Solar expeditions with the ZEN50 catamaran

by | 3rd July 2023 | Ship & Boat International, Technology

Home News Solar expeditions with the ZEN50 catamaran
With its wingsail activated, the electric motor-powered ZEN50 should achieve top speeds of 14knots+

With its wingsail activated, the electric motor-powered ZEN50 should achieve top speeds of 14knots+

With 17kW of peak solar power at its disposal, and a wingsail designed for optimal wind capture, the new ZEN50 catamaran series is set to bypass the need for the ‘obligatory’ backup diesel genset

The forecast’s for sunshine for builder ZEN Yachts, which has confirmed the pre-sale of the first four units in its solar-powered, ocean-going ZEN50 catamaran class. Currently under build at one of ZEN Yachts’ facilities in the south of Spain, and set to run 100% on renewably sourced electric power – with no fall-back diesel genset in sight – the first two ZEN50 deliveries are scheduled for delivery in Q1 and Q2 2024.

“The balance of energy ins and outs on the ZEN50 is designed so the yacht doesn’t need to be equipped with a genset to operate: hence she is the first yacht of her kind that does not carry any fossil fuels onboard,” ZEN Yachts tells Ship & Boat International. Instead, the expedition yacht’s powertrain, centred around a 160kWh battery bank, has been designed to “function safely for days, even with minimal solar energy harvest and no wind”, the builder continues. And, naturally, this set-up will produce no harmful, polluting emissions.

The ZEN50 was designed by naval architect Julien Mélot, who comments: “[ZEN50] is completely self-sufficient, relying only on sustainable sources of energy.” It’s a good fit, given ZEN Yachts’ stated goal of “accelerating the transition to zero-emission yachting for the entire industry”. Additionally, the company hopes the first ZEN50 units will help to persuade the yachting community that “creating lasting memories on the water without damaging the environment is indeed possible – and can be very comfortable and safe”.

ZEN Yachts recently received €5.5 million (US$5.98 million) of funding from eco-conscious investor Ocean Zero, which was set up to financially support companies attempting to tackle CO2 and other emissions across the maritime sector, whether related to recreational craft or sea-going ships. Ocean Zero has raised the fact that shipping is currently deemed to be a bigger annual producer of atmospheric CO2 than the airline industry.

Solar roof

The ZEN50 has an overall length of 15.7m, a maximum breadth of 8.4m, a moulded depth of 2.7m and a draught of 1.3m, including the keel. A mixture of carbon fibre and Corecell was selected for the cat’s performance-type hulls, to help reduce overall weight: the boat is expected to displace 17tonnes in lightship mode. ZEN Yachts adds: “The vessels’ reverse bows cut through water like a sword cuts through butter: their curvature is reminiscent of graceful dolphin bodies.” The solar roof area occupies more than 50m2 and has an air draught of 5.3m. This area houses the photovoltaic panel spread, featuring a peak power rating of 17kWp, which charges the boat’s lithium iron phosphate (LFP) batteries. In turn, the batteries drive a pair of 50kW brushless DC electric motors. The ZEN50 also has a back-up battery capacity of 5kWh. Given the vessel’s lightweight displacement and solar power, ZEN Yachts states: “The ratio of the ZEN50 is at 1kW per displaced tonne of water, or 1:1, which is far beyond any other blue water CE Cat A yacht in this size range.” It will also be possible to convert the solar roof area into an upper deck.

The catamaran’s main deck spans more than 70m2, while the flybridge area covers 22m2 and is located at a height of 7.3m from the water surface. The bridge area, meanwhile, occupies 30m2, while the accommodation section (split port and starboard) covers another 22m2. The ZEN50 has been designed for a complement of 12 passengers and can be configured to feature up to four double ensuite cabins, and a double and single. Additionally, the saloon and three onboard dining areas can be converted into extra sleeping areas. Throw in five WCs, and “this is simply unrivalled on a 50’ catamaran”, ZEN Yachts comments.

The general arrangement of the ZEN50’s main deck

The general arrangement of the ZEN50’s main deck

Wingsail bonus

AYRO manufactured the ZEN50’s computer-operated OceanWings32 wingsail, which elevates the vessel’s overall air draught to 15.3m. The OceanWings32 model was originally developed for Oracle Team USA, which incorporated the sail aboard USA 17, winner of the 2010 America’s Cup in Valencia. According to ZEN Yachts, the ZEN50 is actually the first series-production leisure craft to be fitted with this particular wingsail.

The OceanWings32 is controlled via a touchscreen on the bridge. “The two parts of the wingsail can be hoisted and lowered independently and with the simple touch of a button,” ZEN Yachts says. The ZEN50 can be ordered without the sail, though it should prove a good range/speed extender for those who want more of a ‘racing’-style experience.

Having undertaken a performance study with French naval architecture firm VPLP Design, ZEN Yachts has calculated that the cat should be able to achieve maximum speeds of 14knots and upwards on the e-motors and OceanWings combined. Running on e-motors alone, a top speed of 10knots is more likely.

When it comes to cruising speed, the ZEN50 should comfortably retain between 4.5-5knots when running solely on solar. Add wind power, captured through the OceanWings, and a speed of anywhere between 6-9knots is achievable. In daytime conditions, with the sun up, cruising speeds of 8-10knots are entirely feasible, the performance study indicated. Altogether, the ZEN50 has a range of more than 180nm over a 24-hour period.

The ZEN50 will also carry an electric tender, charged by the mother vessel, for those guests who wish to explore more restricted and shallow waters.

The 15.7m boat is hoped to “accelerate the transition to zero-emission yachting for the entire industry”, says ZEN Yachts

The 15.7m boat is hoped to “accelerate the transition to zero-emission yachting for the entire industry”, says ZEN Yachts

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