These are said to be the first liquefied natural gas (LNG)-driven RoPax ships to be constructed for the Polish maritime industry.
With an overall length of 195m, the vessels will be operated by ferry firms Unity Line and Polferries.
They will have 4,100 lane metres for vehicles as well as space to accommodate 400 passengers.
The ships will provide services between the Swedish ports of Ystad and Trelleborg and Swinoujscie, Poland.
Each ship will be equipped with four Wartsila 31DF dual-fuel engines, which can operate either on wholly bio-LNG or a blend of bio and conventional LNG.
The operators aim to sail the ships entirely on bio-LNG by 2025.
Apart from the Wartsila 31DF engines, the firm will also deliver its LNGPac fuel storage, supply and control system.
Unity Line parent company Polsteam technical director Grzegorz Wardzyński said: “High efficiency and sustainability are essential in today’s operating environment, especially in the Baltic Sea, which is an Emissions Control Area. The Wartsila 31 engine represents the latest engine technology available and this, coupled with Wartsila’s vast experience in LNG solutions, made the choice easy for us.”
Wartsila Marine Power sales general manager Matthias Becker added: “Decarbonisation is a front and centre issue for the maritime sector, and this focus is reflected in the choice of the Wartsila engines for these ferries.
“Optimal engine performance is essential in maximising fuel efficiency and minimising exhaust emissions. These new vessels will become an important part of Poland’s transport infrastructure, and we are proud to be a partner to this project.”
Last month, Wartsila received its first order from Van Oord for five Wartsila 32 methanol-fuelled engines.