The Virginia-class series of nuclear attack submarines represents one of the most important undersea components of the modern United States Navy (USN). Some 48 total boats of the group are planned with sixteen completed as of late-2017. The latest of these is USS South Dakota (SSN-790), laid down on April 4th, 2016 and christened on October 14th, 2017. The boat is part of the Block III batch featuring a modified bow section as well as improved technologies. Electric Boat (General Dynamics) was responsible for her construction after the contract was awarded on December 22nd, 2008.
The boat displaces 7,800 tons under load and has a length of 377 feet with a beam measuring 34 feet. Power is from an S9G series nuclear reactor unit generating 40,000 horsepower to a single shaft astern. This provides essentially unlimited range (an estimated thirty-three year lifespan for the reactor is reported) and speeds reach up to 25 knots. On board there is a crew of 134 (14 officer-level candidates) and mission endurance is limited to food supplies and general maintenance schedules.
The armament suite of the attack submarine consists of 4 x 533mm torpedo tubes cleared to fire the Mk 48 torpedo series. About 37 reloads can be carried. Beyond this the boat also supports the launching of the BGM-109 "Tomahawk" land-attack cruise missile and twelve Vertical Launching Systems (VLSs) are installed. The boat can fire these while completely submerged so as to maintain its position away from enemy eyes. The "Harpoon" anti-ship missile is also another ranged option for the boat and the type can also release naval mines as needed.
The general profile of SSN-790 is consistent with the Virginia-class. The nose section is rounded for hydrodynamic efficiency and contains a sonar fit as we well as the four torpedo launch tubes. Ahead of midships is the conning tower / sail and various communications and sensors are installed on the structure. The hull is tubular and tapers at the stern where a cruciform plane arrange is featured. Aft of this is the single-shaft propeller unit which is shrouded for noise reduction. The entire boat is also optimized for stealth through various noise-reduction means. Surface-search and navigation radars are carried as well as a complete electronic warfare suite.
The Virginia-class Block III group includes USS North Dakota, USS John Warner, USS Illinois, USS Washington, USS Colorado, USS Indiana and USS Delaware. USS South Dakota and USS Delaware officially remain "under construction" as of this writing (2017). The versatility of these boats is such that it can undertake intelligence-gathering missions, support special operations forces, defend contested sea-spaces and deny strategic areas from the enemy.