Combining an ultra lightweight hull with a huge solar roof, the all electric ZEN50 catamaran uses an automated wingsail to extend its range without requiring the use of any fossil fuels.
The OceanWings OWS 3.2 fully automated semi-rigid wingsail has been designed and built by Ayro, a spin-off of the world class yacht designer and naval architects VPLP. Their technology first caused a stir when the wingsail-equipped USA 17 Oracle brought home the 2010 America’s Cup for Larry Ellison’s Team Oracle.
Airplane wing turned upright
A wingsail is essentially an aircraft wing turned upright that provides horizontal ‘lift’ (instead of vertical) to assist a boat being on tack. The automation is achieved through sophisticated software that monitors and analyzes wind and water conditions and adjusts the angle of the wingsail for optimum efficiency.
VPLP has continued to develop and automate it over the years, and it was installed on the Energy Observer hydrogen research vessel in 2019. Two years of feedback from more than 20,000 km of sailing around the world have enabled the Ayro team to fine tune the algorithm commanding the wingsail.
While it all may sound a bit complicated, the automation of the wingsail actually makes sailing a little simpler. It is controlled at the touch of a finger from screens in the helm station and the two parts of the wingsail – one rigid and one flexible – can be hoisted and lowered independently with the simple touch of a button.
Julien Mélot, creator of the ZEN50, says “For those who want to undertake ocean passages with zero emissions and no particular knowledge of traditional sailing, the ZEN50 equipped with the OceanWings 3.2 is the perfect vessel.”
Electric propulsion – in particular zero emission propulsion – has been Mélot’s passion since he graduated from the University of Lisbon in 2010 with a Masters in Naval Architecture to go along with his degrees in Mechanical and Electrical Engineering.
In 2016 he took a ‘jukung‘ – a traditional Indonesian outrigger – fitted it up with solar panels and built an electric 10kW outboard to propel it, using an old Yamaha 2 stroke as the base. He and a crew of 3 took the boat on a 2,000km voyage across the Indonesian archipelago without burning a single drop of fuel. They even used its battery as a temporary power station for one village they visited. And that electric outboard is still in use today.
In 2020 he designed and built the Aquanima solar electric catamaran, which took home the first Gustave Trouvé Electric Boat Awards in the Over 8 metre category. This is some of the background that led him to join ZEN Yachts as CEO and to design the ZEN50. The name is an acronym for Zero Emission Nautic.
Low energy consumption, large solar roof
Mélot says “I know from experience that to achieve complete energy self-sufficiency, a true solar boat needs to have a low energy consumption and a large solar roof area to harvest the solar energy. The ZEN 50 excels in both with her gigantic solar roof and her high performance lightweight hulls.”
Those hulls are made of light composite material like Carbon fibre and CorecellTM . In order to ensure minimal drag, the catamaran’s hydrodynamic performance was optimized through an in-depth Computational Fluid Dynamics analysis.
Combining that light weight and hydrodynamic efficiency with a solar roof that provides 17kWp (17 kiloWatts peak) electricity gives the ZEN50 a solar power to displacement ratio of 1 to 1 (17 kW / 17 tonnes) which allows the yacht to be completely self-sufficient in terms of energy.
“We wanted the ZEN to be a true solar boat,” says Mélot. “That’s why the first unit in construction is not equipped with any generator and will not carry a single drop of fossil fuel onboard.” He notes that a electric tender can also be recharged by the mother vessel.
In order for most large electric boats, including solar electric catamarans, to provide the combination of speed and range that their clients want, they need to have a diesel generator on board.
For day trips and short coastal cruises the electric alone gives them the noise and fume-free relaxation they are looking for. If they need to go fast for any length of time, though, the batteries deplete and if the boat is not near land the generator needs to kick in. The diesel doesn’t actually power any motors, it charges the battery to power the electric motors. In this type of hybrid usage the genset is a range extender.
Range of 180 nautical miles over 24 hours
That is one of the roles the OceanWings play on the ZEN50. Mélot says “Our clients are very eco-conscioius and have already implemented this philosophy in many aspects of their lives, including their homes and cars. On the ZEN50 the wingsail acts as a totally carbon free and zero emission range and speed extender.”
The two 50kW motors of the ZEN50 are powered by a 160 kiloWatt hour battery and solar panels, and with the wingsails she can reach speeds up to 14 knots and sail continuously at speeds varying between 6 and 10 knots. Over 24 hours that can add up to a range of 180 nautical miles. Zero emissions, zero fuel costs.
The focus on efficiency is combined with plenty of creature comfort. The length of 50 feet (15.7m) and a beam of 27 feet (8.4m) provides space not only for lots of solar panels, but lots of living space. The flybridge, for instance, measures 34m2 (365 ft) – the same kind of space you would find on an 80’ motoryacht.
A wide range of interior layouts are offered and include different cockpit configuration, charter and owner cabin versions, wet outdoor galleys and head. Depending on the configuration there can be 2 large day beds, up to 3 dining areas for over 10 people, 1 professional galley and 2 wet kitchens, 5 heads, up to 4 double ensuite cabins, 1 bunk double and 1 single together with both saloon and dining areas converting into extra sleeping areas.
As the first production yacht to incorporate wingsails, the ZEN50 brings a whole new dynamic to solar electric boating. “Our customers are looking for a yacht that allows them to enjoy the experience of being on the water and reconnecting with the elements. Now those who dream of sailing the oceans with their families can do so without leaving a carbon footprint.”
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|15.7 m / 50 ft
|8.4 m / 27 ft
|1.3 m / 4.3 ft (including keel)
|2 x 50 kW
|160kWh (5kWh backup)
|Solar Only: 4.5 – 5 kn
|Solar and Wing: 6 – 10kn
|Over 24 hours: 180Nm