Op-Ed: Simulation tools in shipbuilding

Credit: NAPA

By Joakim Heinolainen, Technical Consultant, and Janne Huotari, Senior R&D Engineer, at NAPA Design Solutions

Simulation tools have long been fundamental to ship design and operation, supporting everything from voyage optimization to stability analysis. However, their role is rapidly expanding and evolving. Beyond traditional applications, these tools are now being integrated much earlier and more broadly in the design process, enabling designers to virtually test and refine vessel concepts before construction begins. This shift is allowing for faster, smarter decisions grounded in data and tailored to real-world conditions.

As the maritime industry navigates the path to decarbonization, we’re entering a new multi-fuel era filled with emerging propulsion technologies, alternative fuels, and energy efficiency solutions. These innovations hold enormous promise to reduce emissions and operational costs. Yet with so many variables in play, a key challenge arises: how do you determine which technologies will deliver the greatest benefit for a specific vessel and its operational profile?

Shipowners and operators are increasingly seeking design innovations that not only meet tightening environmental regulations but also help with operational performance and safety. These decisions must move beyond static assumptions. Instead, they must be grounded in how a vessel will actually operate; where it sails, how it loads, what weather it faces, and how often it’s in port.

For instance, the success of battery-powered propulsion systems in ferries and tugs is largely driven by the predictability of fixed short-sea routes, where charging infrastructure can be reliably accessed. Meanwhile, wind propulsion technologies have the best results on trans-oceanic voyages where consistent wind patterns allow for meaningful fuel savings. The availability of bunkering infrastructure is equally important; methanol, ammonia, and LNG offer clear emissions benefits but may not be viable if refueling options are limited along the route.

However, fuel type is only one of many factors naval architects must account for. Design teams must integrate new fuel systems and engine technologies while optimizing hull shape, capacity, and structural integrity. Making sure these are well balanced in a way that enhances overall efficiency and meets regulatory standards is key. Traditionally, such assessments relied on rules of thumb and data from similar vessels, but that data is often fragmented or too generalized, limiting innovation.

That’s where simulation tools offer a critical advantage. By repurposing the tools already in use for voyage planning, it’s possible to generate actionable insights at the design stage, well before a ship hits the water.

Three steps to simulate future vessel performance

To explore the potential of this approach, we applied a three-step simulation process to a conceptual RoPax newbuild planned for operating between Stockholm, Mariehamn and Helsinki. Three design variations with different dimensions and configurations were tested, keeping the weight constant. Based on its operational profile, we simulated 26 voyages for the year 2023 by following these steps:

1. Built a hydrodynamic model: Leveraging the 3D model used to design the vessel as a base, a hydrodynamic model predicted performance across various speeds and sea conditions. Tools like the NAPA Performance Model provided a foundation which could be customized to reflect unique design features, saving significant time compared to building models from scratch.
2. Defined an operational plan: This step outlined operational regions, ports, speeds, and loading conditions. For retrofits, existing operational data guides the process, while newbuilds can leverage AIS data from NAPA’s extensive database of 60,000 vessels to gain insights into typical operations by vessel type and region.
3. Simulated realistic voyages: Combining the hydrodynamic model and operational plan, NAPA Voyage Optimization simulated the ship’s performance on specific routes using historical weather and sea conditions. This includes estimating speed, engine loads, fuel consumption, and emissions.

The results provided vital insights. For instance, we found the vessel would likely spend around 50% of its time at full speed, 25% in port, and the remainder at lower speeds. This information directly informs propulsion system design, ensuring the engine is appropriately sized for actual operations, not just peak performance.  With the tools available, we can rapidly perform similar analyses for any ship design operating under any profile. This enables the evaluation of vessel motions, estimated arrival times, and fuel consumption, as well as comparisons of various energy systems and fuels under real-world environmental conditions.

Beyond energy efficiency, these simulation tools support decisions around structural strength, seakeeping, and route-specific fuel strategies. By modeling fuel consumption across different design iterations, owners can weigh the cost and emissions trade-offs of using methanol, ammonia, or other fuels, factoring in regulatory impacts such as EU ETS and FuelEU Maritime compliance.

The maritime industry stands at a pivotal moment. The demand for greener vessels that don’t just comply with regulation but deliver lasting commercial value is rising. For widespread adoption, decision-makers need data, not guesswork. Advanced simulation tools, integrated with real operational data, can close that gap. They allow designers to move from rule-based design toward dynamic, evidence-based decision-making.

The outcome of the data and simulation evolution is a new generation of vessels, designed with precision and optimized for real-world performance.