ISSUE 011 Autumn 2021 Candela C-7 hydrofoil speedboat dossier l In conversation: Robert Hoevers l Battery recycling focus l Vehicle dynamics insight l ZeroAvia hydrogen-electric aircraft digest l Motor materials

outer skin is just 2 mm thick,” Philippot explains. “Their engineers know from impact tests that this arrangement works, and we know that having a similar system is key for minimising weight while maintaining safety. “Most speedboats opt for a sandwich-type outer skin instead, but not only is that too heavy for the C-7, it also isn’t strong enough to help with distributing the loads that concentrate around the three ‘legs’ of the boat.” To simulate the load distributions, CAD and FEA were used extensively to closely predict the behaviour of the carbon composite, although as mentioned, a lot of real-world tests were needed to get the foil to twist without breaking or being too pliable. Future plans The C-7 is now the best-selling premium electric boat in Europe, thanks in no small part to its foiling-based powertrain that offers its owners 95-97% lower operating costs compared with a traditional diesel- or gasoline-powered speedboat. From a commercial perspective, such low operating costs, and the greater profitability they could bring, naturally appeal to maritime fleet operators. To that end, in addition to expanding its production of C-7s, Candela is growing its portfolio to develop and produce larger boats for use as water taxis and commuter ferries – an immense market across not only Northern Europe, but also the Gulf States, East Asia and realistically any coastal city with large waterways. At the time of writing, the P-12 water taxi (see sidebar on page 29) had been officially unveiled, and will be delivered to its first customers soon. This 8.5 m-long vessel carries up to 12 passengers (hence its name) and consumes 1 kWh/nautical mile, which the company estimates is a twelfth of the energy consumption of standard IC-engined water taxis. The P-30 (see sidebar on page 29) is still in development. Its dimensions are less clear – a 30-passenger initial version is the target – but the concept is scalable up to 300 passengers. In addition to a top speed of 30 knots and a cruise of 20-plus knots, with minimal wake disturbances for other ships and 95% less g-force disturbance, Candela sees it as a game-changer for waterborne commuting and urban transport in general. “Waterways these days are mostly seen as obstacles that have to be overcome: you build a bridge over them, or a tunnel under them,” Mahlberg says. “What if we could use them for low-cost, high-speed electric transport instead? In many cities, waterways offer excellent cross-traffic connections but are mostly unused.” Data gathered on these new vessels and the new electric components they use can be expected to inform the engineering on future versions of the C-7 and other Candela vessels. Speci ications C 7 Hydrofoiling speedboat Battery-electric powertrain Hull: carbon composite Power source: 400 V lithium-NMC battery, 40 kWh Dimensions: 7.7 x 2.4 m Maximum draft: 1.5 m Weight: 1300 kg Maximum speed: 30 knots Cruising speed: 22 knots Maximum power: 55 kW Maximum range between charges: 50 nautical miles at 22 knots; 8 nautical miles at 5 knots in ‘limp-home mode’ Maximumwave handling: 1.2 m The P-30 is the largest of Candela’s planned vessels; its design will be scalable for carrying up to 300 passengers at a top speed of 30 knots while foiling 30 Autumn 2021 | E-Mobility Engineering Dossier | Candela C 7 speedboat