Ship Performance Research Articles

Evaluating vessel technical performance index using physics-based and data-driven approach

Ship's performance and its emissions are affected by several factors like operational state, weather, and maintenance condition. Rating ships with performance indices, such as AER, is not really helpful as these factors are affected by the ship's technical and operational condition, obscuring the benefits of energy-saving technologies and improved maintenance condition. To promote energy-efficient ships and reduce emissions, DNV proposed a simple and intuitive Vessel Technical Index (VTI) which is expected to represent the change in technical performance of ships over time. This paper presents two different schemes to estimate VTI, namely, physics-based and data-driven approaches, to validate their applicability as well as compare their performance. The results are based on the measured in-service data from a bulk carrier, equipped with advanced sensors for speed and wave measurements. Although the VTI values from the data-driven approach are slightly overestimated, the mean trend of VTI over time, representing the change in performance of the ship, is quite comparable. The uncertainty in the results is reduced almost by half using the measured wave spectrum for physics-based VTI, whereas the data-driven approach creates an opportunity for ship performance monitoring without the need for speed-through-water measurements, which are considered unreliable for most ships.

Decarbonizing shipping in ice by intelligent icebreaking assistance: A case study of the Finnish-Swedish winter navigation system

Ice often complicates shipping in extremely cold regions, leading to energy-consuming, expensive transportation. Ship performance can be significantly improved with icebreaking assistance that uses specialized ships called icebreakers to create navigable pathways in ice fields. Icebreakers are a critical and expensive resource with high energy consumption that must be judiciously utilized for efficient traffic flow. Optimizing icebreaker usage requires careful consideration of multiple factors related to weather, ships, and regulations. The existing decision support tools for icebreaker management primarily aim to minimize the total waiting time of ships, which may result in allocation of excess icebreakers. The paper presents a novel simulation-based approach for decarbonizing shipping in ice by intelligent icebreaking assistance. The proposed approach optimizes icebreaker assistance for both eco- and cost efficiency, allowing for more sustainable icebreaking policies. A case study representing a simplified configuration of the Finnish-Swedish Winter Navigation System demonstrates this approach to come up with alternate operating strategies that can significantly improve the emission and/or cost (e.g., up to 7 percent less greenhouse gas emission or up to 14.2% lower costs). Results show that the proposed approach is promising, for providing recommendations on environmental and economic policies to decarbonize the Finnish-Swedish icebreaking assistance.

Fast and Intelligent Ice Channel Recognition Based on Row Selection

The recognition of ice channels plays a crucial role in developing intelligent ship navigation systems in ice-covered waters. Navigating through ice channels with the assistance of icebreakers is a common operation for merchant ships. Maneuvering within such narrow channels presents a significant challenge for the captain’s skills and ship performance. Therefore, it becomes essential to explore methods for enabling ships to navigate through these channels automatically. A key step in achieving this is the accurate recognition and extraction of boundary lines on both sides of the ice channel. An ice channel line recognition method based on the lane line detection algorithm UFAST is implemented. The method is trained and tested on the constructed ice channel dataset, with the test results showing that the average recognition accuracy reaches 84.1% and the recognition speed reaches 138.3 frames per second, meeting the real-time requirement. In order to solve the current lack of authentic ice channel images, ice channel navigation scenes are built based on UE4, and synthetic ice channel images are rendered. The method in this paper is also compared with the traditional non-intelligent Otsu threshold segmentation method and the intelligent instance segmentation method YOLACT for performance analysis. The method in this paper has 9.5% higher ice channel recognition accuracy and 103.7 frames per second higher recognition speed compared with YOLACT. Furthermore, ablation studies are conducted to analyze the relationship between the number of gridding cells in the proposed method and ice channel recognition accuracy.

Arctic weather routing: a review of ship performance models and ice routing algorithms

With the accelerated melting of the Arctic sea ice, the opening of the Northeast Passage of the Arctic is becoming increasingly accessible. Nevertheless, the constantly changing natural environment of the Arctic and its multiple impacts on vessel navigation performance have resulted in a lack of confidence in the outcomes of polar automated route planning. This paper aims to evaluate the effectiveness of two distinct models by examining the advancements in two essential components of e-navigation, namely ship performance methods and ice routing algorithms. We also seek to provide an outlook on the future directions of model development. Furthermore, through comparative experiments, we have examined the existing research on ice path planning and pointed out promising research directions in future Arctic Weather Routing research.

Powering performance prediction of a semi-displacement ship retrofitted with Hull Vane

This study predicts the powering performance of a semi-displacement ship, both without and with a Hull Vane (HV). HV is an energy-saving appendage fixed at the transom bottom of the ship's hull. Although the HV is commercially known as a successful resistance-reducing device, there are no studies in the literature examining its effect on propulsion performance in detail. In this study, the effect of the HV on the propulsion performance is investigated and a practical method is proposed as an engineering application to reduce the computation time. Initially, the idealized disc model based on Blade Element Theory (BET) is preferred to create a thrust force instead of using an entire physical propeller. The dynamic motions of the ship are reflected in the computational analysis. Subsequently, the sliding mesh technique, which models the exact propeller geometry, is implemented to calculate the self-propulsion characteristics without and with HV. These computations are achieved by employing a two-phase flow solver available in OpenFOAM. This study provides a significant demonstration to clarify the effect of HV on powering performance. It not only decreases effective power by 11.41% but also increases the propulsive efficiency by 2.1%, which reduces the brake power by 14.61% in total at service speed.

A CFD-based evaluation of ship speed at EEXI draft

This paper presents a simulation of ship speed for an existing containership at EEXI draft using Computational Fluid Dynamics (CFD). The simulation is divided into two steps namely (a) the numerical prediction of ship performance at model scale, and (b) the extrapolation of results to full scale. Model scale numerical simulations of ship resistance, open-water propeller and ship-propeller-rudder interactions at demonstrated. The method is at first validated by comparing against available experiments and at second stage full-scale ship performance is assessed by an extrapolation method. Comparison of the ship speed predicted by CFD against experiments demonstrates a difference of 0.05 knots when the same extrapolation coefficients are applied.

Assessment of the economic, environmental and safety impact of biofouling on a ship's hull and propeller

This paper presents a transparent methodology for predicting the speed/power performance of a ship under various conditions, considering the influence of biofouling on ship's hull and propeller. The biofouling development on ship surfaces are represented by surface roughness and their influence on ship performance are accounted for following Granville's model for hull resistance and an ITTC examined model for propeller characteristics, respectively. The established methodology is applied to the examination of the performance of a tanker under adverse conditions and typical service conditions. For the minimum power, we discuss the importance of implementing a suitable numerical method for determining the propeller operation point. Results show that the power reserve will decrease with the roughness increase. In service conditions, the required power increases with the fouling development. Under certain fouled conditions, the service speed cannot be achieved. Lastly, the fuel consumption and associated cost and GHG emission are calculated for a given voyage and the result signifies the tremendous impact of biofouling development on ship operation. The innovation of the work refers to its capability of analysing the influence of the roughness development on hull and propeller surfaces separately using minimum amount of ship information.

Generation of naturalistic and adversarial sailing environment (NASE) for intelligent test of autonomous ships

—Intelligence testing and verification of autonomous sailing capability is crucial to the development and deployment of autonomous ships. The prevailing approach is to establish a real test site on the sea or create a life-like simulator to test the autonomous sailing functions. However, due to the high dimensionality of the naturalistic sailing environment and the rareness of encounter events, hundreds of millions of miles and long test cycles would be required to demonstrate the collision avoidance performance of autonomous ships, which results in huge consumption. A novel approach is presented to generate the naturalistic and adversarial sailing environment by employing the sparse but adversarial adjustments into the naturalistic sailing environment. Our method can be used to enhance the existing sailing environment simulations to accelerate the autonomous ship test process. Firstly, the naturalistic probabilistic distributions of ship sailing behaviors are analyzed. Then, the naturalistic sailing environment (NSE) is generated to achieve real-world renderings. Moreover, the characteristics of ship maneuvering behavior at different encountered situations are identified. Furthermore, the naturalistic and adversarial sailing environment (NASE) is established by sampling maneuvers of the background ships (BS) from the importance functions at critical moments. It ensures the authenticity of the scenarios and increases the generation probability of encounter scenarios. The effectiveness of the proposed naturalistic and adversarial sailing environment model in the simulation of narrow waterway environment is proved. Compared with the naturalistic sailing environment, the proposed model can accelerate the generation speed of the critical scenarios and improve the generation efficiency of encounter scenarios.

Operational Performance of People's Cruise Ships at the Port of Pare-Pare

The role of people's shipping or traditional ships as a means of sea transportation is needed to encourage and encourage economic development in underdeveloped areas. This study aims to identify the operational performance of people's shipping vessels at the Port of Pare-Pare. This research was conducted with a qualitative method through semi-structured interviews with the aim of obtaining in-depth information from respondents regarding information on the operational performance of people's shipping vessels and community perceptions regarding the operational performance of these people's shipping vessels. After looking at the discussion presented, it can be concluded that the provision of transportation depends on the supply function. This function describes the correlation between the amount of goods offered by the market and the price level offered. The number of transportation services available depends on several factors, including vehicle capacity, road and terminal capacity, as well as the level and quality of management.

Real-time control of ship's roll motion with gyrostabilisers

The safety of ship manoeuvring operations is greatly affected by large roll motions under severe wave conditions. While existing studies have focused on optimizing hydrodynamic performance devices, these approaches may not be effective under realistic sea conditions where wave frequency and direction are irregular. Thus, predicting ship motion tendencies and implementing a reasonable control approach is crucial for improving ship safety. This study proposes a novel and practical control strategy that can effectively suppress roll motion of ships under realistic random wave conditions. The approach utilizes a real-time controller based on model predictive control (MPC) that is actuated by a dual gyrostabilizer. The ship's roll motion response in beam waves is calculated using one degree-of-freedom hydrodynamic modeling, and the wave memory effect is taken into consideration by employing system identification. A synthetic mathematical model of MPC and the dual gyrostabilizer method is introduced in state-space representation to compensate for wave excitation moment in real-time. The proposed method's efficacy is validated by comparing with a roll stabilization scenario of a particular ship in the literature, and control performance of a standard ship under regular and irregular wave conditions is separately discussed. Results indicate that the proposed method can significantly reduce roll motion amplitude and is feasible for nonlinear ship motion control problems. This study sheds light on the multi-degree-of-freedom motion control of ships under beam wave conditions.

Research on Scale Effect of Resistance Components for Full-Formed Ship Based on Large-Scale Model Towing Test

In recent years, the International Maritime Organization (IMO) has gradually introduced more stringent new Ship Energy Efficiency Design Index (EEDI) bills, and transport ships are more inclined to reduce the speed and increase the length and square coefficient to meet the design requirements. However, the size of the ship model that can be accommodated in the towing tank is seriously limited. Under the action of the scale effect, the accuracy of the prediction results of the resistance performance of large ships is particularly prominent. To break through the limitations of the test site, a large-scale ship model resistance towing test system and data analysis method in the port were established. By comparing with the results of small-scale model tests in the towing tank, the applicability of the 1957 ITTC friction line and Grigson friction line in the resistance prediction of the full-formed ship was analyzed, and the scale effects of resistance components were also examined. The results show that the scale effect of the form factor of full-formed ships is weak. The three-dimension method based on the empirical formula of mixed-form friction resistance of ITTC-Grigson is more suitable for predicting the resistance performance of full-formed ships.

On the drag reduction and heeling stability of a heeled planing air cavity hull

The air cavity planing hull enables the feasibility of running at a low drag-to-lift ratio at high speeds by reducing the wetted area. During the voyage, the ventilation rate and heel are essential parameters for the performance of the air cavity ship (ACS). In this study, three-dimensional Reynolds-averaged Navier-Stokes equations coupled with the volume of fluid method (RANS-VOF) are applied to examine the characteristics of the ACS across a wide range of ventilation rates (Cq = 0–1.120) and heel angles (β = 0–5 deg). The drag reduction and cavity morphology of the ACS are well predicted by the numerical method. The difference between the predicted total resistance and the experiment is less than 5%. The air cavity gradually develops from the meniscus growth cavity (MGC) (Cq ≤ 0.168) to the bottle neck stable cavity (BNSC) (Cq ≥ 0.336) with increasing Cq. Once a stable cavity form (i.e., BNSC) is established, the excessive ventilation would expand the tail air leakage opening in width and thickness. Under the effect of the heel, air coverage and drag reduction are diminished with a critical heel angle (β) of around 2 deg. When β ≥ 2 deg, the cavity shape gradually degenerates to the one-side branch cavity (OSBC). The air coverage also has a negative effect on the heeling stability, which means that the smaller heeling moment may cause a greater heel angle. More importantly, the restoring moment reduction monotonically decreases from 54.3% to 7.1% with the increment of heel angle, which deteriorates the heeling stability of the ACS.

Exploring the potential of iron powder as fuel on the design and performance of container ships

This article examines the potential implications of using iron powder as an alternative fuel on the design and performance of container ships. Iron powder is a relatively new alternative energy carrier and one in which little research has been done into the application on-board vessels as part of the maritime energy transition. The key benefits of iron powder are that it is a circular energy carrier and the combustion process emits no greenhouse gases. Transitioning to iron powder is expected to have far reaching implications for the design and performance of ships. Thus, this paper aims to perform the first study assessing the potential of this concept applied to container ships. To do so, a preliminary design space was explored with a custom parametric design model developed to generate preliminary designs of iron fuelled container ships as a function of the operational profile. Using this parametric design model, it was identified that iron fuelled container ships are weight limited, unlike conventionally fuelled container vessels. Furthermore, iron fuelled container ships are best suited for short voyages at low cruising speed. For these voyages, it was concluded that iron fuelled ships are economically feasible; however, other alternative marine fuels are likely more profitable than iron due to the low efficiency of iron fuelled ships and the high cost of iron per unit energy.

Hydrodynamic performance of a full-scale ship with a Pre-Swirl Duct: A numerical study with partially rotating grid method

This study investigates the hydrodynamic performance of a full-scale KVLCC2-S ship fitted with a Pre-Swirl Duct using CFD simulations. Four different propeller rotation representations are employed to evaluate the impact of the Pre-Swirl Duct on the ship’s performance. The study introduces a partially rotating grid method for two-phase flows, implemented within the Naval Hydro Pack library based on foam-extend software. The results of the study reveal that prediction of power savings depends on the accuracy of the numerical propeller representation. Non-inertial, partial, and inertial propeller representations predicted power savings while the actuator disc method predicted increase in delivered power. The partially rotating grid method provides a less computationally expensive alternative to the inertial propeller rotation representation, but at the cost of reduced accuracy. Furthermore, the study challenges the conventional analysis that attributes the power savings to improved propeller-hull interaction, suggesting that increased propeller efficiency is the primary cause.

A Study of the Resistance Components of Planing Hull Using Interceptors

The extreme motions created a negative effect on planing hull. Otherwise, interceptors enable the improvement of hydrodynamic characteristics of the highspeed craft. The total drag of the ship can be divided into two components: pressure and shear forces. This project specifically aims to predict the drag component based on CFD simulation with and without an interceptor based on resistance components. The volume of fluid is used in a compound with a RANS solver to determine drag and trim in calm water conditions. SIMPLE algorithm using overset mesh and DFBI was modeled free in heave and pitch to simulate the rigid body motion as a response to shear and pressure drag exerted by the fluid. A grid independence study has been used to predict uncertainties using time-step and grid spacing. Additionally, to guarantee to proceed with the simulation, ITTC recommendations had been followed. The benchmark study was undertaken as an experimental comparison by Park et al. In general, ship performance was controlled by pressure force in the displacement phase and planing phase, the shear and pressure forces are balanced. The interceptor can decrease the pressure force by 5% in the hump region and planing phase.

A multi-objective cooperative particle swarm optimization based on hybrid dimensions for ship pipe route design

Pipe route design has an important influence on ship performance. The main objective is to generate pipe routes satisfying complicated constraints in 3D space. The design process includes two parts: mathematical modeling and automatic optimization algorithm, where facility simplifying is an essential part of the mathematical modeling. However, previous studies mainly focused on pipe layout algorithms based on single objective optimization, and facility simplifying need to rely on artificial assistance. Nowadays, the optimization algorithm which can give several feasible solutions for designers, and the implementation of automatic pipe route design receive much attention. Therefore, this paper presents a multi-objective cooperative particle swarm optimization based on hybrid dimensions (HDMCPSO) for ship pipe route design (SPRD), which adopts multi-particle dimensions strategy and cooperative update mechanism via representative of each subswarm based on multi-objective particle swarm optimization (MOPSO). The framework can solve the two separate NP-hard problems of facility simplifying and pipe layout compatibly, and obtain high-quality Pareto solutions. To fully evaluate the effectiveness of HDMCPSO, the pipe length, bend number and assembly are optimized as the objectives, and a real piping system of ship engine room is used to compare different methods reported in the literature. The results show that HDMCPSO has generality which can simplify different facilities models and obtain better engineering pipe layout solutions.

Marine vessel energy efficiency performance prediction based on daily reported noon reports

ABSTRACT The marine vessel performance is quite critical in the maritime applications. In addition to internal variables like fuel, propulsion type, and loading condition, external factors such as fouling, sea state, currents, and more affect ship performance. The goal of this study is to create a model to predict ship slip rate based on specified noon report data which contain sea, wind, WED, and, DAS. 30 different noon report values of a crude oil tanker have been conducted on the same route with similar loading condition and they have been analysed by the MLR and the ANN respectively. Although a meaningful relationship between the variables couldn’t create among the variables by the MLR, predicted ship slip values are very close to the verified ones in the ANN. Minor differences could be caused by changes in the amount of hull fouling, vessel loading conditions, reverse or different currents, quite unsettled weather, and sea conditions.

Course-Keeping Performance of a Container Ship with Various Draft and Trim Conditions under Wind Disturbance

IMO presented the standard for ship’s manoeuvrability which every ship is recommended to satisfy. Although it specifies a full load and even keel condition as the condition at which the standard applies, practically, ships are operated under various loading conditions of cargo. From this viewpoint, the authors have conducted manoeuvring tests of a container ship under five loading conditions with different combinations of the draft and trim, and one of the authors established the manoeuvring mathematical model of the ship for each condition so far. This study focuses on the course-keeping performance of the same ship under these loading conditions under wind disturbance. It is the aim of this study to discuss both the influences of loading condition and wind condition simultaneously on the check helm and attitude of the ship while maintaining the target course. For this purpose, the arrangement of containers and their weight distribution were designed as exact as possible. For example, the ship with a trim by bow, which is commonly preferred for fuel efficiency, needs to have a larger check helm for course keeping, especially under the condition of wind disturbance diagonally from behind. This kind of knowledge would be useful for safe navigation.

Modelling of ship resistance and power consumption for the global fleet: The MariTEAM model

A system that can reliably estimate power consumption based on operational profiles and weather conditions is needed to evaluate global shipping emissions and alternative reduction scenarios. Due to a lack of detailed ship information, uncertainties in collected data, and computing complexity, many prior bottom-up investigations used simplified calculations and empirical equations. Some methodologies offered only approximate estimates that were not enough to capture power consumption trends based on the global fleet’s geographical, seasonal, and operational features. This work intends to develop and implement a power prediction method that can be applied in a bottom-up approach based on fleet composition and trading patterns. We present a comprehensive approach for powering prediction, encompassing data pre-processing, ship resistance estimation, and propulsion efficiency, based on the Maritime Transport Environmental Assessment Model. The model’s predictions match well with full-scale measurements of three operating ships and 2018 EU-MRV (European Union-Monitoring, Reporting, and Verification) data on annual fuel consumption and emissions for ships. The average error with the MRV data on annual CO2 emissions is below the median of 3% and the semi-interquartile range of 14%. Thus, the proposed model can be used to simulate the power performance and energy consumption of worldwide shipping.

Life cycle framework construction and quantitative assessment for the hydrogen fuelled ships: A case study

The integration of hydrogen energy into the maritime industry requires a comprehensive evaluation of the life cycle of hydrogen fuel, encompassing all stages from production to operational use in ships. This research aims to analyze the entire technology chain of marine hydrogen fuel. Six methods of hydrogen production, including steam methane reforming, coal gasification, coke oven gas, propane dehydrogenation, water electrolysis, and biomass gasification, are evaluated with regard to their energy consumption, environmental sustainability, and economic cost. The life cycle assessment is divided into two processes: hydrogen production and hydrogen fuel cell ship application. Calculations are based on a real-world case study of Dalian Port in China. A sensitivity analysis is also performed to assess the impact of various ship-specific conditions, such as speed, route distance, and transportation conditions, on the performance of hydrogen fuel-powered ships. The findings indicate that the current power cost structure does not necessarily make electrolytic hydrogen production the most environmentally responsible option. In the long-range route, the life cycle cost of water electrolysis is 2.49×106USD. Among the six methods, coke oven gas hydrogen supply method produces the highest carbon emissions. The optimal sailing speed of hydrogen fuel cell ships is between 14 and 14.5kn.