How design flexibility is reshaping the ship engine market.

The market for mid-bore engines - the two-stroke engines that deliver main propulsion for all but the biggest merchant ships - has traditionally been seen as a stable business: large in volume, conservative in design. But what was once a steady market has been evolving rapidly recently, from 5,000–7,000MW sold in 2018 to 10,000–15,000MW per year today. Alongside this growth, changes in fuel strategy, cost pressures and operational requirements are driving a new phase of competition.

A market ready for change 
Historically, standardised ship designs, repeated series builds and tight yard-owner relationships have together created what might be called a “design lock-in” effect for mid-bore engine selection. Switching engines implies foundation changes, piping rework, engineering risk, crew retraining and new spare parts inventories, which are all unwelcome in price-sensitive projects.

 But as new market dynamics emerge, shipyards and owners are taking the opportunity to view engine selection through a fresh lens. Change doesn’t have to be a negative – in fact, it’s essential to not only stay competitive but also compliant. 

Flexibility becomes a priority 
Compliance with decarbonisation rules continues to influence investment decisions. At the same time, uncertainty around future fuel availability, pricing and regulation is making long-term fuel decisions more challenging. As a result, many owners are prioritising flexibility, rather than committing fully to a single future fuel pathway, operators are increasingly seeking propulsion solutions that allow adaptation over time as market conditions evolve. 

This has renewed interest in retrofit-ready engine concepts that can support future fuel transitions without major structural modifications.
For WinGD, fuel flexibility and retrofit capability have become key parts of our mid-bore strategy.  Our engines are designed to support efficient operation on today’s fuels while also preparing vessels for future conversion pathways when required.

This approach has gained increasing attention among Chinese shipowners and shipyards, particularly as operators look for practical solutions that support both commercial competitiveness and long-term compliance planning. With almost 200 mid-bore engines (X52 / X62 long and short stroke) in the production pipeline since 2025, several engines have already been ordered with pre-installed future-fuel retrofit features, while all current WinGD mid-bore engines are designed to support future conversion without structural modification.

Looking beyond engine price
Cost is a key factor for mid-bore engines, but purchasing decisions are increasingly influenced by long-term operational value rather than initial engine cost alone. Factors such as installation simplicity, engine-room integration, maintenance support and lifecycle reliability are becoming more important for both shipyards and owners. 

WinGD’s Integrated SCR solutions, for example, can help reduce engine-room footprint and simplify installation processes.

In a market where delivery schedules remain tight, reducing integration complexity can provide direct commercial benefits for shipyards. At the same time, compact engine footprints and foundation compatibility can help reduce switching complexity when evaluating alternative engine suppliers.

Lifecycle support is also becoming a more important consideration. Owners increasingly expect long-term technical support, operational optimisation and service capability throughout the vessel lifecycle, particularly as fleets prepare for future fuel transitions.

Looking ahead
While some forecasts suggest softer demand for large container vessels in the coming years, mid-bore engine demand is expected to remain strong across multiple vessel segments such as bulkers, feeder containers and tankers. As fleet requirements evolve and operational flexibility becomes increasingly valuable, mid-sized vessels are expected to play a larger role across several shipping markets. This is likely to further increase the strategic importance of the mid-bore engine segment. 

As operators continue to evaluate future fuel pathways and long-term fleet strategies, access to flexible propulsion technologies and global lifecycle support will remain increasingly important. More information about WinGD’s solutions and services is available here