The U.S. Navy’s New Robotic Ship for Tracking Chinese Subs

A quiet transformation is taking place in the U.S. Navy as it slowly introduce a new fleet architecture. The Navy will see a gradual shift from large surface combatants such as guided-missile cruisers and destroyers to proportionately smaller surface combatants, which next to frigates and littoral combat ships will include a significant number of unmanned vehicles (UVs) in the coming decade.

The principal impetus behind this shift is the Navy’s new “distributed lethality” warfighting concept, chiefly developed to counterbalance naval forces of near-peer competitors like China by more heavily arming surface ships with anti-ship and land-attack missiles rather than concentrating the fleet in offensive formations underpinned by a strong integrated network of C4 (command, control, communications, and computer) systems and sensors. 

Under this new concept, the future fleet is supposed to be composed of manned and unmanned warships with the former acting as command and control for the unmanned surface combatants packed with sensors and missiles. Put otherwise, UVs are expected to effectively execute so-called “three D” missions, that is, missions that are “dull, dirty, or dangerous” including mine-hunting and anti-submarine warfare (ASW), next to others.  

As a Congressional Research Service (CRS) report notes: “UVs can be particularly suitable for long-duration missions that might tax the physical endurance of onboard human operators, or missions that pose a high risk of injury, death, or capture of onboard human operators.” Of additional value is that UVs are less expensive to procure than manned surface ships because they do not need extra space, protection, and other support systems for a crew.

At the end of this transformation the Navy wants the majority of its cruisers and destroyers replaced by a much greater number of lighter manned warships and UVs. This vision is slowly becoming reality. The U.S. Navy has launched three separate UV programs – large and medium surface UVs, as well as extra-large unmanned underwater vehicles (XLUUV) – and requested from Congress over $4.5 billion in funds for researching and procuring new UVs over the next four years. The most advanced of the three is the so-called medium unmanned surface vehicle (MUSV) program with a first prototype, the Sea Hunter, handed over to the service in early 2018.

The Sea Hunter had its origins in a program of the Pentagon’s Defense Advanced Research Projects Agency (DARPA) known as the anti-submarine warfare continuous trail unmanned vessel (ACTUV). The program was launched in 2010 in partnership with the Navy’s Office of Naval Research (ONR). The result was a MUSV 140-ton heavy trimaran prototype, christened Sea Hunter in 2016, which has served as a testing platform for UV technology ever since. 

The MUSV has been specifically designed for ASW missions. Fitted with a fifth-generation medium-frequency hull-mounted sonar system for conducting active and passive sonar searches, the unarmed Sea Hunter will eventually be capable of operating autonomously for 60 to 90 days and will surveil large stretches of ocean territory. In the event the MUSV detects a submarine it is meant to guide U.S. Navy aircraft, subs, or surface combatants to the enemy sub’s location to destroy it. In one known test in 2016, the Sea Hunter reportedly successfully tracked a submarine from a one kilometer (0.62 miles) distance.

During another test in the last quarter of 2018, the Sea Hunter became the first ship to successfully autonomously navigate from San Diego, California, to Pearl Harbor, Hawaii, and back without a single crew member onboard. It was the first mission of its kind conducted by any navy in the world. According to the Navy’s surface warfare director, Rear Admiral Ronald Boxall, the Sea Hunter prototype has yielded useful insights into operating UVs.  “We’ve got Sea Hunter out there today, and we’ve done some incredible things with [it] in terms of its autonomy: teaching it how to get from point A to point B safely,” he was quoted as saying by Defense News in January 2019.

The U.S. Navy plans to award a contract for the construction of a single MUSV prototype in the first quarter of 2020, followed by a second robot ship in 2023. At a length of between 12 meters (about 39 feet) and 50 meters (about 164 feet), the MUSVs are expected to accommodate intelligence, surveillance, and reconnaissance (ISR) payloads and electronic warfare (EW) systems. Notably, according to the Pentagon, MUSVs “will be designed to be attritable assets if used in a peer or near-peer conflict.” In other words, in a fight with the Chinese People’s Liberation Army Navy (PLAN), for example, the MUSVs are expendable and can be lost in combat. 

The service also intends to procure eight large unmanned surface vehicles (LUSV) and nine XLUUVs between 2020 and 2024 from commercial vendors. This rapid expansion has met some opposition from Congress and it is unclear whether such a large number will be approved. To help with the integration of unmanned platforms, the Navy created a Surface Development Squadron (SURFDEVRON) earlier this year. The nucleus of this new unit will be the two MUSVs, the first of which is to be delivered in 2022.

What is clear is that the transformation of the U.S. Navy surface fleet’s architecture has begun, although it will be some time before the first UVs will be deployed in actual combat missions. The bottom line is that the quantity of deployable platforms will play an important role in future naval conflict. 

According to Pentagon estimates, a UV will cost approximately $15,000 to $20,000 per day to operate, while the average costs of operating a guided-missile destroyer with ASW capabilities are around $700,000 per day. As a result, the U.S. Navy could field dozens of ASW UVs at a fraction of the cost of the ships currently designed for ASW missions. In that sense, the old axiom that quantity can become a quality of its own should not be forgotten by U.S. naval planners and policy makers.