Stockholm, the Swedish capital, is renowned for its expansive network of waterways. When comparing its infrastructure to cities like Hamburg or Rotterdam, one particular detail stands out: Stockholm’s industrial port is situated roughly 50 km south of the city centre. This means the inner harbour could be exceptionally quiet and clean—were it not for the diesel-powered passenger ferries.
These ferries are currently the only vehicles in the city’s public transport network that still rely on fossil fuels. The company Candela aims to change this by replacing them with electric vessels, powered by a remarkably efficient and environmentally friendly propulsion system.
The Candela ferry ‘flies’ above the water
Typically, electric boats mirror the design of traditional petrol or diesel vessels. The hull sits in the water, pushed forward from the stern by a water jet or propeller. In this conventional design, the motor doesn’t just have to move the weight of the ship and its passengers; it must also displace the water in front of the boat. This creates significant drag and generates large wakes in the vessel’s trail.
Candela has opted for a hydrofoiling design for its ferries. This involves fitting the hull with underwater wings and electric motors that resemble small aeroplanes. Once the vessel reaches speeds of approximately 20 km/h, these foils lift the ferry out of the water, significantly reducing drag.
Developed in collaboration with the electric car manufacturer Polestar, the “Candela C-Pod” motors are exceptionally quiet and eliminate the need for sensitive components like gearboxes or mechanical clutches. According to the manufacturer, they deliver 320 kW, equivalent to nearly 900 hp. The direct-drive system further reduces vibration and has proven to be remarkably efficient in initial testing.
Electric ferries cut emissions by 95 percent despite higher speeds
From an environmental perspective, these electric ferries offer a major advantage: they produce 95 percent fewer emissions than the diesel models currently in use. Life-cycle assessments conducted by Candela also indicate a smaller carbon footprint across both production and the entire service life compared to conventional boats.
The latest and largest model to date, the Candela P-12, is projected to save around 1,670 tonnes of CO2 equivalents annually. The 12-metre vessel has a capacity of 30 passengers.
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During sea trials, Candela’s vessels were able to complete the “Pendelbåt 89” route between Stockholm City Hall and Tappström significantly faster. Once again, this is down to hydrofoiling technology; because it creates less drag, the boat produces a much smaller bow wave. Consequently, the Candela P-12 can maintain higher speeds with minimal disruption to other vessels or fragile riverside ecosystems.
Initial trials proved that passengers value these faster, quieter, and more comfortable journeys, with a 30% increase in ridership on the line.
Following a winter break in 2024, the model—christened “Nova”—resumed service in Stockholm. Since April 2025, it has been operating seven days a week instead of five, ferrying 30 passengers at a time from the city centre to Tappström.
