I’m on a boat. The boat does not float. At least not in the traditional sense. The manufacturer says somewhat enthusiastically that “it flies.” In reality it hovers two feet above the water, propped up on stilts attached to two horizontal carbon-fiber fins—hydrofoils—that slice through the waves, raising the hull clean out of the sea. Underwater, a torpedo-shaped, battery-powered propeller mounted along the rear foil thrusts all 1.6 metric tons of the Candela C-8 forward.
The boat is out on the San Francisco Bay, zipping around in the sweet spot between two iconic Bay Area tourist destinations: the Golden Gate Bridge and Alcatraz Island. It is a sunny and balmy day, a fluke of Mediterranean conditions that’s out of character from the area’s typical vicious February chill.
The all-electric C-8 is a luxury watercraft engineered by Swedish maritime manufacturer Candela, but the battery is made by the EV company Polestar—a subsidiary of Geely, the Chinese conglomerate that also owns Volvo. While Polestar has focused the bulk of its efforts on land vehicles, it has partnered with Candela to give the C-8 its juice box. And it is the very same one—the boat uses the 69-kWh battery pack found in the Polestar 2. Volvo has a long history of making marine engines, but this is the first time its EV sister brand has got its feet wet.
The C-Pod, a dual-motor cigar-shaped drive unit with contra-rotating propellers that’s been redesigned from the previous C-7 for more efficiency, launches the C-8 into a very different kind of boating experience, and is the key to the C-8’s abilities.
With Great Power Comes Great Efficiency
One of the main challenges with direct drive electric motors is that the motor is spinning at the same speed as the propeller. Electric machines are typically most efficient at higher speeds, whereas propellers are most efficient at lower speeds. So Candela designed a drive unit that, instead of having one big motor and one big propeller delivering the torque needed, split the torque into two motors and two propellers. This means the size of both the motors and props could be reduced. A boon for a smaller propeller is the tip speed is reduced for the same rotational speed. That in turn means the C-8’s twin props can stay below the limit of cavitation (the cause of reduced performance, blade damage, vibration, and noise) even with a high rotational speed.
Not stopping there, Candela also created a passive cooling system for the C-Pod using just the cold seawater on the outer surface of the housing—thus no need for rotating parts in the cooling system and no cooling fluids. Simpler, effective, and less to go wrong.
Such efficiency and innovative mechanics naturally drives performance. When the boat gets up to about 16 knots (that’s 18 mph for you landlubbers), it takes off, the bulk of it lifting out of the water, supported by the hydrofoils underneath. The vessel levels out, and you’re skimming above the waves, leaving barely a wisp of a wake behind. And with more of the boat out of the water, the less drag there is. The result feels more like a hovercraft than a traditional boat.
Last year, Candela made waves (sorry, but I’m obligated to go overboard with the nautical puns here) when it announced a similar “flying” ferry that would shepherd passengers along their commutes in Stockholm. That pilot program is scheduled to set sail sometime later this year. In the meantime, Candela is in the process of launching its much zippier recreational watercraft. Candela showed off the C-8 at CES back in January and is manufacturing its first batch of orders. It says it plans to ship them in the next few weeks.
The C-8 is 28 feet long (8.5 meters) and weighs 1,750 kilograms, or roughly 3,900 pounds. Nearly the entire structure—from the vacuum-infused hull to the chairs—is built out of carbon fiber to allow the weight to be significantly less than similar boats.
It seats eight people, but maybe five or so comfortably if you don’t like being packed shoulder to shoulder. A Tesla-esque touchscreen panel is embedded in the console just above the steering wheel, providing navigation guidance, a speedometer, and various lighting and engine controls. A small forward staircase lets you access the bow of the boat. It also doubles as a trapdoor, the whole unit swinging upward to reveal a hatch underneath. Below deck is a cabin complete with beds, lights, and a toilet smack dab in the middle. Candela says the cabin can sleep two adults and two children, but you’d all really have to like each other.
High-End, High Testosterone
The C-8 is very much a luxury vessel. It costs $390,000, and has frequently been lazily called a Tesla of the sea. The clientele, so far, is probably whom you’d expect: everyone from wealthy male Tesla owners to wealthy male entrepreneurs. So far, Candela has sold roughly 150 of its C-8 powerboats. Of those customers, only two have been women.
My demo on the Bay lasts for a couple hours. Tanguy de Lamotte, Candela’s US CEO, captains the helm for most of it. He drives in smooth, flowing arcs across the water, carefully lining us up so photographers can snap striking shots and drone footage with San Francisco landmarks in the background. Eventually, I drive the C-8 for maybe 15 minutes or so. Overall, it’s a breeze to pilot (admittedly, I am testing it on a calm day, so the choppiness is already minimal). Push forward on a lever to adjust the throttle and steer with a small wheel at the helm. The C-8’s top speed is capped at 30 knots (35 mph).
Candela claims the battery can go an impressive 57 nautical miles (66 miles) at 22 knots on a single charge, so European jaunts from Monaco to Saint-Tropez—or, back in California, Marina Del Ray to Avalon on Santa Catalina Island—are potentially on the cards … if you’re on your own, that is. Load up to the full 8 passengers and that drops to 48 nautical miles (55 miles). Once you’ve drained the power, just like the Polestar car, the boat’s 69-kWh battery can be charged from 10 to 80 percent in 45 minutes.
Surprise, surprise, the high-end C-8 feels very nice to drive. It also feels curiously un-boatlike, at least for anyone accustomed to the longstanding seafaring tradition that is having your knees buckle every time the boat slams against a wave. By contrast, the C-8 is borderline buttery when in “flight” mode. The hydrofoils position the boat above the majority of waves, and the carbon stilts are slim enough to scythe through the water like tiny dolphins. Behind the scenes, Candela’s internal computer, the (sigh) Flight Controller, uses avionic sensors, like those that track position on an aircraft, to constantly adjust to the propulsion, gyroscope, and angle of the hydrofoils to keep the boat balanced. When turning or hitting a particularly large wave, the system impressively counterbalances to keep the deck level and the ride smooth.
I ask what happens if you jackknife the boat and make the most jarring, sharpest turn possible. De Lamotte says the system will simply slow the boat down to correct and stay stable. I don’t get a chance to test this out, however, or the results of any other precarious maneuvers—partly because de Lamotte asks me not to, and partly because we also have two photographers onboard, and I’d rather not kill my colleagues.
The one time we encounter any real chop is when de Lamotte steers through another boat’s wake. Speeding propellers churn up the water with innumerable little air bubbles and create what’s known as prop wash. When the C-8 hits the swirling wake behind them, it crashes down from its perch onto the sea. It’s not a painful landing, just a sudden transition into “regular boat” mode. As soon as we get back up to speed, the hydrofoil physics do their job and the boat takes off again.
One of the C-8’s other party tricks is that it does indeed have a “regular boat” mode. The foils are retractable, transforming the craft into a standard electric boat, albeit with reduced range. In this function, ideal for shallow waters or in extreme weather, the foils and C-Pod are protected by the hull.
In a way, the smoothness of the C-8’s ride belies the speed at which you’re traveling, making the journey feel almost weirdly plodding. Perhaps I’m just accustomed to the casual danger that comes with normal cool guy speedboating. That said, the tradeoff from white-knuckle adrenaline does make it ideal for those who are prone to seasickness. When the C-8 is cruising past 16 knots, there’s barely any of the stomach churning associated with your usual means of aquatic conveyance. When the boat has slowed or stopped, however, it does sit back down in the water, beholden to the same pitching and rolling of the waves as any other buoyant object out there.
But it’s not all smooth sailing. The screen at the helm, for instance, isn’t working right. As soon as we set out and boost the throttle up to “takeoff” speed, the screen glitches out, flashes a red-lettered “Flight controller error” message, then crashes to black. It only switches back on when the boat stops. This is hardly ideal, but the Candela reps insist the C-8’s software is still able to calculate everything in the background to keep us afloat. At no point do we crash or explode, so thankfully there’s probably something to that.
Speed, Range, Silence
The silent hero of the whole trip, however, is the electric motor hidden beneath a cover in the back. I say “silent” because a major benefit of this power system is that it’s much quieter than the grating gurgle of a diesel-powered boat. I can actually hold a conversation while we hurtle ahead at full speed. At least when the wind isn’t whipping my hair into my mouth.
Candela is eager to flaunt its environmental chops. An electric motor, in theory, causes less havoc than a diesel-powered one. No direct consumption of fossil fuels, no leaking various engine goop into the water below. The act of hydrofoiling over the water also aims to reduce energy use, as there’s less drag from all that water on the bow. Candela claims energy consumption is cut by 80 percent compared to a normal, gas-powered boat of the same size.
An electric hydrofoil boat—like an electric car—is likely cleaner than its gas-guzzling predecessors, but splurging nearly $400,000 on one isn’t exactly an act of environmental responsibility open to all. The boat is a blast. But chances are that the C-8 is not going to make any real dent in the climate crisis, no matter how good it might make the wealthy people who buy it feel about themselves.
Recreational boats will not have the environmental impact land vehicles do, but companies are still eager to electrify people’s transit. Candela is just one company among many in the rising tide of electric boats. Other upcoming e-boats include the splashy ArcOne, and hydrofoil-equipped options like the Artemis, as well as the retro-futuresque Seabubble. The C-8 isn’t even necessarily the most ostentatious of them. And the boat is selling—soon to be out on, or above, a wave near you.