The Wärtsilä 25 is a medium-speed 4-stroke marine engine with a future-proof, upgradeable modular structure that makes it easier than ever for you to target net-zero. Available in cylinder configurations from 6L to 9L and with a power output ranging from 1.7–3.4 MW, the Wärtsilä 25 provides reliable performance whether you are using it as a robust main propulsion engine or as a cost-efficient and flexible auxiliary engine. The engine is available in diesel and dual-fuel versions and now introducing ammonia.
Ammonia will play a big role in the decarbonisation of shipping. One major piece in the puzzle – dual fuel engine technology – has been missing until now. In 2020, Wärtsilä initiated the world’s first full-scale ammonia engine test, scaled it up and now an ammonia 4-stroke engine is ready to be introduced.
The Wärtsilä 25 is perfect for use as a main engine onboard smaller merchant vessels, fishing boats, tugs, dredgers, and offshore support vessels. Whether you are looking for a diesel, biofuel, or dual-fuel engine for your main or auxiliary
application, the Wärtsilä 25 is the answer. The Wärtsilä 25 Ammonia engine will help you immediately reduce greenhouse gas emissions by a minimum of 70% compared to a diesel engine.
All engine versions feature common rail, high-pressure fuel injection that enables cylinder-wise combustion control and fuel-injection settings for each operating point.
The NextDF feature of the Wärtsilä 25DF engine improves engine combustion and efficiency – and cuts emissions significantly. When operating on LNG fuel, you get
What’s more, the feature will further cut the Wärtsilä 25 DF engine’s NOx emissions that fall below IMO Tier III levels already.
When the engine is operating on LNG fuel, the NextDF feature reduces methane emissions to less than 2% of fuel use across all load points, achieving as low as 1.1% of fuel use in a wide load range.
The NextDF feature is available as an option for
The feature can also be integrated into existing Wärtsilä 25DF engines.
Choose the NextDF feature and you can future-proof your fleet with Wärtsilä 25DF engines, comply with known future regulatory requirements and achieve substantial operational savings.
Integrate Wärtsilä 25 engines with batteries. This flexible, hybrid system will give you:
Better fuel efficiency. The hybrid system will enable the engines to run at optimal load, which saves fuel – and money. You can also save on maintenance because there will be less wear and tear on the engines.
Lower emissions. Less fuel burned means that the hybrid system generates less emissions, too.
Better operational flexibility. The smart hybrid system makes it possible to switch smoothly between power sources. This will deliver consistent, reliable performance even under varying operational conditions.
Learn more about the benefits from a smart hybrid solution.
No matter what version of the engine you start with, the upgrade path is secured by the Wärtsilä 25’s outstanding modularity, which future-proofs your investment.
The modular, upgradable design allows you to reduce vessel fuel consumption and emissions from the first mile while providing the readiness to run on alternative fuels whenever viable – all without compromising performance. Whatever future fuel emerges as the most appropriate for your operations, the Wärtsilä 25 is ready for the challenge.
Keep your engine in top condition and you can get the best performance while minimising operating costs. Wärtsilä can help you: choose a Lifecycle Agreement with us and you will know that our experts will assist you in planning, preparing, and executing maintenance.
We can coordinate spare parts and make sure that a skilled maintenance workforce will be available. The AI-powered solutions and predictive analyses combined with expert knowledge will ensure the optimal performance of your vessel.
A Lifecycle Agreement with Wärtsilä can keep you a step ahead. You will have true peace of mind and you can focus on your core operations. Learn more about service agreements.
Get technical data and system proposals for designing W25, W25DF and W25 Ammonia marine engine installations.
Discover the benefits others have already gained from Wärtsilä 25 engine.
