What is the difference between a Silent Yacht and a conventionally powered yacht?

Conventional motoryachts are powered by diesel- or gas-engines. Additionally they use to have a generator on board to supply all household appliances.

Depending on the size of the yacht, in sum 2 or 3 diesel-engines are working for propulsion and household.

Also sailing-yachts need a diesel-engine. Depending on the operational area and the wind- and weather-conditions, additionally to the sails a diesel-engine is needed for the propulsion of the boat. When anchored in a quiet bay, the diesel-engine ensures the energy-supply of the consumers.

Most yachts are using gas for cooking, the open flame heats up the interior of the yacht and cause an imminent threat. On many yachts the consumables like water and energy are managed in a way that enforces the skipper to visit a marina every two or three days to charge the batteries and to buy water for shower and drinking. Larger Yachts operate water-makers, air-conditioning and generators. They do not need to got to a marina but they have to run the generator.

The use of a combustion-engine is inevitably combined with noise, exhausts vibrations and oily films in the water. Is it that, what you are looking for in an otherwise quiet bay?

A conventionally powered boat has a range of 300 to 500 nautical miles under diesel-engine. With a sail the range can be extended – but only when the wind is coming from the right direction and in matching force.

How does cooling and heating work?

When the windows have to be closed in bad weather or when mosquitoes are outside, you will enjoy using the unique aeration-system. It is installed in all cabins, bathrooms and the saloon. It provides individually adjustable cool and fresh air at any time. It also can be combined with the air-conditioning. The roof overhang and the UV protection of the saloon windows also help to keep the inside of boat cool. In reverse mode the heat-pump provides a cosy interior for an all-season use.

What kind of batteries and storage capabilities are built in?

Lithium batteries – high energy density, the same product as Tesla uses. To be more flexible, we always use the latest generation which is a bit more powerful. The storage capacity depends on the chosen configuration, it enables you to go up to 20 knots and to run air conditioning all night without the need to start the generator.

Can you summarise the testing process of the first Solarwave 46? What did you learn that has had the biggest impact?

We ran the following long-term tests:

2005-2009 with a converted Fountaine Pajot 37, in which we installed the same household appliances as on our current boats – fridge, freezer, washing machine, electric oven, induction cooktops, coffee-machine, bread-maker and a water-maker. In addition we installed solar-panels and wind-generators and all necessary equipment to measure the energy production and consumption.

2010-2013 with Solarwave 46, a dedicated solar-yacht which we launched in 2009. More then 12.000 miles exclusively solar-powered, you con find more information here://www.solarwave-yachts.com/english/history
We found out, that spending less is the key factor, so we worked a lot on reducing the energy consumption e.g. by insulation the hull to increase the efficiency of the AirCon and we optimised the hull and the propulsion system for higher performance and less consumption.

How was the decision made to be fully hybrid-electric, with no fuel onboard (except the diesel generator set as a range extender)

After several years of testing we found out, that the overall energy balance of solar-panels is much better than of a sail. In an average application – holiday boat or world traveller, the energy produced by the solar-panels – which are specially designed for this purpose – exceeds by far the energy produced by the sails for propulsion. It is a simple fact, that you use a sail only a fraction of the time, whereas the solar-panels produce energy every single minute of daylight, energy you can use for propulsion AND for cooking, cooling the boat, refrigeration, washing-machine, water-maker etc.

How many kW do the panels generate?

On the SILENT 55 about 10 kWp, which results in about 60 kWh per day. This enables you to travel up to 100 miles every day, exclusively powered by the sun and run all the amenities like air conditioning, TV etc. as well as domestic appliances.