RINA unveils Mermaid ship design to cut fuel use and emissions

RINA has introduced Mermaid, a new ship propulsion concept aimed at helping owners reduce fuel use, emissions and operating costs while staying flexible as shipping’s decarbonisation path shifts. The design is being developed for tankers, bulk carriers and container ships, with RINA saying the concept can also improve power resilience and protect long-term asset value.

Why it matters: - Mermaid is designed to help shipowners cut fuel consumption and emissions without locking into a single future fuel. - The concept aims to preserve long-term asset value as shipping regulations and technology choices keep changing. - RINA says Mermaid could also improve onboard power resilience during critical operations.

What happened: - RINA unveiled Mermaid, a future-ready ship propulsion concept, in Hamburg, Germany, on Aug. 27, 2026. - The concept combines a shaft generator, propeller shaft clutch and battery energy storage in a new propulsion architecture. - RINA says Mermaid is intended for a maritime decarbonisation future that remains uncertain.

The details: - Mermaid expands the role of a vessel’s two-stroke main engine beyond propulsion and lets it become the primary source of onboard power. - When a vessel arrives in port, the propeller is disconnected while the main engine keeps generating electrical power. - Mermaid reduces reliance on less efficient auxiliary engines by allowing the main engine to supply electrical power directly or charge batteries. - Once charged, the batteries can provide onboard power while the main engine operates more efficiently. - RINA says the setup can lower fuel consumption, emissions and operating costs. - The concept is designed to improve propulsion efficiency without committing owners to a specific fuel pathway. - Mermaid is fuel agnostic. - As slow steaming becomes more common, many vessels now spend much of their operating life below their original design speeds. - The hybrid propulsion scheme is meant to match propulsion power more closely to real operating conditions. - The concept can reduce the need to install excess engine capacity. - The battery system adds another source of electrical power and supports resilience during critical operations. - RINA’s analysis indicates Mermaid can reduce fuel consumption by more than 1,000 tonnes per year in some applications. - Lower fuel use and emissions can also reduce future compliance costs. - RINA says the concept may also offer safety benefits by reducing the risk of power loss for propulsion and electric systems. - The concept is applicable to tankers, bulk carriers and container ships. - Mermaid is currently being developed into a fully detailed design after encouraging feedback from shipowners and shipyards. - RINA said Mermaid reflects its commitment to practical engineering solutions that balance commercial performance with long-term decarbonisation goals. - RINA is a certification and engineering company serving the Energy, Marine, Infrastructure & Mobility, Certification, Industry and Real Estate sectors. - RINA reported 2025 revenues of more than 1 billion euros, more than 7,000 employees and 200 offices in 70 countries. - RINA said it is a member of key international organizations and contributes to the development of new legislative standards. - More information is available on RINA’s website.

Between the lines: - The concept is built around flexibility, not a bet on one fuel winner. - Antonios Trakakis, RINA’s Energy Transition Solutions Technical Director, said ships ordered today may still be operating in the 2050s, so owners need designs that remain commercially and technically sound for decades. - Trakakis said Mermaid can deliver immediate operational and commercial benefits while limiting the need for costly future modifications. - Trakakis said the market still lacks consensus on which fuels will dominate shipping’s future. - The message is clear: shipowners are being pushed to prepare for multiple decarbonisation scenarios at once.

What’s next: - RINA says Mermaid is moving into a fully detailed design phase. - The concept’s next step will likely depend on continuing feedback from shipowners and shipyards. - If adoption grows, the approach could influence how newbuilds are designed around hybrid power, efficiency and future fuel uncertainty.

The bottom line: - Mermaid is RINA’s pitch for a ship design that saves fuel now and stays useful no matter how shipping’s energy transition unfolds.