The MS Turanor PlanetSolar, the world’s largest solar-powered boat, has adjusted its itinerary to account for less than optimal forecast sun conditions.

The boat was originally scheduled to carry a scientific research team from the University of Geneva from Boston, where the boat left this week, to Iceland, Norway and Paris. The team is collecting samples from the Gulf Stream and chose to take the expedition aboard PlanetSolar in order to avoid any contaminates created by traditional fossil-fueled vessels.

Covered in solar panels, the boat left the Mediterranean three weeks later than expected due to poor weather conditions. And this late in the season, the solar catamaran’s crew said it would be hard to predict an exact arrival date in Iceland.

“Although the days are still long around Iceland in mid-August, the low angle of the sun relative to the boat's photovoltaic panels would compromise the optimal acquisition of solar radiation,” boat captain Gérard d'Aboville said in a statement. “These sunlight conditions and the bleak weather forecasts for the rest of the summer prevented us from being able to guarantee a precise arrival date.”

There’s no doubt the boat would make the journey successfully. But the unpredictability posed unique challenges for the research team’s scheduling as different team members are supposed to trade off positions on the boat.

So, instead of traveling across the Atlantic in the north, the boat will zigzag in an out of Gulf Stream eddies along the eastern coast of North America, according to a release from the PlanetSolar team.

The eddies are large vortices that break off from the main part of the Gulf Stream and influence heat exchanges with the atmosphere and the growth of phytoplankton, said University of Geneva Professor Martin Beniston.

“This new itinerary is an opportunity for our research,” Beniston said. “This is the area where we expect to find the most interesting scientific results.”