March 10, 2010: Now that the U.S. Navy has completed the A-RCI (Acoustic Rapid COTS Insertion) program to upgrade the sonar systems on all of its nuclear submarines, they are beginning to purchase TB-29A towed sonar arrays for their SSNs (attack boats). Ten TB-29As have been ordered so far, at a cost of $3 million each. These arrays increase detection capability more than four times. This is especially useful in shallow water, against diesel-electric subs. In underwater combat, whoever gets spotted first, tends to lose.
The TB-29A uses the same COTS (Commercial off-The-Shelf) design as the recent sonar upgrade on American submarines. The A-RCI program involved more than installing faster computers and more memory. The sonar gear was modified so that it can more easily take advantage of new processors and memory developments. Since these items have been doubling in power, every 18-24 months, for over 40 years, it's about time. In the past, submarines often had sonar systems powered by decade old CPUs, and memory chips that were no longer manufactured. Fortunately, the navy is not alone in running ancient gear, so there were suppliers who bought up old CPUs and memory SIMMs, and sold the stuff to the navy. Sometimes, however, particularly old components could only be found on eBay.
The navy began the A-RCI program in 1998, but it has taken over a decade to debug the system and get the gear into 44 subs, as such major modifications could only be done when the boats came in for refueling (usually halfway through their careers) or for some other major repairs or maintenance. The new Virginia class boats have A-RCI built in.
Sonar, particularly the passive (just listening) type, depends heavily on computer processing power to detect and identify anything out there. The towed arrays collect even more information, which the more powerful multi-core CPUs and gigabytes of RAM can quickly turn into useful information.