FLY ELECTRIC
The extraordinary story behind the world’s first 100% electric foiling sportsboat
For something that looks as cool as the Candela Seven, it’s hard to believe that the starting point was a mathematical equation. But that’s exactly how it came about. In 2014 a crack team of boffins with experience ranging from fighter jet control technicians to America’s Cup hydrodynamicists, assembled in Stockholm to try and solve a seemingly intractable problem – how to create an all-electric boat with the range and performance to match a petrol one. The fact is that a 25ft sportsboat uses 15 times as much fuel as a family car, yet pound for pound even the most advanced battery holds 15 times less energy than petrol. To resolve these two conflicting issues, they had to find a way to drastically reduce the energy consumption of their proposed boat. The mathematical equation they devised looks as dense as a block of concrete but it worked and the result is the Candela Seven – a lightweight carbon-fibre sportsboat that uses active foils and computer-aided flying controls to skim above the waves.
Thanks to their efforts, this next generation foiling sportsboat uses a claimed 75% less energy than a conventional GRP planing sportsboat. To put that in perspective, the Candela Seven requires just 28hp to keep it flying along at 20 knots.
The foiling system accounts for a big part of that saving as it halves the hydrodynamic drag of a normal planing hull. The ultralight carbon fibre construction is responsible for another big chunk of it – even with its 240kg BMW i3 battery pack in situ, the Candela Seven weighs just 1,300kg or roughly half that of a Chris-craft 27 Corsair. The final piece of the jigsaw is the super efficient 55kw electric motor, which not only delivers maximum torque at zero rpm but also generates far less waste heat than an equivalent fossil-fuel engine.
FOILED AGAIN
The proof, as ever, is in the pudding and although we haven’t yet been able to test one ourselves, Candela has carried out extensive sea trials of its own both in Sweden and the Caribbean. Its figures claim a top speed of 30 knots and a real world cruising range of 50nm at 23 knots. Nor is the test boat a fancy one-off prototype, Candela has already delivered 12 finished Sevens to customers around the world, including a number of wealthy silicone valley tech entrepreneurs keen to show off their green credentials without sacrificing on style or functionality.
Candela claims there is no compromise to make in terms of the driving experience either. Quite the opposite, with almost no engine noise, no fumes, a minimal wake and an exceptionally
smooth ride, the Seven is said to be more like riding on a magic flying carpet than bouncing up and down on a planing sportsboat. That’s because with its foils extended, the hull rides 1.3m above the water, allowing all bar the tallest waves to pass harmlessly beneath it. Again, the Seven has been thoroughly sea-trialled in choppy seas and stiff winds to verify this.
Perhaps the most intriguing aspect of its design is the advanced flight control system that makes it all possible.
Much like a modern delta-wing fighter jet, the Candela
Seven is too dynamically unstable in flight to be controlled by conventional manual controls. Instead it relies on a powerful onboard computer linked to seven different sensors feeding information at a rate of 100 times a second to make continual small adjustments to the foils and maintain a stable flight. To achieve this, a pair of fast-acting electrically powered struts move independently fore and aft to twist the main carbon foil like the ailerons on a plane. All the helmsperson has to do is point the wheel in the direction they want to travel and apply the throttle, the computer takes care of the rest. This includes deploying the foils for take off and landing, managing the boat’s pitch, roll and ride height when in flight and scanning the waves immediately in front of the boat to adjust them all accordingly. It even heels the boat into turns like a normal v-shaped planing hull to reduce lateral G-force and give a more natural helming experience.
The foils themselves are flat wing-shaped blades rather than curved moustache-style foils and comprise a large central foil on a pair of vertical retracting struts and a smaller t-shaped foil integrated into the slender lower leg of the electric outdrive unit. This tilts up and down much like an elongated outboard engine to adjust its angle and reduce the draft in displacement mode. When fully retracted the main foil tucks in tight against the hull in a cutout that also acts as a step between the deep-vee forward section of the hull and the much flatter aft section. This enables it to draw just 0.5m in low draught displacement mode but also creates more ‘ground clearance’ at the stern once the boat is up and flying. In foiling mode it draws a modest 0.4m, ensuring that the foils and propeller stay submerged beneath the waves for a smoother more comfortable ride.
If this all sounds a little too good to be true, take a look at the video footage on our website (www.mby.com/can7) or Youtube channel
(www.youtube.com/ybwtv) to see the Candela Seven in action. Much of it is shot in quite rough, breezy conditions but the boat looks remarkably composed, skimming over the lumps and bumps and banking into turns like a motorbike on a race track. There is even footage of it towing a wakeboarder.
SEEING IS BELIEVING
A payload of up to 410kg means it can carry five passengers and one skipper, the limiting factor being the amount of power needed to lift the boat up onto its foils rather than any structural limitations of the foils. The 40kwh lithium-ion battery takes around 12 hours to charge using a standard 230V/16A cable and the boat comes fully equipped with a six speaker Bower and Wilkins stereo system and a choice of nine hull colours.
A 4G connection to a Cloud based app keeps the owner fully informed of charge states and geo-location even when not on board and provides remote access to the boat’s systems for Candela technicians and software updates.
Unsurprisingly all this technology comes at a price but even that isn’t as eye-watering as might be expected. The base price before tax is €245,000, which includes a 1 year service and support agreement. The only factory options are a customised trailer with a built-in electric winch (€8,000) and a full-length cover (€5,000). Factor in the reduced fuel and running costs – Candela claims a 95% saving – and it’s not hard to see how you can make a case for it, especially if you happen to be a silicone valley tech billionaire. Until then we are holding out for a sea trial of our own once the lockdown lifts, we promise to report back in more detail then.