October 5, 2013: After the Cold War ended in 1991, the U.S. Navy got the Congress to agree that the United States required an SSN (nuclear attack sub) fleet of at least 48 boats. Since the 1990s, increased submarine construction by Russia and China means that number is apparently safe for now. But because only 2 new American SSNs were built in the 1990s, the current SSN force of 55 boats will drop to about 40, before recovering in the 2030s. The cause is the sharp cut in SSN construction in the 1990s, the fact that it takes over 5 years to build each new SSN, and the older Los Angeles SSNs approaching the end of their useful lives (33 years) meant that the force of available SSNs is shrinking. The navy is trying to reduce the shortage by speeding up construction of new Virginia class SSNs (from about six years to five), extend the life of some Los Angeles class boats by a few years, and base some SSNs in the Western Pacific (Guam) to shorten the time needed to get to where they are needed (the coast of China and Russia as the main Chinese sub base is on Hainan Island and Russia’s is north of Japan on the Kamchatka Peninsula).

This year the navy has received the tenth of 30 Virginia class SSNs. That was the USS Minnesota (SSN 783), which arrived 11 months ahead of schedule and is the last of 10 Block II Virginias. In 2008, the navy got its fifth Virginia 8 months ahead of schedule and under budget as well. The Virginia’s are taking less time to build and are arriving at the rate of 1 a year. That will increase to 1 or 2 a year over the next decade.

The Virginias cost about $2.2 billion each. They displace 7,800 tons, are 114.9 meters (377 feet) long, and 10.36 meters (34 feet) wide. Top speed is over 50 kilometers an hour, max depth is more than 250 meters (over 800 feet). The Virginians are armed with Tomahawk cruise missiles (in 12 vertical launching tubes) and four 53.3 cm (21 inch) torpedo tubes that can fire MK 48 torpedoes or deploy naval mines.

More important are the large number of electronic systems carried. These make the Virginias more difficult to detect and much better at detecting what is out there, which enables these subs to be more effective at espionage and scouting. The electronics can also quickly detect and identify incoming torpedoes and rapidly use countermeasures. The passive (listen only) sonar system is backed by a huge library of sounds. Virginias are also designed to operate in shallow waters and carry a SEAL Delivery Vehicle (sort of a minisub for getting SEALs ashore) on the deck of the sub. With a dozen or so SEALs on board a Virginia will be carrying nearly 150 people.

Virginia’s nuclear reactors are the new type that does not have to be refueled, having sufficient nuclear material to last 33 years. The reactors generate enough heat to provide 40,000 horsepower, as well as ample electricity for all the electronics. The block II models used less costly construction techniques, while the 8 Block III boats will have some design changes and new technology.

The U.S. currently has three classes of SSN. Most are the 6,900 ton Los Angeles-class SSNs. 62 of these submarines were built and 41 are still in service. Armed with 4 53.3 cm torpedo tubes, they carry 26 weapons for those tubes (either the Mk 48 torpedoes or BGM-109 Tomahawk cruise missiles). The last 31 Los Angeles-class SSNs built added the Mk 45 vertical-launch system (VLS), which carries another twelve Tomahawks. If built today these late model Los Angeles class boats would cost about $1.5 billion each. The first of these entered service in 1976, and the last one in 1996. These boats can last 30-35 years before they must be retired or undergo extensive (over half a billion dollars’ worth) of refurbishment and refueling. This can take 4-5 years and will keep the sub going for another 10-15 years. The navy is seeking enough money from Congress to refurb some of the elderly Los Angeles class boats and prevent the SSN fleet from shrinking below 45 boats.

29 9,000 ton Seawolf-class SSNs were supposed to replace the Los Angeles boats but Seawolf proved too expensive, and that problem was one of the main reasons for the lack of new SSNs in the 1990s. Only 3 Seawolfs were built. The Seawolf was designed for the Cold War, carrying 50 weapons (torpedoes, cruise missiles, or Harpoon anti-ship missiles) for its 8 660 mm (26-inch) torpedo tubes. Seawolf was fast (top speed of over 60 kilometers an hour) and much quieter than the Los Angeles boats. To replace the un-built Seawolfs the Virginia-class was designed. Think of it as a Los Angeles size hull with a lot of Seawolf technology installed. The Virginia class boats ended up costing about half as much as the Seawolfs. But that was largely possible because the Virginias used a lot of the new technology developed for Seawolf.