Astute class submarine

Astute-class SSN profile
HMS Ambush in 2012
Class overview
Name:	Astute class
Builders:	BAE Systems Maritime – Submarines, Barrow-in-Furness
Operators:	Royal Navy
Preceded by:	Trafalgar class
Cost:	Over £1,370M per boat (2015 est.)
Built:	2001–present
In commission:	2010–present
Building:	4
Planned:	7
Completed:	3
Active:	3
General characteristics
Type:	Nuclear-powered fleet submarine
Displacement:	Surfaced: 7,000 to 7,400 t (7,300 long tons; 8,200 short tons) Submerged: 7,400 to 7,800 t (7,700 long tons; 8,600 short tons)
Length:	97 m (318 ft 3 in)
Beam:	11.3 m (37 ft 1 in)
Draught:	10 m (32 ft 10 in)
Propulsion:	Rolls-Royce PWR 2 reactor, MTU 600 kilowatt diesel generators
Speed:	30 kn (56 km/h; 35 mph), submerged
Range:	Unlimited
Endurance:	90 days
Test depth:	Over 300 m (984 ft 3 in)
Complement:	98 (capacity for 109)
Sensors and processing systems:	Thales Sonar 2076 Atlas DESO 25 echosounder 2 × Thales CM010 optronic masts Raytheon Successor IFF
Armament:	6 × 21 in (533 mm) torpedo tubes with stowage for up to 38 weapons: Tomahawk Block IV cruise missiles Spearfish heavyweight torpedoes

The Astute class is the latest class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy. The class sets a new standard for the Royal Navy in terms of weapons load, communication facilities and stealth. The boats are being constructed by BAE Systems Maritime – Submarines at Barrow-in-Furness. Seven boats will be constructed: the first of class, Astute, was launched by Camilla, Duchess of Cornwall, in 2007, commissioned in 2010, and declared fully operational in May 2014. The Astute class is the replacement for the Trafalgar-class and Swiftsure-class fleet submarines in Royal Navy service.

The Astute-class programme began in the 1980s when the Ministry of Defence (MOD) launched a number of studies intended to determine the capabilities and requirements for the replacement of its Swiftsure and Trafalgar-class fleet submarines. These studies, called project SSN20, were conducted during the Cold War, when the Royal Navy maintained a strong emphasis on anti-submarine warfare to counter increasingly more capable Soviet submarines. To match this growing threat, the studies concluded that project SSN20 should be a revolutionary design, with significantly enhanced nuclear propulsion and firepower, and a more sophisticated "integrated sonar suite" and combat systems. Similarly, the United States Navy, which was facing the same threats, went on to design and build the Seawolf class. The estimated costs of project SSN20, although great, were not considered a "constraint".

However by 1990, the Berlin wall collapsed and the Cold War came to an end. Project SSN20 was promptly cancelled and a new set of design studies were started, this time, with "cost control" as a key objective. The Trafalgar class had been an evolved derivative of the preceding Swiftsure class, thus, in order to reduce cost and technical risk, it was concluded that this new class of fleet submarine should "build upon" the Trafalgar design. This became known as the Batch 2 Trafalgar class (B2TC), with approval for the studies phase given in June 1991. While the philosophy behind B2TC was that of a modern and improved Trafalgar, early design concepts of B2TC were also heavily influenced by the then under construction Vanguard class, in particular, its nuclear steam raising plant (NSRP).