Risk-based design (RBD) has become increasingly important in naval ship design as traditional, prescriptive regulations struggle to keep pace with technological innovation and system complexity. Innovative concepts often fall outside the assumptions embedded in existing rules, requiring designers to justify safety and performance on risk grounds rather than on compliance alone. At the same time, model-based systems engineering (MBSE) is widely used to manage system complexity, yet risk information is still predominantly captured in document-based artefacts that remain weakly connected to system models.
This separation between design models and risk documentation results in fragmented traceability, excessive documentation overhead, and limited reuse of risk knowledge as designs evolve. While previous work has addressed process-level integration between RBD and MBSE, the question of how qualitative RBD artefacts can be meaningfully represented within system models remains largely unresolved.
This thesis proposes a new method that aims to address this challenge. The results show that qualitative RBD artefacts can be embedded as explicit, traceable elements within an MBSE environment by integrating hazards and acceptance criteria directly into functional system models. Using a representative naval bunkering scenario as a pilot case, hazards are linked to functional chains and supported by model-based criteria that underpin ALARP (as low as reasonably possible) decision-making. This enables risks to be evaluated in the context of system behaviour and architectural allocation, rather than as isolated compliance documents.
Compared to traditional document-based RBD workflows, the proposed approach reduces reliance on manual traceability and supports more context-aware risk reasoning in all design phases. These results indicate that combining MBSE and RBD not only mitigates the limitations of prescriptive regulation, but also provides a more robust foundation for informed decision-making in innovation-driven naval ship design. ... Read more

To address the maritime industry’s need for reduced fuel consumption and greenhouse gas emissions, this study explores the integration of wind-assisted ship propulsion (WASP) into existing deck equipment. Specifically, it investigates the feasibility and performance of incorporating a Flettner rotor into a crane structure on a general cargo vessel. A concept development phase identified the rotor-integrated design as the most promising option, followed by a performance evaluation phase using four case studies. These cases examined the effects of rotor sizing, rotor positioning, wake interference from cargo, and the aerodynamic impact of the crane boom. Results show that while integrated rotors face performance constraints compared to standalone systems, mainly due to size limitations, their elevated mounting position can offer advantages. The study concludes that integrating a Flettner rotor into a crane is viable, offering space-saving benefits, though further research is needed to refine aerodynamic modeling and validate the mechanical design. ... Read more

Modularity is often mentioned as a method to make a vessel’s design flexible during its lifetime. However, literature often focuses on ways to apply modularity to naval vessels instead of asking if modularity improves the vessel, or the organizational process, at all. This paper aims to build a framework to give the naval architect valuable insights into the possible benefits and the technical impact of modularity application. When a system is
deemed a feasible module, a final evaluation is performed to assess if the modular variant of the system actually improves the vessel or the organizational process.

This research presents a framework consisting of a Modular Function Deployment (MFD), Analytical Hierarchy Process (AHP), and Knowledge Based Engineering (KBE) model to assess the suitability and technical feasibility of modular systems. The MFD aims to identify high-potential modular systems based on modularity drivers defined and rated by the naval architect. Next, the AHP aims to map the most important functions of the vessel. Since modularity always comes with increased weight, the naval architect can use the AHP to ask
themselves if the system fulfills a function that is important enough to embrace the increased weight. With the KBE model, the technical impact of modular systems can be assessed in terms of weight, estimated draft, and stability. When a system scores high on the MFD, it indicates the system would benefit from modularity. When its accompanying function scores high on the AHP, it indicates the system fulfills an important function. The technical impact of making the system modular can be assessed with the KBE model. If the technical impact is
deemed acceptable, the system can be labeled as a ‘feasible’ module. The final effectiveness assessment will indicate if the feasible module actually improves the vessel’s design or the organizational process. This way, a framework will be developed which gives the naval architect valuable insights into the potential benefits and costs of modularity.

A case study will be presented on a landing platform dock and the future air defender (FuAD) of the RNLN. Results show the FuAD has higher-potential systems for modularity, so the KBE model is applied to only the FuAD. In the KBE model, an air surveillance radar and Laser-Directed Energy Weapon (LDEW) are modeled as a non-modular system and then as a modular variant. This way, the impact of making a system modular is assessed. The KBE model results in a technically feasible module for the air surveillance radar and LDEW. The final effectiveness assessment results in a preference for a non-modular air surveillance radar and a modular
LDEW. This shows that modularity does not necessarily improve the system and a structural way to approach modularity and compare it to a non-modular variant is required.

The framework can be applied to a wide variety of vessels, including commercial vessels. The framework uses generally applicable methods, and by combining them in a structural way the decision-making on whether to use modularity or not can be improved. For naval vessels, the effectiveness depends on the intentions of the end user. By qualifying the expert opinion using AHP, both by identifying the most important functions and the final evaluation, this intention is integrated into the framework. This also personalizes the outcome: based on the intentions of the end-user, completely different outcomes can be retrieved from this framework. After computing the framework for a specific vessel type, the results can partially be applied to other vessel types, within the same organization due to the end-user intentions mentioned above, as well. If a modular system is preferred over the non-modular variant, this implies the other vessel types will also benefit from this system as a module. Since this system is already defined as an HLP in the KBE model, the system can easily be imported into another
design. The hull form can be easily changed as well since this already is an external Rhino file imported into the Python file. These factors make the framework applicable to a wide variety of different vessel types. ... Read more

To reduce the environmental impact of the maritime sector, the International Maritime Organization (IMO) has established emission limits and ambitious sustainability targets. While superyachts are currently exempt from many of these regulations, they must align with IMO’s objectives to establish the yachting industry as a responsible sector and adapt to the increasing application of these emission limits. Focusing only on new builds is not sufficient to meet ambitious targets, and sustainable refit of existing yachts is also essential. This applies not only to motor yachts but also to sailing yachts, which face unique challenges due to limited space which further complicates integrating alternative fuels like methanol or hydrogen, given their lower energy density. Despite various studies exploring alternative energy solutions, there remains a research gap in understanding the trade-offs associated with different energy configurations installable in a refit to minimize energy demand and emissions. To address this, an assessment model that evaluate technical feasibility, emissions, docking time, and Total Cost of Ownership (TCO) for different energy configurations is developed. Results from the assessment model, applied to two Royal Huisman sailing yachts of different size across various owner profiles, reveal that integrating alternative energy solutions requires significant reductions in energy demand. Feasible configurations range from using a single fuel HVO configuration for conservative owners to hybrid solutions involving HVO and methanol for more open to changes owners. Ultimately, owners willing to implement various energy reduction methods can achieve several feasible and sustainable configurations. ... Read more

This thesis presents a data-driven design approach for emission reduction using bunker delivery notes (BDNs) to help support the revised IMO strategy to achieve net-zero greenhouse gas emissions by international shipping close to 2050. This research supports the Horizon Europe’s Digital Twin for Green Shipping (DT4GS) project which focuses on the development of digital twins (DTs). Part of this project involves the development of a DT-supported method for the design and retrofit of ships. DTs are a promising approach for supporting maritime decarbonization efforts due to their simulation and big data handling capability. Despite the abundance of shipping data and growing digitalization, the potential of using ship operational data for decarbonization efforts remains not fully exploited. A data-driven method such as a DT could fill this gap. However, as DTs, by definition, require real-time connection between a physical entity and the digital representation, developing a true DT for new-build alternatively fueled ship designs remains a challenge. This research thus starts by looking into retrofitting using data from existing ships.

A design framework is proposed to construct digital models to support a DT for retrofitting purpose. The proposed framework is tested on a case-study using a 300-meter bulk carrier. Since January 2019, operational ship data is collected through BDNs, a mandatory data collection method for ships of 5000 GT and above, adopted by the IMO. Constructing a DT based on BDNs is considered to be convenient as it provides a solid source of operational data in the future.

First, the available data from the BDNs is preprocessed using an adopted framework based on data science literature. The resulting 5,678 data points are used for the construction of a model representing the bulk carrier and a model representing the green ship technologies part. A fuel consumption model is constructed to represent the bulk carrier. It utilizes a gray-box modeling approach, consisting of a white-box resistance model and a black-box artificial neural network. Both models incorporate environmental-dependent inputs. The investigated green ship technologies for the potential retrofit are represented by various wind-assisted ship propulsion (WASP) systems, namely a towing kite, a DynaRig sail, and a Flettner rotor. These systems are modeled using a white-box modeling approach, together with available wind data. Using an adopted integration framework, based on the propeller-engine matching procedure, both representations are combined into one green ship digital model.

An environmental assessment is performed using the IMO's EEXI and CII assessment tools, respectively evaluating the design and operational aspects of the potential retrofit. Additionally, a financial assessment is conducted using the payback period. Results showed the design implications and emissions reduction potential of implementing such systems which will guide the retrofit decision by the ship's owner.
... Read more

Facing the critical challenge of reducing greenhouse gas (GHG) emissions in the maritime industry, this thesis explores the potential of smart control systems using Reinforcement Learning (RL) for autonomous sailing. Traditional controls for sailing fall short in navigating the complex, dynamic conditions of maritime environments. RL has shown to be effective for continuous control applications in these types of conditions, however, primarily in simulated environments. Therefore, this study aims to show the potential of RL for autonomous sailing control (ASC) by means of a small scale project. A fast-time simulation of an Optimist is used to train the sailing controls required to reach an upwind target. The controls are then transferred to a robotized Optimist in a real-world environment to test the transferability of the simulation trained controls. First, the reality gap, or modelling error, between the simulation and real-world environment is quantified to be able to assess the performance of the used techniques to bridge the existing gap. The sim-to-real techniques of Domain Randomization (DR) and the addition of observation noise (ON) are applied during the training process. To test the effectiveness of the trained RL controls, the best performing ones in the simulation are selected and tested in the real-world environment. The performance of the RL controlled Optimist is compared to state-of-the-art controls in robotic sailing. Their performances are measured and compared by means of success rate and a physics-based metric that calculates the efficiency of the sailboat to use the power of the wind to propel itself, called the energy ratio. The results show that the RL controls are highly successful in the sailing simulation, however, the transfer to the real-world remains a major challenge. DR does improve the sim-to-real transfer, resulting in an agent that is able to reach a 100% success rate throughout 12 runs in the real-world environment. ... Read more

Due to the IMO regulations on emissions, Wind Assisted Propulsion Systems have become more and more interesting for shipowners. One of those Wind Assisted Propulsion Systems is the VentoFoil from Econowind. However, to enable the decision of the shipowner on whether and where to place VentoFoils on board, this research aimed to construct a VentoFoil Adoption model, assessing the environmental and financial consequences of specific VentoFoil placement options. With this, the main research question is: ‘What is the impact of VentoFoil placement on ships from a ship owner’s perspective?’ The VentoFoil Adoption Model for Econowind required a Technology Adoption Decision-support model that could operate within a short computational time while incorporating an adaptable weather matrix. During the literature study on the existing models regarding WASP models, a research gap was identified. The gap primarily lies in integrating low-fidelity force modelling with financial decision support.

The VentoFoil Adoption model was constructed with a baseline calculation in which no VentoFoils were placed onboard. This baseline included the hull resistance and the wind forces on the deckhouse for all possible wind directions and speeds. After that, the VentoFoils were placed on deck, for which the VentoFoil forces were added with respect to the baseline calculations. The VentoFoil forces were calculated including the interaction between the deck and the VentoFoils, using a turbulent separation layer. The interaction between the deckhouse and the VentoFoils was simulated using a triangle shape in which the wake is turbulent. Lastly, the interaction between the VentoFoils was included using a parametrized wakefield in which the apparent wind angle changed based on the distance between the VentoFoils. From the resulting polar plots, the financial and environmental benefits of VentoFoils are illustrated. Fuel savings are achieved when sailing at reference speed and lower power, and increased cargo yield is realized at higher speeds with reference power. This is dependent on the weather probability matrix.

To demonstrate the practical application and effectiveness of the model, a case study was performed using the VentoFoil Adoption Model on the Magritte, a bulk carrier currently sailing with two 16-meter VentoFoils. From a shipowner’s perspective, the conclusion was made that two 30-meter VentoFoils would in the long term be more cost-effective. For most combinations of fuel price and cargo yield, the payback time of the case at reference power and thus higher sailing speed was lower, making it the favourable operational decision.

A validation using the ‘validation square method’ was performed on the method used within the VentoFoil Adoption Model. The empirical performance validity was investigated by comparing the results from the sea trial data of the MV Sunnanvik and the results from the model. The results are within a reasonable range.

The answer to the main research question can be found with the model. Multiple placement options can be inserted, giving the benefits and costs for well-considered decision-making of the ship owner on whether and where to place VentoFoils on board.
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There is uncertainty as to whether the stability criteria in the Dutch regulatory framework for commercial cruising vessels are safe and obtainable for the current Dutch commercial sailing fleet. Therefore, this paper aims to determine a suitable set of intact stability requirements for monohull sailing vessels operating under the Dutch flag, striking a balance between safety and practicality. A literature review was conducted to identify potential stability risks and the state-of-the-art of sailing stability criteria. Models of representative vessels in the Dutch sailing fleet have been defined to study the practicality and safety level of various stability criteria in more detail. It is concluded that the current criteria are not obtainable for sailing yachts designed to sail at large heel angles. Moreover, it was found that the current criteria cannot identify vessels that can be vulnerable to squalls or waves. Therefore, a new set of criteria is proposed, which is more practical for vessels in the Dutch commercial sailing fleet, whilst providing an improved measure of safety. ... Read more