I appear to have one of those brains that is permanently ‘on’, and as a result have had a long-term on-off relationship with insomnia. I’ve tried the lavender pillow, the warm milky drink, the ‘worry notebook’ by the bed, but never found the cure – until now. Last week, Silent Yachts, an Austrian company which manufactures the first (and only) ocean-going solar-electric production catamarans in the world, invited me onboard their 55 footer. Gliding noiselessly across the waves, this boat comes with a one-way ticket to slumberland – if, of course, there isn’t an interview with the Founder and CEO to be conducted.
“Silent Yachts comes from passion, and that’s the original meaning of the word passion, to suffer,” said aforementioned CEO Michael Köhler. “Over the years, myself and my wife Heike have owned many different types of boats and always found ourselves suffering with insufficient energy systems where the energy supply didn’t grow to meet demand. Nowadays, every kind of household appliance from fridge to TV, dishwasher to washing machine, is installed on a boat, but the power supply has largely remained the same. Any solutions have been either inefficient or plain stupid. Manufacturers install 100 horsepower engines to produce 300 or 500 watts of energy just to cool the butter in the fridge. This is crazy. On several occasions, we retro-fitted better energy systems to our boats and did the same for friends and clients. However, we were still unhappy as the propulsion systems were fuel-based. Ten years ago we built Silent Yachts hull number one. And, here we are 20 or so hulls later.”
Michael continues: “Most people crave a sunny rather than a windy holiday destination, so solar is our power source of choice. In theory, this yacht uses zero litres of fuel – the sun did its job this morning and filled the batteries. The result is a very cost-effective boat, but there are other benefits. Without an engine running, there are no vibrations, no noise and no fumes. Instead, you glide silently and connect with nature in the most respectful way.”
“Of course we also want to offer luxury, and this means a large American-style fridge freezer, a washing machine, dishwasher, induction hob, air conditioning, but we have installed everything in the most productive manner. The entire yacht is carefully insulated to reduce power demand for air conditioning, and there is a large roof overlap on the deckhouse to prevent too much sun flooding in the windows. Conventional salon windows can have a bit of a greenhouse effect and need a lot of interior cooling.”
“The last four days we’ve been cruising with clients a total of more than 16 hours each day, had all appliances on, cooked most meals, and used the generator just two hours – in total. A conventional yacht would have had the generator running with greater frequency to keep the air conditioning and water maker operational, not to mention the financial and environmental cost of 300 to 400 litres of fuel. To illustrate the point, we moored alongside a catamaran a few nights ago and they had the generator running at anchor all evening to stop their beer going warm. It’s certain they would have to head to a marina to top up with shore power and fresh water, whereas we can just go from bay to bay. No marina required – ‘just add water’.”
But what happens when the sun goes in? “It’s true that the solar panels don’t work at night, neither do they operate at their best in very heavy cloud cover,” explained Michael, “but the batteries do a great job of storing that energy. These batteries have a capacity of 210kWh and, right now, we’re consuming 10kW, so we could do 21 hours at this speed without topping up and without having to run the generator. Our top speed is 18 knots, but you would only want to do that for a short period of time as it would rapidly drain the batteries.”
“There is ‘electric boat’ competition out there, but very little, and it tends to be of the hybrid variety with limited range at very slow speeds. Most are monohulls and they have perhaps one row of solar panels which keep the fridge running and not much else. Silent Yachts is the only production solar-electric catamaran and we offer faster cruising and a much bigger range due to our larger solar array and battery capacity.”
“Like the batteries in electric cars, the Silent Yachts batteries are designed to have a long life, but will wear out eventually. We offer an eight year warranty and, thereafter, they will still have functionality, but will at some point need replacing. If you had a sailing boat, you would likely have to exchange the sails and rigging around the same time and, believe me, this would cost more than new batteries. Also, the good news is that in ten years’ time those batteries will be cheaper, lighter and better. The same goes for our solar panels. Manufacturer Sunpower guarantees 80% efficiency after 25 years but, after that time span, you will happily change them as more efficient panels will be available for much less money.”
Michael concludes: “Astonishingly, even though we have built it, shown it and proved it, people still say it cannot work. This is why it’s important for us to invite people on private sea trials to test it, and then it’s really not such a hard sell. Then, the only discussion we need is how to customise the boat to suit their tastes and needs. We build a Silent 55 in nine to 12 months from scratch and can create a four, five or six en-suite cabin layout. We have even put in gyms, workshops, Jacuzzis and saunas. And, with two trampolines, sunpads and corner lookout seats to the fore, window seats on the wide port and starboard decks, dining and sunbathing to the aft, plus sunbathing and dining on the flybridge, absolutely everyone on board gets their space and privacy.”
The Silent Yachts range currently features the 55, 60 and 80 with prices starting at 1.4 million euros for the entry-level model. Collectively, the yachts have won a number of awards over the years, including the UIM (Union Internationale Motonautique) Environmental Award Special Mention for ‘Environmental Benefit’ in 2018 and co-winner of the ‘Innovation’ category in the Boat International Ocean Awards in collaboration with the Blue Marine Foundation in 2019.
By Sarah Forge