Submarines: Virginia The Larger


August 14, 2021: The U.S. Navy has found a breakthrough naval weapon with its new Block 5 Virginia class SSNs (Nuclear powered attack subs). Just like the battleship revolutionized naval power a few years before World War I (1914-18), along with ocean-going submarines during that war and, by the 1930s, aircraft carriers, the new Virginia can carry a lot more guided missiles, high-tech torpedoes and naval mines than ever before because all these weapons on an SSN have proved to be a decisive weapon. SSNs can travel at high speed underwater to trouble spots and deliver massive firepower and get there before the aircraft carriers can. As the Block 5 Virginias begin to enter service, so will a lot of new, or renewed, guided missiles and “smart mines” that became available as the first Block 5s get closer to their first appearance.

The Navy is already spending a lot of money on its new SSNs. The Navy has twenty Virginia class SSNs in service with 60 to 70 or more to be eventually built, depending on how much money is available and how well the substantially improved Block 5 models do. Over the last five years the speed of construction has increased as well as the rate of delivery, which is (now one or two a year, in order to replace the aging Los Angeles class boats.

Each block of Virginias represents improvements, some of them substantial. There are currently five subclasses of Virginia, each identified by a Block number. There are four Block 1s, all in service by 2008. Th six Block 2s were all delivered by 2013. Eight Block 3s were all in service by 2020 and ten Block 4s, with three in service by 2021 and the rest by the mid-2020s. The ten Block 5s won’t all be in service until the early 2030s and future Blocks will be based on the larger and more heavily armed Block Vs.

The Navy currently expects to build 66 Virginias but the importance of the large and more heavily armed Block Vs may increase that to over 70 subs with most of those based on the Block 5. Blocks 1-4 of Virginia are all armed the same way but eight of the ten Block 5s have additional space to store and launch missiles and can carry 65 missiles and torpedoes, 75 percent more than earlier Virginias. This is accomplished by adding a VPM (Virginia Payload Module) to the current design. This adds 25.6 meters to the length of the sub and increases displacement to 10,400 tons. The VPM adds four more of the large launch tubes that can hold different sizes of missiles. For example, each of launch tubes can carry seven Tomahawk cruise missiles or a smaller number of new missile designs in development, like the hypersonic missile. Earlier Virginias already had older individual launch tubes forward of the sail (conning tower). The VPM is added behind the sail. The VPM design was not ready when the first block 5 began construction so the first two Block 5s will lack the VPM and be the same size as earlier Virginias. These two Block 5s will have all the other additional features common to all Block 5s. This includes improved electronics and sensors and it is believed that the passive sonar in these model Virginias have much longer and accurate detection ranges. The Block 5 will also receive a large number of other equipment upgrades.

The additional missile capacity of Block 5 and subsequent Virginias is also meant to replace the cruise missile capacity being lost as the four Ohio-Class SSGNs (cruise missile carrying subs) are retired. These four boats are SSBNs (ballistic missile carrying subs) that were converted so their 24 ballistic missile launch tubes could carry seven tomahawks each. Two of the missile tubes were dedicated to carrying navy SEAL gear but the others carried 154 Tomahawks. The success of the Ohio SSGNs led to the VPM, although it will require 22 VPM equipped Virginias to replace the Tomahawk carrying capacity of the SSGNs. This was seen as an advantage because there were few instances where an SSGN had to fire all or most of their Tomahawks. The VPM does not turn the Virginia into an SSGN because all Virginias are still attack boats.

The Block 1-4 Virginias cost about $2.2 billion each. They displace 7,800 tons and 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 Block 1-4 Virginias are armed with twelve Tomahawk cruise missiles (in vertical launching tubes) and four 53.3 cm (21 inch) torpedo tubes that can fire MK 48 torpedoes or naval mines. The Block 5s with the VPM will cost about $3.5 billion each.

More important are the large number of electronic systems carried. These make the Virginias more difficult to detect, 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) outside the sub. With a dozen or so SEALs on board, a Virginia will be carrying nearly 150 people.

Virginia’s nuclear reactors are a 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 2 models used less costly construction techniques, while the eight Block 3 boats have some design changes and new technology. The most dramatic improvements came with Block 5.

Development of Block 5 was accelerated by the appearance of new weapons for Virginia. In 2018 the navy returned the ENCAP (encapsulated in a container that is fired from a torpedo tube) Harpoon anti-ship missile to active service. The Navy withdrew the ENCAP Harpoon in 1997 but in 2018 test fired one of them, apparently refurbished for the occasion, and found they still worked as they were supposed to. The ENCAP Harpoons were initially replaced by an anti-ship version of the Tomahawk, which was to be withdrawn but remained in service with more upgrades. With the collapse of the Soviet Union in 1991, the major naval adversary of the United States soon disappeared. The smaller Russian state could not afford to maintain, much less operate, the huge Soviet fleet. Now China is replacing the Soviet fleet as a major naval threat and new ship designs and weapons are back in favor.

By American 1999 subs were just carrying land attack Tomahawks, not just because the Soviet navy was gone but also because for either Harpoon or Tomahawk you have to have a general idea of where the target is before you fire the missile, which has its own terminal guidance system for locating a ship nearby and hitting it. But the subs rely on stealth for protection and that means few transmissions while underwater. For the ENCAP Harpoon, the 1990s passive sonar could, under the right conditions, locate a surface target out to about a hundred kilometers. Half that was needed, in most cases, for the Mk48 torpedo, which also had a terminal guidance system and could, at slow speed, reach a target out to about a hundred kilometers.

Since the 1990s there have been major improvements in the passive (just listening) sonar the subs use most of the time, as well as the tech used for a submerged sub to receive, or, less frequently send, electronic information. When receiving data the sub does not reveal its position to anyone monitoring that area of the ocean for transmissions. Sending data, even briefly, exposes the sub’s general location to being discovered.

Subs now have many more “periscope” capabilities. The conventional optical periscope has been replaced by devices that can be sent to the surface tethered by cable. These tethered devices can receive satellite and other electronic messages, as well as send. That means a sub could send up its sat receiver so many times a day when in a combat zone to receive updates on enemy activity. These could include firing orders for distant ships (or land targets) to be fired on using missiles. The latest version (Block II+ER) Harpoon has a 300-kilometer range and much better terminal guidance and countermeasures. But it is still a slow (800 kilometers an hour) missile while the most modern anti-ship missiles have terminal attack speeds of more than three times that. Then again for a surprise attack Harpoon can be useful as it comes in very low (“sea skimming”) often avoiding enemy radar. One possible situation would have an enemy ship detected by satellite or UAV with location information sent to a sub within Harpoon range (or able to move into range) which could then fire one or more ENCAP Harpoons and then go hide. ENCAP Harpoons blasting from the sea surface makes a lot of acoustic and visual noise. Another option is the ENCAP UAVs proposed for subs. These can be launched more quietly and spend several hours searching an area for any targets and sending the sub brief message bursts with the location of any targets. One version of ENCAP UAV has been developed that be launched from the smaller countermeasure launchers,

The navy is not spending a lot of money on bringing the ENCAP Harpoon back into service. It is going to upgrade some older Harpoons and ship them as ENCAP weapons for possible use under the right conditions. The navy, as expected, isn’t providing details and the details may involve some new tech or tactics that are best kept secret.

Another new weapon is the Hammerhead mobile mine. Hammerhead are encapsulated bottom mines that use a Mk 54 lightweight torpedo, which is normally carried by ASW helicopters and aircraft. Mk 54 has a range of ten kilometers and a guidance system that is regularly updated. Hammerhead is being used in a similar fashion to a larger version of this used during the Cold War that was deployed by surface ships and used the larger Mk 48 torpedo. In 1983 the navy introduced an earlier version of the Hammerhead concept as the Mk 67 SLMM (submarine launched mobile mine) that carried the older Mk 37 torpedo. The Mk 37 was a late World War II design that was used into the 1970s. By 1987 there were still some in storage and they were adequate for SLMM. The SLMM was out of service by the 1990s with the end of the Cold War. Hammerhead is an encapsulated system equipped with improved passive sensors to detect and identify submarines and surface ships and attack specific types of targets, like diesel-electric subs or larger warships or commercial ships. Hammerhead is not only being carried by the Virginias, especially the Block 5 but also by the new Orca autonomous diesel-electric sub that can carry and deploy a dozen Hammerheads.

The U.S. currently has three classes of SSN. Most are the 6,900-ton Los Angeles-class SSNs. Sixty-two of these submarines were built and 28 are still in service. Armed with four 53.3 cm torpedo tubes, they carry twenty-six weapons for those tubes (either the Mk 48 torpedoes or BGM-109 Tomahawk cruise missiles). The last 31 Los Angeles-class SSNs added the Mk 45 vertical-launch system (VLS), which carried 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. But there’s barely enough money to keep building Virginias and no time or cash to refurb elderly Los Angeles class boats. That was why the number of Virginias planned was increased to 66 and the tempo of construction speeded up. This means the American SSN fleet will not shrink from 55 in 2013 to under 45 by 2030. The current building plan keeps the SSN numbers at or above fifty and, with all of the new Virginias based on the Block 5s, the new SSN fleet will be a lot more capable than the old one.

The first attempt at doing that failed. Twenty-nine 9,000-ton Seawolf-class SSNs were supposed to replace the Los Angeles boats but Seawolf proved too expensive. Only three were built. The Seawolf was designed for the Cold War, carrying fifty weapons (torpedoes, cruise missiles, or Harpoon anti-ship missiles) for its eight 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.


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