U.S. Navy Beefs Up Anti-Sub Capabilities

USS Lassen. Navy photo.

USS Lassen. Navy photo.


The U.S. Navy appears to be quietly modifying some of its Arleigh Burke-class destroyers with a new sonar system possibly optimized for detecting increasingly quiet Chinese submarines.

Photos (before and after) of the destroyer USS Lassen show a recent addition to the 9,000-ton vessel’s fantail — her back-end — that could be the interface for a towed sonar array.

Towed arrays are, in essence, a cluster of microphones attached to a cable that can be up to a mile long. The microphones “listen” for the machinery noise of very quiet submarines. Towing means the deploying vessel’s own machinery noise does not interfere with the microphones’ reception.

China has steadily expanded its fleet of modern nuclear and diesel-powered submarines in recent years, replacing a much much larger fleet of antiquated Soviet-style diesel boats. The Navy has vowed to restore eroded anti-submarine skills to cope with the undersea fleets of China and other nations.

For decades, the Navy has relied on the AN/SQR-19 TACTAS towed array. In 2008, the Navy began purchasing the improved AN/SQR-20 Multi-Function Towed Array, built by Lockheed Martin. The AN/SQR-20 is meant to be more sensitive and more reliable. The Navy plans to fit the new array to existing Burke-class destroyers, Ticonderoga-class cruisers plus the new DDG-1000 destroyer and the Littoral Combat Ship.

The Navy has been coy about how many new arrays it plans to build and exactly which ships will carry it. The array’s possible appearance on Lassen is surprising and important because, prior to now, Lassen and the roughly 30 other “Flight IIA” destroyers did not carry any towed array. Fitting such a large sub-class of destroyers with improved submarine-hunting gear could result in a noticeable shift in the undersea balance of power.

Also, the new towed arrays can also be combined with swimming robots. The robot, tethered to the end of the array, could help maneuver the array to preferred positions. Alternately, the bot could tow the entire array on its own, provided the array is not too large.

The Flight IIA destroyers are designed to accommodated the WLD-1 Remote Minehunting System, a snorkeling robot. The same basic ‘bot design could be attached to the sonar array, but so far the Navy has not publicly expressed any interest in doing so.

This entry was posted in David Axe, English.

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