Wärtsilä and Stena building world’s largest hybrid vessels

Energy efficiency

Finland – Wärtsilä will supply three new RoPax vessels for Stena RoRo, Europe’s largest ferry company, with its hybrid propulsion system.

Two of the ferries will have a battery capacity of 11.5 MWh, making them the largest hybrid vessels ever built in the marine industry. This battery power is roughly double what is typically used for hybrid propulsion today.

Stena RoRo and Brittany Ferries collaborated on the ships’ design and development, and they will be chartered to Brittany Ferries for long-term service between Portsmouth, England, and the French ports of St Malo and Caen. Wärtsilä had previously been contracted to supply the main and auxiliary engines, gearboxes, controllable pitch propellers (CPPs), thrusters, the fuel gas supply system, Nacos navigation and automation, as well as an integrated control alarm and monitoring system for the vessels. The ships will be able to operate on either LNG or battery power.

The vessels will be outfitted with the Navius MRS-3, a next-generation Leclanché energy storage system that outperforms comparable marine batteries in terms of size and weight.


The ability to integrate multiple vessel systems and real-time optimization of the on-board energy system are important features of hybrid vessels. Wärtsilä brings together a diverse range of system expertise in ship power and propulsion machinery. When the advantages of a hybrid propulsion system and shore power are combined, it can save up to 15% on GHG emissions when compared to a conventional diesel mechanical propulsion system.

China Merchants Jinling (Weihai) Shipyard is constructing the vessels. The ferries are expected to be delivered in 2024 and 2025.