The sun21 crew at the press conference after their arrival in New York (Beat von Scarpatetti, David Senn, Michel Thonney, Martin Vosseler, Mark Wüst, from the left)
Arrival in New York City
The mayor of Miami, Manuel A. Diaz, presents the crew the Keys to the City of Miami.
Arrival at Martinique.
The sun21 heading to Martinique.
On the way to the Canary Islands.
Due to a storm the sun21 sought refuge in the harbour of Casablanca (Morocco).

Our responses to some commonly raised questions

What does the number "21" mean in the names "transatlantic 21" and "sun21"?

The number 21 refers to the 21st century and is a reminder that the solar boat aims to be a future-oriented contribution to the solution of imminent environment problems. The changeover to renewable energy is one of the key factors of the 21st century. Other projects concerned with sustainable development also bear the number 21 in their names:,

How dangerous will the crossing be?

The crossing is no more dangerous than an equivalent voyage with a yacht. "sun21" has been designed for sailing on the high seas and has all the necessary equipment. It meets all the security regulations and has been approved by the Swiss Federal Shipping Authorities. Electric motors are known to be especially reliable. The timing of the crossing has taken the meteorological situation into consideration in order to avoid hurricanes. Moreover, with Martin Vosseler an experienced physician will be a member of the crew. Michael Thonney is responsible for security on the boat. If the sea is restless, the crew members attach themselves to the deck with the help of belts and ropes. In emergencies, they can use a whole set of auxiliary devices: On the one hand, tools such as walkie-talkies, GPS, emergency transmitters or shortwave radio; on the other hand, resources like a dinghy, life raft, signalling mirror, emergency rockets, smoke signals or life rings with light buoys.

How does the boat move when the sun is not shining?

This is not a problem. Photovoltaic cells produce electricity with daylight alone. Furthermore, half of the energy produced will be stored in batteries. This enables the boat to move at night. If the sky is overclouded for a long period, then the speed will be reduced.

How much does the project cost and who is paying?

The boat will cost about CHF 700,000. The project has been financed by a group of idealistic individuals networked by Dr. Daniela Schlettwein in Basel. The boat will be sold after the journey.

What will happen to "sun21" after its arrival in New York?

The boat can be used in many different ways. The beautifully roofed deck offers a comfortable space for excursions or parties with relatively large groups. The comfort during a journey is unique because of its calm and steadiness, and maintenance costs are modest. We shall decide about the future of the boat during the journey. Every offer is welcome.

Why is "sun21" not going to circumnavigate the world?

In theory, this would be possible – without one drop of gasoline "sun21" could travel on for several years. Of course, the boat is rather slow and a trip right round the world would take quite some time. Furthermore, the boat is not equipped for all global oceans. MW-Line, however, together with the PlanetSolar team, have already started to plan a first circumnavigation with a solar-hydrogen boat. The experience with transatlantic21 will feed into this new project.

Why do we not see more solar boats?

This is a good question. The time is definitely ripe for the broad inclusion of solar techniques into shipbuilding. No other vehicle is more suited to convert photovoltaic energy into mobility. And solar boats are easy to maintain. All the various boats built by MW-Line have proven successful and have already transported several million passengers.

How does the crew sustain itself during the Atlantic crossing?

On the Canary Islands, the last stop before the passage, the crew bought provisions for 40 days: fruit and vegetable, pasta, lentils, rice, eggs, rusks, a couple of canned goods, dried vegetable and juices. Thanks to the fridge in the kitchen of the boat, a few meat and milk products were also included. The crew would cook a warm meal in the evening except when the sea was rough. The fruit and fresh vegetable were over after two weeks; as a result, the menu became increasingly modest towards the end of the 30-day journey. However, the crew did not have to limit itself to special survival food.

From where does the crew obtain potable water on the high sea?

Before the Atlantic crossing, about 240 litres of bottled mineral water were stowed away in the boat. This stock was sufficient for drinking and cooking purposes. Additional freshwater was carried along in the hull of the "sun21", where water tanks with a capacity of 520 litres had been put. Towards the end of the passage, the crew mostly cooked with this tank water.

How does the "sun21" find its way?

In contrast with the first Atlantic crossers, who had to orientate themselves with the help of the sun and stars, the "sun21" navigates with modern instruments. The satellite-supported GPS system allows skippers to receive information about the position of the boat at any time. Further tools indicate the force and direction of the wind, water depth and travelling speed. The autopilot enables the ship to automatically maintain a chosen course. The monitor of board computer displays an overview map with the position and course of the boat, the covered stages and the distance to the next station of the journey. Nonetheless, the crew still continues to rely on the compass, maps and books for the planning of the route.

Have you got any questions?

Please do not hesitate to contact us. We will endeavour to give you a competent answer.