In Phase 2, Serco will finalize ship design, build the ship, and work through a series of rigorous testing activities before taking it to sea for a three-month demonstration event.

The first robotic navy ship will be called Defiant. The 210-metric ton MUSV-class [medium unmanned surface vessel] ship aims to maximize performance, reliability, and maintenance efficiency while still carrying significant payload at tactically useful ranges. The goal is to achieve ultra-reliability objectives by integrating distributed hybrid power generation, podded propulsors, and high-capacity batteries.

A key philosophy of NOMARS is "graceful degradation," which allows individual equipment to fail over time by having enough system-level redundancy to meet full system requirements at speeds of at least 15 knots after one year at sea. The major system components of the selected design are modularized, so repairs can be conducted with equipment typically found in yacht-yards worldwide. This maintenance philosophy supports rapid turnaround, allowing the ships to spend a majority of their lifetime at sea performing missions.

DARPA has also been working on an unmanned ship to kill submarines.