Swedish electric boat maker Candela Speed Boat AB is launching its second-generation hydrofoiling leisure electric boat. Building on its first-generation C-7, the new C-8 boat is larger, more comfortable, and designed to bring electric boats to the wider market.

With the C-7, the company says it demonstrated that its hydrofoil technology not only allows for a long range on electricity but also provides a better experience than conventional boats—primarily in a smoother ride. However, the C-7 was more like a hand-built sports car, and it was never intended for volume production, said Gustav Hasselskog, Candela’s Founder and CEO. With the new C-8, the company is pushing the technology to the next level, focusing on greater comfort and designing it for efficient mass production.

Candela says its mission is to speed up the transition to fossil-fuel-free lakes and oceans. The company was founded in 2014 by Hasselskog, when inspired by the likes of Tesla, he was struck by how regular gasoline boats are “disastrously destructive” to the environment and unnecessarily expensive to operate. This insight sparked 5 years of R&D, during which his team cracked the formula behind the world’s first electric boat that can compete with fossil fuel boats in terms of speed and range. Among the top execs helping him steer the Candela ship are Hans Ahlinder, Chairman; Frederick van den Oudenalder, COO – Production & Service, Alexander Sifvert, CRO – Sales & Marketing; and Annie Fornelius, CFO.

With the C-7, Candela claims it put the world’s first electric hydrofoil boat in serial production. Combining long range, high speed, and a silent drivetrain, the company says it was the first electric boat that could outperform fossil-fuel powerboats. It is also developing the electric 30-person P-30 shuttle ferry and 12-person P-12 water taxi.

Boosted by large investments from the TED Foundation’s Chris Anderson among others, Candela has been able to scale up R&D at an exponential rate over the past two years.

 

Much cheaper to own

The C-8 features many of the amenities expected in a premium cruiser. The 8.5 m (27.9 ft) long boat with a 2.5 m (8.2 ft) beam has a large, comfortable cockpit with seating for eight people, a big sunbed, and a spacious front cabin equipped with beds for two adults, two kids, and a marine toilet. Total seating accommodation is for 6+2 people.

At €290,000 (excluding VAT), the C-8’s asking price is said to be on par or lower than many conventional, fossil-fuel powerboats in the 28- to 29-ft (8.5- to 8.8-m) range. However, once purchased, the company says that C-8 is virtually free to own and use. The cost of operating a C-8 is 95% lower than for combustion-engine boats, thanks to the company’s efficient hydrofoil powertrain.

Equipped with the new C-POD direct-drive pod motor, the C-8 requires neither oil changes nor regular maintenance. The motor is rated for 3000 h service-free use, which the company says is equivalent to 50-100 yr of recreational boating. When moored, the C-8’s hydrofoils can be retracted above the waterline, minimizing growth and the need for antifouling.

“It’s basically free boating, and hassle-free boating, for the first time in history,” said Hasselskog.

According to the company, the C-8’s new and improved hydrofoiling technology cuts energy consumption by 80% compared to conventional boats, allowing a long all-electric range even at high speeds. Combined with the C-POD drivetrain, the boat can cruise for longer distances than any electric powerboat before it—over 50 nautical miles on the lithium-ion battery pack’s 44-kW·h capacity at a speed of 22 knots. At that speed, it only draws 16 kW (21 hp) from the battery. (A conventional, planing, 28-ft cabin cruiser is typically equipped with a 300-hp (224-kW) gasoline outboard motor.) The charging time for the pack is 2 h with a three-phase source.

 

The silent C-POD

The C-8 is designed to be a totally silent motorboat. There’s no transmission noise and no sound from waves hitting the hull, enabled by the foil system. Only faint wind noise reminds riders that they’re cruising at 30 knots.

In other boats, the motor is typically in a box above the waterline, transferring thrust to the propeller through a complicated set of shafts, bearings, and gears. The C-POD gets rid of the gears, with two ultra-compact yet powerful electric motors mounted under the water in a torpedo-like enclosure, directly driving the propellers. Each motor is coupled directly to a propeller, the contra-rotating units adding to efficiency through minimized frictional losses.

To accomplish this, Candela’s engineers had to rethink electric motor design. Since electric motor volume is largely proportional to torque, they opted to increase the rpm and lower the torque to boost C-POD power density. The best way was to split the thrust needed with two propellers, which allowed for propellers with smaller diameters and thereby higher rpm—enabling the smaller motors.

“The engineering challenge was to make the electric motors compact enough,” explained Hasselskog. “Being submerged, they have to have a very small diameter in order to cause minimal drag.”

Placing the motors under the water elegantly solved the problem that all electric motors face: heat. Engineers designed the slim pod drive to be directly and efficiently cooled by the flow of seawater, enabling higher operating temperatures and extracting more power from the motors.

An added benefit is silence. The company says that gasoline outboards are some of the noisiest machines out there, with decibel levels climbing into the 90s as they near wide-open throttle; some noisy boats can hit 100 decibels, loud enough to damage the human ear. Even conventional electric outboards are not as quiet as they could be since the gears emit a whining sound at high speeds.

“Candela C-POD has no gears and is therefore totally quiet,” said Hasselskog. “No rattling, no squeaking, absolutely no noise, even at 30 knots.”

The C-POD will also be fitted to Candela’s P-30 electric shuttle ferry and P-12 water taxi. Developing 50 kW for take-off, a single motor has enough thrust to propel the P-12 at a speed of 30 knots. For the company’s bigger 30-person shuttle ferry, two C-POD’s will provide the same speed.

 

Elevated driving experience

Learnings from the C-7 were applied to the more efficient C-8 foil system. The company says that a typical planing boat has a lift to drag ratio of 4, a seagull is at 10, and an albatross with its long sleek wings is at 20. The C-7 reached 15, but with some re-thinking, the C-8 ended up at 17.

Take-off is where a foiling boat uses the most energy, so the Candela engineering team spent considerable effort on optimizing the C-8’s hull. Using advanced computational fluid dynamics, the boat’s stepped hull is designed to use very little energy from standstill until 16 knots, which is when the boat becomes foilborne. The maximum take-off load is 815 kg (1796 lb).

“I think we have pushed the hull performance as far as is possible,” said Hasselskog.

The boat’s “flight controller” automatically adjusts the foils to keep the boat level and steady on the move.

Candela developers put a lot of effort into understanding how to translate the feeling of a tight driving experience into mechanics, electronics, and software. To shorten the system’s reaction times, they developed their own height sensors. They’ve also taken out mechanical “play” in the entire system, so the boat reacts to steering-wheel inputs more quickly.

However, if the driver wants a more relaxed experience over long distances, in an industry-first for leisure boats the C-8 is equipped with fly-by-wire steering and has Autopilot-like features. When the driver lets go of the wheel, the boat will automatically steer a set compass course. More features will follow as the C-8 is upgradeable via over-the-air software updates like every Candela.

All of the C-8’s subsystems and software were developed in-house to make for seamless human-machine interactions. To do this, Candela employs more than 25 engineers from fields like mechanical engineering, control systems, machine learning, software, electronic engineering, and hydrodynamic design.

“Making an integrated user experience was really important for us,” said Hasselskog. “We don’t rely on third-party suppliers for software, and we make most hardware ourselves. This may be the iPhone moment for boats.”

All settings are controlled from the 15.4-in screen running Candela’s proprietary user interface. The Candela app lets the owner control the boat’s various systems from ashore.

 

High market expectations

Candela is expecting the C-8 to be the first electric boat that will outsell fossil-fuel competitors by a wide margin. The company believes this will be possible by combining a price that is on par with fossil fuel boats with the benefits of electric hydrofoiling—superior seakeeping, total silence, very low operating costs, zero maintenance, and a seamless user experience.

“We believe we will make several thousand Candela C-8’s over the coming years,” said Hasselskog. “Once you have tried it, you realize that this is the way boats must look like in the future.”

C-8 production starts this fall at the company’s Stockholm factory, with the first customers taking delivery during spring 2022.