60 MINUTES about Solar Impulse; http://www.cbsnews.com/news/solar-powered-plane-aims-to-fly-around-the-world/

This seems to be the SI 1 project.

They have to fly 83,4 km/h average to make it in 20 days.

http://geography.about.com/library/faq/blqzcircumference.htm

A 170 km/h ship and flying only on day time could be faster !?