August 2021

44 n TRANSPORTATION July/August 2021 www.drivesncontrols.com Electric speedboat foils rivals in Monaco race A n electrically powered speedboat that rides above the surface of the water on computer-controlled hydrofoils has won the world’s biggest competition for electric and new energy boats, which took place in Monaco last month. The C-7 craft, developed and built by a Swedish firm called Candela, averaged a speed of more than 27 knots (50km/h), despite rough weather and big waves, and crossed the finishing line in the 1/8 nautical mile race at more than 31 knots (57km/h), beating 14 other e-boats including conventional-hulled electric powerboats with motors that were ten times more powerful. The C-7 is the first hydrofoiling electric boat in serial production and is claimed to have become the best-selling premium electric boat in Europe since its introduction in 2019. The 7.6m-long vessel needs only 25hp (18.6kW) to cruise at a speed of 20 knots (37km/h). Its maximum consumption is 87hp (65kW) during take-off and it is claimed to use 80% less energy than conventional boats. Conventional planing powerboats of the same size suffer from high hydrodynamic drag, and usually need motors rated at several hundred horsepower to reach high speeds. Candela's communications manager Mikael Mahlberg says that the e-boat has more in common with an aircraft than a boat. The control system resembles that of a modern jet fighter. “As a driver, you just steer and control the speed, everything else is handled by the computer,” he says. “And, by flying above the water, you also get a smoother ride in choppy weather.”Waves of up to 1.2m high simply pass under the hull. The on-board computer adjusts the hydrofoil automatically 100 times per second to compensate for crosswinds, waves and varying loads. Using inputs from several sensors – including two ultrasonic sensors in the bow that measure wave heights, and others that gauge roll and pitch – the controller computes the foil’s optimum angle of attack to ensure a smooth ride. The boat rides on two underwater wings made from carbon composites. Its drag is half that of conventional vessels and, at speeds above 20 knots, its energy consumption is 80% less than that of a traditional 8m-long petrol-powered boat. Candela claims that the C-7 is 95% cheaper to run than a petrol-powered boat. A full charge costs €5-7, compared to the €200 of fuel that a comparable fossil fuel boat would need to achieve a similar range. At its top speed of 30 knots, the C-7 has a range of 32 nautical miles. At 20 knots, the range extends to 50 nautical miles and the boat can travel for more than two hours on a single charge. The boat is powered by a custom- designed electric motor that is rated at 65kW for take-off, and 37kW when operating at full speed, but can drop to 16kW when travelling at 23 knots. The boat can carry a load of 700kg in addition to its driver. It is powered by a 40kWh lithium-ion battery – the same one that BMW uses in its i3 electric cars. The foils can be retracted for storage or when entering shallow ports. Candela is planning to enlarge its family of hydrofoil boats. Next year, it will launch an electric ferry in the city of Stockholm, as well as a 12-passenger taxi, called the P-12, which has a range of 45 nautical miles at 20 knots. It believes that such vessels could be particularly useful for locations such as Venice, where it would reduce air pollution and the damage to the ancient buildings caused by the wakes of conventional water taxis and tourist boats. The 12m-long P-30 ferry to be operated in Stockholm will cost half as much to run as the city’s existing fleet of 60 diesel ferries, many of which are more than 50 years old. It will carry up to 30 passengers, cruising for three hours at 20 knots and, because it produces little wake, it will be able to operate faster in city centres where conventional vessels need to slow down. The ferry will be powered by two 60kW pod drives and a 180kWh lithium-ion battery. Its top speed will be 30 knots. n An electric speedboat that lifts out of the water on hydrofoils beat conventional vessels with much larger motors in the world’s biggest competition for e-boats which took place in Monaco last month. Electric hydrofoil taxis could reduce pollution levels in Venice as well as damage to the city’s medieval buildings Candela’s electric hydrofoil craft beat off more than a dozen rivals – some of them much more powerful – to win an e-boat race in Monaco last month