Characteristics Of Ship Research Articles

Research on the Give-Way Ships Determination Based on Field Theory

The Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs) stipulates ships’ obligations when encountering each other. However, human action remains a primary cause of collision accidents. In the complex environment of mixed navigation involving MASS and manned ships, the applicability of the COLREGs for determining the give-way ship has faced certain challenges. Therefore, this study proposes a model for determining the give-way ship, combining ship characteristics and using an asymmetric Gaussian function to construct the potential field of stand-on ships from the perspective of give-way ships. It constructs the cost function based on field theory to determine the respective avoidance costs for both ships in a crossing situation, with the ship incurring the lowest cost selected as the give-way ship, followed by a case study to validate the model. The research is dedicated to coordinating avoidance action objectively, effectively reducing maritime collisions, and providing exploratory guidance for collision avoidance decision-making in future mixed navigation environments.

An Investigation into Using CFD for the Estimation of Ship Specific Parameters for the SPICE Model for the Prediction of Sea Spray Icing: Part 2—The Verification of SPICE2 with a Full-Scale Test

A hybrid CFD–ML model for the prediction of sea spray icing, SPICE2, was developed in Part 1 of this study in Deshpande et al., 2024. The SPICE2 model is an extension of the ML model, SPICE, where some of the variables required for icing rate predictions: local wind speed, spray duration, spray period, and spray flux, are computed from CFD simulations. These, along with the air and water temperatures, and the salinity from the metocean data are used for the prediction of icing rates at different locations on a moving vessel. The existing full-scale icing measurements proved to be not detailed enough for the purpose of the verification of sea spray icing prediction models and the verification of the SPICE2 required distribution of sea spray icing data on the vessel surface in addition to the vessel design for simulation. A full-scale sea spray icing test was conducted in 2018 by Sundsbø et al. on a fully enclosed lifeboat equipped for the Goliat field in the Barents Sea. The 3D design of the same lifeboat, together with the corresponding metocean conditions and ship characteristics was used for the simulation of the vessel-specific parameters required for the verification of the icing rate and distribution prediction from the SPICE2 model against the measured distribution of sea spray icing rates on the lifeboat surface. The availability of the 3D model of this lifeboat, in addition to the fact that the icing measurements from this test were detailed enough to attempt a model verification served the purpose of validating the SPICE2 model. The icing rates measured on this lifeboat are used for the full-scale validation of the SPICE2 model that is proposed in Part 1 of this study. It was seen that the icing rates predicted by SPICE2 concurred with 9 of 13 selected locations on the lifeboat. The ones which did not showed very little deviation from the measurements. The icing rate and distribution prediction with SPICE2 were satisfactorily validated against full-scale icing measurements. This is a first attempt in modelling sea spray generation using CFD and further research into CFD for the estimation of spray flux is suggested.

Influence of energy-saving devices on the hydrodynamic characteristics of a waterjet-propelled ship: Experimental and numerical investigation

Installing stern energy-saving devices can help conserve energy and enhance ship speed, particularly for medium-to-high-speed ships. This study focuses on a waterjet-propelled ship and examines the performance of two energy-saving devices: the interceptor and stern flap. The investigation involves conducting a comparative analysis through towing-tank experiments and utilising Reynolds-averaged Navier–Stokes (RANS) numerical methods. The findings suggest that incorporating energy-saving devices alters the capture flow of the waterjet-propelled ship. Furthermore, these devices reduce ship resistance, resulting in a maximum decrease in the impeller speed of the self-propulsion point up to 5%. Following the installation of energy-saving devices, the propulsion efficiency of the waterjet-propelled ship demonstrates an enhancement ranging from 0.5% to 5.7%. This increase in propulsion efficiency emerges as a principal factor contributing to the energy savings facilitated by the stern energy-saving device. Upon comparison, it was found that within the Fr range of 0.3–0.5, the stern flap exhibited a superior energy-saving effect. Conversely, when Fr exceeded 0.5, the interceptor demonstrated a more pronounced energy-saving effect. Finally, the mechanisms of the stern energy-saving devices are elucidated based on the momentum velocity coefficient, thrust deduction fraction, and changes in the internal and external flow fields of the waterjet-propelled ship.

Underwater radiated noise explained from ship characteristics and operating conditions - Model obtained from the MARS database

Understanding how ship characteristics and operating conditions impact underwater radiated noise (URN) is key to identifying essential avenues for noise reduction and predict associated risks for the marine life. Previous studies have revealed that current models could only explain up to 50% of the observed variability in URN levels. In this study, we used a unique dataset, collected within the Marine Acoustic Research Station (MARS) project (www.projet-mars. ca/en). The dataset is consisting of ~1000 acoustic signatures from vessels in the St. Lawrence shipping lane (eastern Canada), and 174 high-quality signatures from partner vessels following an optimized measurement protocol and considering design parameters, meteorological, and oceanographic data. Applying functional regression, as described by MacGillivray et al. (2022), we quantified the relationship between vessel characteristics, operation conditions and URN. Our findings quantify the direct effect of the speed, size, and draft on URN across a frequency range of 10-500 Hz. Using these relationships, we propose a tailored URN predictive model representative of the St. Lawrence fleet. We then compare its performance to previously published models and asses the gains linked to the active collaboration of ship owners, contributing to the wide range of available operation conditions available in our dataset.

Differentiation in the Process of Learning English by Future Ship Engineers

Traditional methods of teaching English do not always allow us to consider the individual characteristics of future ship- engineers, their learning pace, cognitive styles and level of training, which can lead to the loss of motivation to learn and failure to master the material in full. The article substantiates the basic principles of differentiated learning (variability of tasks, frontal work, pair/group, and independent assignments). The research describes multi-level tasks for groups, considering different levels of English language proficiency. It is emphasized that differentiated learning contributes to the development of various skills important for ship's engineers, such as critical thinking, solving professional problems, high-level English for communication in an international crew, teamwork, etc. The author emphasizes the need to plan tasks for each stage of the lesson for groups with different knowledge bases and levels of training. It is important to anticipate possible difficulties that students may encounter in mastering the material and to use differentiated individual tasks in the classroom system. The advantages of differentiated learning are revealed: considering the individual characteristics of students, increasing motivation to learn. The disadvantages are also pointed out, since differentiated learning requires considerable effort and time from the teacher to plan classes, prepare various materials and tasks. Criteria for assessing the knowledge and skills of future specialists are proposed, since students of different groups perform different tasks and study according to different programs when learning maritime English. It is emphasized that the systematic use of different types of exercises for a particular group, taking into account the topic, stage of study and didactic goals, is optimal for improving the assimilation of knowledge of students

Dynamic Calculation Approach of the Collision Risk in Complex Navigable Water

It is vital to analyze ship collision risk for preventing collisions and improving safety at sea. This paper takes Ningbo-Zhoushan Port, a typical complex navigable water, as the research object. Firstly, a probabilistic conflict detection method based on an AIS data-driven dynamic ship domain model is proposed to achieve effective ship conflict detection under uncertain environments. Then, a ship group identification method is proposed, which can extract the ship groups with conflict correlation and space compactness. Finally, according to the characteristics of ship traffic in complex navigable waters, the dynamic calculation of ship collision risk is carried out from individual, regional, and local multi-scale perspectives. The experimental results show that the proposed method can detect the collision risk in a timely, reliable, and effective manner under complex dynamic conditions. As such, they provide valuable insights into ship collision risk prediction and the development of risk mitigation measures.

Numerical Investigation of Oblique Currents’ Effects on the Hydrodynamic Characteristics of Ships in Restricted Waters

The influence of oblique currents in narrow and shallow channels causes the fluid flow around ships to become complex. To analyze the hydrodynamic characteristics of a ship in such channels, it is essential to examine the influence of oblique currents on the ship’s hydrodynamic characteristics. In this study, current direction, ship speed, current speed, and water depth were identified as determinants affecting the hydrodynamic characteristics of a ship. Numerical simulations were conducted on a large oil tanker to investigate the effects of these factors on the ship’s hydrodynamic characteristics. The viscous fluid flow was modeled using the unsteady Reynolds-averaged Navier–Stokes (URANS) equations in conjunction with the k-ε turbulence model. The URANS equations were discretized using the finite volume method. The numerical results indicate substantial differences in the hydrodynamic characteristics of ships under oblique current conditions compared to still-water conditions. At a current direction of β = −45°, the direction of the sway force is consistent with that of still water’s sway force, which is an attractive force. The yaw moment at β = −45° changes from a bow-out moment under still-water conditions to a bow-in moment. Conversely, at a current direction of β = 45°, the sway force shifts from an attractive force under still-water conditions to a repulsive force. The yaw moment acts as a bow-out moment, which is consistent with that observed in still-water conditions. Furthermore, the influence of hydrodynamic characteristics on a ship varies significantly with changes in ship speed, current speed, and water depth. To ensure the safe navigation of ships, it is essential to develop and apply comprehensive strategies and countermeasures that account for practical conditions.

Insights into the Global Characteristics of Shipping Exhaust Emissions at Berth

The need for an accurate inventory of ship emissions is vital for atmospheric scientists assessing the environmental impact of shipping and for policymakers aiming to regulate and incentivize emission reduction. This study used data from 189 international ports, related to ship arrivals and departures, to develop emissions inventories. Emission characteristics were examined in detail, classifying emissions by factors like ship type, month, and region. The analysis identified oil tankers and container ships as main emitters among ship categories. A detailed analysis of the monthly distribution of emissions from vessels at berth worldwide was conducted based on precise arrival and departure times. Singapore, Rotterdam, and Antwerp were the ports with the highest emissions from ships at berth. Overall, this study presents the spatial and temporal emission characteristics of ships at berth in 3912 ports around the world, which can support the development of emission reduction strategies in port management.

A spatiotemporal co-occurrence pattern mining algorithm based on ship trajectory data

Finding the potential spatiotemporal co-occurrence behavior patterns of large groups of ships while sailing is a challenging problem of great importance in many real-world applications. Through spatiotemporal data mining of ship trajectory data, route rules, navigation behavior, and potential anomalies can be mined, providing important support for maritime management, navigation safety, and emergency response. With the analysis and mining of ship trajectory data in some hotspot sea areas, this paper introduced a ship spatiotemporal co-occurrence pattern mining algorithm based on association rules. Based on the research of data model and the judgment criterion of spatio-temporal co-occurrence law, such concepts as candidate set, frequency set, and instance set are introduced together with the key procedure of algorithm, including pruning and pasting of candidate sets, screening of instance sets, definition of association reasoning, and association rule mining. Subsequently, the process of implementing the spatiotemporal co-occurrence pattern mining algorithm is devised. In the end, the algorithm is verified by taking the automatic identification system data of ships in hotspot sea areas as the source data. The proposed algorithm can find several ship combinations with spatiotemporal co-occurrence regularity in these hotspot sea areas, and the association rules on the co-occurrence of several ships. The performance of the proposed algorithms is illustrated on a real-world ship trajectory database and made a detailed comparative analysis. The results are very promising in terms of computational time. The experimental results show that our algorithm can effectively identify the motion patterns and behavior characteristics of ships, which provides an important reference and support for Marine traffic management, ship safety and Marine environment protection. The research results of this paper are of great significance for improving the efficiency and safety of maritime traffic, and also provide new ideas and methods for further research in related fields.

Spectral and statistical analysis of bow wave breaking characteristics of KCS ship

Spectral and statistical analysis of bow wave breaking characteristics of KCS ship

Selection model of chemical tanker ships for cargo types using fuzzy AHP and fuzzy TOPSIS

There are many chemical tanker ships on the market with very different characteristics. However, their operational performance for cargo types remains uncertain. Also, it is unclear which criteria should be taken into consideration primarily in the selection of chemical tanker ships. Therefore, choosing the most suitable ones for the cargo to be transported is an important problem for maritime companies. In this respect, the study aims to determine suitable chemical tanker ships for the four main cargo groups transported by them: animal and vegetable oils, corrosives (abrasives), organic chemicals, and petroleum products. A methodology that combines the fuzzy AHP, fuzzy TOPSIS, and clustering methods is used. 30 alternative chemical tanker ships are determined to represent the characteristics of all ships with a tonnage of 1–30 k DWT on the market. They are clustered into performance levels according to their fuzzy TOPSIS ranking scores. Consequently, a chemical tanker selection manual is developed based on the common characteristics of high-performance ships as well as the order of importance of criteria. It is envisaged that it would be a reference for ship operators and shipowners in the selection of suitable ships for the type of cargo.

Investigation of emission characteristics of a marine cargo ship in real-world conditions

Pollution caused by ship emissions will considerably impact coastal areas. A test system that matched the actual conditions of a ship was designed based on a portable emission measurement system (PEMS), and the emission characteristic of gaseous and particle emissions and the particle size distribution of the ship's main engine were investigated under real-world operating conditions. The results showed that the emission concentrations of the main pollutants fluctuated greatly under the departure, anchoring, and docking conditions, and the peaks of CO, CO2, and NOx emissions appeared under these transient conditions. The emission concentrations of CO2, hydrocarbons, particle number (PN), and particulate mass increased with the increase in speed. The PN-based particle size distribution of the engine presented a unimodal distribution under daily operating conditions. The maximum emission factor of NOx based on the engine power was 29.53 g/kWh at the engine speed of 66 r/min. The results of the study may contribute to supplementing the emission factors of this type of ship, and provide data support for monitoring and assessment of the marine environment.

Ship Autonomous Berthing Strategy Based on Improved Linear-Quadratic Regulator

There has been significant interest in the research field of ship automatic navigation, particularly in the area of autonomous berthing. To address the key challenges of path planning and control during ship berthing, we propose an enhanced Linear−Quadratic Regulator (LQR) control approach, reinforced by the Covariance Matrix Adaptation Evolution Strategy (CMA−ES), along with an adaptive berthing strategy decision model. This integrated framework encompasses ship motion control, path planning, and berthing strategy selection to facilitate adaptive and autonomous ship berthing. Initially, a dynamic mathematical model of ship motion is established, taking into account wind and current interference effects. Subsequently, an adaptive environment−aware berthing strategy model is introduced to enable automatic selection of berthing strategies based on spatial relationships between environmental factors and the berth. By utilizing the refined LQR method, autonomous motion control for ship berthing is achieved. To validate the effectiveness of our controller, comprehensive simulation analyses are conducted under varying operating conditions to encompass crucial factors such as large drift angle characteristics of ships, shallow water effects, and bank effects across seven diverse working conditions. The simulation results underscore the robustness of our proposed method in responding to environmental interference while demonstrating its capability to select appropriate berthing strategies based on varying operational scenarios.

A decision framework for Chinese-style cruise ship design based on informativeness weight method and group consensus reaching model

In recent years, the European cruise ship design style has failed to meet the cultural needs of Chinese users, leading to a growing demand for cruise ships incorporating Chinese elements. The richness and uniqueness of Chinese culture make most existing cruise ship design decision-making methods inapplicable for Chinese-style cruise ship design. This article introduces a decision-making framework for Chinese-style cruise ships to address this gap based on the informativeness weight method and the group consensus achievement model. This framework determines decision criteria based on the characteristics of Chinese-style cruise ships and Cultural Hierarchy Theory (CHT), and it employs trapezoidal fuzzy set theory to manage the fuzziness of the decision-making environment, resulting in decision matrices. Furthermore, a bilateral negotiation model for group consensus achievement is introduced to reach group consensus among decision-makers (DMs), adjust the decision matrix, and calculate the weight of each expert. The informativeness weight method is used to determine the weight of each criterion, and the TOPSIS method is applied to establish option scores and rankings. By analyzing three Chinese-style cruise ship design options, the paper validates the effectiveness of this decision-making method. A comparative analysis of the informativeness weight method and the bilateral negotiation consensus achievement model further demonstrates the superiority of this decision-making framework.

Investigation on the coupling damage effects of ships subjected to near-field underwater explosion loads

Near-field underwater explosions generate complex load forms and cause destructive strikes on ships. To investigate the damage characteristics of ships under the combined effect of multiple loads, local and overall damage modes were first investigated through the combination of experimental tests and numerical simulation. Then a series of numerical simulations of full-scale ships subjected to near-field underwater explosions with different stand-off distances, equivalents, and detonation positions were carried out. The damage effects of shock wave, bubble pulsation, after flow, and water jet loads on ships were analyzed. The results show that the combined effects of different loads lead to different damage modes. Shock waves and after flow loads are the main cause of local damage and hogging damage, while pressure difference and bubble adsorption are the main reasons for the hogging damage. Finally, a criterion was proposed to determine the damage modes of ships under near-field underwater explosions.

Bulbous Bow Shapes Effect on Ship Characteristics: A Review

Abstract Hydrodynamic optimization is an effective and robust design method that is indispensable in ship hull form performance. Marine engineering and naval architecture have displayed significant interest in integrating bulbous bows on combatant ships. This review aims to gather and assess the existing knowledge regarding the effects of bulbous bow shapes on the hydrodynamic characteristics of combatant ships in terms of historical background, design principles, and impacts of bulbous bow shapes on ship resistance, ship motion in seaways, squat, and seakeeping performance. The review evaluates the effects of bulbous bow shapes on hull hydrodynamics using computational fluid dynamics (CFD), model testing, and full-scale experiments. The text delves into the complexities of improving hull shape and how the bulbous bow design interacts with many operational factors like draft, speed, and sea conditions. This research offers scholars, naval architects, and marine engineers a comprehensive insight into the intricate effects of bulbous bow shapes on combatant ship performance. It aims to consolidate current material to enhance our comprehension of ship design and operation by identifying knowledge gaps and suggesting future research areas.

Ship Detection in Synthetic Aperture Radar Images under Complex Geographical Environments, Based on Deep Learning and Morphological Networks.

Synthetic Aperture Radar (SAR) ship detection is applicable to various scenarios, such as maritime monitoring and navigational aids. However, the detection process is often prone to errors due to interferences from complex environmental factors like speckle noise, coastlines, and islands, which may result in false positives or missed detections. This article introduces a ship detection method for SAR images, which employs deep learning and morphological networks. Initially, adaptive preprocessing is carried out by a morphological network to enhance the edge features of ships and suppress background noise, thereby increasing detection accuracy. Subsequently, a coordinate channel attention module is integrated into the feature extraction network to improve the spatial awareness of the network toward ships, thus reducing the incidence of missed detections. Finally, a four-layer bidirectional feature pyramid network is designed, incorporating large-scale feature maps to capture detailed characteristics of ships, to enhance the detection capabilities of the network in complex geographic environments. Experiments were conducted using the publicly available SAR Ship Detection Dataset (SSDD) and High-Resolution SAR Image Dataset (HRSID). Compared with the baseline model YOLOX, the proposed method increased the recall by 3.11% and 0.22% for the SSDD and HRSID, respectively. Additionally, the mean Average Precision (mAP) improved by 0.7% and 0.36%, reaching 98.47% and 91.71% on these datasets. These results demonstrate the outstanding detection performance of our method.

Variability in airborne noise emissions of container ships approaching ports

Container ships emit airborne noise that can vary significantly due to diverse vessel characteristics and operating conditions. This study aims to investigate the factors influencing noise emission from container ships moving in ports to enhance our understanding and improve noise prediction models. Using a dataset comprising long-term sound pressure level measurements, video recordings, and weather station data, a multiple regression analysis was conducted to assess the impact of static (ship-specific) and dynamic (pass-by specific) variables on noise emission. Static variables included ship dimensions and age, while dynamic variables encompassed distance from the microphone, speed, and draught. A k-means unsupervised clustering analysis was performed using 1/3rd octave band spectra to identify subcategories of container carriers based on sound emission characteristics. Significant correlations between emissions and both static and dynamic variables were found. The k-means clustering analysis yielded distinct subcategories of container carriers based on their sound emission profiles. This study highlights the importance of considering various factors, including ship characteristics and operating conditions, when assessing noise emission from container ships. By better understanding the factors contributing to noise emission, we can effectively mitigate noise pollution and minimize the impact on surrounding communities.

PROBLEMS OF FIRE PROTECTION IN THE RO-RO SPACE OF ROLL-ON/ROLL-OFF SHIPS DURING AN ELECTRIC VEHICLE FIREPart 1 Problem areas in fire protection of cargo decks of ro-ro ships in the context of an electric vehicle fire

The advancement of electric vehicles is linked to the increasing concern about the world’soil resources running out and the problem of global climate change. As global sea trade keepsexpanding quickly, the characteristics of ships also change, as they become bigger, carry morepassengers, and new risky goods emerge, including, for example, electric vehicles. The articlediscusses challenges of preventing fires on ro-ro ships with regard to electric car fires, which arebecoming more recognizable due to their increasing prevalence and consists of two parts. Part 1covers some key challenges of fire safety on the cargo decks of ro-ro ships when an electric carcatches fire and the main aspects of fire safety regulations for seagoing roll-on/roll-off ships inthe ro-ro space. Problematic areas were considered in the following aspects: features of maritimetransport, specifics of cargo carriage on a ro-ro vessel, the difficulty of evacuating sailors andpassengers from a burning ship, specifics of firefighting on a ship, challenges and dangers ofelectric vehicle fires and lack of adequate fire protection and procedures on a ro-ro ship in termsof an electric car fire. The second part of this article presents some possible solutions to improvethe fire safety of ro-ro ships, on cargo decks, and the author’s idea of implementing a new fireprotection device consisting of fire ventilation. No other study has addressed fire safety challengesof ro-ro ships with such depth, especially given the emerging risk of electric cars.

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.