Not so long ago, a passenger ship’s engine room was noisy, dirty and chaotic. Controls were largely manual and there was a relentless need for hands-on maintenance.
Today, all of that has changed. Step inside a modern engine room and you’ll be met with a clean, high-tech and meticulously organised space. Hybrid propulsion systems deliver quieter power, while digital displays track hundreds of sensors in real time. Automated controls are now capable of managing everything from propulsion control and fuel handling to emergency shutdowns.
One of the biggest drivers of this transformation is the push for greater sustainability. “Probably the biggest trend is the increasing requirements for environmental performance,” says Mia Elg, research and development manager at Finland-based ship design company Deltamarin. “That means introducing alternative fuels to vessels.”
Fully electric systems and battery hybrid machinery are becoming increasingly popular for ro-pax ferries, according to Juuso Reunamo, Deltamarin’s machinery and alternative fuel expert. “Shore power has also been introduced to many vessels due to upcoming European Union regulations. The FuelEU Maritime regulations, for example, consider shore power to be zero carbon. This makes it one of the most cost-effective ways to decarbonise a ship.”
But an increasing focus on environmental sustainability also brings growing compliance requirements. “Recent MARPOL regulations to reduce ship pollution have required large and complex new equipment such as ballast water treatment systems and engine exhaust scrubbers and reactors to be fitted,” says Ken Goh, general manager at Danish naval architect firm KNUD E. HANSEN. “Increased fuel efficiency through the Energy Efficiency Design Index (EEDI) has led to increasing use of hybrid propulsion systems, shaft generators and increasingly complex energy recovery systems.”
Reunamo agrees. “Increased Safety of Life at Sea (SOLAS) regulations with Safe Return to Port (SRtP) have mandated machinery redundancy requirements for passenger ships,” he says. “This has led to multiple engine rooms and a more complicated equipment arrangement.”
Modern engine rooms are high-tech and meticulously organised spaces (credit: KNUD E. HANSEN)
For naval architects, the impact is significant. Modern engine rooms are crowded spaces, consequently they must be planned carefully.
“Energy efficiency and alternative fuels typically require more equipment, piping and cabling,” says Reunamo. “We increasingly need to consider compartmentation and use space much more efficiently.”
Even shipowners not ready to commit fully to a single alternative fuel are now asking designers to build engine rooms with more flexibility for the future. “Many operators have chosen to keep using residual fuels in their newbuilds, which has meant the engine room has to be designed for tri-fuel handling with heavy fuel oil, marine diesel oil and gas fuels like LNG or methanol,” says Goh.
Managing multiple fuels can be risky if not handled correctly. That is why engine room layouts are increasingly designed to minimise high-risk areas and centralise systems. “For alternative fuels, the placement of tanks, fuel handling rooms and engines is optimised to reduce piping and potential hazards,” says Reunamo.
As complexity grows, the key question for operators becomes how to maintain safe and efficient operations with systems that are less intuitive than legacy diesel arrangements. “Overall, ship machinery is becoming increasingly complex,” says Elg. “With new energy sources, ship operators encounter additional safety risks. Fire safety is a central focus, while fuel toxicity can also be an issue. Alternative fuels may need different fire extinguishing systems, for example.”
Designers therefore have to perform a careful balancing act; they need to prioritise safety without overwhelming crews. “We aim to achieve maximum efficiency while keeping systems simple enough for crews to monitor and operate correctly,” says Elg.
This approach extends to redundancy and SRtP compliance. “Overall control systems should be prioritised over individual controls,” says Reunamo. “Vital systems must remain operational, while less critical systems can be isolated efficiently.”
Some passenger ferries are moving towards battery-boosted machinery which has necessarily changed the layout of the engine room (credit: Mia Elg/Deltamarin)
Digital tools have become vital to help manage this increased complexity. Many fuel system providers, for example, have introduced monitoring capabilities to automatically stop the fuel supply in the event of a leak.
“As alternative fuels and hybrid systems increase the number of operational interfaces, features that reduce the possibility of human error in an increasingly complex system are essential,” says Reunamo.
While many digital controls are now automated, Goh says caution needs to be taken when rolling out these features. “Increased engine room automation with sensors and actuators have no doubt helped crews operate and manage their engine rooms, but automation is a double-edged sword,” he says. “Although it reduces workload, increasing automation also means more points of failure and often more difficulty when troubleshooting problems. This was highlighted in March 2024 by the MV Dali incident, where a loose signal wire caused a blackout and loss of ship control with the vessel colliding and destroying the Francis Scott Key Bridge in Baltimore. This led to huge disruptions to both local traffic and billions of dollars in port trade.”
Ultimately, the experts agree that digitalisation cannot replace the fundamentals. That means getting the initial design of the engine room right and installing the correct equipment from the outset. From a predictive maintenance perspective, it also means establishing the right data foundation.
“Subscription-type preventive maintenance schemes from engine makers are very good, but many operators are dissuaded by the high cost of the service,” says Goh. “This has led to the growth of third-party suppliers and consultants who claim to provide the same service at a fraction of the cost. Regardless of who delivers the service, issues such as correct sensor installation, sensor reliability and interference-free data logging can complicate, or completely undermine, preventive maintenance efforts.”
Despite advanced automation and digitalisation, the modern engine room remains a space where human expertise is irreplaceable. “Even with advanced systems and high levels of automation, there are still many ways to operate a vessel,” says Elg. “To achieve maximum efficiency, crews must understand not only the fundamentals, but also the specific ship and its systems. That’s why we are increasingly supporting operators with training on SRtP situations to ensure that crew can operate a specific ship in the worst-case scenarios. We are also providing energy efficiency courses that concentrate on overall efficient operation.”
Goh agrees, adding that while the move towards new fuels, systems and technologies is exciting, humans will remain at the heart of the engine room for the foreseeable future. “Electrification is a defining mega-trend of sustainable transportation and presents an opportunity for ship machinery systems to be designed for unmanned and autonomous operation,” he says. “However, shipping is still many decades away from such a future, since the development of fuel cells and hydrogen handling systems takes time. Until then, experience and hands-on time in the engine room are still of the utmost importance for legacy internal combustion engines and their support systems.”
Driving efficiencies below deck
New innovations from companies such as Alfred Maritime and Pinfabb are helping shipowners to optimise energy use, cut fuel consumption and improve operational performance.
Alfred Maritime’s Meyer Energy Management System (MEMS) has reached a new milestone, now offering full-day operational forecasts powered by the shipyard’s sophisticated digital twin. This update is focused on optimising hotel systems – the primary energy consumers on passenger ships – to further drive down fuel consumption and greenhouse gas emissions.
According to Alfred Maritime, this new feature can unlock an additional five per cent reduction in energy usage. By directly linking a digital twin simulation framework to a live energy management system, MEMS offers a globally unique solution that bridges the gap between virtual modelling and real-world maritime operations.
Italian company Pinfabb has developed Poseidon4, a digital control system for stabilising fins. The system was designed to improve how fin stabilisers are operated and maintained, particularly as shipowners place greater emphasis on energy efficiency and remote diagnostics. One of Poseidon4’s key features is an Eco Mode intended to reduce stabiliser drag and lower energy consumption. The system also supports remote monitoring and assistance, which can reduce the need for onboard service visits. Poseidon4 includes maintenance planning tools within the control interface, aimed at helping crews track servicing requirements more easily. The system can also incorporate online weather data and artificial intelligence-based logic to optimise stabiliser use in changing conditions.
Discover more insights like this in the Spring/Summer 2026 issue of Cruise & Ferry Review. Don’t miss out – subscribe for FREE and get the next issue delivered straight to your inbox.