How an MBSE case study on the conversion of a ship to green fuel supports the Netherlands’ Maritime Master Plan
In the Netherlands, the maritime sector is very broad, including transport, food production, defence, coastal protection and support for renewable energy at sea. The common factor is ships.
In recognition of the significant levels of greenhouse gas emissions from shipping, the country has a Maritime Master Plan (MMP) that focuses on the development, construction and operation of climate-neutral ships – ultimately aiming for 40 demonstration vessels that will run on three alternative fuels. It is also investigating how the corresponding processes can be supported by a digital platform on which data is shared and stored.
Jaap Janssen, Consultant – MBSE Engineer, explains how Starion supported the MMP’s recent assessment of digital platform options, in particular through a case study exploring the conversion of a ship to green fuel using Starion’s CDP4-COMET MBSE platform.
Demonstrating MBSE for maritime design
The MMP consists of a group of private and public partners, some of whom visited the Concurrent Design Facility of the Dutch Ministry of Defence in Soesterberg on 9 September 2024 for a meeting on ‘digital collaboration’ within the Joint Maritime Data Platform (JMDP) network.
During this visit, Starion presented the results of a model-based system engineering (MBSE) pilot case from the Dutch Naval Design (DND) programme and a case study on a project to convert a vessel to green methanol fuel. These presentations showed how digital collaboration is already possible, whether that is using federated data sharing (as the JMDP envisions) or using a centralised MBSE platform, and how it can help in reducing development lead times and, consequently, the overall cost of ships.
The case study we presented supports this by showcasing how an MBSE approach and a platform such as Starion’s CDP4-COMET, which was used for this case study, can be of great value by speeding up design iterations and reliably converging towards a compliant design solution.
Conversion project scope
The case study focussed on a survey and research vessel that is driven by four marine gasoil generators, with the goal of creating a ‘zero-emissions’ vessel by replacing two of its four original generators with green methanol generators. At the same time, the converted vessel must remain able to fulfil its original operational user needs, as well as ship class requirements to ensure its safe operation.
Why MBSE?
The MBSE approach offers many advantages that are of value specifically for a conversion project:
MBSE allows concurrent design
An MBSE platform is used as a single source of truth (SSOT) with the most up-to-date engineering data that is accessible by all engineers. This allows them to work on the same design simultaneously, without having to wait for the results of another engineering discipline.
MBSE enables efficient comparison between multiple design options
Since both the system architecture and the corresponding design parameters are stored on one MBSE platform, users can define multiple system architecture configurations next to each other as design options. This is especially helpful for conversion projects, as it provides a very easy way to see the impact of an architectural change to an existing design on the corresponding design parameters.
MBSE provides automatic requirement validation
The availability of all design parameters in one SSOT makes it possible to link these parameters directly to the requirements specified for the conversion. This allows the MBSE platform to automatically check whether the defined design option meets these requirements.
MBSE supports faster design iterations
The ability to compute the impact of an architectural design change to parameters and their linked requirements directly from the MBSE platform allows much faster design iterations.
MBSE can connect multiple engineering tools
The use of an MBSE platform facilitates the connection of multiple engineering tools – computational fluid dynamics, finite element method, hydrostatics, etc. – from multiple engineering disciplines with each other.
Modelling approach
In a conversion project, one aspect that is unique is that many elements of a system’s architecture will remain unchanged. The goal of this conversion was to replace two out of four generators with green methanol-powered alternatives while still maintaining the ship’s operational and class requirements. Consequently, the first step was to define a model architecture that included only those system elements where changes were expected to happen as a result of the conversion.
For this case study, changes were mainly foreseen in:
- The addition of systems specifically required for the use of methanol as fuel
- The tank arrangement
- The diesel and methanol generators.
The rest of the ship was summarised as a “black box” system with corresponding weight and centre of gravity parameters, which were required for stability calculations.
Next, each of these system architecture elements was provided with parameters that were either directly or indirectly necessary to determine whether the current design option would meet the specified design requirements. Where applicable, these parameters were linked to the respective requirements.
Lastly, for each of these parameters a calculation method had to be defined to determine the parameter’s value. For this purpose, the following engineering tools, models and calculations were connected to the model on the CDP4-COMET platform:
- Tank arrangement calculation: Each tank compartment was provided with location, volume and fuel type parameters, based on which the calculation would determine a combined weight and centre of gravity as well as a combined fuel capacity per fuel type. This calculation also included weight and fuel volume penalties for all tank compartments used to store methanol due to the additional necessary ‘cofferdam’ (an empty safety barrier to prevent leaks from spreading to other parts of a ship).
- Ship endurance calculation: Based on the resulting fuel capacities, this calculation would determine the maximum amount of time that a ship can operate at sea on both diesel and methanol without having to refuel, according to the current design.
- Mass and centre of gravity calculation: Whenever a new tank arrangement calculation was released, the mass and centre of gravity location of the current design option was updated.
- Hydrostatics model: The updated weight and centre of gravity parameters at ship level were used as input into the hydrostatics model to recalculate the ship’s stability parameters (e.g. draft, metacentric height, trim and list angle).
The main design space* for this conversion project was optimising the tank arrangement: deciding which tank compartment should store which fuel type or be dedicated as a ballast tank. Therefore, after making any change to the tank arrangement, the evaluation of the four calculations listed above in sequence formed one complete design iteration.
* Design space refers to the part of a design that can be changed – the parameters or configurations – in order to (hopefully) meet the design requirements. In this case, for example, the ship’s hull shape was something we were not allowed to change. Therefore the hull shape is not part of the design space.
Results
The main challenge for the design of the vessel conversion in this case study was to meet the minimum endurance required using methanol fuel while still meeting the required trim and list angle parameters.
The trim and list angle were affected by certain tank arrangement changes; the 3D Viewer function in CDP4-COMET’s Web Application was found to be a useful way of visualising why this happened. Combined with the ability to automatically verify the design requirements, this MBSE approach offered a reliable way to converge to a design that met the specified requirements for this case study.
In summary
The case study undertaken for the MMP event showed that a minor investment in time up front to set up a model, with support from specialists from all relevant engineering disciplines, could significantly help in providing insight into the impacts of certain architectural design changes on the required design parameters. If it turned out that certain design requirements were no longer met, it was immediately clear which aspect of the design must be prioritised during the next design iteration.
Find out more
- View the Netherlands Maritime Master Plan case study presentation
- CDP4-COMET Requirements Verification case study: Ship Conversion to Methanol
- CDP4-COMET 3D Viewer Case Study: Ship Conversion to Methanol
- Discover our full range of MBSE services and solutions
- Read more about CDP4-COMET, our MBSE and concurrent design tool
