Two new gas carriers to stay ahead of environmental standards with Wärtsilä 25 Ammonia engine

Technology group Wärtsilä will supply its Wärtsilä 25 Ammonia auxiliary engine, together with a NO _x reducer (SCR) and gas valve unit (GVU), for two new 51,350 m ³ capacity midsize LPG/liquid ammonia carrier vessels. The engine will support reduced emissions and improved operational efficiency, while helping the vessels meet evolving sustainability requirements. The ships are being built at Nantong CIMC Sinopacific Offshore & Engineering (SOE) shipyard in Shanghai and will be owned by a joint venture between Navigator Gas and Norway-based Amon Maritime, Navigator Amon Shipping AS. Wärtsilä will also supply the propulsion system, including a Controllable Pitch Propulsion solution designed to optimise efficiency and reliability. The order for the engines, SCR and GVU was booked by Wärtsilä in Q2 2026, whilst the order for the Controllable Pitch Propeller system was booked in Q3 2026.

As the shipping industry transitions to decarbonised operations, ammonia is emerging as a promising carbon free marine fuel capable of achieving the IMO’s net-zero-emissions target for 2050. Wärtsilä has played a leading role in developing engine solutions able to operate with alternative fuels, and already in 2023 introduced the marine sector’s first commercially available 4-stroke engine-based solution for ammonia fuel. The ammonia-fuelled engine supports the industry’s transition towards lower-emission vessel operations.

“Wärtsilä has demonstrated industry-leading capabilities in enabling future low and zero-carbon fuels to become viable. By selecting the Wärtsilä 25 Ammonia engine, we expect to dramatically reduce the ships’ environmental impact, while supporting compliance with evolving regulatory requirements,” says Mr. Kaj S. Pilemand, Director of Vessel Operations, Navigator Gas.

The ammonia engine aligns with the shipping industry’s accelerating shift towards decarbonised operations. When running on sustainable ammonia, total greenhouse gas emissions can be reduced by at least 90 percent compared to equivalent diesel engines. In addition, the Wärtsilä propulsion system optimises vessel operations by integrating the entire shaft line arrangement. The Controllable Pitch Propeller system is designed to deliver high efficiency, operational reliability, and reduced emissions.

“This project reflects the continued momentum behind carbon-neutral and zero-carbon fuels, with ammonia emerging as one key pathway. It also highlights the growing demand for flexible, propulsion solutions that support new, more sustainable operating models. In short, these vessels have been designed for lower-emission operations, and Wärtsilä’s solutions will support those ambitions,” comments Stefan Nysjö, Vice President of Power Supply, Wärtsilä Marine.

The Wärtsilä equipment is scheduled for delivery to the yard commencing in June 2027.

Wärtsilä Marine in brief
Wärtsilä Marine is a global pioneer in power, propulsion and lifecycle solutions for the marine market. We develop industry-leading technologies, advancing maritime’s transition to new fuels. We support building an end-to-end digital ecosystem where all vessels and ports are connected. Ultimately, Wärtsilä Marine is driving the shipping industry forward on its journey towards a decarbonised and sustainable future through our broad portfolio of engines, propulsion systems, hybrid technology, exhaust treatment, shaft line solutions and digital technologies, as well as integrated powertrain systems. Our offering, which is underpinned by our performance-based agreements, upgrades, lifecycle solutions, decarbonisation services, as well as an unrivalled global network of maritime expertise, delivers the efficiency, reliability, safety, and environmental performance needed to support a safe and sustainable future for our customers, our communities and our planet.
www.wartsila.com/marine

Wärtsilä in brief
Wärtsilä is a global leader in innovative technologies and lifecycle solutions for the marine and energy industries. We emphasise innovation in sustainable technology and services to help our customers continuously improve environmental and economic performance. Our dedicated and passionate team of 17,900 professionals in 199 locations in 78 countries shape the decarbonisation transformation of our industries across the globe. In 2025, Wärtsilä’s net sales totalled EUR 6.9 billion. Wärtsilä is listed on Nasdaq Helsinki.

www.wartsila.com

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Wärtsilä’s 25 Ammonia engine will help two new midsize gas carriers – owned by joint venture, Navigator Amon Shipping AS – reduce emissions, improve operational efficiency, and stay ahead of evolving sustainability requirements. © Wärtsilä Corporation