Silent 55 Green Power and Solar Panels

SILENT55_1 - yacht and sea

The Silent 55 is a new kind of boat which uses solar power via special panels, li-ion batteries and electric motors by Silent-Yachts. This boat sets a new trend in terms of ecologically oriented and careful yachting that respects nature and guarantees owners full comfort in total silence.

Michael Köhler, CEO of SILENT-YACHTS, explained: “Purely solar-powered yachts become a commercial reality now. Even if we keep a diesel generator on board our catamarans, this is for safety reasons. An owner of the SILENT 46, for instance, told me that he did not start a generator for the last two years despite he spends the whole summer on the boat with guests cruising around Greek islands.

Köhler adds: “Solar is a more practical generator of power than wind, hydro-generation or other technology because the sun is much more reliable than the wind in the common holiday destinations. Most people are searching for a sunny – not for a windy – holiday destination. Hydro generation only works when the boat is being moved – not on anchor. When moving, the hydro generation reduces the speed in the same way as it generates energy minus the loss for friction and efficiency. It decelerates the boat twice as much as it generates power. Nobody can beat physics. The efficiency of the panels that we use in SILENT-YACHTS is 23%, which is strong in today’s world. We use Sunpower panels, by far the most efficient commercially available panels on the market. There is a perception that with time solar panels become less efficient. This is not an issue anymore. Sunpower guarantees 80% efficiency after 25 years. Believe me, after that time span, you will be glad to change them voluntarily, as more efficient panels will be available for much less money.

Silent 55 - 2 yacht and sea

Battery technology problem has also been passed. “Advanced batteries allow SILENT catamarans to cruise day and night without stopping”, comments Michael Köhler. “As technology improves, we can go faster during the night and the batteries will be lighter due to higher energy density.


The Silent 55is available in several power configurations to suit a variety of cruising applications. All of them stick to the SILENT-YACHTS philosophy of relyingmainlyon solar power for propulsion and onboard power needs.

The standard “Cruiser” version of the Silent 55 has 2 x 30 kW turnable saildrives e-motors, while a more upgraded “E-Power” version is equipped with 2 x 250 kW e-motors. There is also a “Hybrid Power” version with 2 x 220 hp diesel engines and two 14 kW electric motors. A “Sailor” version can be equipped with all the previously mentioned drivetrain configurations and is rigged with a mast and sails to provide additional propulsion in fair winds.

With 30 high-efficiency solar panels rated for approximately 10 kilowatt-peak, the Silent 55 uses maximum power point tracking (MPPT) solar charge regulators and lithium batteries, which provide capacity for all-night cruising, while a 15-kVA inverter provides power for all household appliances. The systems requires hardly any maintenance and produce no fumes or noise. Because of that, the operational costs of the vessels are substantially lower compared to power yachts using more traditional propulsion systems.

Michael Köhler, SILENT-YACHTS CEO, said “What this represents to the yachtsman, among other features, is the ability to cruise for many hours at normal speed and throughout the entire day and evening at reduced speed. SILENT-YACHTS sets the standard for an entirely new feeling in yachting: No fuel. No maintenance. Pure solar-powered luxury.


The Silent 55 is available in five different layouts ranging from three to six staterooms with three or four heads. A full-width central owner’s stateroom is the centerpiece in three of the layouts, with guest staterooms located in port and starboard hulls. All staterooms offer double or twin berths, and all heads include a separate shower. Other layouts are available on request.

In all configurations, careful attention has been paid to onboard ergonomics. The staterooms, heads and saloon on the Silent 55 are all created to welcome every person into spaces that are adapted to human size and create a comfortable environment for living, even for extended cruising. Large portlights and flush deck hatches admit natural light.
On the Silent 555, the interior layout is centered on a shared onboard space, a huge 40 m² combination of saloon, helm and galley, with enough space for the crew to gather. The skipper will never be lonely at the lower helm as plenty of companion seating and an aft galley will keep the crew around. 
Three of the layouts feature a forward owner stateroom that capitalizes on the 8.46-meter beam of the yacht for a spacious layout with a walkaround double berth. Other accommodation plans optimize the space with additional staterooms as SILENT-YACHTS uses a modular construction and efficient design methods that allow additional layouts at reasonable prices.
With wide side decks for safety moving fore and aft, the Silent 55 has a spacious cockpit sheltered by a large hardtop overhang, and enormous open foredeck space. In addition, the flying bridge promises to allow helmsman and guests to enjoy time together underway with superior lines of sight all around the boat.
The Silent 55 is equipped with the company’s aeration system, which provides cool and fresh air to all accommodations, heads, and in the saloon. The air-flow in each space is individually adjustable and can be used when the weather conditions require the windows to be closed. In addition, a reverse-cycle heat-pump system can be used to heat the interior when necessary, ensuring all-season comfort. The insulated hull ensures efficient achievement of desired onboard temperatures.


The Silent 55is built using vacuum-bagged resin infusion to create a lightweight glass-sandwich composite construction that has sound- and temperature-insulating qualities. The hull is reinforced with carbon fiber at stress points, and uses vinylester resin to prevent osmotic blistering.

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The Silent 55 hull shape was designed using extensive tank testing for optimal efficiency. The molds were then created using CNC milling for true replication of the refined, enhanced shape in the tooling. The Silent 55 has a shape both above and below the waterline that is designed to slip through the wind and waves with minimal resistance.

Designed with sealed deck sections and collision compartments for safety, the Silent 55 uses watertight bulkheads and integrated interior furniture to create a torsion-resistant hull structure. The electrical system can allow such features as a powered aft swim platform, a 1,500-watt electric windlass, and other features yachtsmen have come to expect on world-class oceangoing cruising yachts.

Onboard experience

Because the Silent 55 is designed to range everywhere as a true ocean-going cruising yacht that is self-sufficient, she is equipped to keep her crew happy and comfortable for virtually any voyage. It starts with the benefits of the propulsion system. The Silent 55 can cruise efficiently for up to 100 miles a day for weeks. At the same time, the arrangement of the components enables the system to power all onboard systems without need of fuel to power a generator. Because of her revolutionary design, the Silent 55 travels just with the sound of the wind, and the water streaming past the hull, with no smoke, noise, or vibration of engines.

The generator is only used to recharge the batteries in the rare case when higher speed is required for longer periods of time or if the weather is bad for several days,” Köhler says. In addition to the ergonomics of the living spaces, the Silent 55 – thanks to her advanced conveniences – offers a comfort level that sparks peace of mind. A water-maker powered by the solar-electric system, produces enough water to supply a full six-stateroom company with reasonable rate of consumption. 

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On the Silent 55, all onboard appliances operate on the 220/110-volt system, to which her crew might be used to from their homes. The galley has refrigerator and freezer space to sustain the crew and an efficient induction cooktop, precluding the need for carrying propane.

Under normal, average holiday conditions, the boat is self-sufficient with unlimited range without burning fuel,” Köhlersays. But perhaps even more importantly, the time under way is spent enjoying the sounds of wind and water, with no fumes or vibration, with no noise but the laughter of friends and family.

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