The Astute class submarine is the latest submarine in the British Navy, as of 2007. This huge submarine has an appearance similar to a whale, and is nuclear-powered, not requiring a single refueling over its 25 year lifetime. It is not unique in this regard, though.
The Astute class submarine is built by BAE Systems at the city of Barrow-in-Furness, on the central west coast of Britain. The submarines will cost about $2.4 billion US Dollars (USD) each. The Astute class consists of attack submarines, in contrast to ballistic missile submarines such as the Vanguard class.
In United States Navy parlance, the Astute is a SSN, meaning ship submersible (SS), nuclear-powered (N) submarine. SSNs are known as "attack" or "hunter/killer" subs, and their primary purpose is to find and destroy enemy subs and surface vessels to protect the surfact fleet. The Astute class was developed to replace the aging Swiftsure class of attack submarines. A couple of the more recent Trafalgar class also need replacing.
In 1997 the United Kingdom announced it was contracting with BAE Systems to build 3 Astute submarines which ultimately ended up costing $4 billion USD after a $2.2 billion USD cost overrun, and more recently has contracted for another four for a cost of an additional ~$9 billion USD. To visualize the cost of the Astute, imagine building a 30 story high-rise with a thick hull of military-grade steel, fill it with some of the most expensive communications, stealth, and weapons technology known to man, and make it capable of diving up to 300 m (984 ft) of water, where pressure is 30 times that at sea level, with negligible risk of hull rupture. The Astute is outfitted with a nuclear reactor, four giant turbines, 100 km (62 miles) of cabling, and 10 km (6.2 miles) of pipe work for more than one million components in total. Modern submarines are expensive.
A few statistics on the Astute follow. The submarines have a displacement of 7,800 metric tons, length of 97 m (323 ft), hull diameter of 11.3 m (37 ft), height of 10 m (33 ft), a speed of 29 knots (54 km/h or 37 mph), and a test depth (maximum dive under peacetime circumstances) of 300 m (984 ft). In the Royal Navy, test depth is about 4/7th of crush depth, we can estimate the crush depth at 525 m (1,722 ft) below the surface. The Astute normally has a complement of 98 officers and men, but a capacity of 109.
The Astute class is 30% larger than the United Kingdom's previous nuclear attack submarines, ending the process of "hot bunking" whereby men on opposite shifts have to share the same bunk. The first three Astute submarines to be built are the HMS Astute, HMS Ambush and HMS Artful.