Driverless ships don’t have to worry about crowded roads. And they don’t need bunks—or toilets.

Four hundred years after the trans-Atlantic crossing of the Mayflower, a ship of the same name will retrace its historic voyage. But while the original Mayflower bore 102 passengers to Plymouth Rock, this one will ply the seas for about two weeks next spring with no living souls aboard.
Promare, a U.K. ocean-research nonprofit, in partnership with International Business Machines Corp., will unveil this new, fully autonomous Mayflower on Sept. 16 in Portsmouth, the same seaside English town from which its namesake set sail…