For years, the maritime industry’s decarbonisation debate has focused on a single question: which fuel will power the ships of the future? LNG, methanol, ammonia, hydrogen and other alternatives all offer potential, yet no clear winner has emerged. As a result, shipowners face major investment decisions amid technological uncertainty, evolving regulations and changing market demands.
But the challenge goes beyond fuel selection. Vessels ordered today could remain in service well into the 2050s, operating through decades of regulatory and technological change. Rather than attempting to predict the dominant fuel of tomorrow, shipowners increasingly need vessels designed to adapt to multiple possible futures. Flexibility is becoming a key consideration for long-term competitiveness.
This thinking has led to RINA’s development of Mermaid, a propulsion concept designed not around a specific fuel, but around improving efficiency while reducing investment risk. Mermaid combines a two-stroke main engine with a shaft generator, propeller shaft clutch and battery energy storage system. This allows the main engine to generate electricity while the vessel is in port, charging batteries that can supply onboard power demand. According to RINA, the concept improves engine efficiency while reducing fuel consumption, emissions and operating costs without committing owners to a particular fuel pathway.
The concept also addresses the growing trend towards slow steaming. By integrating auxiliary engines and battery storage in a hybrid propulsion arrangement, Mermaid is designed to better match power supply to actual operating conditions while maintaining flexibility and reducing the risk of power loss for both propulsion and onboard electrical systems.
According to RINA, the concept can reduce fuel consumption by more than 1,000 tonnes annually in certain applications while lowering future compliance costs. The company sees Mermaid as an example of designing vessels that can adapt to future technological and regulatory developments.
Hall B4.EG, Booth 310
