Wärtsilä has secured orders to supply ammonia-fuelled auxiliary engines and a complete propulsion package for two 51,350-cbm midsize LPG/liquid ammonia carriers owned by Navigator Amon Shipping AS, according to Wärtsilä.
The vessels are being built at Nantong CIMC Sinopacific Offshore & Engineering (SOE) in Shanghai. Each ship will receive a Wärtsilä 25 Ammonia engine, a selective catalytic reduction NOx system and a gas valve unit, alongside a controllable-pitch propulsion solution integrating the shaft line.
The engine, SCR and gas valve unit orders were booked in Q2 2026, while the controllable-pitch propeller package was booked in Q3 2026. Deliveries to the yard are scheduled to begin in June 2027.
Wärtsilä said total greenhouse gas emissions can be cut by at least 90% against an equivalent diesel engine when the Wärtsilä 25 runs on sustainable ammonia. The group introduced what it called the marine sector’s first commercially available four-stroke, ammonia-fuelled engine solution in 2023 as shipping works towards the IMO’s net-zero target for 2050.
“By selecting the Wärtsilä 25 Ammonia engine, we expect to dramatically reduce the ships’ environmental impact, while supporting compliance with evolving regulatory requirements,” said Navigator Gas director of vessel operations Kaj S. Pilemand.
Navigator Amon Shipping AS is the vessel-owning joint venture formed by Navigator Gas and Norway-based Amon Maritime.
Nantong CIMC Sinopacific Offshore & Engineering is the shipbuilding entity constructing the two carriers.
Wärtsilä Corporation is a technology group serving the marine and energy industries. Its Wärtsilä Marine business supplies engines, propulsion, exhaust-treatment, shaft-line, hybrid and digital systems, as well as lifecycle services. The group employed 17,900 people across 199 locations in 78 countries and generated 2025 net sales of €6.9bn ($7.9bn).