The urgent need for alternative ways of vessel propulsion over the past few years created a growing interest in rediscovering wind as a source of propulsive force. While many concepts for harnessing the power of the wind have been developed so far, their actual implementation on real ships still remains at a scarse level since it brings with it many challenges. These challenges include the design of the wind assisted propulsion systems to fit the confines and meet the demands of each individual vessel they operate on. The re-discovery of the Flettner Rotor - an idea first brought up by German engineer Anton Flettner - opened up a new realm of possibilities for using that concept on modern cargo and passenger vessels. This research project aimed to deepen the already existing base of knowledge by extending it and providing a methodology within the context of numerical simulations for developing and assessing rotor sails and their placement on the decks of cargo vessels. This includes a detailed analysis of the influence of some of the main design parameters of these rotors. A dual rotor setup was examined to highlight potential interactions between the individual rotors of a multi rotor setup. This dual rotor setup was compared to a target rotor. The latter was designed based on the findings from an analysis of rotor design parameters. Both the target rotor and the dual rotor setup are subjected to three different wind conditions, varying in their direction. The spin ratio was observed to be the primary operational parameter to influence the generation of lift and drag, with higher spin ratios resulting in higher lift and drag coefficients throughout all examined geometric configurations. The analysis also found that both the aspect ratio and disc diameter ratio have an influence on the lift and drag coefficients, with lift coefficients being proportional to rotor aspect ratio, while the drag coefficient was observed to be inversely proportional to aspect ratio. The disc diameter ratio was found to have a major influence on drag, with higher disc ratios yielding lower drag coefficients, especially at higher spin ratios. The dual rotor setup showed a noticeable interaction between the rotors in a beam wind condition due to a change in the angle of inflow on the downstream rotor. Pressure distributions on both sides of the rotor were also analyzed to further highlight the reasons behind the observed effects for both parts of the analysis, showing dominating effects on the suction side.
Shipping is highly efficient yet a significant greenhouse gas emitter. Achieving the IMO's 2050 carbon-neutrality target demands exceptionally efficient new vessel designs. However, ship design is complex due to the vast number of interacting options - e.g. hybrid electric architectures, renewable integration, sector coupling, and energy storage. Energy system design remains a largely manual, iterative process based on prior experience, often overlooking unconventional concepts. The Maritime Energy System Optimizer (MESO) addresses this gap. MESO is a modular Python platform optimizing the architecture, dimensioning, and operation of sector-coupled ship energy systems via a genetic algorithm. Fitness is evaluated through operational, component, and volume costs, with operation optimization using the open energy modeling framework. Its novelty lies in unbiased architecture optimization over dynamic load profiles, reducing design iterations. MESO is demonstrated in two case studies - a cruise ship's multi-energy system and a container ship's auxiliary electrical system - identifying efficient, unconventional configurations.
The inland waterway transport sector faces challenges such as digitalization, adaptation to climate change and the integration of alternative propulsion technologies. Given the long service life of ships, the targets agreed in the Mannheim Declaration for reducing air pollutant and greenhouse gas emissions and the taxonomy screening criteria require the rapid development of measures to increase environmental sustainability. Simply further improving the already inherently good efficiency of shipping is not enough. The introduction of the EU Emissions Trading System, the Corporate Sustainability Reporting Directive and approaches currently being developed to assess greenhouse gas intensity of inland waterway transport will further promote the avoidance of CO2 and other greenhouse gases. Today, fossil diesel fuel is still widely used in inland waterway transport. The bio-based fuel HVO has also been available for some time, but its availability is limited by the need for sustainable feedstock. A large number of pilot projects have been launched in recent years with the alternative energy sources hydrogen and methanol, as well as batteries. As no clear trend towards a particular technology is yet apparent, other options such as ammonia are being considered in the sector. Ammonia is also a suitable storage and transport medium for renewable green hydrogen. However, the combustion properties and safety requirements of ammonia pose major challenges for its use as a motor fuel. The CAMPFIRE consortium is running several projects on the conversion and storage of green ammonia as part of future energy systems. One of these projects is developing a propulsion system for inland waterway vessels that runs on pure ammonia as fuel. The main components of this system are an ammonia cracker, which converts a partial flow of the fuel into hydrogen, and a high-speed combustion engine that runs on liquid ammonia and a small amount of hydrogen as an ignition enhancer. The CAMPFIRE Open Innovation Lab (COIL) is currently being built in Poppendorf near Rostock to test the technologies developed. Various configurations (ignition, injection, combustion chamber design, etc.) were tested and evaluated as part of systematic combustion process investigations for the engine as the central energy converter for ship propulsion. The engine achieves comparable performance values and efficiencies to the conventionally operated basic diesel engine. An exhaust gas aftertreatment system will be used to comply with emission limits. It can be assumed that this system can consist of already known technologies. Based on the results obtained, a concept for a prototype engine was derived, which will be examined in detail at COIL in conjunction with the ammonia cracker. The use of ammonia as a fuel also leads to new requirements for ship design. Due to the hazardous substance classification of ammonia and the potential environmental hazard, appropriate safety precautions must be taken. Using the example of an existing ammonia tanker that operates on the Rhine and its tributaries, a concept was developed for the integration of the above-mentioned propulsion system, including the fuel tank and the fuel treatment system. The planning of the conversion of the inland vessel, taking into account the necessary safety measures, was evaluated as part of a risk analysis.
The size of Wind-Assisted Propulsion System (WAPS) installations, exploited to reduce fuel consumption and emissions, is growing. Ship stability is critical and typically ensured through additional stability criteria, although a harmonized regulatory approach is currently non-existent. This paper presents a limited-scope case study analysing selected criteria using the E-ship1, perhaps the first rotor sail equipped newbuild. Different rotor sizes visualize the effect of variations between the additional criteria and the impact of passive depowering. This study demonstrates that current criteria are unsatisfactory and that the effect of operational factors, not unilaterally considered, can be significant. The maximum wind velocity at which rotor sails may be operated varies significantly with criteria, and rotor sails' impact on stability is not as significant as traditionally assumed, attributable to their passive depowering behaviour. Criteria optimisation and the use of type-specific criteria may therefore carry considerable benefits, enabling a safe increase of operational efficiency.
This paper presents a suite of mathematical models for predicting ship manoeuvring in shallow water and during ship-ship interactions, to capture complex hydrodynamic effects under restricted water conditions and dynamic ship-ship interactions, with a focus on overtaking scenarios. A regression-based manoeuvring model is first introduced, in which hydrodynamic forces and moments are systematically extended to account for shallow water effects through dedicated correction functions. To address dynamic interaction phenomena, a Fourier-based model is developed for the prediction of time-dependent forces and moments during overtaking manoeuvres, explicitly incorporating the influence of vessel speed, lateral separation, and water depth. The required hydrodynamic coefficients are obtained from high-fidelity CFD simulations using OpenFOAM, supported by tailored numerical procedures for efficient zero-frequency force estimation. The proposed models are systematically validated against experimental model-scale data and available full-scale measurements. The results provide new insights into ship dynamics in confined environments and under interaction conditions.
This paper presents an extension to the Duisburg Test Case (DTC) by including benchmark data on ship resistance and self-propulsion in shallow water. The DTC, which represents a hull design for a typical 14,000-TEU post-Panamax container ship, has been extensively studied under deep water conditions. This study presents experimental hydrodynamic data for the DTC operating in shallow water, focussing on three water depth-to-draught ratios: 4.0, 2.0, and 1.2. All experiments were conducted under calm water conditions and the data are publicly available. The results provide valuable data for validating numerical methods and enhancing our understanding of the hydrodynamic characteristics of large container ships in shallow water environments. This study addresses a notable gap in the literature, as high-quality benchmark data for extreme shallow water conditions ($h/T=1.2$h/T=1.2) remain largely unavailable for established benchmark ships with hull forms typical of deep-sea shipping.
The current paper presents a comprehensive analysis of ship hull structures through both analytical and numerical methods, focusing on critical loading scenarios such as bending moments, shear forces, and torsional moments. The analytical approach employs section modulus calculations, simple beam theory, and the Smith method to derive stress and strain distributions at each transverse cross-section of the offshore support vessel. Concurrently, a numerical analysis using LS-Dyna discretizes the vessel model into finite elements with a mesh size of 0.04 m, enabling detailed evaluation of structural responses along the ship length. Comparative results demonstrate strong agreement between analytical and numerical findings, validating the accuracy of the numerical approach. This research underscores the effectiveness of LS-Dyna simulations in predicting stress and strain distributions under various loading conditions. Moreover, it introduces a combined refined analytical validation method, enhancing the reliability of numerical analyses within the elastic limit, marking a significant advancement in SHM field.
This study identifies a cost-effective decarbonization strategy for a deep-sea container vessel to meet the greenhouse gas emission (GHG) reduction targets set by the International Maritime Organization (IMO) and European Union (EU). For assumed scenarios for technology availability and costs until 2040, we assess the techno-economic viability of selected energy-saving technologies and alternative fuels under regulatory constraints. Our findings indicate that, for the considered vessel type, speed reduction, air lubrication, and hull maintenance are the most cost-efficient measures to reduce GHG emissions through 2030, after which stricter regulatory thresholds make it necessary to shift to clean alternative fuels. Among the alternative fuels evaluated, we identify ammonia as the most cost-effective.
Reducing CO2 emissions in the shipping industry is pursued through electrification of the propulsion system and renewable energy sources. Several studies investigated the optimization of power allocation in such systems from an ecological and economic perspective. It is still not fully described how these optimization results are transferred from the simulation to a real ship-power-system (SPS). For reliable and applicable results to be universally valid, system-level models are required that cover time-dependent power output characteristics. A hybrid SPS with fuel cells, energy storage system (ESS) and diesel generator, is simulated in Matlab/Simulink with focus on these subsystem interactions. State machine agents with linearized power output and averaged converter efficiencies alongside a rule-based hierarchic power allocation are applied. The validation shows high compliance with measurement data despite the model's simplicity, neglecting characteristics of power electronics in detail.
Offshore wind turbines are exposed to extreme environmental conditions inside monopiles where microbially induced corrosion (MIC) occurs. In this study, microbial in situ incubation experiments were carried out at different water depths inside a monopile. First results indicate that water depth-related seasonal stratification of the inner water column clearly influences microbial consortia and the grade of corrosion. At a water depth of 6 m, iron-oxidizing microbes dominate under aerobe conditions, while sulphate-reducing and methanogenic microbes are prevailing close to the sea bed at 21 m in temporarily anoxic and sulfidic bottom water. The S355 steel specimens show significant corrosion after several months of in situ incubation, however pronounced pitting was not observed. The focus of this study is the development of long-term in situ observation methods of MIC inside offshore monopiles to finally test adapted corrosion mitigation strategies.
This work presents the development and validation of a test rig for open-water propeller testing, designed for use in the towing tank at the University of Applied Sciences Emden/Leer. The goal was to create a cost-efficient, modular, and precise system capable of measuring thrust, torque, and rotational speed. The propeller is based on the Wageningen B-series and manufactured using additive techniques with varying layer heights. To assess the structural behaviour, a truss support structure was designed and analyzed using both FEM tools and analytical methods, including Castigliano's theorem for stiffness verification. Several sets of repeated measurements were carried out under submerged (in-water) and dry (bench) conditions; the resulting data were used to derive correction factors that compensate for system-related losses. The flow behaviour around the test rig was observed at increasing propeller speeds, revealing vortex formation and turbulence at higher rpm. Validation against Wageningen reference data showed mean absolute relative errors of approximately 11% for torque, 10% for power, and 18% for thrust in the operative range (300-500 rpm). The test rig thus delivers reliable and reproducible data for further research in hydrodynamics and propulsion efficiency.
This paper presents the development of a machine learning (ML) algorithm to predict the hydrodynamic coefficients to calculate the motion behavior of a vessel in frequency domain. The aim is to develop a less laborious and faster method compared to the conventional procedure for determining the hydrodynamic coefficients for added mass, damping, and excitation forces by radiation-diffraction models with linear potential flow solvers based on Boundary Element Methods (BEM). Physics-informed machine learning was utilized to incorporate physical laws directly into the ML models, ensuring accurate and physically consistent predictions. The ML-algorithm is trained and validated with a database created by the software ANSYS AQWA. The approach is performed on the Jack-Up Vessel(JUV) Innovation, owned and operated by DEME.
Shipbuilding, a pivotal industry supporting shipping, fishing, wind energy, and defence, confronts global competitive pressures amidst contemporary challenges. Despite its significance, the sector faces ongoing challenges in achieving digital maturity. This study is part of a research that aims to expedite the shipbuilding digital transformation, particularly by identifying current applications of key enabling technologies (KETs) in the shipbuilding activity through a comprehensive literature review. The KETs are first identified, then they are categorized based on two criteria: the main focus of the technology and the specific function in the shipbuilding process. While the analysis reveals an extensive quantity of applications (88), they are rather scattered and do not present a strong trend, predominantly relying on traditional approaches and backing mass production-like processes. It is also shown that the applications of KETS in the shipbuilding industry is still very immature, with only 15% of applications in the deployment phase, while the vast majority remain in the conceptual or development phases. Moreover, this study highlights the interconnected nature of these KETs, that point to the need to support shipyards in setting key priorities and strategies for their implementation. The study concludes by proposing avenues for future research to address these challenges and boost the shipbuilding industry towards its digital transformation.
Predicting the manoeuvrability of surface ships under realistic environmental conditions is a challenging task. Accurate prediction of ship manoeuvrability requires knowledge of the hydrodynamic forces and moments acting on a ship, from which manoeuvring hydrodynamic coefficients can be derived. A particular challenge arises when dealing with ships equipped with complex propulsion systems navigating in shallow waters, such as inland waterway ships. Here, efficient numerical approaches solving Reynolds-averaged Navier-Stokes equations and Euler equations are presented to calculate the hydrodynamic forces and obtain manoeuvring hydrodynamic coefficients. The proposed methods are demonstrated for two case studies: an inland waterway vessel with a complex propulsion system and a modern containership. This work advances the field of ship manoeuvrability prediction by providing an efficient and accurate means of calculating hydrodynamic forces for ships navigating in shallow and extremely shallow water.
Due to the growing requirements on energy efficiency of ships, certain problems and challenges arise for the design of rudders and propellers. For the rudder, the focus changes for many ship types from solely being a manoeuvring device to positively influencing the propulsion. This paper summarizes a hybrid calculation method for the calculation of rudder forces and for the evaluation of the bidirectional interaction between propeller and rudder for the early design stage. The new hybrid calculation method couples a lifting line approach for multi-component-propulsors with a panel method and a two-dimensional boundary layer method. The calculation results of the developed method are validated with measurements from several model tests. Finally, an application for full-scale predictions is presented.
While an undeniable progression is taking place in the shipping industry in terms of smart maintenance studies, the development of frameworks for the data pre-processing of marine systems sensor data has not yet been fully addressed. Data pre-processing is critical due to the current challenges that need to be addressed within the sector concerning unreliable outcomes and the appearance of distinct operational states. Such challenges need to be adequately addressed to avert under-utilization of data and computational inefficiency, whilst ensuring data quality and integrity. Accordingly, a data pre-processing tool is proposed to contribute towards implementing more sophisticated methods for addressing the challenges currently experienced within the sector. This data pre-processing tool is comprised of three distinct modules: (1) data imputation, (2) outlier detection and (3) operational state identification. A tool that is combined with a user interface to make accessible data pre-processing methodologies within the shipping sector.
This paper delineates the process necessary for generating a large number of loading conditions for a seagoing cargo vessel, which are needed for an extensive analysis of the ships seakeeping behaviour. First legislative and operational limits of the floating position and its properties are described. This is followed by the chosen mathematical representation of the cargo and ballast iteration process. Results are presented for four different types of cargo vessels and concluded with an outlook on possible applications.
Elastic deformations of ship hulls caused by waves increase bending moments and hull accelerations compared to those of a rigid hull. The paper quantifies these effects for a large containership in three different natural head seaways by simulating rigid ship motions and vibrations. The simulation method uses a Rankine panel method to model the flow around the ship. Results show that, depending on the seaway, the fatigue damage rate of the real, elastic ship was up to twice that computed for the rigid ship, whereas the maximum total (still-water + wave) bending moment was up to 18 percent larger, and the standard deviation of the acceleration up to 10 percent larger. Moderate hull shape modifications, which were intended to reduce slam-induced vibrations, resulted in only small reductions of these effects. Because maximum vibrations are caused by seldom-occurring heavy slamming events, statistically reliable results require simulations of more than one hour duration for every selected seaway.
