Candela’s Faith in Foiling Ferries

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Candela’s first commercial craft, the P-12, is a fully electric foiling ferry for 30 passengers, shown here during sea trials near Stockholm, Sweden.

In the rarefied world of fully foiling electric boats with carbon hulls and appendages, sensor-based digital ride control systems, and hefty price tags, Candela grabbed the spotlight by delivering on its promises early. Now the company is refocusing, scaling its technology for mass transportation.

The Swedish boatbuilder was founded in 2014 by Gustav Hasselskog. At age 40 and tired of driving a conventional gas-guzzling powerboat to his family’s island cabin in the Stockholm archipelago, he began looking into electric alternatives. Fast electric boats already existed, as did foiling technology and electronic ride control systems (see “Rising to the Occasion,” Professional BoatBuilder No. 172, page 22). But fusing electric propulsion and foiling in one production vessel broke new ground.

Ten years later, Candela has more than 200 employees and has sold about 200 boats to customers who didn’t blanch at a $400,000 sticker price. The company selectively shares information with the press and is tight-lipped about financials. But it would not be where it is today if it hadn’t raised cash for product development and building production capacities. Published reports estimate Candela’s valuation at approximately €100 million, with €45 million raised since 2021 in two investment rounds led by EQT Ventures. To scale up production, the firm recently announced another funding round of €24.5 million ($26.7 million). In addition, Hasselskog is listed as inventor on four patent applications by Candela, three for the boat and one for the method and the controller that handles the motion of a hydrofoil watercraft. Early 2024 finds Candela pushing into the public transportation market with the recent launching of its 30-passenger P-12 model. The foiling catamaran has been undergoing sea trials in the Stockholm archipelago and is expected to start commercial service later this year.

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The C-8, with a bow cabin, is a larger, more refined craft than the original C-7. The C-8 is available in various configurations and is trailerable, thanks to the fully retractable foil system.

Before we get into the technical details of the P-12, it is necessary to look back at the C-8, the company’s 283 (8.6m) trailerable stepped-hull model with retractable foils, available as a runabout with a bow cabin, as a center-console, and as an eight-passenger taxi. It was the second step in the evolution of Candela’s technology stack—drivetrain, hull, ride-control system—developed in-house with a talented workforce including: French hydrodynamicist Michel Kermarec, who worked for America’s Cup teams Oracle and American Magic; and manufacturing engineer and product manager Gabriele De Mattia from Italy, who took a C-8 to the United States Powerboat Show in Annapolis, Maryland, last fall.

Prior to that, in 2019 the company’s first model—the 22 (6.7m) C-7 bowrider powered by a modified Torqeedo electric outboard—was launched. “We have improved and simplified the build process a lot,” a company spokesman e-mailed. “In the C-7, we had a frame or stringer system that was glued together from multiple parts; in C-8 the frame is one piece. We have evolved from a two-sensor system in the C-7 to a six-sensor system in C-8, capable of mapping a 3D image of the water surface ahead for improved seakeeping.”

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A C-7, the firm’s first recreational boat,
with a forward cockpit and a modified electric outboard, foils past
the Venetian palazzi

Candela’s Swedish production shop turns out one boat a week but is working to increase capacity. Built of vacuum-infused carbon fiber over 6mm PVC core, the hull weighs about 110 kg (243 lbs), including the carbon grid to support the foil loads, according to De Mattia. Light displacement of the C-8 is 3,860 lbs (1,721 kg). It is powered by a pod drive (called a C-Pod) with a permanent-magnet AC motor (PMAC) mounted on the aft foil. The motor produces about 50 kW to get the boat foilborne, helped by two counterrotating propellers with five blades forward and four blades aft. Under the cockpit sole is a 69-kWh Polestar automotive lithium-ion battery of nickel manganese cobalt (NMC) cell chemistry, cooled by glycol and capable of propelling the boat 57 nm at 22 knots in foiling mode. The C-8 specs specify a charge time of 6.5 hrs (0%–100%) using 11-kW AC, and 35 min (10%–80%) at 135 kW DC.

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The aftfoil and strut assembly shows the propulsion pod and two small counterrotating propellers, with five blades forward and four blades aft.

On the test ride, I saw Candela’s foils extend and retract with electric motors. The draft at rest varies from 18 (46mm) with foils up to 411 (1.5m) fully extended. Under way the boat draws 211 (0.9m) when planing and 27 (0.8m) in foiling mode. When it was safe, De Mattia put the throttle down, and the C-8 with three adults on board popped out of the water and went about its foiling business. But our ride was short and the water was flat, so there was no chance to see the C-8’s behavior in a seaway. In a collision, the foils would shear off at an engineered breaking point.

The passenger-carrying P-12 catamaran is a different product for a different market, but at 394 it shares vital elements with the C-8. It is much smaller than the 79′ foil-assist ferry proposed by Green City Ferries for New York, and it retains the C-8’s foil configuration with twin electric pod motors mounted on the aft foils. But these larger C-Pod Max models produce 340-kW combined peak power to get the vessel foilborne at around 16 knots with a payload of 30 passengers. Candela did not disclose the size, kind, or make of the batteries powering the P-12.

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Technicians guide a liquid-cooled Polestar 2 69-kWh battery assembly into place as a crane lowers it into the hull under the cockpit of a Candela C-8.

With an extendable automatic bow ramp that adjusts to quay heights from 0.2m to 2m (8 to 66), the P-12 is a modern waterbus, capable of traveling at 30 knots while eliminating tailpipe emissions, spray, wake, and most vessel motions when in full-foiling mode. Theoretically that means the no-wake zones with speed limits to slow conventional boats can be transited at higher speeds, provided that lawmakers grant exemptions (Candela says it secured such from the City of Stockholm). But even without them, the company argues, fast waterborne transit can significantly cut commute times compared to conventional ferries, land-based public transit, and personal cars, while alleviating road congestion.

Candela calls the P-12 a “sustainable profit machine,” and a “game-changer in terms of operational costs,” which if true would appeal to cash-strapped operators of public transport services looking to reduce personnel and maintenance costs. With submerged electric motors that don’t require regular oil changes, fuel polishing, or transmission service, the simplified routine and preventative maintenance supposedly helps reduce downtime. In Candela’s marketing pitch, a fleet of small P-12s could conceivably replace large diesel or electric ferries on certain routes, offering passengers more frequent service and shorter wait times. “Usually, electric ships are slow [and] lacking range, while being very expensive to operate, as they require huge investments in infrastructure like dock charging,” the company said. Also, in theory Candela’s P-12 could run with only one operator without crew, further reducing cost.

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Passengers leave a docked P-12 via a fold-down ramp at a stop along the route in the Stockholm archipelago.

“Since it will be serial-produced, we can sell it at a competitive purchasing price of €1.7 million,” the company stated. While that clearly appeals to purchasing managers of large public transportation agencies, the boat must comply with the Jones Act to transport passengers for hire in the U.S., meaning its keel has to be laid here.

But for now, Candela’s focus is squarely on Sweden, where the latest model seems a welcome addition to local transit infrastructures. “We’ve begun serial production of the P-12 at our Stockholm factory to meet increasing global demand,” a press release quotes CEO Hasselskog. “The second P-12 vessel, set to join Stockholm’s public transport system by 2024, will ferry citizens between the island suburb of Ekerö and the city center.”

—Dieter Loibner