Spanish wind assisted propulsion system (WAPS) developer bound4blue has received type approval design certification (TADC) from DNV for its model 3-24 eSail, the company’s largest and most powerful installed suction sail.
The approval confirms the system’s compliance with DNV’s established classification requirements for safety, structural integrity, and design robustness. bound4blue’s model 3 range is designed for larger vessels and projects looking to maximise the possible propulsive contribution from wind power. Units range from 24m to 36m in height. The Model 3-24 is the first of the new design to be installed, with two units fitted on the DNV classed Klaveness Combination Carriers newbuild Baltazar in April 2026. With an expanded sail surface area and optimised aerodynamic profile, the system maximises lift generation, enabling shipowners to achieve greater fuel savings and emissions reductions across a wide range of vessel types.
José Miguel Bermúdez, CEO and co-founder, bound4blue, said: “Achieving type approval from DNV for our most advanced installed eSail is an important step forward, both for us and shipowners looking to harness optimal benefits from wind propulsion. Independent validation from a leading classification society like DNV confirms that the technology meets relevant standards for reliability and performance. Such class developments are essential for accelerating uptake across the industry. They reduce uncertainty, support acceptance by regulators, insurers and charterers, and give shipowners the basis they need to invest in proven, future-ready solutions. Ultimately, they support the eSails’ potential as a trusted, scalable tool for decarbonisation.”
Cristina Saenz de Santa Maria, CEO DNV Maritime, added: “At DNV, we are committed to supporting the maritime industry in navigating the energy transition, and we are pleased to award this type approval to bound4blue, as it expands the range of technical solutions available to the industry. We’re now beginning to see the next generation of WAPS units. One of the key enablers of these developments is the parallel evolution of technical standards, which have been a vital part of building acceptance in the market. This means working closely with technology providers to assess new solutions against independent technical standards, and we look forward to further collaboration in this area.”
Built on bound4blue’s established Model 2 platform, the 3-24 eSail features a wider chord and increased sail surface area compared to earlier designs. This enables enhanced aerodynamic efficiency and higher propulsion output, while maintaining the system’s ease of integration, with limited additional system complexity, such as tilting mechanisms. With fully autonomous operation, eSails use boundary layer suction technology, drawing air across an aerodynamically optimised surface to generate propulsive force and reduce main engine fuel consumption and CO2 emissions. This supports both cost reductions and regulatory compliance, including frameworks such as FuelEU Maritime and the EU ETS, as well as contributing directly to CII ratings and compliance with EEXI requirements.
According to bound4blue, WAPS is already the ‘solution of choice’ for a growing number of leading shipping companies, with recent installations for names such as Maersk Tankers, Eastern Pacific Shipping, Odfjell, Amasus and Louis Dreyfus Company. Designed as a simple, plug-and-play solution, the fully autonomous systems can operate alongside conventional propulsion systems while supporting the adoption of future fuels such as methanol and ammonia, helping shipowners reduce fuel consumption, emissions, and regulatory exposure.
Image: José Miguel Bermúdez, bound4blue, receives the TADC from Cristina Saenz de Santa María, DNV Maritime (source: bound4blue)
