Spartan Scout
Spartan Scout, an Advanced Concept Technology Demonstration, is a crewless surface watercraft, also known as an unmanned surface vehicle (USV) developed by the United States in 2001, and first demonstrated in late 2003. The craft, a rigid hull inflatable boat, weighs 2 tons, and is in length. It has a .50 caliber machine gun, as well as various sensors such as electro-optical and infrared surveillance and surface search radar. The Spartan is capable of carrying a payload. According to a press release from the United States Navy, the Spartan Scout will also come in a version, capable  of carrying a payload. Although a two-man boat crew is needed to deploy the Spartan Scout, once deployed it is capable of working autonomously or semi-autonomously. During its demonstration deployment, the Spartan Scout was configured for surface surveillance and force protection, although it can potentially be configured for more complex missions.