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This research paper presents an effective approach to reducing marine pollution and costs by determining the optimal marine alternative fuels framework for short-sea shipping vessels, with a focus on energy efficiency. Employing mathematical models in a Python environment, the analyses are tailored specifically for conventional and fully autonomous high-speed passenger ferries (HSPFs) and tugboats, utilizing bottom-up methodologies, ship operating phases, and the global warming potential approach. The study aims to identify the optimal marine fuel that offers the highest Net Present Value (NPV) and minimal emissions, aligning with International Maritime Organization (IMO) regulations and environmental objectives. Data from the ship's Automatic Identification System (AIS), along with specifications and port information, were integrated to assess power, energy, and fuel consumption, incorporating parameters of proposed marine alternative fuels. This study examines key performance indicators (KPIs) for marine alternative fuels used in both conventional and autonomous vessels, specifically analyzing total mass emission rate (TMER), total global warming potential (TGWP), total environmental impact (TEI), total environmental damage cost (TEDC), and NPV. The results show that hydrogen (H2-Ren, H2-F) fuels and electric options produce zero emissions, while traditional fuels like HFO and MDO exhibit the highest TMER. Sensitivity and stochastic analyses identify critical input variables affecting NPV, such as fuel costs, emission costs, and vessel speed. Findings indicate that LNG consistently yields the highest NPV, particularly for autonomous vessels, suggesting economic advantages and reduced emissions. These insights are crucial for optimizing fuel selection and operational strategies in marine transportation and offer valuable guidance for decision-making and investment in the marine sector, ensuring regulatory compliance and environmental sustainability. [ABSTRACT FROM AUTHOR]

This research paper presents an effective approach to reducing marine pollution and costs by determining the optimal marine alternative fuels framework for short-sea shipping vessels, with a focus on energy efficiency. Employing mathematical models in a Python environment, the analyses are tailored specifically for conventional and fully autonomous high-speed passenger ferries (HSPFs) and tugboats, utilizing bottom-up methodologies, ship operating phases, and the global warming potential approach. The study aims to identify the optimal marine fuel that offers the highest Net Present Value (NPV) and minimal emissions, aligning with International Maritime Organization (IMO) regulations and environmental objectives. Data from the ship’s Automatic Identification System (AIS), along with specifications and port information, were integrated to assess power, energy, and fuel consumption, incorporating parameters of proposed marine alternative fuels. This study examines key performance indicators (KPIs) for marine alternative fuels used in both conventional and autonomous vessels, specifically analyzing total mass emission rate (TMER), total global warming potential (TGWP), total environmental impact (TEI), total environmental damage cost (TEDC), and NPV. The results show that hydrogen (H2-Ren, H2-F) fuels and electric options produce zero emissions, while traditional fuels like HFO and MDO exhibit the highest TMER. Sensitivity and stochastic analyses identify critical input variables affecting NPV, such as fuel costs, emission costs, and vessel speed. Findings indicate that LNG consistently yields the highest NPV, particularly for autonomous vessels, suggesting economic advantages and reduced emissions. These insights are crucial for optimizing fuel selection and operational strategies in marine transportation and offer valuable guidance for decision-making and investment in the marine sector, ensuring regulatory compliance and environmental sustainability.

In the face of developments in maritime transportation due to globalization, ports are tending toward new tugboat investments in order to respond to the increasing demand. Due to the high costs of tugboats, organizations may face high investment costs. It is important to determine the most suitable number of tugboats, considering the variables in a port area where towage services will be provided. In this study, a simulation model was developed to determine sufficient tugboat allocation according to some variables in ports. The simulation model was subjected to various experiments, and statistical analyses of the obtained results were performed. The relationships between the variables affecting the level of towage service were revealed. [ABSTRACT FROM AUTHOR]

This paper discusses the path-following control of a ship or other floating object by pushing using a single autonomous tugboat. To do this, we first formulate a reduced dynamic equation that contains the dynamics of both the ship and the tugboat without contact force terms, and is expressed by independent variables, such as ship variables (surge, sway, and yaw rates), allowing us to deal with the ship and tugboat as a single system to control the independent variables. It is assumed in this study that the contact between the ship and tugboat is a point contact, and the contact point does not slip. To manipulate the motion of a ship by pushing, the pushing force must be exerted without slipping at the contact point. Thus, the contact force is derived from the dynamic equations of the ship and tugboat and the velocity constraints on the contact point, and its feasible region is defined. This contact force condition is then incorporated into a path-following control method using the reduced dynamic equation to handle the contact force during the pushing operation. The contact force is checked to determine whether it is likely to be exerted outside the feasible region; if so, the control gain used in the path-following control is switched to a smaller value. Simulations under different paths and contact positions are performed, and the results demonstrate that the proposed pushing control method allows the ship to follow a given path correctly while maintaining the contact condition. [ABSTRACT FROM AUTHOR]

Assisting harbour tugboats are essential for safe navigation in ports and for berthing/unberthing operations. Because the port infrastructure needs to be updated in the coming age of autonomous ships, autonomous tugboats or remotely controlled tugboats are expected to be part of the navigation assistance provided by future ports. Although there have been some studies on the design of cooperative control of tugboats, few studies have focused on the mathematical model of their cooperative manoeuvres. Particularly, in the case of pushing assistance, tugboats have often been treated simply as a kind of side thrusters attached to the assisted ship. Thus, we present a new framework of the mathematical model for cooperative manoeuvres that considers the coupled motions among tugboats and a ship as precisely as possible. Solving the dynamics of all tugboats as well as the assisted ship can render the model more advanced and realistic, and is the most significant contribution of this study. The simulation tool based on the proposed model can be used as a plant model in designing and verifying the tugboat's manoeuvring control system in the future. In this study, as examples, considering a tentative control method, some unique scenarios were simulated to demonstrate the cooperative manoeuvres. [ABSTRACT FROM AUTHOR]

Microbiologically influenced corrosion (MIC) has a significant cost to many industries, including naval engineering. In this case-of-study, three tugboats developed pitting corrosion in the carbon steel of the inner hulls. Grade A naval steel was used for the hull sheets but the inner side (corroded) showed only two protective layers of paint. The maintenance employed seawater, which ended up in the bilge and made MIC possible. Bilge's waters were submitted to physicochemical, biological and molecular tests. DNA analyses confirmed the presence of Pseudomonas spp. and Desulfovibrio spp. in water samples and, consequently, a MIC mechanism was proposed to explain the corrosion process. In addition, a biocide treatment was evaluated and a new maintenance protocol was recommended. This work highlights the importance of the engineering design to prevent MIC in marine transports and provides some guidelines to treat it. [ABSTRACT FROM AUTHOR]

In this paper, through the continuous analysis of the engine oil of a 2600HP tugboat in 4 years, the detection data of spectrum, viscosity, moisture, degree of vulcanisation, pH, fuel dilution, flash point, and oxidation degree are obtained. The variable of these parameters over time is discussed. Nothing abnormal wear is found in the main friction parts of the engine. Lubricating oil is seriously vulcanised and acidification, which affects the oxidation degree. The performance of oxidation, sulphisation, PH, and fuel dilution is seriously degraded. The coupling effects of water content, acid value, alkali value, vulcanisation degree, and mechanical impurity should be considered in determining the oxidation and ageing of lubricating oil. It should be noted that excessive loss of alkaline additives in tugboat operation. The results provide an effective reference basis and experience guidance for better judging the wear state of the friction pair and condition-based maintenance based on lubricating oil. [ABSTRACT FROM AUTHOR]

The recent surge in fuel costs and stringent gas emission regulations mandated by the International Maritime Organization (IMO) has prompted research into integrating renewable energy and energy management strategies (EMS) onboard ships. This study illustrates the computation, simulation, and optimization of a hybrid renewable energy system (HRES) to ensure continuous power supply for auxiliary loads and critical systems on both conventional and fully autonomous tugboats. The primary aim is to design an optimal HRES with minimal annualized cost of system (ACS) and a higher proportion of renewable energy while using an artificial bee colony (ABC) algorithm. Validation of optimization outcomes is conducted using particle swarm optimization (PSO), genetic algorithm (GA), and Hybrid Optimization of Multiple Energy Resources (HOMER) Pro. The HRES incorporates diesel generators (Gensets), photovoltaic (PV) arrays, vertical axis wind turbines (VAWT), and battery banks. The optimal HRES configuration for both conventional and fully autonomous tugboats is found to be Genset/PV/VAWT/Battery. We observe that the ABC algorithm exhibits superior convergence, reliability, cost-effectiveness, renewable energy fraction, and reduced carbon emissions compared to alternative algorithms. Results of robustness tests suggest that the shipload variation, fuel prices, temperature fluctuations, wind speed and solar irradiance along the navigation route have significant impact on the optimal HRES configuration. Ultimately, we conclude that the fully autonomous tugboat demonstrates superior performance in terms of costs, carbon dioxide emissions, and renewable energy fraction compared to its conventional counterpart. • Optimization of a HRES aboard both traditional and fully autonomous tugboats is conducted. • A comparative study of three metaheuristic algorithms is undertaken to determine the optimal HRES configuration. • ABC emerges as the most effective algorithm for allocating the optimal HRES setup. • The proposed energy management strategy efficiently reduces carbon dioxide emissions, dump energy, and the annualized cost of the system. • Sensitivity analysis and Post Ad hoc test are performed on the optimal HRES and the metaheuristic algorithms. [ABSTRACT FROM AUTHOR]

Aiming at the problem of high fuel consumption of the main engine of tugboats in port operations, from the perspective of ship management energy saving, an optimization method of tugboats fuel-saving and speed based on the improved tugboat algorithm was proposed. By analyzing the energy transfer mechanism of the ship, engine and paddle, the optimization model of its main engine fuel consumption was established, and the optimization research on the speed of each section of the tugboat in a certain voyage was carried out. The beetle antennae search algorithm (BAS) is a new optimization algorithm in recent years, which has obvious advantages in the optimization of mathematical models with complex structures, but there are also some problems such as slow convergence and easy access to local optimal states. For this reason, an improved beetle antennae search algorithm(IBAS) was established to better to meet the application requirements. Through the calculation and analysis of an example, the proposed algorithm was used to optimize the fuel consumption of the main engine of the tugboat. The results show that the proposed algorithm has fast convergence speed and high optimization efficiency. Compared with the beetle antennae search algorithm and the ant colony algorithm (ACO), the proposed optimization algorithm keeps a faster operation time and improves the accuracy of optimization results. [ABSTRACT FROM AUTHOR]

Currently, business development, especially in the maritime sector, has quite rapid progress in Indonesia. Recently, the shipbuilding industry's development is an effort to improve competitiveness with the global market. With the increasing development of the shipbuilding industry in Indonesia, cost accounting as a cost information system is challenged to develop the shipbuilding industry, requiring high product quality. This matter requires the company to decide on proper budget planning not to experience losses. Activity-Based Costing (ABC) System is a system to determine costs using activities to classify costs to produce indirect costs that are more systematic and relevant. Activity-based costing systems identify resources in each department's activities to provide information about a product's cost. It collects indirect costs and allocates them to various products in proportion to the product volume. Therefore, activity-based costing can estimate the product costs and individual activity costs used in the production well. The first step is classifying activities, associating various costs with various activities, determining homogeneous cost groups, and determining group rates. The second step of this stage is the determination of overhead prices selected from each cost group. This research compares indirect costs to the construction of 2x1800 HP tugboat ships according to traditional cost accounting methods with the Activity-Based Costing System method. The first method's result is 3,432,920,043 IDR and the second method is 2,231,760,472 IDR.

Tugboat is an important auxiliary tool for safe operations at ports. The fuel consumption of tugboats directly affects the energy consumption of water transportation in the port area and the operating costs of barge companies. To analyze the energy-saving and emission-reduction methods of tugboats in the port area, this paper proposes an optimized plan for the high fuel consumption problem of a full-slewing tugboat operating at a port. This research first starts from the perspective of route design and takes the shortest route as the goal, proposes the use of genetic algorithm (GA) to optimize the route of the tugboat. Second, combined with the mechanism of the energy transfer process of the ship, engine, and slurry, the fuel consumption model of the tugboat's main engine is established. To minimize fuel consumption, the speed of the tugboat's entire voyage is optimized with the help of GA. The results of the example analysis show that GA can realize an efficient optimization of the tugboat route, save on the fuel consumption of the main engine, and improve the operation efficiency of the tugboat. It is suitable for the route planning of the tugboat in the multi-task operation of the port. GA is used in the tugboat speed optimization problem. The sailing plan is more fuel-efficient than the economical speed sailing plan for an entire journey. The proposed method provides ideas for fuel saving and consumption reduction of the tugboat main engine, achieves the maximum reduction of fuel consumption under working conditions without affecting normal production, which is conducive to port ship barge companies to save operating costs, and also provides a reference for the selection of the actual tugboat main engine. [ABSTRACT FROM AUTHOR]

This study evaluated the Hook-up installation of an offshore site construction process, which is the final step in an offshore site installation process. During Hook-up installation, the offshore structure can have a detrimental effect on the work stability due to low-frequency motion. Moreover, economic costs can be incurred by the increase in available days of a tugboat. Therefore, this study developed a numerical analysis program to assess the dynamic behavior of mooring systems during hook-up installation to analyze the generally performed installation process and determine when the tugboat should be released. In this program, the behavior of an offshore structure was calculated using Cummin’s time-domain motion equation, and the mooring system was calculated by Lumped mass method (LMM). In addition, a tugboat algorithm for hook-up installation was developed to apply the Hook-up procedure. The model used in the calculations was the barge type assuming FPSO (Floating production storage and off-loading) and has a taut mooring system connected to 16 mooring lines. The results of the simulation were verified by comparing with both MOSES, which is a commercial program, and a calculation method for restoring coefficient matrix, which was introduced by Patel and Lynch (1982). Finally, the offset of the structure according to the number of tugboats was calculated using the hook-up simulation, and the significant value was used to represent the calculation result.

Tugboat operations present a high degree of risk and to prevent accidents, the crew must know and manage very well all the necessary maneuvers. Stability is a critical aspect for the safety of tugboats and towing operations, so recently new international regulations have been developed. The tugboats perform several functions, the main one being pulling, but by being equipped with certain equipment and installations, the tugboats are intended for rescue, firefighting, depollution, ice breaking and occasional transport. For this study, two categories of tugboats were considered to determine the geometric characteristics, hydrostatic, of stability and longitudinal strength. The Modelmaker module is used to create the ship's body (Geometry File), the superstructure and all appendages, after which the compartmentation is created and the types of compartments and tanks are positioned in the ship's body. To determine the safety of the two tugboats from the point of view of stability, the heeling moment (the heeling arm) that occurs during towing with the righting arm was checked. At the end, the safety status of the two categories of tugboats was analyzed and new projects were proposed for the future, regarding the use of stability criteria for tugboats. [ABSTRACT FROM AUTHOR]

This paper proposes the optimal shape of an LNG fuel tank with a lattice pressure vessel (LPV) design for a tugboat. The LPV is a Type C tank with a design philosophy of “design by analysis,” which facilitates greater variability of shape compared with other traditional Type C tanks. Further, compared with conventional cylindrical fuel tanks, the LPV provides better volumetric efficiency. Considering the shape of a fuel tank room, a trapezoidal shape of the LPV is concluded as the most optimal design. This study performs two major analyses of the LPV: structural and heat transfer analyses. First, a design procedure of the LPV based on structural analyses is elaborated. The finite element method is used for the analyses. Furthermore, the results guarantee that the maximum stresses by applied loads do not exceed an allowable stress limitation. Second, the heat transfer analysis of the LPV is conducted. LNG boil-off gas generation is analyzed based on various insulation materials and the degree of acuum.

In this study, a motion control problem for the vessels towed by tugboats or towing ships on the sea is considered. The towed vessels, such as barge ships, are used for several purposes. Generally, these vessels have no power propulsion system and are towed using ropes and towing vessel (tugboats). The basic mathematical model of the towed vessel in which three active rudders are attached was introduced from a previous study. Owing to the dependency of the motions of the towed vessel to the towing ship, a method is suggested to cope with the undesirable disturbance and improve the tracking performance. For the simulation study, a model of the towed vessel with a towing ship is made, and necessary physical parameters are identified from the experiment. For the defined and linearized model, a control system is designed, and the control performance is also evaluated. A simulation study is conducted and the effectiveness of the proposed control strategy is verified.

In view of the problem of tugboat configuration in LNG terminal, taking the environmental operation standards and conventional operating conditions of LNG ship maneuvering given in the domestic and foreign codes as input conditions, we analyzed the tugboat configuration method of LNG terminal through the calculation method given in foreign codes, comprehensively considered the environmental conditions, safety factors and risk assessment, and gave different tugboat configuration schemes for different environmental operation standards. The relevant research methods and conclusions can provide reference for LNG terminal project. [ABSTRACT FROM AUTHOR]

An active vibration isolation system is retrofitted to a diesel generator set in a tugboat to determine the effectiveness of such a system in a realistic practical environment. The system consists of six bespoke inertial actuators chosen to make minimal modifications to the machinery arrangement, and a DSP-based controller. Six accelerometers are collocated with the actuators on the top of six isolators to act as error sensors, and six accelerometers are placed below the isolators to give a measure of the global vibration of the ships structure below the generator set. A hydrophone is also placed in the water to give an indication of the underwater noise due to the generator. The control strategy employed is six-input and six-output decentralized adaptive feedforward control with the reference signal being derived from the signal from an optical tachometer on shaft between the engine and the generator. To suppress the vibration at all the dominant forcing frequencies, an electrical circuit generated the half engine orders required from the measured reference signal. The experimental results show that the combination of the active control system and the passive isolators is effective in reducing the global vibration and the acoustic pressure at the hydrophone position. [ABSTRACT FROM AUTHOR]

The global greenhouse gas emitted from shipping activities is one of the factors contributing to global warming; thus, there is an urgent need to mitigate the adverse effect of climate change. One of the key strategies is to build a vibrant maritime industry with the use of innovation and digital technologies as well as intelligent systems. The digitization of the shipping industry not only provides a competitive edge to the shipping business model but also enhances ship operational and energy efficiency. This review paper focuses on the big data analytics and machine learning applied to harbour craft vessels with the aim to achieve fuel efficiency. The paper reviews the telemetry system requires for the digitalization of harbour craft vessels, its challenges in installation, the vessel monitoring and data transmission system. The commonly used methods for data cleaning are also presented. Last but not least, the paper considers two types of the machine learning systems, i.e., supervised and unsupervised machine learning systems. The multi-linear regression and hidden Markov model for supervised machine learning system and the artificial neural network, grey box model and long short-term memory model for unsupervised machine learning are discussed, and their pros and cons are presented.

International shipping is the source of around 3% of global CO2 emissions. Liquefied natural gas (LNG) is currently considered the only reasonable and commercially advanced alternative to the petroleum-based ship fuels. Liquefied natural gas can make a significant contribution to the diversification of transport fuels, reducing the greenhouse gas emissions from ships and heavy vehicles. The introduction of LNG technology as a drive for inland ships is a complex process. It requires activities in various areas, including development, legislation, building infrastructure, construction of new ships or their reconstruction. The greatest problem now seems to be the certainty of investing in the new fleet or their reconstruction. It is therefore desirable to assure shipowners that the investment in renewing or reconstruction should be guaranteed. This paper provides a study of reconstruction of the inland tugboat (tug) to a dual fuel system (diesel - LNG). A tugboat used by Slovak shipping company was chosen as a model vessel. The results presented a comprehensive design of the main and auxiliary engine remodelling, as well as the design of the vessel's tanks and show how the conversion affects the basic navigational characteristics of the tugboat. Finally, the results point to the conversion methodology which is partly applicable to another type of inland tug, considering the individual specificities. [ABSTRACT FROM AUTHOR]

Fuel consumption is an energy conversion that converts the chemical energy of a fuel into another energy at a certain time. Fuel consumption must always be monitored because it will affect the company’s profit. Since fuel is a significant expense, the company must be efficient in its usage to allow the company to grow. The author summarizes the problem and tries to solve the problem using quantitative research methods. The research is conducted at the branch office by interviewing the company’s staff. PT. Transcoal Pacific is a company that focused on its service at preparing ships to carry cargo in coal. The company monitors the fuel consumption using a fuel lock system, so the target can be reached in using fuel as few as possible and get maximum profit. Based on the result of this research, it is clear that the company lacks the aspect of fuel monitoring. This causes the target cannot be reached. The old fuel lock cannot be applied by the tugboat and dragging where the vessel swept away by sea current that may increase fuel consumption. The company has to increase the monitoring aspect and implement the obligation to solve the problem to improve fuel consumption efficiency. [ABSTRACT FROM AUTHOR]

An active vibration isolation system is retrofitted to a diesel generator set in a tugboat to determine the effectiveness of such a system in a realistic practical environment. The system consists of six bespoke inertial actuators chosen to make minimal modifications to the machinery arrangement, and a DSP-based controller. Six accelerometers are collocated with the actuators on the top of six isolators to act as error sensors, and six accelerometers are placed below the isolators to give a measure of the global vibration of the ships structure below the generator set. A hydrophone is also placed in the water to give an indication of the underwater noise due to the generator. The control strategy employed is six-input and six-output decentralized adaptive feedforward control with the reference signal being derived from the signal from an optical tachometer on shaft between the engine and the generator. To suppress the vibration at all the dominant forcing frequencies, an electrical circuit generated the half engine orders required from the measured reference signal. The experimental results show that the combination of the active control system and the passive isolators is effective in reducing the global vibration and the acoustic pressure at the hydrophone position.

Selection of a tugboat to be used in a port according to the operations to be carried out is a difficult problem that requires many criteria to be evaluated at the same time. This selection requires high experience as well as technical knowledge about tugboats and operations. In this study, a numerical analysis was carried out within the framework of design, operational and financial criteria to develop a method to select a tugboat. The propulsion/manoeuvring systems used in the tugboats were investigated and different criteria related to the tugboats with different propulsion systems were evaluated by subject matter experts through a survey including technical and financial data. The responses were interpreted with the fuzzy analytic hierarchy process to select a suitable tugboat alternative based on the type of propulsion system. [ABSTRACT FROM AUTHOR]

For safe ship berthing, all steps involved, from bringing the ship to the fairway area to directing it to the final wharf position at a desirable speed, need to be performed properly. In this article, a support system is proposed to automatically bring the ship into the berth after completing the maneuvering process. This proposed system requires no involvement of a shipmaster, enabling automatic ship berthing in marine practice. Three fuzzy controllers are proposed to conduct different tasks of berthing. The first controller is designed to control the movement of the ship in a longitudinal direction towards the wharf while the second controller stabilizes the relative bearing error with respect to the tugboat. The final controller is responsible for bringing the ship into a wharf according to crabbing motion with bow thruster and tugboat simultaneously. Compared to other approaches, ours has a wider range of adoption, better generalization capability, and is more suitable for marine practice. Comprehensive experiments in numerical simulations are carried out, showing the superior performance of the proposed support system for automatic ship berthing.

With the increasing deep water oil & gas exploration, there is also an increase of the demand for offshore operations involving multi-vessels. Such operations require high level planning and coordination, which in most cases occurs by information exchange at the operation level, being each vessel commanded independently. Examples of such operations are offloading, subsea equipment installation and research operation, always involving multiples dynamic positioned (DP) vessels. The advantage of the cooperative control arises with the reduction of the relative positioning error during station keeping or transient maneuvers. In this work, consensus control concepts are applied combined with the DP System of each ship. The cooperative DP controller will be investigated with the analysis of the coupled dynamics of the vessels. The influence of cooperative control gains on the whole system will be discussed, using the frequency response of the open loop system. Fully nonlinear time-domain simulations and experimental results will be used to demonstrate the operation of cooperative control. Besides that, comparisons between the small-scale experiments and equivalent numerical simulations will be carried out, validating the numerical's results. The adopted design requirements are also demonstrated to be met. [ABSTRACT FROM AUTHOR]

Tujuan studi ini adalah memperoleh instrumen utang dan ekuitas untuk yang tepat untuk pendanaan proyek investasi tugboat dan tongkang PTMS, memperoleh komposisi/struktur pendanaan yang tepat untuk proyek investasi tugboat dan tongkang PTMS, mendesain action plan untuk proses perolehan dana proyek investasi tugboat dan tongkang PTMS. Metode yang digunakan adalah analytical hierarchy process yang digunakan sebagai pengambilan keputusan untuk pemilihan instrumen pendanaan yang digunakan, dan pemilihan struktur pendanaan yang tepat untuk mendanai proyek investasi dengan pendekatan cost of capital. Hasil yang didapatkan adalah sesuai dengan kondisi internal dan eksternal perusahaan,bahwa instrumen yang digunakan adalah saham biasa dan hutang bank, sedangkan struktur pendanaan yang tepat untuk membiayai proyek tersebut adalah 90% saham dan 10% utang bank.

The recent researches on the automatic berthing control problems have used various kinds of tools as a control method such as expert system, fuzzy logic controllers and artificial neural network (ANN). Among them, ANN has proved to be one of the most effective and attractive options. In a marine context, the berthing maneuver is a complicated procedure in which both human experience and intensive control operations are involved. Nowadays, in most cases of berthing operation, auxiliary devices are used to make the schedule safer and faster but none of above researches has taken into account. In this study, ANN is applied to design the controllers for automatic ship berthing using assistant devices such as bow thruster and tug. Using back-propagation algorithm, we trained ANN with set of teaching data to get a minimal error between output values and desired values of four control outputs including rudder, propeller revolution, bow thruster and tug. Then, computer simulations of automatic berthing were carried out to verify the effecttiveness of the system. The results of the simulations showed good performance for the proposed berthing control system.

The braking force produced by tugboat has been scarcely examined and little data on the proper characteristics of the braking force can be obtained. Therefore, it is necessary to investigate the braking performance of tugboat. In this paper, the braking force characteristics of tugboat-self in braking condition are obtained and the related unstable phenomena is pointed out and analyzed according to the results of model experiments. Furthermore some new understanding on the braking co-operation by using tugboat is suggested. [ABSTRACT FROM AUTHOR]

• Life cycle assessment of tugboats' diesel and hydrogen power systems is conducted. • Hydrogen fuel cells for tugboats can reduce global warming impact by up to 85%. • Exposure to toxic substances when adopting hydrogen fuel cells is discovered. • Recycling in the decommissioning stage reduces environmental burden by up to 44%. Hydrogen fuel cell has benefits in reducing greenhouse gas emissions and air pollutants. This study conducts Life Cycle Assessment to evaluate the environmental impact of two power systems (hydrogen fuel cells and diesel engines) in tugboats. Results indicate evident reduction potential in global warming (83.9–85%), acidification (45%), eutrophication (54%) and photochemical oxidation (50%) when adopting hydrogen. Specifically, the hydrogen-powered tugboat can reduce up to 48,552,160 kg CO 2 equivalent of global warming, 51,930 kg SO 2 equivalent of acidification, 11,476 kg PO 4 - equivalent of eutrophication, and 2,629 kg C 2 H 4 equivalent of photochemical oxidation compared to the diesel tugboat. However, exposure to toxic substances of hydrogen-powered tugboats, especially in marine aquatic, will increase due to the processes in the hydrogen fuel cell manufacturing and hydrogen fuel supply stages. Additionally, the recycling of materials in the decommissioning stage will reduce the overall environmental burden for both power systems, varying from 8.5% to 44%. [ABSTRACT FROM AUTHOR]

The global greenhouse gas emitted from shipping activities is one of the factors contributing to global warming; thus, there is an urgent need to mitigate the adverse effect of climate change. One of the key strategies is to build a vibrant maritime industry with the use of innovation and digital technologies as well as intelligent systems. The digitization of the shipping industry not only provides a competitive edge to the shipping business model but also enhances ship operational and energy efficiency. This review paper focuses on the big data analytics and machine learning applied to harbour craft vessels with the aim to achieve fuel efficiency. The paper reviews the telemetry system requires for the digitalization of harbour craft vessels, its challenges in installation, the vessel monitoring and data transmission system. The commonly used methods for data cleaning are also presented. Last but not least, the paper considers two types of the machine learning systems, i.e., supervised and unsupervised machine learning systems. The multi-linear regression and hidden Markov model for supervised machine learning system and the artificial neural network, grey box model and long short-term memory model for unsupervised machine learning are discussed, and their pros and cons are presented. [ABSTRACT FROM AUTHOR]

For safe ship berthing, all steps involved, from bringing the ship to the fairway area to directing it to the final wharf position at a desirable speed, need to be performed properly. In this article, a support system is proposed to automatically bring the ship into the berth after completing the maneuvering process. This proposed system requires no involvement of a shipmaster, enabling automatic ship berthing in marine practice. Three fuzzy controllers are proposed to conduct different tasks of berthing. The first controller is designed to control the movement of the ship in a longitudinal direction towards the wharf while the second controller stabilizes the relative bearing error with respect to the tugboat. The final controller is responsible for bringing the ship into a wharf according to crabbing motion with bow thruster and tugboat simultaneously. Compared to other approaches, ours has a wider range of adoption, better generalization capability, and is more suitable for marine practice. Comprehensive experiments in numerical simulations are carried out, showing the superior performance of the proposed support system for automatic ship berthing. [ABSTRACT FROM AUTHOR]