Wind-assisted propulsion systems (WAPS) are technologies that use wind power to supplement a ship’s main engine. These systems generate additional thrust from wind, thereby reducing engine load, fuel consumption, and greenhouse gas (GHG) emissions.

Several wind-assisted propulsion technologies are currently deployed in commercial shipping, primarily rigid wing sails, rotor sails, and suction sails. While all aim to reduce fuel consumption and emissions, they rely on different aerodynamic principles and system architectures.

To learn more about WAPS: Wind-Assisted Propulsion Systems: A Solution to 2026 Shipping Challenges

OceanWings provides automated rigid wing sails. Similar to aircraft wings, these sails generate propulsion through lift created by a pressure difference between the windward and leeward sides of the profile (Bernoulli’s principle). OceanWings’ thin, double-element design ensures high manoeuvrability and operational agility.

Thanks to their high aerodynamic efficiency, the sails can generate positive thrust across a wide range of apparent wind angles (AWA), starting from as low as 5°. Unlike active systems, OceanWings’ rigid wing sails require lower auxiliary energy demand.

To learn more about our products: Rigid Fixed Wingsail (OW RF) - OceanWings

OceanWings validates aerodynamic performance through a combination of numerical simulations, wind tunnel testing, and full-scale sea trials. Computational Fluid Dynamics (CFD) is used to optimise the wing geometry and predict performance across a wide range of wind conditions. These results are then validated experimentally in controlled wind tunnel environments. Finally, real-world data collected onboard operating vessels confirms performance under actual sailing conditions. This multi-step approach ensures robust, reliable, and scalable performance predictions.

Wind tunnel testing is an experimental method used to measure how air flows around an object under controlled conditions. A scaled model of the wind-assisted propulsion system (WAPS) is placed inside a tunnel where airflow speed and direction can be precisely controlled. Although WAPS operate under complex conditions in which airflow interacts with the ship’s hull, superstructure, and multiple sails, wind tunnel testing enables engineers to quantify these effects by isolating specific variables such as wind angle, speed, and system configuration. These results are typically converted into non-dimensional coefficients (e.g., lift and drag coefficients), which can later be applied to full-scale systems.

At scheduled intervals during regulatory dry docks, qualified technicians carry out inspections to verify that all components remain in good condition, are properly secured, and are free from damage. Additional routine inspections and maintenance activities help prevent potential issues and ensure that the system continues to operate safely, reliably, and efficiently over time. Contrary to active systems, OceanWings is passive, with no maintenance-demanding rotating equipment or high power consumption device and therefore requires minimal maintenance. Over the past two years on Canopée, OceanWings has demonstrated an average operational availability of 99.6%.

To learn more about our services: Services - OceanWings

The Energy Efficiency Design Index (EEDI) is a key regulation introduced by the International Maritime Organization (IMO) to reduce the carbon intensity of the global shipping fleet. The EEDI, which applies to most newbuild vessels, sets limits on CO₂ emissions per tonne-mile based on a vessel’s technical design parameters and energy efficiency performance.

The Energy Efficiency Existing Ship Index (EEXI) extends the EEDI framework to existing vessels, ensuring that older ships improve efficiency to remain operational. It is a one-time mandatory certification for vessels over 400 GT.

The Carbon Intensity Indicator (CII) is a measure of a ship’s energy efficiency. It is expressed in grams of CO₂ emitted per cargo-carrying capacity and nautical mile. Ships are rated A (major superior), B (minor superior), C (moderate), D (minor inferior), or E (inferior performance level), with stricter thresholds introduced progressively toward 2030. Ships rated D for three consecutive years, or E in a single year, are required to develop a “plan of corrective actions.”

The CII applies to ships of 5,000 GT and above, which account for 85% of total CO₂ emissions from global shipping. This includes bulk carriers, gas carriers, general cargo ships, tankers, container ships, combination carriers, LNG carriers, Ro-Ro vessels, and cruise passenger ships.

FuelEU Maritime is a regulation adopted by the European Union aimed at promoting the use of renewable and low-carbon fuels and clean energy technologies for ships. It sets well-to-wake greenhouse gas (GHG) intensity limits on energy used onboard ships over 5,000 GT operating in the EU and European Economic Area (EEA), measured as GHG emissions per unit of energy (gCO₂e/MJ).

Ships equipped with wind-assisted propulsion technologies can benefit from a reward factor, which effectively improves the annual GHG intensity of the energy used onboard. This improvement can reach up to 5%, depending on the ratio of effective wind power (Pwind) to installed propulsion power (Pprop). With advanced wind propulsion technology, OceanWings helps the shipping industry reduce emissions and comply with regulations such as FuelEU Maritime, enabling maritime operators to benefit from these reward factors.

To learn more about the benefits for shipping: Benefits for Shipping - OceanWings

The EU Emissions Trading System (EU ETS) was extended to maritime transport emissions on 1 January 2024. It covers greenhouse gas (GHG) emissions from ships during operation (tank-to-wake) and operates under a cap-and-trade system, where emission allowances are gradually reduced over time in line with EU climate targets.