1,000-Hour Ocean Testing Achieved for Autonomous Surface Vessel Propulsion System

The Blue Water development team has surpassed 1,000 hours of ocean-based testing for a proprietary propulsion system designed to power Autonomous Surface Vessels (ASV).

This milestone exceeds the original 720-hour land-based testing requirement established by the Navy. The testing program integrated several critical subsystems beyond basic propulsion, including electric power generation, a full sensor suite, and fuel polishing.

As the Navy grows its uncrewed surface fleet for transoceanic missions, vessels must be able to operate unmanned at sea for months at a time, with robust engine and propulsion systems being foundational to developing this hybrid fleet.

While earlier Navy testing focused on the 720-hour baseline established in 2021, Blue Water sought to exceed that threshold by validating its systems in more demanding, real-world maritime conditions.

Real-World Maritime Test Environment

Testing was conducted using a 100-foot, 165-ton vessel stationed in New Bedford, Massachusetts. This platform allowed for the integration of components required for the Navy’s Modular Attack Surface Craft (MASC) program, such as autonomy sensors, power electronics, and fuel management systems.

By moving testing from a laboratory setting to the open ocean, the team exposed the hardware to harsh maritime conditions, including saltwater corrosion, UV radiation, biofouling, and temperature extremes. Operations were conducted seven days a week across three shifts to simulate continuous mission profiles. The system was designed to operate across varied load profiles, both within and beyond the engine’s optimal power rating.

Before testing began, the team identified which design decisions required careful upfront evaluation and which could be refined through iteration, allowing critical elements to be set early while enabling rapid testing and improvement elsewhere.

Rather than limiting experimentation, the testing program emphasized rapid learning through continued testing and refinement. A modular system architecture allowed components to be swapped and modified quickly as issues were identified. Each failure was followed by root cause analysis, with findings incorporated into subsequent design improvements to strengthen overall system reliability.

Building System Reliability

System reliability was achieved through multiple incremental design and operational measures. These included the use of high-quality diesel engines and long-life components, operating systems below maximum stress levels to extend service life, and minimizing vibration to reduce wear, leaks, and chafing.

Durability was further improved by reducing connector counts, replacing hoses with welded piping, polishing fuel, and adding protective measures to contain potential leaks. Automated preventative maintenance functions, including lube oil changes, were incorporated alongside continuous monitoring for leaks, overheating, and vibration. Redundancy was applied at the system level to ensure the overall propulsion system met operational requirements.

Blue Water’s 1,000-hour milestone represents an initial benchmark in an ongoing test program aimed at extending long-duration autonomous operations at sea. Further testing is planned to increase system endurance and robustness in support of the Navy’s vision for a resilient hybrid fleet.