Yacht Class n°19 (dec 2019/jan-feb 2020)
At a time when climate change has become a refrain, reducing carbon dioxide emissions seems a priority. The time has come for electric propulsion, and that’s the choice of the Austrian yard Silent-Yachts, builder of “ecological” catamarans. Its flagship model: the 55, whose E.Power version, becomes the “standard bearer” of non-polluting units.
Written by Alain Brousse – Photos : All rights reserved
It is hard not to see the photovoltaic panels on the flybridge hardtop, but also on the aft and forward part of the very same fly. But that does not mean that these sensors are enough to produce the energy required by the two 250 kW engines. They will only be used as a back-up, provided favourable climatic conditions, in other words on a sunny day. Anyways, you cast off in fine weather, with fully charged, lithium-ion batteries banks, the “fuel”. Needless to say, don’t forget the consumption in kilowatts and the range, which is counted in hours! This is why, like for combustion engines, our technical sheet indicates the consumption by speeds, but in kW, which allowed us to figure out the operating time and range. An extreme example, you want to join Corsica from Antibes on the Silent 55 E. Power (about 110 miles). Considering the 210 kW capacity of the batteries pack – or rather 180 kW to keep a safety margin -, the only solution is to maintain 3 knots of speed, which mean that it would take nearly 37 hours to reach Calvi… You can also rely on the energy supplied by the solar panels, which represents about 80 kW, provided there is a 16-hours sunny day. The all-electric is thus the only way to navigate without CO2 emissions. An auxiliary conventional diesel generator (100 kW) is also available for those less confident in the purely electric mode. And finally, in case you need recharge the completely drained battery pack, don’t forget it will take two and a half days. According to its manufacturer, batteries have a lifespan of 10 years and more than 2 000 cycles.
Respect for the environment
This is it for the purely technical aspect, now let’s cast off the Silent 55’s ropes… in silence, of course, especially at an idling speed. Port maneuvering can be managed with only the reversers and bow thrusters. Once at sea, on a nascent chop, we discovered that even though the electric engines generate barely perceptible vibrations and noise level, the catamaran’s hulls alone create bow waves and thus washes that inevitably cause tunnel resonances. Add to that the propeller, and you will find out that at 10 knots, an electric catamaran cannot go unnoticed. Actually the 56 dbA we read in the living room and master is close to what we usually note on motor yachts. But in electric mode, this Silent is the champion of pollution control and isn’t that the most important thing? Now, let’s forget offshore navigation to focus on day trips and coastal cruising. Given her limited speed, the behaviour of this electric catamaran does not surprise us. She hardly rolls and shows lateral stability. Facing the wave, she will naturally pitch slightly. Handling her from the flybridge helm is such pleasure that we found it difficult to join the interior helm station, a place that will be welcoming at the slightest whim of the weather. Located on starboard on the open plan main deck, it enjoys a slightly restricted visibility of the bow and better one of the sides.
The layouts are sometimes original
As for the outdoors, we immediately noticed that the flybridge has a limited size of only 20 m2 for quite a simple reason: its aft is dedicated to solar panels (12 m2). Even so, this flybridge features a transverse sofa on portside and serves a dining area with a table for four to six, plus a two-person sunbed located to starboard of the helm station. Spacious but barely more generous, the 25 m2 cockpit features a transverse sofa and a dining area for four on portside. The foredeck offers two single sunbeds and two trampolines that act as a sunbathing area with headrests. Note the original feature at the beginning of the port side deck: a settee for three passengers seeking privacy or to enjoy the passing landscape. The Silent 55’s habitability is characterized first by a 30 m2 open plan living area with two galley cabinets and a refrigerator in the entrance area. Then comes the open plan living area featuring a dining table and sofa for six, with on the opposite side a retractable TV screen concealed in the pilot seats support cabinet. Still on the main deck, the nacelle accommodates the master with an aft-facing king-size bed, opposite to the wardrobes. Its bathroom occupies the forward part of the starboard hull, which also accommodates an aft guest cabin. As for the port hull, it houses two guest cabins, both en suite. That should reassure owners or tenants of this type of units. According to the brand’s founder, Michael Köhler, it did not take long for the Silent 55 long to seduce shipowners who could not conceal their satisfaction to be able now to sail cleanly.