The problem with powering any form of transportation with electricity is that it requires heavy batteries. This is especially a problem for boats, because they suffer from drag in the water. To address this, Candela uses hydrofoils, legs that extend into the water and act like wings, propelling the boat into the air as it picks up speed like an airplane during takeoff. “In the port, the foils are completely retracted, so they are protected,” says Hasselskog. “But then you lower the foils and you step on the accelerator and there it goes. The control system takes care of the entire take-off sequence, it’s like an airplane.”
Hydrofoils are not new, but electric propulsion and automated steering are. The carbon fiber Candela P-12 has dual drive systems powered by 180 kWh batteries, allowing it to run for three hours before needing a recharge. With a length of 12 meters and a width of 4.5 meters, the 8.5-ton boat will carry 30 seated passengers.
A super-fast flying boat sounds like a surefire way to lose your breakfast on the commute, but the Candela has sensors fed into an automated flight control system to adjust its height and roll and tilt up to 100 times per second to adjust the speed. to ensure a smooth ride regardless of the weather. “Through the control system, we can disable all vertical movements of the boat,” says Hasselskog, which tends to cause seasickness. “So far no one has gotten seasick on our boats.”
All of that means that when built, the Candela P-12 should use less energy per passenger than a hybrid electric bus, go faster than a car and cut fuel and maintenance costs by 40 percent. And since it glides above the water, it is less disruptive to the local environment, both above and below the water.
Candela couldn’t simply enlarge his existing boat to build the P-12 – the regulations require a thicker hull, fire protection systems for the batteries and, confusingly, separate toilets for passengers and the single crew member, who will operate all ships. time.
Aside from the toilets, there’s another regulatory challenge: Speed limits on inland waterways are usually as low as six knots (7 mph), but hydrofoils are most efficient at top speed. Such speed limits are for safety and to reduce the wake, which boats like the P-12 don’t cause. “The solution is to work with port authorities and ferry companies to get a waiver,” said Charles Haskell, decarbonization program manager at maritime consultancy Lloyd’s Register. Around Stockholm, that limit is 12 knots, although Candela has a temporary exemption during the trial.
Not all cities can use waterways as highways, but it can be an attractive idea for coastal agglomerations. Rival flying boat maker Artemis is testing its version in Belfast, while Hasselskog has held talks with authorities in Istanbul and across the Middle East. Representatives of the Water Emergency Transportation Authority (WETA), which operates ferry services in the San Francisco Bay Area, visited Stockholm to see how the Candela P-12 works.
For coastal cities like Stockholm, ferries can become the watery equivalent of trams without having to build infrastructure such as rail, although charging systems are needed. “If it behaves like a light rail at sea enabling hundreds of people who would have gone by car, then we need more of that,” said Paul Chatterton, a professor of urban futures at the University of Leeds. “The speed is a red herring … in a large urban river environment you need large large vessels that can carry a lot of people over short distances.”
Hasselskog argues that a large fleet of smaller boats offers more flexibility than larger ferries and could mean they are used on demand, eliminating the need for timetables or fixed stops. The idea is also being touted by hydrogen-powered hydrofoil water taxis made by SeaBubbles, which have been trialled in Lyon, France. Smaller boats have a different purpose: to transport maintenance personnel and supplies to offshore wind farms, Haskell says, solving a problem of getting personnel to locations many miles offshore without arriving seasick.
Even without top speeds, water taxis and boat buses hold promise for cities with waterways, Chatteron says, pointing to the popularity of Venice’s vaporettos. And beyond passenger traffic, slow, electric barges can take cargo off the road. “You can move a lot of things with little or no energy,” Chatterton says, “and many European cities have canals.” Whether it’s electrically powered flying ferries or energy-efficient barges, making better use of urban waterways makes sense for sustainability, Hasselskog says. “You don’t need any special infrastructure, the water is just there,” he says. “That’s probably why they used to be used — just go.”
