The US Navy is planning to make robotic ships - basically sea-bots that are armed to the teeth (gear? mechanical head?):
Lastly, there's the "Fleet Class," capable of staying in the water for 48 hours straight, and reaching speeds of up to 35 knots. The eleven-meter long USV would be used to do everything from carrying commandos to shore, jamming enemy communications, neutralizing mines, and delivering a "Harbor Class" drone. Naturally, it would carry its own guns and torpedoes, too, so it could conduct 'high end' surface warfare missions."