Maneuvering Characteristics Of Ship Research Articles

Intelligent shipping: integrating autonomous maneuvering and maritime knowledge in the Singapore-Rotterdam Corridor

Designing safe and reliable routes is the core of intelligent shipping. However, existing methods for industrial use are inadequate, primarily due to the lack of considering company preferences and ship maneuvering characteristics. To address these challenges, here we introduce a methodological framework that integrates maritime knowledge and autonomous maneuvering model. Based on historical maritime big data, the framework offers customized routes for companies with specific routing preferences. The autonomous maneuvering model then evaluates the safety and reliability of the routes by considering ship motion characteristics and ocean hydrodynamics. We validate its effectiveness on the world’s longest Green and Digital Shipping Corridor between Singapore and Rotterdam. Results demonstrate that our model can provide customized route design for companies and enhance safety for shipping. The framework could serve as a fundamental structure to build a fully digitalized platform for route customization and evaluation for global shipping, optimizing operational decision-making and safety assurance.

Research and Application of Path Planning for Unmanned Ships

As a new product brought about by technological progress, unmanned ships have shown great potential for application in various fields such as ocean exploration, resource development and utilization, environmental monitoring, and maritime rescue in recent years. Path planning is one of the key technologies for unmanned ships to achieve autonomous navigation, which involves multiple aspects such as environmental modeling, algorithm design, collision avoidance rules, and ship maneuvering characteristics. This article aims to explore the current research status, key technologies, and future development trends of unmanned ship path planning, in order to provide reference for the further development of unmanned ship technology.

Autonomous navigation decision-making for ships in complex estuarine waters: Methodology and validation

This study focused on key scientific issues in the autonomous navigation for ships, including constraints on environmental and navigation rules, limitations on ship maneuverability, and collision avoidance mechanisms, to address the challenges of autonomous navigation decision-making for ships in complex estuarine waters and validate the feasibility and accuracy of the proposed methodology. A novel autonomous navigation decision-making method that can dynamically adapt to residual errors in a system and the random movements of target ships was proposed. The predictive model used to calculate decision plans and the simulation model used to execute and validate decision plans were separated. Environmental constituent elements were classified and modeled to digitize the environment. A navigation scenario was constructed based on the fusion of virtual and real information. The control and process prediction methods were proposed based on the nonlinear ship maneuvering characteristics. Navigation rules were summarized, analyzed, and integrated into the decision-making and execution process. The collision avoidance mechanism and calculation method for feasible course and speed range were studied. Simulation experiments were conducted using the North Channel of the Yangtze River Estuary as an example. The results demonstrated that the proposed method can accurately make autonomous navigation decisions, safely avoid collisions, and timely track routes in nearly realistic scenarios.

Four-DOF Maneuvering Motion of a Container Ship in Shallow Water Based on CFD Approach

With the continuous increase in ship size combined with the generally slower increase in the sizes of waterways, the need for the prediction of ship maneuvering in shallow waterways continues to attract attention from the international scientific community. Ship behavior in shallow water is relevant in seabed effects that result in changing the hydrodynamic forces acting on a ship. In this study, the maneuvering characteristics of a container ship with four degrees of freedom in shallow water are analyzed. The Reynolds-Averaged Navier Stokes approach in Ansys Fluent code is used to produce the maneuvering coefficients through the simulations of forward running, static drift, static heel, circular motion, the combined motions, and the pure roll motion of the KRISO container ship. The maneuvering characteristics of the ship are estimated for evaluating the ship behaviors in shallow-water conditions. The obtained results show that the roll has a significant decrease and the ship’s turning diameter has a significant increase when the ship operates in a shallow waterway. The predictions of the maneuvering characteristics of the ship are in good agreement with those of free-running model tests, indicating that the numerical simulation based on the Computational Fluid Dynamics method has compromising capability to predict the maneuvering derivatives and the four-DOF ship maneuvering motion in shallow water as well.

Comprehensive Assessment of Hull Geometry Influence of a Modernized Ship on Maneuvering Performance and Propulsion System Parameters

The necessity to preserve economic efficiency of cruise ships operation stipulates fleet modernization in order to avoid expenses on ordering and construction of new ships. In this paper an approach based on hull length increase in the process of ship modernization is discussed. The method of evaluation of changes in maneuvering characteristics of ship after modernization is developed taking into account the operational parameters of propulsive electric power plants. The calculations are based on the analysis of transient modes of propulsive power plants operation during the corresponding maneuvers. The parameters influencing the characteristics of ship motion during turning circle are revealed; their significance is estimated, comparative analysis of the effect of ship hull length on maneuvering parameters before and after modernization is carried out. It was shown that in some cases the characteristics of the ship’s controllability and operating parameters of the ship power plant after modernization remain within the permissible limits. The comparative results show that the increase in hull length leads to insignificant deterioration of the main maneuverability characteristics while the electric power plant indicators practically do not deteriorate, which confirms the expediency of such modernization.

A decision support system for autonomous ship trajectory planning

This study presents an approach to enhance human–machine collaboration in autonomous ship trajectory planning. A decision support system is developed, considering crucial environmental factors such as ocean currents, wind, and tidal information, alongside the integration of narrow channel geometry, squat effect, and Under-keel-clearance (UKC). The Dynamic Consequence Analysis (DCA) risk assessment method is utilized to establish dynamic safety domains, incorporating ship maneuvering characteristics and potential failure scenarios. The Multi-objective Particle Swarm Optimization (MOPSO) algorithm is then employed to generate alternative trajectories, optimizing five objective functions: minimizing safety domain violation, consecutive speed changes, path length, deviation from the initial plan, and deviation from the initial estimated time of arrival. Furthermore, two Multi-criteria Decision Making (MCDM) methods, Multi-Objective Optimization by Ratio Analysis (MOORA) with user preferences, and the Entropy Weight Method (EWM) with automatic weight allocation, are employed to rank alternative solutions from the Pareto front. Finally, a clustering method is employed on the Pareto front solutions. The outcomes that serve as representatives for these clusters are then merged with the highest-rated alternative solutions from MCDM methods. This combined set forms the basis for the final decision-making process carried out by the operator. While dynamic obstacles are not considered in this study, evaluation across three scenarios demonstrates the effectiveness of the proposed decision support system for trajectory planning.

A comparative analysis of course keeping and turning circle for a 37000 tdw chemical tanker

The maneuvering characteristics of ships represent complex phenomena, 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.

A study on interaction among hull, diesel engine and propellers of a twin-screw ship during turning circle maneuver

A marine propulsion plant will experience power fluctuations during ship maneuvers. In the turning circle maneuver, the propulsive load increases significantly, and the power required by the two shafts of a twin-screw ship may be completely inconsistent. To protect the propulsion plant, the interaction between the engine and the propellers should be studied in depth. In this paper, the twin-screw ONRT ship and the 16PA6-STC diesel engine are selected as the study objects. A series of captive model tests are simulated by using CFD method to obtain the hydrodynamic derivatives and hull-propeller-rudder interaction coefficients in the MMG model. The effective wake fraction is computed under the maneuvering conditions. Turning circle maneuver of the ship is predicted by using the established MMG model, and the predicted ship maneuvering characteristics show good agreement with the available experimental results, which verifies the CFD-based modeling method. Finally, a dynamic model of hull-engine-propeller system is established on the simulation platform for evaluating the operating characteristics of propulsion plant. The propeller loads are predicted and the interaction among hull, engine and propellers is investigated. This study helps to provide a deeper insight into the engine operation behaviors during turning circle maneuver of a ship.

Ship Collaborative Path Planning Method Based on CS-STHA

Ship path planning is one of the key technologies for ship automation. Establishing a cooperative collision avoidance (CA) path for multi-ship encounters is of great value to maritime intelligent transportation. This study aims to solve the problem of multi-ship collaborative collision avoidance based on the algorithm of Conflict Search (CS) and Space-Time Hybrid A-star (STHA). First, a static CA path is searched for each ship by using the space-time Hybrid A-star algorithm, and the conflict risk area is determined according to the ship safety distance constraint and fuzzy Collision Risk Index (CRI). Secondly, the space-time conflict constraint is introduced into the multi-ship cooperative CA scheme, and the binary tree is used to search for an optimal navigation path with no conflict and low cost. In addition, the optimal path is smoothed by using cubic interpolation to make the path consistent with actual navigation practice and ship maneuvering characteristics. Finally, considering the constraints of the International Regulations for Preventing Collisions at Sea (COLREGs), the typical two-ship and multi-ship encounter scenarios are designed and simulated to verify the effectiveness of the proposed method. Furthermore, a comparative analysis of actual encounters and encounters based on CS-STHA is also carried out. The results indicate that the proposed algorithm in the study can obtain an optimal CA path effectively and provide a reference of CA decision-making for autonomous ships.

A Collision Avoidance System Based on COLREGs Rules for Autonomous Surface Vessels

The proposed mathematical model in this study consists of two parts, one is the maneuvering model, called MMG (Mathematical Model Group), and the other is a control algorithm based on traditional PD control system. The MMG model is used to compute the ship's maneuvering characteristics, and a ship can safely reach target coordinates with the help of a control algorithm if it encounters any obstacles along the way. Because of the suitable hydrodynamic coefficients of Esso Osaka, the proposed mathematical model is evaluated using trial test data from Esso Osaka. Firstly, the maneuvering characteristics of the ship were determined by performing the turning and zigzag tests for different velocity of the ship. By comparing the results obtained with the trial test results of the Esso Osaka, the suggested model was verified. Secondly, the ship's route was obtained for a determined target coordinate. Thirdly, a new route is automatically obtained by assuming that there is an obstacle between the starting point of the ship and the target coordinate determined for the previous simulation. As a result, this new route is created thanks to the virtual coordinates determined in accordance with the COLREGs rules. Since the maneuvering characteristic values of the ship are included in the written algorithm, it directly affects the determination of the virtual coordinates. Therefore, it is very important to find accurate maneuvering characteristics. Evaluating the simulation results obtained from the proposed mathematical model, it is concluded that a safe route has been created between the coordinates determined for the Esso Osaka ship. Moreover, the ship reaches the target coordinate without any collision.

Effects of Hull and Control Surface Roughness on Ship Maneuvering

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed. Introduction The effects of hull roughness, including fouling, are known to affect the performance of a vessel, especially as measured in additional fuel consumption and less so, the number of voyages in a lifetime. Today, there is significant attention given to hull surface cleaning, coating, and propeller polishing to address these issues. In addition and even less known are the effects on the maneuvering performance of a vessel. For naval vessels, they may affect the success of the mission. Roughness of the hull can occur because of a number of factors including hull material used and quality of construction, mechanical damage in operation, roughness from paints and coatings and their method of application, damage to the coating during maintenance, corrosion and pitting of the hull structure material, and biofouling influenced by the type of antifouling paint or coating and method of application. The roughness never ceases to increase during the vessel’s life. Starting with the hull material and construction, then the effects of different paints and coatings, operations, dry-docking intervals, and approach to maintenance, it is possible to develop a lifetime roughness profile.

The influence of control laws of frequency-regulated electric motors on electric ships’ maneuvering characteristics

Relevance. In shipbuilding, there have been trends in the use of electric motion. The most important advantages of electric vessels are the high maneuverability, which contributes to the safety of maneuvering operations. Electric propelling power plants (EPPP) are most often built on the basis of asynchronous frequency-controlled electric motors (EM). More and more attention is being paid to electric vessels with a unified electric power system. Electric propelling plant (EPP) is the largest power consumer. The transient modes of its operation significantly affect the parameters of the electric power of the ship network, which raises the requirements for the quality of transient processes in the EPP. On this basis, both the indicators of maneuverability and the quality of electric power of the ship network should be the quality indicators of the control of the EPP on maneuvers. Status of the issue under consideration. Three laws of control of frequency-regulated electric motors are used in the theory of electric motion: at a constant moment; at constant power; at quadratic load. For a real engine, deep frequency control according to one of these laws is not possible, since the motor overload capacity will either be lowered at low frequencies or overestimated in nominal mode. Constant overload capability can only be ensured if there is a variable correlation between voltage and frequency. In the case of frequency control of electric ships’ electric motors, the task becomes more difficult, since a set of indicators characterizing the ship's maneuvering characteristics, transient processes in the EPPP and the parameters of electric power of the ship network should be chosen as the criteria of regulation quality. This leads to the need to clarify the control laws. The purpose of the work is the search for frequency control laws of electric motors that are able to provide better maneuverability of electric vessels. Research results. A structural diagram of EPPP as part of an electric ship’s propulsive complex has been made. A mathematical model of transient operation modes has been worked out on its basis. An algorithm and a package of application programs for calculating the basic mode indices of the complex have been developed. The estimation procedure of the basic indicators of quality of maneuver operation performance is worked out. The model and method of calculation make it possible to study the influence of EM control laws on the electric ships’ maneuvering characteristics, on transient processes in the EPPP and on the parameters of electric power of the ship network. The research was carried out on the example of the science-research vessel MV SANCO STAR. Maneuver modes for various control laws are calculated and the performance indicators of maneuver operations are evaluated. A comparative analysis of the results made it possible to find the best EM control laws on maneuvers. Conclusions. With respect to electric vessels with frequency-controlled electric motors, the proportional control law has significant advantages over other control laws. At the same time, increasing the supply voltage of the EM in transient modes opens the possibility of increasing the efficiency of performing maneuver operations. It is recommended to form the control laws of the EM voltage as analytical dependencies, in which the correlation between the relative voltage and the relative frequency changes gradually depending on the depth of regulation. Specific analytical dependencies are obtained from the results of optimization calculations of control laws.

An Effective Ship Control Strategy for Collision-Free Maneuver Toward a Dock

Ship maneuvering toward a dock is a hot research topic in the field of autonomous ships. How to realize autonomous low-speed maneuver to a designated location under environmental disturbances is the fundamental problem at present. In addition, potential collisions with other nearby vessels and evasive maneuvers that meet maritime regulations increase the complexity of maneuvering. This paper presents an effective ship control strategy for collision-free maneuver toward a dock. In the strategy, a line-of-sight (LOS) algorithm is utilized to steer the ship along a pre-planned path toward the dock. A collision risk factor that takes ship's maneuvering characteristics, ship domain and relative velocity into account is designed for collision avoidance. Evasive maneuvers complying with the main rules of the international collision avoidance regulations at sea can be achieved based on the risk factor. A ship bumper is constructed, based on which the strategy can switch to either “path following” or “collision avoidance”. Numerical simulations for different encounter situations including head-on, starboard-crossing and overtaking under wind perturbations are carried out. The results show the proposed strategy is able to keep the ship domain free during maneuvering and steer the ship to the docking area in a safe and appropriate manner.

Ship Route Planning Based on Double-Cycling Genetic Algorithm Considering Ship Maneuverability Constraint

In order to complete automatic route planning in the complex navigation environment, this paper proposes a quadratic optimization genetic algorithm combining the motion characteristics of the ships. Furthermore, the constraints of the maneuvering characteristics of ship are considered to calculate the accurate planning routes fast. First of all, the turning and speed reduction model of ships are established, which is the foundation for the accurate calculation of approach states between the own ship and target ships. Second, in order to check the position relationship between the planned route and the land objects (such as the islands and rocks) on the chart, a detection algorithm between lines and irregular polygon boundary based on quadtree method is acquired. Third, a new genetic algorithm based on double-cycling optimization is proposed by this paper. Aiming at the complex problem of comprehensive collision avoidance planning under the conditions of static and dynamic obstacles, this paper realizes an efficient and feasible solution of dynamic programming for ship route. Finally, the algorithm is verified on a test fireboat, and the experiment data prove the feasibility and effectiveness of the proposed algorithm by this paper.

실선시험에 의한 DWT 8,000톤 선박의 선회성능 – Semi–balanced rudder and flap rudder –

This study is intended to provide navigator with specific information necessary to assist the avoidance of collision and the operation of ships to evaluate the maneuverability of dead weight tonnage 8,000 tons Oil/Chemical tanker. The actual maneuvering characteristics of ship can be adequately judged from the results of typical ship trials. Author carried out sea trials based full scale for turning test in ballast condition and full load condition, semi balanced rudder and flap rudder. The turning circle maneuvering were performed on the starboard and port sides with rudder angle at the normal continuous rating. The results from tests could be compared directly with the standards of maneuverability of IMO and consequently the maneuvering qualities of the ship is full satisfied with its.

실선시험에 의한 DWT 8,000톤 선박의 조종성능 – Semi–balanced rudder and flap rudder –

This study is intended to provide navigator with specific information necessary to assist the avoidance of collision and the operation of ships to evaluate the maneuverability of dead weight tonnage 8,000 tons Oil/Chemical tanker. The actual maneuvering characteristics of ship can be adequately judged from the results of typical ship trials. Author carried out sea trials based full scale for turning test, Z maneuvering test, man overboard rescue maneuver test, inertia stopping test. Consequently, Overshoot yaw angle of the semi balanced rudder and flap rudder in zig-zag test showed and , respectively. The maneuverability of the vessel was good in the flap rudder. The man overboard rescue maneuver maneuverability test was most favorable in the flap rudder and the full load condition. The results from tests could be compared directly with the standards of maneuverability of IMO and consequently the maneuvering qualities of the ship is full satisfied with its.

Research on the Design for Bridge Channel Buoy

The reference basis for channel buoy design in China at present is the inland navigation standard, but about bridge channel buoys design, there are a lot of insufficient places in the standard. The channel buoy reasonable design method is put forward in this paper according to the ship maneuvering characteristics.

선박조종성능 평가를 위한 실선 실험연구

At the design stage, it is very important to know the ship maneuvering characteristics from the view point of ship performance and for the safety of navigation. IMO only gives some criteria for in full load even keel condition. However, the ship generally is operated not only in full load condition but also in half load condition or ballast condition. Therefore we must estimate the ship maneuvering in different loading condition to ensure that the ship will satisfy with IMO rules and navigate safely in every condition. In this paper, we have investigated the maneuvering characteristics of a ship by simulation and experiments with real ship. By comparing with the results of simulation, the real ship tests conform with simulation test and previous researches. Therefore, the method base on real data is well done to estimate the ship maneuvering in different loading conditions. The change of ships manoeuverability accoriding to ships operation conditions was estimated.

Installing single-propeller twin-rudder system with less asymmetric maneuvering motions

The inflow characteristics to each one of the rudders of single-propeller twin-rudder system are investigated. It is shown that this inflow is not parallel to ship's centerline. This may result in asymmetric maneuvering characteristic of the ship thereby reducing ship's maneuvering performance. For this purpose, a method of installing single-propeller twin-rudder system is proposed. This method is called “virtual zero rudder angle” arrangement. Here, each one of the twin-rudder is set at an angle corresponding to the inflow to the rudder. The improvement in ship's maneuvering characteristics with “virtual zero rudder angle” arrangement is investigated using experiments and numerical simulations for different ship types. It is shown that this arrangement may also improve ship's propulsion performance.

Evaluation of Container Ship Maneuvering Characteristics from View Point of Ship Handling Ability

Evaluation of Container Ship Maneuvering Characteristics from View Point of Ship Handling Ability