Pushing the boundaries of battery-electric ferry design
With a 40 MWh battery system on board, Incat’s latest catamaran newbuild has made headlines as the largest purely electric ferry to date and likely pioneer of a new vessel class. The vessel’s design was optimized in line with DNV’s updated class rules, ensuring a high level of safety while supporting innovation.
Ferry operators around the world are increasingly adopting alternative propulsion solutions to reduce emissions and noise, particularly in ports and coastal areas, with growing demand for sustainable tourism further reinforcing the trend.
Why ferry operators are choosing electric multihull
The shift is particularly evident in the growing popularity of lightweight battery-electric multihull vessels. Combining low water resistance with high energy efficiency, they can significantly reduce operating costs, while expanding charging infrastructure is making electric operation increasingly viable. As a result, they have taken the lead in ferry newbuilding, with a market share of 68% forecast for 2026, according to Fortune Business Insights.
Multihulls are more manoeuvrable than conventional monohulls. Thanks to their wider decks, they can accommodate more passengers and vehicles, while higher speeds make them especially suitable for routes requiring several runs per day. In addition, their inherent stability reduces rolling in rough seas, improving passenger comfort.
The business case for lightweight battery-electric ferries
DNV’s ship register reflects the trend towards electric propulsion: at the end of 2025, the DNV-classed fleet included 433 battery-powered vessels in operation, with another 271 under construction.
For the high-speed craft (HSC)segment, speed is no longer the primary selling point. “The market situation is a bit confused right now,” says Robert Clifford, founder and chairman of shipbuilding company International Catamarans Pty Ltd (Incat), one of two Australian shipbuilders specializing in large aluminium high-speed catamaran craft. Slower speeds are ultimately a better option, Clifford adds, simply because the battery power will last longer. “We are currently building craft for design speeds of 25 to 30 knots, but speeds of around 20 knots would be better. IMO’s High-Speed Craft Code (HSC Code) does not even define such a category, although there is a huge market for ferries running marginally below the high-speed bracket."
As battery-electric ferries mature, the focus is shifting from speed to efficiency. That trend plays to the strengths of lightweight aluminium construction. “Scale is working for us,” says Clifford, noting that larger aluminium vessels are becoming increasingly economical. While aluminium remains more expensive than steel, the higher initial investment can be offset by lower operating costs. Combined with battery-electric propulsion, the reduced weight lowers energy demand and shortens charging times, helping operators maximize vessel availability. “The combination of aluminium and battery is really a winner; the industry is still learning about that,” says Clifford.
World’s largest battery-electric aluminium ferry enters service
The trend towards larger battery-electric aluminium ferries reached a new milestone in August 2026 when Uruguayan-Argentine ferry operator Buquebus took delivery of China Zorrilla, the world’s largest battery-electric aluminium vessel to date. Serving routes across the Rio de la Plata estuary between Argentina and Uruguay, the ferry was named in honour of the celebrated Uruguayan actress.
Built by Incat in Hobart, Tasmania, as Hull 096, the roll-on/roll-off ferry is 130 metres long with a beam of 30.5 metres. Designed by Revolution Design Pty Ltd, it can carry up to 2,100 people (including crew) and 226 cars at a service speed of 25 knots. The vessel is the eighth Incat-built ferry delivered to Buquebus, reflecting a long-standing partnership between the two companies.
The battery challenge behind the world’s largest electric ferry
China Zorrilla’s electric propulsion system and quad waterjets in each hull were supplied by Wärtsilä, with the four 10.290 MWh lithium-ion battery systems manufactured by Corvus Energy. The three-deck ferry operates on a 30 nautical miles (56 km) route between Buenos Aires and Colonia del Sacramento twice daily, recharging her batteries at each end of the run. One charge cycle takes about 95 minutes.
The scale of the battery installation reflects Buquebus’ decision to switch from LNG to fully electric propulsion during the project. Seeking to reduce weight and draught, the operator opted for batteries instead of gas fuel tanks and related equipment. “Zero emissions and close to zero noise and vibration are the great advantages of this decision,” says Van Su Do, DNV’s Principal Surveyor in Hobart who oversaw construction of the vessel. The trade-off is a limited operating range, making battery capacity a critical design consideration. “This large ferry required a battery plant of unprecedented proportions that by far exceeds existing statutory conventions, including the light craft code or DNV rules.”
Having worked with DNV for over 30 years and built all of its vessels to DNV rules, Incat appreciates DNV’s flexibility in accounting for the ship’s unusual characteristics and minimizing her weight in a precisely calculated way.
“We have worked together with DNV very well in the past and enjoyed good cooperation, especially on the electrical aspects.”
Risk assessments and safety engineering for large battery systems
“As a novel design, the craft required adaptation to existing building and testing requirements. We worked closely with the yard to develop practical solutions without compromising safety,” says Su. The project also incorporated additional safety requirements introduced in DNV’s updated class rules, reflecting the industry’s growing experience with large-scale battery systems and their unique safety challenges. “We carried out comprehensive risk assessments covering internal fire, external heating, water ingress, collision, grounding, and other incidents based on newly developed, very detailed event scenarios,” says Su.
To enhance impact and fire protection, an additional bulkhead was incorporated into the hull, while the battery installation was divided into four separate insulated compartments. Each battery is equipped with its own cooling system and protective containment designed to prevent faults from spreading to adjacent modules. “A high degree of fault tolerance has been engineered into this system,” Su emphasizes. “Our risk evaluation ensured that risks were reduced to as low as reasonably practicable.”
Clifford adds: “We truly appreciate DNV’s expertise and responsiveness in finding mutually acceptable solutions as the project transitioned to fully electric propulsion.”
Passenger evacuation system tested successfully
Given the vessel’s capacity, emergency evacuation was a key design consideration. Before delivery, China Zorrilla successfully completed testing of its state-of-the-art Marine Evacuation System (MES). The system comprises six 22-metre inflatable evacuation slides connected to 19 open life rafts
“Safety is fundamental to every vessel we build at Incat,” says Clifford. “The successful MES test demonstrates the depth of engineering, planning, and collaboration required to deliver a vessel of this scale.”
How advances in battery technology could extend ferry operations
China Zorrilla was built using today’s state-of-the-art, marine-approved battery technology. However, accommodating such a large battery installation required significant investments in cabling, switchboards, and power electronics. “Accommodating this many batteries on board is a challenge,” says Clifford.
Looking ahead, advances in battery and propulsion technology could make future electric ferries even lighter, more efficient, and capable of operating over longer distances. Clifford points to developments such as lighter electric motors and next-generation sodium-ion batteries, which could offer inherent safety benefits while reducing weight and complexity. Ultimately, he believes battery-electric ferries could achieve ranges of up to 100 nautical miles on a single charge, compared with approximately 50 nautical miles today.
How aluminium could shape the next generation of ferries
Clifford believes the potential of lightweight aluminium construction is far from exhausted. Because ferries typically operate in relatively sheltered coastal waters, he sees no structural reason why aluminium vessels could not grow well beyond their current size. In particular, he believes the large market for English Channel-sized ferries could benefit from lightweight designs that improve efficiency without introducing a significant cost penalty. Meanwhile, Incat has received an order for three vessels similar to China Zorrilla from Danish operator Molslinjen, to be built in DNV class.
Looking ahead, Clifford sees China Zorrilla as a milestone rather than an endpoint. “The industry is still learning what battery-electric ferries can achieve,” he says. “By combining lightweight aluminium construction, advanced battery technology, and close collaboration with partners such as DNV, we are expanding what is possible for the next generation of ferries.”
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