We've written about one of those companies, SkySails, previously, and it recently completed its maiden transatlantic voyage to test the new system. The sail device looks like a puffy hang glider, about the size of a football field. It's attached to the bow of a container ship by a high-strength carbon fiber rope and flies upwards of 100-300 meters into the sky. What makes it different from a traditional sail catching the wind is that the SkySail acts as a giant wing creating lift and translating that to a pulling force on the ship. The sail is controlled by a pod attached between the sail and the connecting rope, which automatically adjusts the angle and position of the sail to provide the most power to the ship. It can even operate at up to a fifty degree angle against the wind.