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This study presents CFD simulations of the KCS model ship, focusing on ship resistance, free-surface behavior, and predictions of sinkage and trim at a Froude number of 0.26. Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the k-ω SST turbulence model. Verification and validation are carried out through a generalized Richardson Extrapolation method, following Stern et al. [1] methodology. Results are compared with experimental data for total resistance coefficient, sinkage, trim, and wave patterns.

The development of projects in the naval field is of crucial importance for the industry. Their success depends on how their costs and duration are managed. The study aims to present how naval projects can be monitored using Earned Value Management (EVM), a technique used to evaluate their performance from the point of view of costs. The Earned Value analysis has been applied to the manufacture and installation of a ballast system on a cargo ship. The results obtained have demonstrated that savings are achieved, and the works are delayed compared to the plan.

Maritime accidents and incidents are a major concern for the shipping industry, even though unified standards exist and solutions have been identified to improve maritime navigation and minimize accidents. This study aimed to carry out a statistical analysis of maritime accidents and incidents in the period 2014-2022, of ships belonging to the EU Member States, highlighting the main shipping areas where maritime accidents occurred, the result ing consequences, the types of pollution, and the main factors leading to maritime accidents and incidents. The results showed that there were 23,814 accidents/incidents, of which 2.6% were very serious accidents, 28.5% were serious accidents, 53.9% were less serious accidents and 15% were maritime incidents.

Due to the multiple cyber-attacks that resulted in financial losses and personal information breaches, cyber security has become an essential issue for the maritime industry today. This research aims to identify the potential cyber risks associated with operational technology (OT) systems on board ships that influence the cyber security of vessels through a state-of the-art literature review. Assessment of the cyber risks on board is carried out according to their likelihood and severity, using a risk score matrix, based on which, they are classified into three categories: high risk, medium risk, and low risk. Based on the classification of cyber risks on board the ship in the three categories, the measures to mitigate them can be defined, to ensure cyber hygiene on board the ship.

This paper aims to analyze global-local structural analysis using a model with three tanks in the central area of an oil tanker. Taking into account the negative effects of petroleum cargo on marine fauna and flora, regulations have been imposed on the reduction of pollution of the marine environment, thus, the stresses and deformations state of tanker vessels is an aspect of great interest in the design phase. Also, the paper captures the influence of the navigation conditions on the structure of the ship's hull and the effect that sloshing in cargo tanks has on the inner hull.

To reduce greenhouse gas (GHG) emissions, according to the vision of the International Maritime Organization (IMO), a good decision-making process is needed for the classification of alternative marine fuels considered as a solution for the decarbonization of maritime transport. The paper aims to classify two alternative fuels (Liquefied natural gas (LNG) and green hydrogen obtained by electrolysis of water, in relation to four criteria (economic, technical, environmental, and social) using the specialized literature. The evaluation of the two fuels in relation to the selected criteria was carried out from a multicriteria perspective using the Analytical Hierarchy Process (AHP) method. The obtained results have shown that LNG is the best option, currently, for maritime transport, considering the operational cost, the available infrastructure, the impact on the climate, and operational safety.

The study analyses the Energy Efficiency Existing Ship Index (EEXI), a regulation introduced by the International Maritime Organization (IMO) to enhance energy efficiency in maritime transport and reduce greenhouse gas emissions. Focusing on a semi-refrigerated LPG tanker, the research explores compliance strategies, including engine power limitation (EPL). The reduction of engine power by 24% resulted in a decrease in ship speed, meeting EEXI requirements with minimal impact on performance. Additionally, ship manoeuvrability was assessed through turning circle simulations before and after EPL. The findings confirmed that the vessel’s manoeuvrability remains within IMO standards, ensuring both efficiency and operational safety.

The design of the river-costal vehicles imposes the assessment by several hydrodynamic and structural criteria. This research involves the evaluation of a river-costal boat made of GRE composite materials at full load condition. The boat’s navigation area covers the Danube in land and costal zones, modeled as irregular oblique waves. The analysis is based on a strip theory hydrodynamic approach and short-term statistical dynamic response approach, delivering the seakeeping performances prediction of the river-costal boat.

Mooring and towing equipments ensure stability, control and safety in stationary (mooring) and transit (towing) situations. Mooring equipment is responsible for securing a vessel in place at a dock, pier, or offshore structure. Proper mooring equipment and reinforcements ensure that the vessel remains safely secured despite the influence of environmental loads. Towing equipment is essential for moving ship over short or long distances, either due to mechanical failures of the vessel or to relocate it. Towing is especially critical in rescue operations. The study involves a chemical tanker detailed strength check at mooring (at pier) and towing (on relocation) cases. In both cases the worst scenario was taken into consideration.

The FEM approach is a well-established computational technique for solving the governing equations of structural mechanics under various loadings. To delve deeper into the FEM approach, we focus on the floating structure of a river barge. This study aims to determine a structure's structural capacity by applying admissible stress criteria following the DNV rules. The structural analysis involves a comparative study of stress levels from the equivalent design wave loads for two river-barge operational conditions, light, and full cargo cases.

Electric propulsion for river ships is an exciting and promising development in the maritime industry. This technology involves using electric motors powered by batteries instead of traditional internal combustion engines. Advances in battery technology, such as lithium ion batteries, have made electric propulsion more viable and cost-effective. It is generally more efficient than internal combustion engines, leading to a better fuel economy and lower operational costs and it produces significantly less pollution compared to traditional engines, which burn heavy oil. This helps reduce greenhouse gas emissions and other pollutants like NOx and particulate matter. In plus, electric motors are quieter than traditional engines, making electric ships more suitable for operations in urban areas and sensitive environments. There are also some ships using hybrid systems that combine electric propulsion with traditional engines, allowing them to switch between power sources depending on the situation.

The paper presents aspects related the influence of the global gases emissions reduction targets on the design and performances of a propulsion system for a bulk carrier. In a first stage, the key elements of the ship propulsion system: main engine and propeller have been chosen and designed. The aim was to obtain the maximum propulsive efficiency at the owner desired speed. Different combinations: diesel engine-optimal propeller have been designed and analysed from the efficiency point of view. In a second stage, considering the mandatory IMO regulations concerning CO2 emissions, the EEDI (Energy Efficiency De sign Index) has been computed for every designed case. To compliance EEDI targets, it was been necessary to reduce the ship speed, and a new propulsion system with lower speed performances has been designed. In this study, ship hull shapes were given and EEDI be came an important and critical factor in the design of the ship propulsion system. Other potential pathways to achieve emissions reduction targets will need to be identify in a future study.

The purpose of this study is to analyze the results obtained from the impact for aluminum profiles in four constructive variants, two with connections and two with bevels.The forms significantly influence the results from a quantitative and qualitative point of view, making it possible to recommend the choice of the type of profile.

This study aims to analyze and compare the influence of steel flat bar beveling around technological cutouts on the stress state of a chemical tanker with a deadweight of 35,622 tons (TDW). Technological cutouts, which are essential for the installation of equipment, passage of cables, and other functional purposes, can cause stress concentration in the ship's structure, increasing the risk of cracking and localized failure. To assess the impact of beveling, two structural models are compared: one with steel plate beveling and one without. Using finite element analysis (FEM) through FEMAP/NX Nastran software, stresses and displacements around the cutouts are examined at four representative points along the cutout’s circumference. The results reveal significant differences in stress distribution between the two models, demonstrating the effectiveness of beveling in reducing local stress concentrations. This study provides insights into improving structural integrity and safety in ship design by addressing the risks associated with technological cutouts.

Antifouling solutions are essential for protecting ship hulls from marine organisms like algae, barnacles, and molluscs, which can slow down the ship and increase fuel consumption. They are crucial for maintaining a ship's efficiency and longevity by protecting the hull from marine growth, which can slow the vessel and increase fuel consumption. Modern antifouling methods, such as specialized paints, copper-based coatings, self-polishing surfaces, silicone coatings, ultrasonic systems, and electrolytic solutions, offer effective ways to combat biofouling. These solutions not only improve operational performance but also contribute to environmental sustainability by reducing the need for frequent cleaning and minimizing the release of harmful biocides into the water. The ongoing development of innovative antifouling technologies will continue to enhance the protection and efficiency of maritime vessels.

The paper presents the stability analysis of a parallelepipedal crane barge, under operational and environmental scenarios, using the AutoShip software, specifically ModelMaker and AutoHydro packages. The characteristics of the crane are length of 42.59 m, breadth of 20.19 m, depth of 1.50 m and a construction height of 3.5 m. The design of the crane was imported from Rhinoceros using .IGES file to software package ModelMaker from AutoShip. The stability analysis wore made in AutoHydro software package from AutoShip. The main contribution of the paper is to highlight the usefulness and efficiency (in terms of rapidity and accuracy) of using software tools (AutoHydro from the package AutoShip) to study nautical qualities (buoyancy and stability) of a parallelepipedal crane barge in several exploitation scenario.

This paper examines the critical cybersecurity landscape faced by maritime SMEs engaged in Ship Design, analysing their vulnerability to various cyber threats including ransomware, phishing attacks, and supply chain compromises. Through a comprehensive review of recent industry reports, regulatory frameworks, and cybersecurity incidents, we identify key risk factors and assess their potential impact on SMEs' operations, reputation, and competitive advantage. Our analysis reveals that maritime SMEs face disproportionate challenges in cybersecurity due to resource constraints, complex supply chain relationships, and the increasing sophistication of cyber threats targeting intellectual property. The paper presents a structured approach to cyber risk management based on established frameworks, emphasizing the protection of valuable intellectual property while maintaining operational efficiency. We propose practical recommendations for implementing robust cybersecurity measures within the resource constraints typical of SMEs, including strategies for threat detection, incident response, and recovery planning.

EEXI was established as a measure for assessing the energy efficiency of existing vessels and aims to reduce CO2 in order to achieve IMO regulations. The purpose of this study is to calculate the EEXI for a 15000 twd chemical tanker and further evaluate the impact of this change on ship manoeuvrability. EEXI estimations were conducted using different approaches while manoeuvrability performances were evaluated by means of different simulation programs. The purpose of this study revolves around striking a balance between optimal operation and achieving energy efficiency.

In this study (Part 1), a method is proposed to adjust the loads to achieve the target hull girder load with or without local loads on ships and ship-like structures. Each force or pressure load is referred to as a local load and the sum of forces and moments integrated with respect to the station is referred to as the hull girder load or global load. The hull girder load is composed of axial force (AF), vertical shear force (VSF), horizontal shear force (HSF), torsional moment (TM), vertical bending moment (VBM) and horizontal bending moment (HBM), each of which is related to each other by forces in the x, y and z directions. The adjustment of hull girder loads is required in hull structural analyses with various model extents and boundary conditions. In the whole ship model, it is necessary to implement more accurate hull girder loads and in the cargo hold, fore and aft body model, it is necessary to adjust the hull girder loads calculated from local loads to the target value. In the adjustment of the hull girder load, it is not only important to adjust it more accurately to the target value, but also the distribution of the added load is very important. In general, the hull girder load is adjusted to the target value by adding forces in the x, y and z directions to nodes in the cross section of the hull. If the forces are placed by considering only the position of the nodes, the loads may be concentrated or applied in a different direction from the placement of the elements, resulting in unexpected stresses or deformations in the structural analysis. It is necessary to consider not only the node position but also the size and orientation of the element for force distribution. In this paper, the load distribution at each node is obtained from the product of the directional effective area of the element and the stress field of the beam. The proposed method is validated by adjusting the hull girder loads to the target value for a beam structure with idealised hull. The method proposed in this study will be applied to actual ships in Part 2 (Jang and Kim, 2025a), and its applicability and extendibility are to be verified. This is considered to be beneficial for ship and offshore structural designers including oil/gas and ocean mobilities.

This study evaluates the effect of notch shape on the fracture toughness of a 500 MPa base material designed for liquefied carbon dioxide storage tanks. This study specifically focuses on assessing the crack tip opening displacement (CTOD) values for different notch shapes, including fatigue pre-cracks (R = 0.025 mm) and electrical discharge machining (EDM) notches (R = 0.07 mm and R = 0.15 mm). CTOD tests were conducted over a temperature range of −55 °C to −140 °C. The results revealed that as the notch radius increased, the degree of stress concentration decreased, leading to an increase in fracture toughness. In temperature-dependent tests, CTOD values consistently decreased as the temperature decreased, with EDM notches exhibiting a lower rate of fracture toughness reduction compared to fatigue pre-cracks, which is attributed to differences in the degree of stress concentration. Scanning electron microscopy analysis of the fracture surfaces revealed the reason for significant differences in CTOD values and fracture behaviors between fatigue pre-crack and EDM notches, particularly at −140 °C, a temperature below the ductile to brittle transition temperature. This study suggests that EDM notches, especially with radii of 0.07 mm and 0.15 mm, can effectively replace fatigue pre-cracks in CTOD evaluations, particularly at temperatures above the transition temperature, offering a more efficient method for assessing fracture toughness in cryogenic environments.

Development of submarine and its safe operational envelope requires an understanding of motion characteristics including emergency rising motion. In this study, the emergency rising motion is investigated using submarine free-running model equipped with ballast systems. The emergency rising test was conducted according to the initial vehicle speed, yaw rate, depth, ballast water discharge ratio and time interval between bow and stern ballast systems. Experimental results reveal that the maximum pitch angle before surface is affected by initial velocity and the operation conditions of ballast systems. In addition, excessive roll occurs after the surface when the submarine passes through the water surface at a negative pitch angle. Furthermore, the system parameters that comprise the emergency rising model are estimated using the collected test data. The identified model is verified by comparing emergency rising simulation with the free-running model test results.

A planing craft is one of the most commonly used types for small high-performance vessels since it helps to mitigate the severe viscous friction between the ship hull and water. Therefore, it is essential to develop methods for quickly and accurately estimating the running attitude during the early design phase and in actual operational conditions. We propose the Extended Modified Logvinovich Model (EMLM) for water entry to address the flow separation problem when a wedge-shaped hull enters the free surface during motion. Utilizing a two-dimensional approximation, we analyzed the fundamental potential flow through mathematical techniques for unsteady flow. As a verification, we calculated the dynamic vertical force coefficient compared with CFD(computational fluid dynamics) based on BEM(boundary element method) and an analytic similarity solution, where the results demonstrated good agreement with experimental data for validation.

This paper presents a new analysis method for predicting welding distortions induced by welding heat during the assembly process in various engineering fields. In the proposed method, the tendon force contributing to longitudinal bending deformation is calculated based on the measured inherent deformations in the welding specimen. Additionally, welding distortions along the transverse and longitudinal directions are simultaneously estimated without undesired numerical errors by adopting orthotropic thermal coefficients. Through the proposed method, reliable numerical solutions can be obtained using only linear elastic analysis with the finite element procedure. Consequently, the proposed method can be easily applied to multi-pass welding problems without requiring additional treatments, as it relies on the inherent deformations for the analysis. The performance of the proposed method is verified through numerical and experimental investigations for fillet-welded structures.

Forecasting the hydrodynamic properties of a ship is crucial for assessing its maneuvering capabilities. This study presents the results of static drift and circular motion simulations conducted on a 37000 tdw chemical tanker. The calculations were carried out using the ISIS-CFD solver, accessible through the FineTM/Marine academic license provided by NUMECA. The flow solution was obtained by numerically solving the Reynolds-Averaged Navier Stokes equations, employing the k-ω Shear Stress Transport (SST) model to represent turbulence. The simulation results were used to determine the linear hydrodynamic derivatives, which were then compared with hydrodynamic derivatives estimated with empirical formulas proposed by Clarke et. al. [1] and Tribon Initial Design module in the absence of experimental results.

The manoeuvring characteristics of the ships represent a complex phenomenon, which includes their capacity for both maintaining a steady course and turning ability. There are no simple methods for evaluating a ship's performance in these aspects. Furthermore, the flow patterns connected to these phenomena are complex and frequently coupled with other factors. The purpose of this study is to evaluate the course keeping and turning performance for a 37000 tdw chemical tanker. Course-keeping is evaluated based on stability criteria, while empirical relations and numerical simulations using hydrodynamic derivatives from both empirical and computational fluid dynamics (CFD) methods are employed to analyse the turning circle and then compared with data from actual sea trials.

The aim of this paper is to present the way in which the main risks that can lead to the pollution of the marine environment of the Black Sea can be ranked using multicriteria analysis, based on the AHP process (Analytic Hierarchy Process). This analysis represents a solid basis for the decision-making process. Based on this hierarchy, the decisionmakers in the maritime field can easily visualize both the risk assessment criteria and the risks that must be taken into account. The analyzed risks (oil spills, shipwrecks, ship collision, fire explosion) in relation to the considered criteria (bad weather conditions, highdensity traffic, human errors, ship age) have been ranked as follows: "ship collision" risk with overall priority = 0.366 is the one that must be considered the most dangerous in relation to the considered criteria, followed in descending order by the risk of "oil spills" with overall priority = 0.303, the risk of "shipwrecks" with overall priority = 0.181 and finally the risk of "fire explosion" with overall priority = 0.150.

The objective of this study is to analyze the global structural strength of a pleasure yacht by advanced FEA approach. This is accomplished by developing and implementing a user FEMAP API script for equilibrating the FEA ship model, in calm water and sagging and hogging wave conditions, for different wave design heights, up to a maximum height of 6.5 meters. The FEA strength is assessed by yielding stress and buckling criteria.

A submarine ballast system represents a combination of dedicated equipment and piping in which the main circulating fluid is either sea water straight from the submarine exterior or air which is compressed at high pressures and then it is stored in pressure vessels onboard. These fluids are, then, introduced in or extracted from various tanks located strategically onboard the submerged vehicle. Because water cannot be compressed and because of it’s density, it will require large amounts of energy and pumps to be able to move all the water within the system in a short period of time that is required for surfacing a submerged vehicle. Therefore, compressed air is favoured for the main deballasting because of the air’s capability of being stored at high pressures and displacing water in a fast manner once it is fed into the ballast tanks, thanks to it’s ability to expand as the submarine emerges and the surrounding water pressure drops. In addition, the compressed air systems must operate for at least a normal surfacing from periscopie depth, but also for surfacing from the maximum depth in the case of an emergency. From an engineering standpoint, ballast tank blowing systems are complex, but nevertheless are vital, for allowing the maneuvering of the submarine and it’s bouyancy within the water it navigates, regardless if it’s in a surfaced or submerged condition and must be done in the smoothest and with as little noise as possible. The requirements of designing and calculation of such systems are covered by the Class and Administration rules and regulations.

This paper presents aspects regarding the analysis of the characteristics and performances of a propulsion system for a crude oil tanker. The study involved several steps: first, the ship’s resistance and the necessary propulsive power were calculated to choose and design the main components: engine, transmission and propeller; to obtain maxim propulsive efficiency at the desired speed, with low fuel consumption and reduced CO2 emissions. Four slow Diesel engines were selected and the optimal propellers were designed to analyse and adopt the more efficient solution. A number of factors were taken into account for ship propulsion system components selection such as: required power, revolution rate to ensure an optimal propeller diameter to be located behind the ship, the specific fuel consumption parameters, desired ship speed, etc.

This study case concerns the prediction of the hydrodynamic response of an offshore heavy lift barge in the regular and irregular waves. The study focuses on predicting the six degrees of freedom responses for the barge in the operation condition when the ship speed is equal to zero, at various heading angles (0~180˚) and for several wave frequencies (0.02~2.0 rad/s). The numerical simulation is carried out using the 3D diffraction /radiation motion solver Hydrostar software that is based on potential theory to predict the wave-body interactions. All the hydrostatics, loading and sailing aspects are initially estimated, and then introduced as an input in the simulation process corresponding to the ship speed and heading directions. For the irregular sea simulations, the ITTC spectrum is used to describe the wave for a generic study case in the Black Sea to make the study feasible for offshore applications in operational conditions where the ship speed is equal to zero.

The purpose of the stress and strain analysis study in the transverse walls of a 50100 tdw tanker is to assess the structural integrity of the vessel and identify potential problems or vulnerabilities as well as methods to improve the strength of the structure.

Modern patrol ships characterised by an 'axe bow' shape allows the placement of an anti-spray rail. These not only reduce drag but also minimize the wave height generated by the ship's bow. This article will present the effect of positioning of an anti-spray rail at various heights on the ship's bow to reduce drag resistance. The most favorable placement scenario will be determined through the results of numerical simulations conducted by using the commercial software Fidelity Fine Marine.

Hydrogen, the carbon-free energy of tomorrow, is being explored as a potential fuel for ship propulsion. It is considered a clean and sustainable alternative to traditional fossil fuels, as it produces zero emissions when used in fuel cells or burned in engines. Hydrogenpowered ships have the potential to significantly reduce greenhouse gas emissions and contribute to decarbonizing the maritime industry. However, it is important to note that the adoption of hydrogen as a mainstream fuel for ships is still in the early stages, and there are various technical and infrastructure challenges that need to be addressed for its widespread implementation.

This study case presents a comprehensive static finite element analysis (FEA) of an equipment foundation aboard a marine vessel, conducted in three distinctive scenarios. The initial analysis adheres to a generalized standard, providing a baseline for structural performance. Subsequently, the same foundation is re-evaluated with the addition of stiffening brackets, aimed at enhancing rigidity and load distribution capabilities. The final analysis transitions from the theoretical models to practical application, examining the foundation as it is truly mounted and integrated within the ship's structure. Each scenario is meticulously compared to assess the impact of design modifications and integration on the foundation's performance.

The International Maritime Organization and the European Commission are demanding increasingly significant decarbonization efforts from shipowners, and maritime freight should be integrated into the EU emissions trading system. Several technologies exist for sail propulsion: the Flettner rottor, rigid panels made of composite materials, sails and in particular the kite, innovative in this field. Studies show that 3700 to 10700 ships could be equipped with sail propulsion systems by 2030. The release of 3.5 to 7.5 million tonnes of CO2 could thus be avoided in 2030. In this article, the fundamentals of the ship propulsion by the wind are presented: a credible, efficient technological proposition available today to ensure the sustainability of transport.

The steering gear system is part of the group of vital installations for a ship. Its role is to ensure course stability and, at the same time, to facilitate the changes of navigation direction. In this context, the technology for assembling the system is well-defined through rules, procedures, and work instructions. A steering system that is correctly assembled according to the instructions and execution drawings will lead to proper operation and, at the same time, the successful completion of applicable steering system tests. The applicable tests for steering systems are depending to the type and purpose of the vessel. However, SOLAS defines a series of general high-level tests that must be performed, and during these tests, the quality of the installation is to be demonstrated. The present work will develop both the subject of the steering gear installation, which directly influences the results of the tests.

The purpose of this study case is to assess the total resistance and investigate the fluid flow around a scale model catamaran varying distance between the diametral planes of the two hulls. This study is focused on accurately determining the total resistance encountered by the catamaran while it moves through water and, additionally, on understanding how the fluid flow behaves around the vessel with these design variables.

This article investigates ship maneuverability by conducting and comparing calculations using two distinct computational platforms. The results obtained from these calculations are subsequently compared with real data from the sea trials. A detailed analysis of the discrepancies between theoretical and empirical results provides insights regarding the reliability and precision of each computational platform in assessing ship maneuverability in the naval domain. This research contributes to improving methods for evaluating ship performance and validating computational platforms used in the industry.

Besides the piping systems used for blowing the main ballast tanks of a submarine by feeding compressed air, a great importance must be given to the flood and vent openings and the mechanisms that operate the covers. From an engineering standpoint, the flood openings must be as small as possible to minimize the noise generated by the water flow.Their number and cumulated area must be determied as to avoid over pressure when feeding compressed air into the ballast tanks that may lead to structural damage. The requirements for designing of such systems are covered by the Class and Administration rules and regulations.

The main objective of this study case is to analyze the response in terms of stress and deformation of transversal frames of a bulk carrier that occur due to the applied loads. This assessment helps ensure the safety of the vessel in terms of structural strength and resistance and to determine the best solutions to apply in unfavorable scenarios. The analysis will be performed on a cargo tank, for three static stress cases, the vessel being placed on still water, on sagging and hogging.

The current study case presents a comprehensive comparison of seakeeping analysis methods, utilizing the seakeeping numerical analysis based on Lewis’s form description of a hull, Ansys Aqwa, and experimental data obtained from the towing tank of the Faculty of Naval Architecture in Galati. The primary objective of this study is to assess the accuracy and reliability of two numerical approaches in predicting the seakeeping performance of a vessel under varying conditions. The experiment was carried out under two scenarios, one with the model at zero speed and another with the model towed at 1.28 m/s and 180o heading angle. The diverse set of conditions aimed to simulate real-world scenarios and capture the dynamic nature of ship motions in waves. The employing of Lewis forms numerical analysis, Ansys Aqwa simulation, and experimental data, the results were compared and evaluated in terms of their accuracy and agreement.

The concept of manoeuvrability is very important for efficient ship operation but also in ship safety. The aim of this paper is to test and perform a comparative analysis of manoeuvrability performance of a 9000 tdw chemical/oil tanker. The comparative analysis has been performed between the results obtained based from two software’s, namely PHP and MPP, but also between the results obtained in the sea trials with the output data from MPP. In this way it will be shown the differences (if any) in terms of manoeuvrability., and if the two used platforms are effective for providing preliminary determination of performances of manoeuvrability.

This study presents a comprehensive Computational Fluid Dynamics (CFD) analysis of an 18-meter motor yacht featuring a trawler hull design with a swim platform. The investigation explores the hydrodynamic performance of the yacht across three distinct drafts and six varying speeds.

Pollution is being discussed more and more in the world. It is known that the production of Glass Fiber Reinforced Polyester (GRP) is a polluting process. Also, the implementation of GRP is a process that can cause various ailments to the personnel who apply it. Over time, boats made of GRP suffer degradation due to interaction with the environment: cracks, exfoliation of the outer layer of gelcoat, etc. These degradations must be remedied, operations that involve the application of substances that are also polluting. More and more traditional manufacturers of sports boats are replacing GRP with aluminum. This, although the process of obtaining it from the ore is not without toxic components, is less polluting and friendlier to the executors than GRP. In this paper, we seek to elucidate the advantages that aluminum has over GRP in the construction of sports boats.

This article provides a review of the varying systems of slow-speed, two-stroke marine engines. The paper begins with the operating principles of the typical two-stroke engine cycle employed in these engines, highlighting the intake, compression, combustion, and exhaust strokes. It then continues with defining and describing other unconventional systems rarely found on engines of different sizes and applications. The focus of the study case is on the systems that prevent pollution, as well as various other systems observed in larger marine engines.

The purpose of this study is to determine the stress states of the plating around the technological cutouts of a 37500 tdw chemical tanker under normal operational conditions, taking into account the efficiency of operational optimization and structural strength increase. This study will assess the stress state in the double bottom region of the ship, which experiences the most significant external loads from hydrostatic water pressure and internal loads from cargo pressure.

The design in early stages of the ships involves several preliminary hydrodynamic analyses, also for the ship operating on river waterways, IN(1.2) navigation class. This technical paper includes two main parts as preliminary assessment for the design constructive versions of a river research ship. The first part is focused in the comparative study of the mono-hull and the catamaran ship design by seakeeping and global strength criteria. The second part is focused on the ship resistance for two mono-hull versions of the river research ship. The study hydrodynamic preliminary results are the initial bases for proper design in next steps of the river research ship.

This study proposes to automate the analysis of wiring diagrams to generate cable lists by using machine learning for text classification and pre-trained Deep Neural Network (DNN)-based image classification to detect cable routes. In shipyards, many drawings are produced for each ship, and analyzing these drawings, especially wiring diagrams, to generate cable lists for the Bill of Materials (BOM) can be a time-consuming and error-prone task. This process is performed manually by reading the cable routes and entering the information into a spreadsheet. To address these challenges, this study aims to automate the information extraction from wiring diagrams. The process involves extracting text from the PDF document and classifying it using machine learning, followed by using DNN-based image classification to trace cable routes and identify the relevant annotations. The developed algorithm was tested on three PDF wiring diagram samples and achieved an average accuracy of about 90%, confirming its effectiveness.

The dynamics acting upon thin flat plates submerged in a fluid are chiefly governed by the delicate boundary layer enveloping their surfaces. Through a series of experiments, we investigated the impact of surface roughness elements on the boundary layer adjacent to a flat plate across a range of Reynolds numbers. The experiments were performed in the Chungnam National University-Cavitation Tunnel (CNU-CT). Three flat plates, each characterized by distinct surface roughness heights denoted by k, were subjected to scrutiny. One boasted a pristine smoothness, while the others bore the deliberate roughness of sandpaper, each with its own unique texture. With precision instrumentation, including Laser Doppler Velocimetry (LDV), we meticulously documented the axial velocity profile and the RMS (Root Mean Square) velocity at strategic points along the flat plates. Through these measurements, we unveiled the boundary layer's thickness, δ, and momentum thickness, θ, elucidating their variations under differing free-stream velocities. As our exploration deepened, the relationship between the local Reynolds number, Rnx, and the non-dimensional velocity profiles, u+ − y+, became apparent. A systematic shift along the log-law line ensued, with both u+ and y + increasing in tandem with the rise in Rnx. Yet, our inquiry did not conclude with observation alone. Employing empirical rigor, we quantified the drag forces acting upon flat plates of varying roughness heights, deriving them from the measured momentum thickness across a range of local Reynolds numbers, Rnx.

The Polymer Electrolyte Membrane Fuel Cell (PEMFC) has been widely developed in the shipping sector, prompting the need to accurately understand its characteristics under various operating conditions and load variations. This study presents an experimental investigation into the steady-state and dynamic characteristics of a 1 kW water-cooled PEMFC stack, aiming to optimize reactant consumption and to assess the PEMFC voltage response under varying load conditions. In the steady-state tests, experiments were conducted at three different stoichiometries of hydrogen and air to evaluate the effect of stoichiometry on PEMFC efficiency. The results showed that the electrical efficiency improved by 10% at lower hydrogen stoichiometry (1.2) compared to the manufacturer's recommended values (1.6). In the dynamic tests, the behaviors of undershoot voltage and open circuit voltage (OCV) were examined using load-step and load-ramp conditions. Results showed that the undershoot voltage could be reduced either by narrowing the load step size and ramp rate or by implementing a reactant supply strategy, which increasing the gas flow rates before increasing the current. A consistent 0.55 V recovery was observed at the OCV after 10 s, regardless of the step sizes or ramp rates of load, indicating that the PEMFC was in good state of health after dynamic load conditions. OCV can serve as an effective diagnostic tool for assessing PEMFC health.