An autonomous ship’s first effort to cross the Atlantic shows the difficulty of the experiment

The vessel’s top speed is a bit above eight knots, or 10 mph, which might seem glacial, but is much faster than the original Mayflower, thought to have averaged just 2 mph. The new vessel is made of aluminum, whereas the first was made of wood. The original was also much larger, roughly 100 feet long, and carried more than 100 people.

Source: WP