One of Denmark’s best known sailing yacht manufacturers has launched their first electric propulsion X-Yacht, a 49 foot, 12 ton X4⁹E equipped with two 10kW electric saildrives from Oceanvolt.
“I’m really happy to say that the time is right to present the first X-Yacht with electric propulsion,” said Kræn Nielsen, CEO of X-Yachts. ”A new range of electric powered sailboats is a natural step for us in order to support a greener future, a nice match with other initiatives, such as being the main sponsor of the Race For Oceans Foundation.”
This first electric propulsion X-Yacht has been built for John Haurum, who is looking forward to using it for ocean cruising, but also appreciates the high performance aspects of the X-Yachts brand, and is sailing the new X4⁹E, now named ‘Flux‘, in the Garmin Round Denmark Race. He also hopes to enter the ARC cross Atlantic rally for cruisers.
Electric propulsion X-Yacht: cruising and speed
“When I met X-Yachts and shared my ideas,” says John, “They immediately committed to the project and shared a common interest in merging innovation, sailing pleasure and a greener future.”
Andras Ørbæk Olesen, Sales Manager of the electric propulson X-Yacht, was also excited. “When I first met John and he told me about his thoughts of having a new boat with electric propulsion, I instantly felt his interest and passion in this eco-friendly system. To John, it was way more than just a product and a new boat – it was a passion for a new future with sustainable energy combined with his passion for sailing.”
Twin motors with ServoProp regeneration
The X4⁹E is a specially adapted version of the existing X4⁹ and considerable development went into the new model. There was close cooperation not only between client and shipyard, but also between X-Yachts and Oceanvolt, engaged because of their long experience in electric motors for sailboats and leadership in regeneration technology. Their website has a page showing their technology is now standard equipment on dozens of monohulls, multihulls and motorboats.
X-Yachts Technical Director John Morsing and his team consulted with the Oceanvolt experts and they decided on two ServoProp SD10 engine pods, each 10 kW and together backed by a 28.8 kWh LiFePO4 (Lithium Iron Phosphate) battery pack. Twinning the 10kW doubles the power – together they can provide about the same power as a 30-40 HP diesel engine – and also provides higher safety through redundancy.
The motors run on 48V, and are mounted on each side of the traditional engine compartment, below the aft cabin bunks. The design team reconfigured the former diesel compartment, which “still has the nice aluminum finish on all sides, but with the noise insulation excluded – it is not needed anymore.”
The ServoProp designation of the motors (SD is SailDrive) indicates they are fitted with Oceanvolt’s award winning ServoProp variable pitch propellers, which work to maximize the capabilities of the Oceanvolt regenerative system.
For sailing boats regeneration (sometimes called hydroregeneration) is one of the major advantages of electrical propulsion over diesel. When driven by the electric motor, energy from the battery is consumed much like a combustion engine consumes diesel. But when sailing under wind power, the rotation of the propellers due to water movement is used to generate electricity and recharge the battery.
8 hours of sailing charges batteries
The X4⁹E can produce up to 3.5 kW when sailing at speeds over 8 knots. This means that sailing for about eight hours will charge the batteries from empty to full. John Morsing adds that “As a side note, this ‘full tank’ is 100% green and free of cost!”
Because the X4⁹E is designed for long distance cruising, it also has an auxiliary 11 kW Fischer Panda diesel generator when long range is required but the wind is not cooperating. Range with pure electric power depends a lot on boat speed, wind and sea state, but a conservative estimate in calm conditions is 22.7 nautical miles at 5 knots.
To give some idea of what kind of range to expect from the electric propulsion X-Yacht, Oceanvolt has provided these use cases (assumption of conditions for all examples is no wind / no waves).
CASE 1: Full or almost full battery bank, need to travel for long distance under power.
- Generator delivers all power (11 kW) to the two ServoProps, i.e they are run at 5,5kW each.
- Boat can travel at 6.7 knots
- Fuel consumption of the generator will be 3.8 litres per hour: 1.7 NM per litre of fuel consumed
- X4⁹E can continue with this setup until diesel in tank is consumed
CASE 2: Need to recharge battery bank while under generator power.
- Power of ServoProps must be decreased to a level lower than 5,5kW each, e.g. to 4kW.
- Generator delivers 11kW: 8kW for the ServoProps, and 3kW for recharging battery.
- Boat speed will be reduced to 6 knots
- Fuel consumption remains 3.8 litres per hour.
- After 10-12 hours max. battery bank is fully recharged, X4⁹E can continue as in Case 1
CASE 3: 15 NM miles to destination. Battery bank 80% full, crew would like to travel as fast as possible to destination under engine.
- With both ServoProps working full power of 2 x 10 kW, boat will sail at 7.8 knots. It will therefore take approx. 2 hours to reach the destination.
- Battery bank is 80% full – not enough to supply the ServoProps all the way to the destination.
- Generator must be started.
- Generator will deliver 11kW to ServoProps, battery bank will deliver the remaining 9kW
- Boat will be brought to the destination under full power.
‘Another great success‘
The X4⁹E is also equipped with solar panels, which are largely used to provide electricity for the boat’s ‘hotel load’: lights, navigation systems, appliances, etc. For those who are not planning blue water cruising the boat is also available as an all-electric model without any diesel generation.
John Morsing said “Finding the right project for our first X-Yacht with electric propulsion was crucial. John Haurum knows our boats well and has a strong passion for green, silent boating”.
For his part, the proud new owner says “Sailing is all about harnessing the wind for energy and pleasure, and committing to an electric saildrive is a mindset and perhaps a changed way of life at sea. X-Yachts and Oceanvolt have taken this mindset to the next level, and when looking back at the heritage and innovation of X-Yachts – I’m sure that this will be another great success.”