Data-Driven Ship Operational Performance Analysis and Energy-Saving Device Performance Estimation
(ESD: WAPS)

Impact of Global Environmental Regulations

In April this year, the International Maritime Organization (IMO) approved the Net-zero Framework, further accelerating the shipping industry’s transition toward decarbonization. While earlier short-term measures (such as EEDI and CII) were entirely regulation-focused, the new framework expands its scope to promote fuel transition and introduces direct carbon costs on greenhouse gas emissions.

When a vessel uses HFO while calling at European ports, it becomes subject to both IMO and EU regulations. In such cases, assuming the vessel’s CAPEX is set at 1, OPEX is estimated at 2, while carbon costs are expected to reach 4–6. As a result, shipping companies are making every effort to minimize these unexpected carbon costs.

Carbon costs are classified into Tier 1 or Tier 2 depending on whether IMO’s Direct and Base criteria are met. Failure to meet the Base criterion results in Tier 2 classification, which carries punitive costs. Conversely, if the Direct criterion is exceeded by using zero-emission fuels, the shipowner (or shipping company) can receive incentives.

To minimize carbon costs, shipping companies must focus on reducing their annual Greenhouse Gas Fuel Intensity (GFI) while simultaneously improving overall energy efficiency.

▶ GFI can be lowered by switching to alternative fuels to reduce GHG emissions or by utilizing zero-emission energy sources such as shore power, wind, and solar.

▶ Energy efficiency can be improved by managing hull and propeller fouling, maintaining engine efficiency, installing Energy Saving Devices (ESDs), and optimizing operations.

Since fuel transition has been continuously featured in Decarbonization Magazine, this article will instead introduce two key topics: measures to improve energy efficiency and the adoption of wind-assisted propulsion systems (WAPS) as a zero-emission energy source.

Data-Driven Operational Analysis for Energy Efficiency Improvement

Improving energy efficiency requires an accurate understanding of a vessel’s actual performance, which in turn depends on how effectively shipping companies utilize available data. Typically, shipping companies manage three categories of operational data: annual fuel consumption, daily fuel consumption, and high-frequency measurement data. All shipping companies collect annual fuel consumption data for IMO DCS and EU MRV reporting, while daily fuel consumption data comes from Noon Reports compiled by navigators. High-frequency measurement data are available only on vessels equipped with smart-ship solutions, where sensors record precise data at high sampling frequencies. The following section examines what each type of data can reveal — and how these insights can guide decision-making to improve operational efficiency and support decarbonization strategies.

·Annual Fuel Oil Consumption
Annual fuel consumption data includes voyage distances, sailing times, and actual fuel consumption by type. This dataset is directly applied in CII (Carbon Intensity Indicator) rating calculations and is essential for evaluating annual environmental performance. However, it only provides macro-level information. For instance, ships of the same type may still show differences in CII ratings, but the precise causes cannot be fully explained, as annual data do not sufficiently capture detailed variables such as operating conditions, weather, speed profiles, or loading status.

· Daily Fuel Oil Consumption
Daily fuel consumption data are segmented by operational status (e.g., port stay, port entry and departure operations, voyage), allowing for a clearer understanding of energy consumption patterns at each stage of operation compared to annual fuel consumption data. By utilizing this data, it is possible to distinguish between fuel consumption during port stay and during the main voyage, thereby identifying which segments are causing inefficiencies. Furthermore, when synchronized with KR’s ocean environmental data, daily fuel consumption can be segmented and analyzed by various key factors. However, since a single daily value is used as a representative figure, this inherent limitation prevents detailed variability from being captured, resulting in low accuracy.

· High-Frequency Sensor Data
Modern ships equipped with smart-ship solutions collect high-frequency measurement data through various sensors. This data, recorded at short intervals (seconds or minutes), provides time-series information that includes both navigational data and engine data.
By analyzing this data statistically, it is possible to identify operating conditions that affect vessel performance — such as speed, draft, and rudder angle. When synchronized with KR’s ocean environment data, external factors (including wind speed, wave height, and sea temperature) can also be statistically assessed. In addition, performance variations under different wave and wind conditions, as well as rudder angle data, make it possible to assess the navigator’s operational habits.
By filtering the measurement data to include only segments where sea conditions are calm and navigation is stable, the vessel’s pure technical performance can be estimated.
When sufficient long-term data are accumulated, voyage-based analysis enables the determination of technical performance degradation over time — such as hull and propeller fouling or engine efficiency decline — helping ship operators identify the optimal timing for maintenance.
In cases where sister ships exist, performance comparisons between vessels are also possible. By classifying parameters such as ship performance, maintenance condition, and engine efficiency decline as technical performance, and factors such as port waiting, sea conditions, and navigational practices as operational performance, operators can identify the optimal measures to improve energy efficiency for each vessel.

Among the three types of data available to shipping companies, high-quality measurement data collected through smart ship solutions are essential for accurately assessing vessel performance. Furthermore, long-term data accumulation is indispensable for analyzing performance degradation over time.

Regulatory Impacts on WAPS Performance and Case Studies

In environmental regulations, incentive schemes are established to reward Energy Saving Devices (ESDs) that contribute to reducing greenhouse gas emissions. Among them, Wind-Assisted Propulsion Systems (WAPS) offer dual benefits compared to other ESDs — simultaneously lowering the GFI and improving energy efficiency, thereby reducing carbon costs.

The dual benefits of WAPS are designed somewhat differently under each regulation. For example, under EEDI, only the top 50% of WAPS performance conditions are reflected, resulting in efficiency values estimated at nearly twice the actual level. In contrast, FuelEU Maritime introduces a reward factor called fwind, which provides an additional 1–5% incentive if WAPS achieves energy savings of 5%, 10%, or 15% or more. Meanwhile, the IMO Net-Zero Framework is designed to provide dual benefits by adding the contribution of WAPS to the vessel’s total energy use when calculating the GFI. Accordingly, KR has developed a procedure for calculating WAPS efficiency in accordance with the relevant regulations, and has conducted comparative analyses to verify consistency and reliability across different evaluation methods.

The target vessel was assumed to be a Very Large Ore Carrier (VLOC) equipped with either five rotor sails or five wing sails. As a first step, WAPS performance was evaluated through Computational Fluid Dynamics (CFD) analysis, and the results were presented in the form of a performance polar chart. The rotor sail showed limitations in utilizing maximum wind speeds due to the need to maintain an optimal ratio between rotor rotation speed and wind velocity. However, it generated strong thrust under beam and crosswind conditions thanks to the Magnus effect. In comparison, the wing sail requires approximately four times the surface area to produce the same thrust as a rotor sail, but it is not restricted by wind speed and can also generate propulsion under tailwind conditions by harnessing both lift and drag forces. If space efficiency and gust-response safety associated with its larger surface area can be ensured, the wing sail has the potential to deliver superior long-term performance.

KR calculated WAPS efficiency using three evaluation methods based on the rotor sail performance polar chart. The first method applied the EEDI evaluation approach, which estimates efficiency during the design stage without considering the vessel’s actual route. It uses the global route wind direction and speed distribution (Wind Matrix) provided by MEPC. The analysis identified approximately 4.5% power savings; however, since the vessel’s actual route was not reflected, this figure is difficult to interpret as a practical operational effect.

The second method analyzed efficiency by extracting global routes based on the AIS data of the VLOC and synchronizing them with ocean environmental data to construct a Wind Matrix. This analysis showed a power saving of about 2.0%, which is about half the level estimated by the EEDI evaluation method.

Lastly, to verify the maximum effect of WAPS, a Wind Matrix was developed for the North Atlantic route where wind conditions are strong. In this case, efficiency increased by up to 5.7%, even for a very large vessel.

In summary, the performance of WAPS varies significantly depending on the evaluation method and route conditions, highlighting the necessity of precise analysis that reflects actual routes and environmental factors.

Third-Party Verification Guidelines for ESDs

Although WAPS offers dual benefits under environmental regulations, many shipping companies are still reluctant to invest. The main reason is that the high initial installation cost and uncertainty regarding efficiency make it difficult to objectively assess the ROI (Return on Investment). Accordingly, KR is establishing a rational efficiency calculation procedure from a third-party perspective, reflecting actual routes and environmental conditions as examined in the previous case. This initiative is intended to help shipping companies assess investment feasibility based on more realistic criteria. In addition, KR is expanding its scope of services by developing efficiency estimation procedures not only for WAPS but also for various other energy-saving devices — including Onboard Carbon Capture Systems (OCCS), Waste Heat Recovery Systems (WHRS), and passive Energy Saving Devices (ESDs) of Category A type attached to the hull.

Decision Support for Energy Efficiency Improvement

KR is developing an operational data analysis solution called KR-POWER, designed to support data-driven decision-making for energy efficiency improvements. The system analyzes operational performance and estimates the actual effectiveness of various Energy Saving Devices (ESDs). The development is being carried out in two phases. Phase 1, scheduled for release at the end of 2025, will integrate shipowners’ operational data with KR’s environmental and AIS data to provide statistical visualization of operational characteristics, weather conditions, and fuel consumption.

Phase 2, scheduled for release by the end of 2026, will further expand its functions to data visualization and performance analysis based on measurement data. Through this enhancement, the system will enable the quantification of fuel consumption by contributing factors, as well as the identification of performance degradation resulting from hull fouling and declining engine combustion efficiency. Building on these analysis results, the system will provide capabilities to predict fuel consumption under hypothetical operating conditions such as draft, trim, and speed, and to simulate the effects of ESDs.

This enables shipping companies to pre-evaluate energy efficiency improvement strategies under various operating conditions. They can assess hull and propeller fouling, coating condition, and engine efficiency from a maintenance perspective; evaluate performance in relation to speed, draft, and trim from an operational perspective; and review the effectiveness of ESDs from a technical perspective, thereby supporting more rational decision-making. In addition, KR is working to integrate shipyard smart ship solutions and shipping companies’ Fleet Control Center data with the KR Smart Ship Platform as part of this implementation.