heave and pitch, and the maximum amount of them are observed in the wave with a length of about 5 times the length of the boat. In addition, the interactive effects of cargo weight and its distribution on the heave and pitch motions are affected by the relative wavelength. Therefore, the more centralized cargo distribution is preferred to increase the dynamic performance of a heavy planing boat with cargo weights more than 50% of the boat’s weight, while moving in short waves (λ⁄L<4); and for light cargo weight, less than 50% of the boat’s weight, the favorite cargo distribution is broad. When the boat sails in long waves, the desired distribution is reversed.

The impact of Covid-19 on the performance of seaports: A Tunisian case study

Rabeb Kammoun — 2024-06-28

The COVID-19 outbreak had a serious effect on the global economy, particularly, on the volume of port trade. This article was intended to investigate the impacts of the economic landscape, severity of the outbreak, and governmental control measures on the import and export goods of eight seaports in Tunisia. To achieve this, panel regression models were employed, utilizing a time series dataset spanning from the first quarter of 2020 to the third quarter of 2022. Based on the attained results, the preventive measures and stringent governmental control index and the cumulative number of confirmed cases have negative impact on the imported and exported goods, though the exported goods have been rather severely affected by the pandemic. At the economic level, the industrial added value has been discovered to be significantly and positively correlated with the imported and exported cargos respective throughputs, while GDP turned out to be significantly and negatively correlated with imported and exported goods. Such findings could be of great help to the shipping companies, port operators as well as the governmental authorities to shift strategies and opt for appropriate measures likely to help in coping with any potential effects of similar crises.

Isentropic and exergy analyses of marine steam turbine segments at several loads

Igor Poljak — 2024-06-28

This research presents isentropic and exergy analyses of marine steam turbine segments at three loads. Turbine segment is a part of any cylinder which is placed between the steam entrance to the cylinder and first steam extraction, between steam extractions and finally between last steam extraction and steam exit from the cylinder. Division of each cylinder to the segments allows insight into the various cylinder parts operation and an observation is the cylinder properly balanced. The analyzed marine steam turbine is composed of two cylinders – High Pressure Cylinder (HPC) and Low Pressure Cylinder (LPC), while each cylinder has two segments. The dominant part of real mechanical power produced in HPC is actually produced in the first HPC part (segment 1), while in LPC, the dominant part of real mechanical power is produced in the last LPC part (segment 4). Segments 1 and 3 have the highest improvement potential (inlet segments of both HPC and LPC) due to the highest isentropic losses and exergy destructions. HPC is much better balanced cylinder because along with isentropic, also exergy efficiencies between its segments (segment 1 and segment 2) at all loads differ lower than 7%, while the same cannot be stated for the LPC which exergy efficiencies between segments (segment 3 and segment 4) at all loads differ more than 20%. Very low isentropic and exergy efficiencies of the segment 3, at all observed loads, indicate that this turbine segment is highly problematic and at least some of the turbine stages mounted in this segment have difficulties in operation or potential malfunction. In addition, segment 3 is also the highest influenced by the ambient temperature change in comparison to other segments. The ambient temperature increase from 5 °C up to 45 °C can decrease segment exergy efficiency between 1.31% and 3.17%, if all the segments and all loads of the analyzed marine steam turbine are observed.

New mathematical models for the load factor of slip pairs of the ship propulsion complex for non-Newtonian lubricants

Oleksandr Kryvyi — 2024-06-28

The method of boundary variation was applied to the solution of the boundary value problem with respect to the Reynolds differential equation for the lubricating layer in the sliding bearings of ship power plants and auxiliary ship equipment, which made it possible to obtain analytical representations for the hydrodynamic pressure, shear stresses, as well as the integral characteristics of the lubricating layer. This made it possible to build new, easy-to-use mathematical models for the load factor (carrying force factor) of the sliding pairs of the ship propulsion complex, considering the non-Newtonian properties of lubricants, i.e. in the case of the dependence of dynamic viscosity on pressure and temperature. Mathematical models take into account geometric parameters of bearings, operational parameters: relative radial clearance and relative eccentricity, angular velocity; as well as viscosity characteristics of lubricants, in particular, dynamic viscosity and piezo coefficient of viscosity of lubricants. A criterion for the applicability of lubricants for given operating characteristics and bearing parameters has been developed, which uses the viscosity characteristics of lubricants. The research results are illustrated in the form of tables and graphs.

Investigations of Rudder-propeller Clearance on Thrust Performance and Flow Field in Vicinity of Propeller

Sunarsih — 2024-06-28

The presence of the propeller affects the hydrodynamics of the rudder in the same way that the ship's hull interferes with the function of the propeller behind and vice versa. Therefore, the arrangement of the propeller and rudder is very important in determining the overall ship propulsion performance. This paper presents a numerical analysis of the KCS propulsion system at various longitudinal clearances with respect to rudder position. The analysis was carried out in a full ship configuration using the KCS hull, propeller and rudder. The propeller clearance was varied based on the existing KCS design, design adjustments and recommendations from DNV respectively by 0.124D, 0.129D and 0.100D. Propeller performance was analysed based on individual variations, interactions between the propeller and rudder, as well as variations in the number of meshes of 0.5 mil, 1.0 mil, and 1.5 mil. The flow distribution around the propeller and the pressure distribution of the rudder inflow onto the rudder surface are also discussed. Numerical examination revealed that DNV's recommended clearance of 0.100D provided the best results and improved KCS propulsion performance compared to existing design. The mesh sensitivity analysis performed revealed that the recommended clearance showed excellent performance in all mesh variations. In response to these findings, modification of the KCS propeller clearance following DNV recommendations would be beneficial to improve overall ship performance.

A BOWTIE MODEL FOR FUEL GAS LEAKAGE INCIDENTS IN AN FPSO ENGINE ROOM

Ayhan Mentes — 2024-06-28

Safety and operational costs are of paramount importance in offshore facilities. Efforts to find new ways to reduce operational costs and minimize risks have led to the development of techniques in the field of safety. Routine checks and equipment maintenance are conducted based on either calendar periods or equipment uptime, using conditional monitoring, to prevent malfunctions through preventive maintenance (PM). PM is a key strategy for ensuring the integrity and process safety of safety barriers in offshore facilities. However, due to challenges in modeling dependencies, determining maintenance intervals, and updating belief in operational data, ineffective safety barriers can occur and lead to incidents. Excessive maintenance can also increase the risk of operational mistakes among workers. This study examines safety and operational issues associated with fuel gas leak events caused by various risk factors in Floating Production Storage and Offloading (FPSO) engine rooms using the bow-tie model. Within this context, safety barriers are defined, encompassing both preventive controls and mitigating measures that can be employed to minimize potential risk factors. Furthermore, the study underscores the importance of maintenance intervals for a specific set of safety barriers, necessitating periodic testing using Condition-Based Maintenance (CBM) tools for FPSO units.

Experimental Study on the Effect of Single Flow Disturber on the Performance of the Straight-Bladed Hydrokinetic Turbine at Low Current Speed

Madi Madi — 2024-06-28

Indonesian Marine Energy Association 2014 provided the results of ratifying the potential of ocean current energy in Indonesia of 17,989 MW. The amount is quite large for the results of several potential points in the territory of Indonesia. However, the potential of ocean currents in Indonesia has not been utilized optimally, even though the current turbine technology is developing rapidly in the world. The existing turbine technology that is already available worldwide cannot be applied directly in Indonesia. This is because the water condition in Indonesia is classified as low-speed current, unlike some countries in the world which are classified as high-speed current. Therefore, a turbine that can work in the condition of the territorial waters in Indonesia, in general, with a low current speed is needed. The turbine technology used in this study consists of turbine A (without a flow disturber) and turbine B (with a single flow disturber). The purpose of this study was to determine the increase in turbine performance at low current speeds. The method used in this study was an in-situ experiment because it was closer to the actual conditions. The results obtained from this study indicated that the addition of a single flow disturber could increase turbine performance at all variations of current speed, namely 0.4, 0.88, and 1 m/s. The most exciting result was that under the low current speed of 0.4 m/s, adding a single flow disturber could increase the ability to self-start from 0 rpm to 7.180 rpm and efficiency from 0 to 4%. In addition, at a current speed of 0.88 m/s with the addition of a single flow disturber, it could increase efficiency from 10.8% to 11.1%. At a current speed of 1 m/s with the addition of a single flow disturber, it could increase efficiency from 16.6% to 18%. That is, turbine B (with a single flow disturber) is very suitable to be applied in the territorial waters of Indonesia, which tend to have low current velocity.

Port State Control of Offshore Supply Ships, MODU and FPSO Units - A Case Study

Ljiljana Peričin — 2024-06-28

The Port State Control system aims to ensure that all ships are subject to regular inspections, with particular attention to the ships of insufficient quality. To this end, during the inspection, priority is given to ships that are considered risky. Thetis database is an information system that contributes to the implementation of the Port State Control within the EU (European Unit). It contains data on inspections performed in the EU ports and the Paris Memorandum area. The Paris Memorandum has 27 member states and covers the waters of European coastal states and the North Atlantic basin from North America to Europe. The main goal of the Paris MoU (Memorandum of Understanding) is to eliminate substandard ships through a harmonized Port State Control system. Namely, inspections should ensure that ships meet international safety standards, are safe for the environment, and provide adequate living and working conditions for workers. The primary responsibility for ensuring these standards rests with the ship owner/shipper while the responsibility for ensuring such compliance rests with the flag state. The aim of this analysis is to determine the number of inspections performed in the ports of the Republic of Croatia and the Republic of Italy, to identify the cause of ship detentions and the most common deficiencies of offshore supply vessels, MODU (Mobile Offshore Drilling Units) and FPSO (Floating Production Storage and Offloading) Units. In the observed period, the impact of the crisis caused by the COVID-19 pandemic was significant, resulting in the decline in the numbers of inspections performed in 2020 and 2021. In 2022, the number of inspections increased, but it still has not reached its pre-pandemic level. During the period that was the subject of research, port state inspections in the Republic of Croatia and the Republic of Italy revealed 241 deficiencies. Five areas with the largest number of deficiencies are: Certificate & Documentation, Safety of Navigation, Fire Safety, ISM, and Life-saving appliances, which follow the trend of the lack in the areas of the Paris Memorandum. The greatest increase in deficiencies was recorded in the areas of Labor Conditions-Health protection, Certificate & Documents (Crew Certificate, Documents), Emergency System and Fire safety area, which led to an increase in the number of offshore supply ships retention during the first half of 2022.

Unconscious bias among seafarers: A review of the theoretical Literature.

Anna Weerakoon Karunatilleke — 2024-06-28

This systematic literature review explores the concept of unconscious bias within the maritime industry, focusing specifically on seafarers. Unconscious bias refers to implicit stereotypes and attitudes that influence decision-making processes without conscious awareness. In the context of seafaring, where diverse crews operate in confined spaces for extended periods, understanding and addressing unconscious bias becomes crucial for fostering inclusive and harmonious shipboard environments and mitigating gender bias.

The review begins by examining theoretical frameworks related to unconscious bias, drawing from psychological, organizational behavior, and maritime literature. Various models, such as the Implicit Association Test (IAT) and social cognitive theories, are explored to provide a foundation for understanding how biases develop and manifest among seafaring populations.

The maritime industry's unique characteristics, including hierarchical structures, cultural diversity, and isolation during voyages, are analyzed to identify specific factors that may contribute to the emergence of unconscious biases. Additionally, the review delves into studies addressing the impact of biases on decision-making, communication, and overall team dynamics within the maritime context.

Furthermore, the review explores interventions and best practices proposed in the literature to mitigate unconscious bias among seafarers. Training programs, diversity initiatives, and cultural awareness campaigns are examined for their effectiveness in promoting a more inclusive and equitable maritime workplace. Based on this review, we conceptualize unconscious gender bias as a socio-technical problem and propose a theoretical framework that offers a combination of technological, organizational, and societal approaches as well as three main propositions to possibly mitigate the biased effects. Lastly, this paper considers future research on the management of unconscious gender bias in the organizational context.

Interrelations between logistics, trade, and law in the Incoterms® context

Juan Vanegas — 2024-06-28

This study uses a comprehensive bibliometric analysis to examine the relationships between the International Commercial Terms (Incoterms®), logistics, and legal issues in the context of international trade. By examining a dataset of 290 documents published from 1973 to 2023 in various academic databases such as Web of Science, Google Scholar, Science Direct, among others, the research aims to identify trends, key issues, and potential future directions in this interdisciplinary field. The analysis reveals a significant increase in publications since 2010, with a focus on topics such as legal and contractual issues, supply chain management, risk mitigation, and the evolution of Incoterms® rules. Co-occurrence analysis emphasizes six distinct clusters, ranging from international trade dynamics and transaction costs to regulatory frameworks and risk management. The abstract content analysis further highlights the interconnectedness of legal, logistical and implementation issues. The study also identifies the United Kingdom, the United States, and South Korea as the most important countries contributing to the field. It is concluded that Incoterms® and its multidisciplinary essence generates a greater interest in the international trade, not only because of its incidence in diverse fields of management; but also, because these rules are updated to regulate better the business transactions. The findings provide valuable insights for researchers, policymakers, and practitioners, and show the importance of considering the multifaceted nature of Incoterms® research and its impact on global trade practices.

EVALUATION OF CONTAINERIZED TRADE AND COMPETITIVENESS AMONG CONTAINER PORTS IN BLACK SEA BASIN

Metin DANIŞ — 2024-06-28

With the increase in trading volume and competitiveness in global trade, ports have become
indispensable and critical rivalry zones for countries. As competitiveness among the firm increase
at a global level, ports become a rivalry zone cause of being the most critical economic structures
and increasing competitiveness for transnational business and trade activities. The Black Sea
Basin is one of the most important waterways in the world in terms of commercial, political and
strategic aspects. The devastating consequences of conflicts and tensions, especially in recent
years, prove the importance of the Black Sea Basin for world maritime trade. Therefore, the ports
of the Black Sea Basin are of great importance. When the existing literature is reviewed, it is seen
that there are many studies on the competitiveness and efficiency issues. Since the studies in the
literature are mostly conceptual, it is obvious that they do not reveal analytical results, which
constitutes a deficiency in the literature. In addition, the lack of a scientific study on the
efficiency of container ports in the Black Sea Basin in recent years has made this study necessary.
The aim of this study is to examine the efficiency and competitiveness of container ports in the
Black Sea Basin, which has a great importance both regionally and globally. The “Data
Envelopment Analysis” (DEA) of the input-oriented CCR model, which is a linear program, was
used to measure the productivity of the ports, and the relative efficiency of the ports was
calculated.

Soft skills in the professional competence of specialists in the maritime industry

Vasyl Zheliaskov — 2024-06-28

The article considers the use of soft skills in the professional competence of maritime specialists and determines their value for the work of sailors. The main soft skills required for maritime professionals were identified: attentiveness, teamwork skills, communication skills, responsibility, etc. A number of methods for the formation and further development of soft skills in maritime professionals have been identified, such as: studying in higher education institutions with maritime specifics, attending courses and trainings in the field of soft skills, studying on the basis of literature and video materials, contacting a coach or trainer, and combining several methods. The practical result of the study is a set of recommendations for improving the effectiveness of soft skills application in the professional competence of maritime specialists. The theoretical result was the identification of the main regularities of the use of soft skills in the professional competence of maritime specialists.