Innovation under the sea

This small, lightweight sonar safeguards against submarines

Just off the coast, the fleet sees no signs of danger. Even the water is calm.

Below the surface, though, an enemy submarine lurks. 

The U.S. Navy already knows it’s there.

With near-peer adversaries advancing their submarine abilities at an alarming rate, the need for technology that speeds up the detection, discrimination and engagement of such threats is more important than ever. A Raytheon Technologies innovation was ready to help — less than two years after the Navy put out the request.

“The Navy needed a new, lighter-weight Variable Depth Sonar system that also met increased detection range and maximum tow speed and depth requirements,” said Joe Monti, a Raytheon Technologies surface ship anti-submarine warfare program director. “In response, we used our research to quickly develop the (variable-depth sonar) from a clean sheet of paper.”

The sonar, also known as the Dual-mode Array Transmitter Mission System, or DART MS, allows littoral combat ships to track submarines in near-shore environments. It also helps to protect the rest of the fleet, especially the floating cities known as aircraft carriers.

"Anti-submarine warfare is a critical mission for our littoral combat ships," said Rear Adm. John P. Neagley, program executive officer for Unmanned and Small Combatants. "Once onboard, the new variable depth sonar will deliver a significant contribution to the Navy's surface (anti-submarine warfare) capability."

Ready from the start

A legacy company of Raytheon Technologies responded to the Navy’s sonar request with a rapid 20-month turnaround, from drawing room floor to rigorous testing to delivery. It helped that the company had a head start.

“In 2012, the Navy started to signal they were looking for a new submarine detection sonar,” Monti said. “They didn’t know what they wanted, just that it should have a dramatic weight reduction, be simple to use and be deployed from both littoral combat ship variants. With that knowledge, our team started work.”

By 2013, the Navy requested innovative ideas on the topic. Raytheon Technologies responded with a unique, single-tow sonar concept traditional anti-sub sonars have to tow both a transmitter and a receiver. When the official request for a sonar came out in 2017, the government was seeking innovative ways to add a VDS to the ships, while reducing system weight and minimizing the impact of launch and recovery operations on a small crew.

The power of partnerships

With the research mostly done, the team turned to its customers and business partners to develop the idea. First, Raytheon Technologies took the unusual step of putting partner subcontracts in place before the main sonar contract had been won — meaning everyone could get to work on Day One, assuming the contract came through. Once that happened, engineers connected with the sailors who would be operating the system, gathering early feedback that enhanced everything from hardware to user interface.

“Collaborative feedback allowed us to introduce real-time improvements that will result in greatly improved safety and operability for the sailors at sea on littoral combat ships,” said Senior Chief Sonar Technician Joe Hart, who is assigned to USS Fort Worth, LCS 3.

Raytheon Technologies teamed with Indal Technologies/Toronto, L3-Adaptive Methods Inc, Purvis Systems, SeaCon, Southbay and SeaCorp. Once under contract, the company also worked closely with the Naval Undersea Warfare Center in Newport, Rhode Island — a key government collaborator.

Also critical was Florida Atlantic University’s Harbor Branch Oceanographic Institute, which recently hosted the full integration and land-based testing of the sonar systems, as well as operation and maintenance training for the U.S. sailors who will use it.

One system, many benefits, delivered

The delivered sonar’s smaller,lightweight design frees up space and manpower onboard LCS ships. While traditional anti-sub sonars require multiple sailors to physically move them overboard, just a few are needed to remotely deploy and operate the single-tow VDS.

It can also be towed at faster speeds and reach depths that optimize submarine detection, unlike conventional platforms. And now it’s in the Navy’s hands, making for a safer and more powerful force at sea.