Ship Maneuvering Performance Research Articles

A Decision Model for Ship Overtaking in Straight Waterway Channels

Overtaking situations are commonly encountered in maritime navigation, and the overtaking process involves various risk factors that significantly contribute to collision incidents. It is crucial to conduct research on the maneuvering behaviors and decision-making processes associated with ship overtaking. This paper proposes a method based on the analysis of ship maneuvering performance to investigate overtaking behaviors in navigational channels. A relative motion model is established for both the overtaking and the overtaken vessels, and the inter-vessel distance is calculated, taking into account the psychological perceptions of the ship’s driver. A decision-making model for ship overtaking is presented to provide a safety protocol for overtaking maneuvers. Applying this method to overtaking data from the South Channel shows that it effectively characterizes both the permissible overtaking space and the driver’s overtaking desire. Additionally, it enables the prediction of optimal overtaking timing and strategies based on short-term trajectory forecasts. Thus, this method not only offers a safe overtaking plan for vessels but also provides auxiliary information for decision making in intelligent ship navigation.

Determination of Maneuvering Force Coefficients for a Destroyer Model with OpenFOAM

_ Ship maneuvering performance can be predicted using various methods, including physical model tests, rapid simulations using coefficient-based forces, and high-fidelity computational fluid dynamics. This article considers the application of computational fluid dynamics for the prediction of hull force coefficients to be used as inputs to rapid maneuvering simulations. The open-source software OpenFOAM was used to simulate forces on the destroyer model DTMB 5415 for steady drift, oscillatory pure sway motion, and oscillatory yaw motion. Recommendations are provided regarding best practices in a number of areas, including domain size, mesh refinement, time step size, and turbulent modeling. Predicted forces for steady drift angles up to 12 degrees are typically within 10%of experimental values. For oscillatory sway and yaw motions, predicted forces are typically within 25%of experimental values. Keywords maneuvering; OpenFOAM; best modeling practices

Path-following control problem for maritime autonomous surface ships (MASS) in adverse weather conditions at low speeds

With the increasing popularity of autonomous vehicles, the maritime industry has focused on the development of Maritime Autonomous Surface Ships (MASS). An essential aspect of autonomous ships is their ability to follow a predetermined path at sea, as deviations from this path can jeopardize navigational safety, leading to accidents like collisions and grounding incidents. Therefore, ensuring that autonomous ships can safely navigate by following predefined routes is of utmost importance. Simultaneously, the implementation of the Energy Efficiency Design Index (EEDI) by the International Maritime Organization (IMO) has raised interest in a ship's manoeuvring performance in adverse sea conditions, aiming to reduce greenhouse gas emissions. The Marine Environment Protection Committee (MEPC) has provided guidelines to determine the minimum propulsion power required to maintain ship manoeuvrability in adverse conditions. This study investigates the path-following performance of a ship operating at low forward speeds in adverse weather conditions using a free-running Computational Fluid Dynamics (CFD) model, enabling accurate prediction of manoeuvring behaviour. The numerical results emphasise the significance of low forward speeds in enabling a ship to follow a predetermined route, offering valuable insights into path-following performance with minimum propulsion power in adverse weather. The study reveals that increasing propulsive power reduces deviations from the predetermined route when the ship encounters bow and beam waves. However, the impact of propulsion power on deviation is negligible in quartering waves during path-following control. This research contributes to improving guidelines for minimum ship powering, ensuring safe autonomous navigation in adverse weather conditions.

Numerical Investigation of Global Ice Loads of Maneuvering Captive Motion in Ice Floe Fields

During escort and convoy operations, icebreakers are often required to maneuver to open up channels or adjust routes due to the prevalence of ice floe conditions in Arctic routes. This study aimed to investigate the global ice load characteristics of the maneuvering captive motions, including constant turning motion, pure yaw motion, and pure sway motion, of the icebreaker Xue Long, using a combination of the discrete element method (DEM) and drag model. First, the method was verified using simulating Araon model tests from the Korea Institute of Ocean Science and Technology (KIOST). In addition, the maneuvering captive motions of the Xue Long model were simulated at varying turning radii, drift angles, and sway and yaw periods, which are typical but currently poorly studied maneuvering motions. Overall, the results of the study showed that the method is able to reproduce the coupling effect of the ship–ice–water system by considering ship–ice interaction and ice resistance, where the mean deviation and maximum deviation of ice resistance are 9.45% and 13.3%, respectively. The influences of the turning radius, drift angle, and sway and yaw period on the ice resistance and transverse force characteristics were studied and analyzed via ship–ice interactions. The present study provides a prediction tool for the assessment of ship maneuvering performance to assist the hull line development and model testing of icebreakers.

Maneuverability indices estimation of nonlinear response model based on full-scale trial data and square root unscented Kalman filter

Research on ship maneuvering performance provides a theoretical reference for autonomous ship navigation control. The gain and time coefficients accurately describe the dynamic performance of the ship. Given the challenge that the unscented Kalman filter cannot ensure the nonnegativity of the state covariance matrix during the filtering process, this study proposed a parameter identification scheme for a second-order nonlinear response model based on the square root unscented Kalman filter. First, the maneuverability indices of the free-running model were identified based on simulation data. Thereafter, the feasibility and convergence performance of the proposed scheme were verified. Based on full-scale trial data with uncertainty interference, the parameters of the second-order nonlinear response model were estimated for the YUKUN ship. The feasibility, effectiveness, and generalizability of the proposed scheme were further verified. The proposed scheme was analyzed based on three perspectives: parameter convergence, estimation results of the maneuverability indices, and yaw angle prediction results. The results obtained using the proposed algorithm were compared with those obtained using the extended Kalman filter. Finally, the proposed scheme can provide a reference for online parameter identification and prior knowledge for course keeping controllers and autonomous navigation control.

Effects of adverse sea conditions on propulsion and manoeuvring performance of low-powered ocean-going cargo ship

Current EEDI (Energy Efficiency Design Index) regulations striving to reduce the installed engine power on new ships for a low EEDI may lead to underpowered ships having insufficient power when operating in adverse sea conditions. In this paper, the operational safety of a low-powered ocean-going cargo ship operating in adverse sea conditions has been investigated using an integrated ship propulsion, manoeuvring and sea state model. The ship propulsion and manoeuvring performance, especially the dynamic engine behaviour, when the ship is sailing in heavy weather and turning into head sea, have been studied. According to the results, the dynamic engine behaviour should be considered when assessing the ship operational safety, as the static engine operating envelope is inadequate for the safety assessment. The impact of PTO/PTI (power-take-off/in) operation and changing propeller pitch on the ship thrust availability in adverse sea conditions have also been investigated. To protect the engine from mechanical and thermal overloading, compressor surge and over-speeding during dynamic ship operations and/or in high sea states, the engine and propeller should be carefully controlled. The paper shows that if in (heavy) adverse weather the propeller pitch can be reduced or if the shaft generator can work as a motor (PTI), more thrust can be developed which can significantly improve the operational safety of the ship.

RANS Computation of the Mean Forces and Moments, and Wave-Induced Six Degrees of Freedom Motions for a Ship Moving Obliquely in Regular Head and Beam Waves

Ship maneuvering performance in waves has attracted much attention in recent years. One of main research efforts for this problem has been devoted to the high-accuracy computation of hydrodynamic forces and moments, as well as wave-induced motions, for ships performing maneuvering motions in waves. The objective of this article is to present a numerical study on the computation of the mean forces and moments, and wave-induced six degrees of freedom motions for a ship moving obliquely in regular head and beam waves. The RANS (Reynolds-Averaged Navier-Stokes) solver based on OpenFOAM is used for this purpose. The RANS computations herein are carried out in a horizontal coordinate system. The numerical wave maker with prescribing values of flow variables on the domain boundaries is applied for the wave generation in the computational domain. However, in order to prevent wave reflection, relaxed zones adjacent to the wave maker boundaries are set up. A new program module is inserted into OpenFOAM to update the flow velocity and wave evaluation on the wave-maker boundaries and in the relaxed zones during the RANS computation. The mesh deformation method is employed to allow the ship to perform motions in space. However, a virtual spring system is attached to the ship so as to restrain the surge, sway and yaw, while heave, pitch and roll are completely free, so that the ship is able to oscillate periodically around a certain position in space. The computed mean forces and moments with the inertia effects agree fairly well with the experimental data, and the computed wave-induced motions are also in quite reasonable agreement with the experimental data. This study shows a very successful computation, as well as the procedure of the RANS results processing.

Free running CFD simulations to investigate ship manoeuvrability in waves

Ship manoeuvrability is closely related to the safety of ship operation in a real seaway; therefore predicting a ship's manoeuvring characteristics is of great importance. However, estimating a ship's manoeuvring performance in waves is challenging because of the complex fluid-structure interactions between hull, rudder, propeller and waves. Traditional methods for the study of a ship's manoeuvrability in waves, based on mathematical models combined with potential flow theory, cannot accurately and effectively incorporate the effect of waves on a ship. On the other hand, unsteady Reynolds-Averaged Navier-Stokes (RANS) computations are capable of resolving the interactions between a ship and waves with high accuracy. The main objective of this study is to carry out a fully nonlinear unsteady RANS simulation to predict the manoeuvring behaviour of a KRISO Container ship (KCS) model in different wave conditions. A dynamic overset grid method was used with the purpose of resolving large ship motions and rudder movement. A course keeping and manoeuvring control module based on a feedback control system was embedded in the simulation to control rudder deflection according to standard manoeuvre mechanisms. Simulation results were compared with available experimental data and showed good agreement, which demonstrates that CFD is a reliable approach to estimate ship manoeuvrability in waves.

Development of Enhanced Two-Time-Scale Model for Simulation of Ship Maneuvering in Ocean Waves

In this study, a modified two-time-scale model is proposed to overcome the limitations of the existing maneuvering analysis model. To this end, not only wave conditions but also all directions of ship operation velocities are considered in estimating wave drift force and moment. Subsequently, the increment of the drift force and moment induced by steady drift and yaw motion of a ship is imposed up to the first derivative of Taylor series expansion. By introducing this bilinear model, the burden of the drift force computation is reduced so that a more realistic and efficient seakeeping-maneuvering coupling analysis can be performed. A turning circle simulation in a regular short wave is carried out using the modified two-time-scale model. Then, the performance is validated by comparing its results with the direct coupling model. Moreover, quantitative improvement of the present numerical scheme and the influence of the operation velocities on ship maneuvering performance are discussed.

GPU-Based DEM Simulations of Global Ice Resistance on Ship Hull During Navigation in Level Ice

The ice resistance on a ship hull affects the safety of the hull structure and the ship maneuvering performance in ice-covered regions. In this paper, the discrete element method (DEM) is adopted to simulate the interaction between level ice and ship hull. The level ice is modeled with 3D bonded spherical elements considering the buoyancy and drag force of the water. The parallel bonding approach and the de-bonding criterion are adopted to model the freezing and breakage of level ice. The ship hull is constructed with rigid triangle elements. To improve computational efficiency, the GPU-based parallel computational algorithm was developed for the DEM simulations. During the interaction between the ship hull and level ice, the ice cover is broken into small blocks when the inter-particle stress approaches the bonding strength. The global ice resistance on the hull is calculated through the contacts between ice elements and hull elements during the navigation process. The influences of the ice thickness and navigation speed on the dynamic ice force are analyzed considering the breakage mechanism of ice cover. The Lindqvist and Riska formulas for the determination of ice resistance on ship hull are employed to validate the DEM simulation. The comparison of results of DEM, Lindqvist, and Riska formula show that the DEM result is between those the Lindqvist formula and Riska formula. Therefore the proposed DEM is an effective approach to determine the ice resistance on the ship hull. This work can be aided in the hull structure design and the navigation operation in ice-covered fields.

Characteristics of Turning Circle and Zig-Zag Manoeuvres of An Indonesian Ferry Ship In Shallow Water

Ship manoeuvring performance is very important in navigation safety, especially when ships operate in shallow water. This paper describes the characteristics of turning circle and zig-zag manoeuvres of Indonesian ferry ships in shallow water. A time-domain simulation program was developed for this purpose. Several parameters such as ship speed and water depth levels have been considered in the simulation. The results shows a significant difference in the ship’s trajectory and speed when the ship manoeuvring in different water depths. The ship manoeuvre trajectory diameter for shallow water (h/T=1.3) is greater than in deep water (h/T=4.0). Meanwhile, the speed of the ship during turns increases with the decreasing depth of the water (h). Likewise, the 20/20° zig-zag manoeuvre of the ship shows that the heading angle in shallow waters has a smaller overshoot angle when compared to the ship manoeuvres in the deep waters.

Preliminary Study of Ship Maneuvering Prediction of Container Ship

Ship maneuvering is defined as the inherent capability of a vessel to turn its path based on the hydrodynamics principles. The maneuvering performance becomes important to the safety of navigation when a ship operates. In case of vessel turning motion, International Maritime Organization (IMO) requires the maximum tactical diameter is five times of the ship lengths. Tactical diameter is the distance travelled by the ship’s center of gravity in a parallel direction to the ship’s initial path. In this paper, semi-empirical approach proposed by Clarke (1983) was used to obtain the first derivative of hydrodynamics equation. After that, the maneuvering performance was calculated using Son and Nomoto’s mathematical model (1981). Based on IMO regulations, the calculation of tactical diameter was conducted with 35° of rudder position. The calculation and analysis of tactical diameter was carried out according to relevant procedure of the ship maneuvering provided by IMO. The calculation result shows satisfactory result based on IMO regulations. The maximum tactical diameter does not exceed the requirements of IMO maneuvering standards. A further investigation was performed to see whether there was any impact on ship’s main dimensions to the maneuverability performance. In the future study, the development of open source software program to analyze the ship maneuvering performance is considered. It is expected to be able to contribute for facilitating in the preliminary ship design process.

P.845The effect of antipsychotic therapy on the social functioning of patients with paranoid schizophrenia

A ship encounters wave loads in actual seas, it is necessary to estimate the ship's manoeuvring performance in waves for its safe operations. In this study, turning characteristics of a KCS model ship in regular waves were investigated by free-running model tests. 35° port and starboard turning circle tests in regular waves were carried out in KRISO Ocean Engineering Basin with variations of regular wave heights, lengths, directions and model approach speeds. Propeller revolution rate was mostly fixed at the constant value corresponding to the full-scale speed of 16 knots in calm water. Ship's turning behaviours in waves can be divided into initial and steady turn phases. Firstly, during initial turns, the ship's safety which is related to avoiding a fixed front obstacle is focused on. ‘DMINw’ is defined as the minimum distance between the fixed front obstacle and the ship initial trajectory. And safety index ‘STw’ is proposed, which is formulated by using the ratio between DMINw in calm water and in waves. The ship becomes safer in head waves than calm water due to small advances. In starboard beam waves, when the ship turns to starboard, that becomes dangerous due to small transfers. In port beam waves, the ship which turns to starboard is mostly safe. But, in short port beam waves, yaw angle is slowly increased and the advance is relatively large. It is hypothesized that the wave drift yaw moments prevent the ship from turning to starboard. Secondly, drifting distances and angles in steady turns are quantified. The drifting distances increase with decreasing wave lengths, when the wave lengths are varied from 0.5 to 1.0 ship length. The drifting distances are approximately proportional to the wave steepness. Finally, approximate formula of STw is proposed. That is formulated as the function of ship advance and transfer in calm water and waves only. DMINw can be simply obtained if the initial trajectory is approximated as the ellipsoidal quadrant. Based on several parametric simulations, it was confirmed that STw is proportional to the cube of the transfer in waves and is inversely proportional to the advance in waves. STw is formulated so that it can be applied to arbitrary ships.

Initial and steady turning characteristics of KCS in regular waves

A ship encounters wave loads in actual seas, it is necessary to estimate the ship's manoeuvring performance in waves for its safe operations. In this study, turning characteristics of a KCS model ship in regular waves were investigated by free-running model tests. 35° port and starboard turning circle tests in regular waves were carried out in KRISO Ocean Engineering Basin with variations of regular wave heights, lengths, directions and model approach speeds. Propeller revolution rate was mostly fixed at the constant value corresponding to the full-scale speed of 16 knots in calm water. Ship's turning behaviours in waves can be divided into initial and steady turn phases. Firstly, during initial turns, the ship's safety which is related to avoiding a fixed front obstacle is focused on. ‘DMINw’ is defined as the minimum distance between the fixed front obstacle and the ship initial trajectory. And safety index ‘STw’ is proposed, which is formulated by using the ratio between DMINw in calm water and in waves. The ship becomes safer in head waves than calm water due to small advances. In starboard beam waves, when the ship turns to starboard, that becomes dangerous due to small transfers. In port beam waves, the ship which turns to starboard is mostly safe. But, in short port beam waves, yaw angle is slowly increased and the advance is relatively large. It is hypothesized that the wave drift yaw moments prevent the ship from turning to starboard. Secondly, drifting distances and angles in steady turns are quantified. The drifting distances increase with decreasing wave lengths, when the wave lengths are varied from 0.5 to 1.0 ship length. The drifting distances are approximately proportional to the wave steepness. Finally, approximate formula of STw is proposed. That is formulated as the function of ship advance and transfer in calm water and waves only. DMINw can be simply obtained if the initial trajectory is approximated as the ellipsoidal quadrant. Based on several parametric simulations, it was confirmed that STw is proportional to the cube of the transfer in waves and is inversely proportional to the advance in waves. STw is formulated so that it can be applied to arbitrary ships.

Mathematical model of the ship manoeuvring

Starting with the initial design phase, the knowledge of the ship manoeuvring performance is an important problem. One of the methods to evaluate the manoeuvring characteristics is based on the time domain simulation of the standard manoeuvring tests. A typical mathematical model that may be used to determine the manoeuvring characteristics of the ships is presented in this paper.

Numerical Evaluation of Ship Turning Performance in Regular and Irregular Waves

AbstractIn this study, ship's maneuvering performance in waves is evaluated using numerical computation. To this end, three degrees-of-freedom (3DOF) planar motions are considered, and modular-type maneuvering model (maneuvering modeling group model (MMG model)) is applied. As external force of the equation of motion, hull force, propulsion force, rudder force, and wave drift force are adopted. In order to calculate wave drift force, seakeeping program which is based on a higher-order Rankine panel method is used by considering wave frequency, wave heading, ship's forward speed, and ship's lateral speed. This wave drift force is pre-calculated, made into database, and used in time domain simulation. The developed simulation program is validated by comparing the computation results of a turning test in regular waves with experimental data. Using this program, turning performance in irregular waves is evaluated and sensitivities for time signal of wave elevation are investigated. Through this study, it is confirmed that the simplified method based on the MMG model including wave drift force can provide good agreement with experimental data in a practical point of view. It can be observed that the simulation results considering the lateral speed show better agreement with the experimental data than those without consideration. In the case of irregular wave condition, the turning performance can be affected by wave random phases. When the ship encounters the beam sea during the turning operation, the wave elevations at that time play an essential role in the change of ship speed and turning trajectory.

System-based prediction of maneuvering performance of twin-propeller and twin-rudder ship using a modular mathematical model

The turning circle and zigzag maneuvering performance of surface combatant, DTMB 5415 have been investigated by using system-based method. Unsteady Reynolds averaged Navier Stokes (URANS) approach is utilized to estimate hydrodynamic derivatives and hull-propeller-rudder interactions. DTMB 5415 is a twin-propeller / twin-rudder ship and there are some studies on the derivation of maneuvering coefficients in the literature but none of them took into account the propeller and rudder forces. In this study, static drift, pure yaw, combined yaw and drift, self-propulsion and rudder tests of DTMB 5415 hull have been simulated in calm and deep water condition. Bare hull PMM simulations were carried out for a fixed Froude number of Fr=0.28, while the simulations related to rudder and propeller were performed at Fr=0.25. Computational results were used by MMG (Maneuvering Modeling Group) model to estimate the maneuvering performance of the ship. Hydrodynamic derivatives from numerically generated forces and moment data were obtained by single-run and multiple-run methods. The results from both methods were tested in an in-house maneuvering simulation code (MANSIM) that solves for ship motions and they were compared with computed turning circle and zigzag maneuvering performances. Although it is known a priori that the multiple-run method would give better solution in overall, it was found that the single-run method can be a good alternative in some specific cases. For the zigzag and turning circle tests, the results from single-run method were found satisfactory when correct PMM test conditions were adopted.

Ship Maneuvering Performance Prediction Based on MMG Model

This paper expounds mathematical model and computer simulation of ship maneuvering, and use MMG’s manipulation of motion mathematic model and related series of experimental results as the foundation, establish the basic model of ship maneuvering movement. Building a simulation model in MATLAB, and carry out simulation experiments on ship maneuvering motion. The simulation results are basically in line with the actual situation.

파랑 표류력을 고려한 선박의 파랑 중 선회성능 해석

This paper performs a numerical computation of ship maneuvering performance in waves. For this purpose, modular-type model (MMG (Mathematical Modeling Group) model) is adopted for maneuvering simulation and wave drift force is included in the equation of maneuvering motion. In order to compute wave drift force, two different seakeeping programs are used: AdFLOW based on Wave Green function method and SWAN based on Rankine panel method. When wave drift force is calculated using SWAN program, not only ship forward speed but also ship lateral speed are considered. By doing this, effects of lateral speed on wave drift force and maneuvering performance in waves are confirmed. The developed method is validated by comparing turning test results in regular waves with existing experimental data. Sensitivities of wave drift force on maneuvering performance are, also, checked.

Determination of ship maneuvering hydrodynamic coecients using system identication technique based on free-running model test

In the recent years, di erent mathematical models have been suggested for maneuvering of displacement vessels that are capable of estimation of vessel maneuvers with acceptable precision. These mathematical models are based on determined hydrodynamic coecients and their accuracy depends on the known coecients used to solve the mathematical model. System identi cation methods are developed to calculate these coecients utilizing input and output data obtained from di erent sources. In this research, a 4.36-m model of KRISO Container Ship (KCS) displacement vessel has been manufactured by berglass, and the maneuver turning tests have been carried by selfpropulsion method. A 3DM-GX1 sensor, together with a protractor and Global Positioning System (GPS), has been used to measure the yaw and rudder angle, position, linear accelerations, and angular velocities of the vessel in di erent times. The hydrodynamic coecients in the mathematical model are determined by the Extended Kalman lter method. Then, the mathematical model is solved and di erent maneuvers are simulated by coecients calculated from the experiments. Simulations are validated by model tests. The mathematical model and hydrodynamic coecients presented in this paper can be applied for optimization of ship maneuvering performance and course control purposes