The Navy Is Hatching a Sea Train

While the U.S. Navy is busy buying a new generation of unmanned warships to serve along manned vessels, those smaller “ghost ships” may need to team up to make crossing oceans easier.
Future unmanned warships could journey across oceans physically connected to one another to make the trip more efficiently. DARPA’s new “Sea Train” concept is investigating the idea of ships that tether, like the individual cars in a train, in order to overcome wave resistance.