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The seven 5,200 ton Trafalgar class nuclear-powered submarines are based at HM Naval Base Devonport, in Plymouth. The 84m long Trafalgar class boats are armed with Spearfish torpedoes, Tomahawk cruise missiles and Sub-Harpoon missiles. They carry 130 crew and can remain submerged indefinitely.

Tomahawk Block IV missiles are built by Raytheon in the US, with missile electronics supplied by its subsidiary in Glenrothes, Fife. BAE Systems and Ultra Electronics in Middlesex have also played a key role in electronics and other aspects of the submarine upgrade to enable launch of the new missile. The latest version of Tomahawk, successfully tested by the Royal Navy last year, is more responsive and flexible than its predecessor and at a significantly lower unit cost. With a third longer range than its predecessor, it can hit targets 1000 miles away, be retargeted in flight, and can send back images to boost intelligence gathering.

The CP inertial navigation system is a computerised system which provides an on-going position of the submarine underwater depending upon the information regarding course, speed, currents etc which is fed into the computer. The on-going position is therefore estimated only; the position requires to be updated at periodic intervals using a surface fix. Communications system includes UHF, VHF, HF and MF radio-equipment. A single retractable radio mast is provided, so only one frequency can be worked at a time and only when the submarine is at or above periscope depth. The radar equipment has a maximum range of about eight miles when at periscope depth but the range is considerably increased when the submarine is on the surface.

Sonar is the primary means of detection of other vessels, above or below the surface, by a submerged submarine. It has two modes, active and passive. In the active mode, sound pulses are transmitted from the submarine, reflected from an object within the beam and returned to the submarine to be detected and analyzed by the sonar receiver. In the passive mode, which is always used, noise transmissions emitted by other vessels or objects are received by the submarine. The bearing of a noise source can be measured and trained sonar operators can estimate from the frequency the type of vessel, and the loudness will give an indication of the proximity.

The primary noise emissions from a surface vessel come from the propeller. Low propeller speeds from large vessels and high propeller speeds from small vessels can easily be recognised. A vessel stopped in the water may still be detected if machinery on board, particularly below the waterline, is running. A vessel or object making no noise emissions will not be detected by passive sonar.

The submarines are equipped with 2020 long range passive sonar on the bow. The arc of coverage does not include an area astern of the submarine. The 2020 sonar is augmented by the 2008 sonar, or underwater telephone, which has three transducers, covering the bow, and the port and starboard sides. These are fixed and cover a fairly wide beam. Integrated with them are two transducers in the fin which can be rotated. The transducer at the back of the fin is integrated with the 2020 bow sonar to give coverage astern. These are normally left in the "omni" position, giving cover but if it is necessary to investigate something they can be trained in a particular direction. This requires them to be manned by a sonar operator. The submarine also has 2007 intercept sonar on either side, which is long range passive and can intercept other transmissions from ships or submarines. The submarine is also equipped with 2019 sonar, which receives active sonar transmitted by other warships. The 'Paris' dome of the submarine is a small dome forward of the fin which houses the active Sonar.

The advanced Sonar 2076 is a fully integrated system comprising bow, flank, fin and towed arrays that can track an object the size of a bus at a distance of more than 50 miles. The fully integrated Sonar 2076 is manufactured by Thales Underwater Systems Ltd at Templecombe, Somerset, with design, software development and systems engineering carried out at Cheadle Heath, Manchester and Church Crookham in Hampshire.

The reactor needs refuelling on average only twice during the boat's service life. Swiftsure and Trafalgar Class submarines are powered by Pressurised Water Reactor Mk1 plant, while Vanguard and Astute class submarines are powered by Pressurised Water Reactor Mk2 plant. In July 2007 the MoD signed a partnering contract with Rolls-Royce worth up to £1 billion over 10 years for the provision and through-life support of pressurised water reactors for the Royal Navy's nuclear powered submarines over the next ten years. The contract covers the reactors and equipment that translate the massive power of the nuclear fission plant into the high pressure steam that drives the submarine's turbines, providing electrical power to the boat's systems and powering its propulsion system. The Nuclear Steam Raising Plant drives not only current submarines but will also power the new Astute submarines. Rolls-Royce has been supplying Nuclear Steam Raising Plants to the Royal Navy for almost 50 years from their production site at Raynesway in Derby, and this new contract will help secure the future of staff working in this part of the business.

The actual cost per annum of operation for ships such as Type 23 frigates, Type 22 frigates, SSNs, Hunt Class minehunters and Sandown Class minehunters will vary considerably dependent on the tasking/maintenance undertaken. Indicative annual costs, including manpower, fuel and stores only, would be in the region of £16 million for a Type 23 and a Type 22 frigate, £11 million for an SSN, £3 million for a Hunt Class minehunter and £2 million for a Sandown Class minehunter.

The pelagic trawler, ANTARES left her home port of Carradale on 19 November 1990 to fish in Bute Sound, northeast of the Isle of Arran, with a crew of four. At the same time the Trafalgar-class submarine, HMS TRENCHANT, was operating in the Clyde exercise area. She was acting as a training vessel for officers on the submarine command course. On 22 November shortly after 0200 hrs TRENCHANT was in Bute Sound, submerged at a depth of 60 meters. TRENCHANT was detecting surface vessels by means of her passive sonar. At 0217 hrs TRENCHANT had a close sonar contact to starboard and turned to port to avoid it. Banging noises were then heard in the submarine and it was assumed by those in the control room that a fishing trawl had been snagged. 'The Sonar Controller reported almost immediately that a trawl had possibly been :snagged and the order to stop engines was given from various sources. The fact that a trawl had been snagged was confirmed shortly afterwards by the noise of the trawl wires dragging down the outside of the submarine. TRENCHANT surfaced at about 0300 hrs and a trawl wire was discovered fouled on the submarine casing. Later in the morning it was reported that ANTARES was missing and a full scale search operation was mounted. The bodies of the four crew of ANTARES were recovered.

In 2000 HMS Tireless docked in Gibraltar for nearly a year to undergo repairs for a leak in the cooling system of its nuclear reactor. Spain, which possesses no nuclear submarines, objects to Britain using naval facilities in Gibraltar to repair its nuclear-powered submarines. When HMS Tireless docked in Gibraltar, the Socialists accused the conservative Popular Party Government of José María Aznar of "incompetence" and of endangering the lives of those living in the area.

HMS Trafalgar was grounded near the Isle of Skye in October 2002 because of basic navigational errors during a training exercise for students. The reactor plant was unaffected, but £5m of repairs were needed on the hull, a complex structure made of thick high-strength steel.

In early 2004 HMS "Trafalgar" completed a major repair at Devonport. Rigorous checks were undertaken to validate all aspects of her seaworthiness prior to sailing. Press reports alleging that the vessel was in an unfit condition to proceed to sea were completely unfounded. Further claims that safety specialists were among those crew members left ashore for medical assessment were also untrue; none of those personnel can be described as safety experts.

HMS Trafalgar returned to sea to test equipment and systems following a major period of maintenance and repair. Before a submarine undertakes such a period at sea it goes through a complex and exhaustive testing procedure by a number of authorities which is fully documented. HMS Trafalgar passed that inspection. If she had any major defects or failing systems she would not have been allowed to return to sea. The allegations made by members of her crew have been assessed by appropriately qualified engineering personnel. The allegations that HMS Trafalgar had major defects which should have prevented her return to sea are unfounded.

Of the 124 crew members on board HMS Trafalgar, 12 expressed general reservations over the material state of the submarine following a period of maintenance and repair. These concerns centred on three areas. These being: the release, as a result of human error, of diesel exhaust fumes into the submarine; a leak into the submarine, resulting from faulty equipment not related to recent maintenance, during pressurisation of the Freon domestic refrigerant gas system; and concerns related to faults to the paint finish of the escape hatch docking seat which had been inspected and judged to be minor and insufficient to prevent successful docking of a rescue submersible if that extremely unlikely event should prove necessary. Following these individual expressions of concern, made through the appropriate channels, and the levels of stress shown by 11 of these individuals, the Commanding Officer decided to remove these sailors from the submarine for medical assessment. In doing so, he acted in the best interests of those individuals and the Service. The twelfth member of the crew who discussed his concerns with the Commanding Officer elected to remain on board and sailed with Trafalgar.

Under the Swiftsure and Trafalgar class Final Phase Update program, the newest four Trafalgar boats were upgraded to bring their equipment up to the standard of the successor Astute class. In April 2008 the Royal Navy's nuclear-powered attack submarine, HMS Torbay, returned to the Fleet following a year-long £8M refit at HM Naval Base Clyde, Faslane, which equipped her to be the most powerful boat in the fleet. In addition to routine maintenance work, the Trafalgar class submarine has been upgraded to carry the latest longer-range Block 4 version of the Tomahawk cruise missile and an improved version of the world-leading Sonar 2076 system. New communications equipment allows internet access even when the submarine is deep underwater, and a new charting system was due to be trialled on board.

In November 2008 environment watchdogs were investigating the leak at Devonport, in Plymouth, from HMS Trafalgar in which 280 liters of contaminated water were spilled. The spill is the largest in 23 years but tests in the river have showed no signs of increased radiation and the Environment Agency says there is no risk to the public. Shortly after midnight on the night of November 6/7, during a standard operation to transfer primary coolant from HMS Trafalgar to an effluent tank on the jetty, a hose ruptured, resulting in a leak of the coolant. A maximum of 280 liters of coolant were discharged from the hose onto the submarine casing, jetty and into the Hamoaze area of the river Tamar.

On 05 December 2009 the nuclear-powered HMS Trafalgar hauled down the flag in a decommissioning ceremony at Devonport. Although 13 is unlucky for some, HMS Trafalgar had a special relationship with the number. The submarine's designated number was SSN-13, she had 13 commanding officers and had two commissions of 13 years each with a nuclear refuelling in between. The sub which will be stripped of its reactor and reusable parts and stored, travelled 200,000 miles on the surface and a further 500,000 miles underwater since its launch in Barrow in 1981.

In may 2010 Britain's Ministry of Defence said it was investigating how two nuclear submarines were allowed to go to sea with a serious safety defect. Turbulent and Tireless went to sea without the use of safety valves designed to release pressure from steam generators in an emergency, according to a leaked official memo written last week and published by The Guardian. Turbulent reportedly operated with the glitch for more than two years, while Tireless was affected for more than one year. Both are nuclear-powered attack submarines. Experts say that the situation meant radioactive water could have leaked into the submarine if pressure had built up to dangerous levels.

Two UK Royal Navy (RN) Trafalgar-class nuclear-powered attack submarines (SSNs) are to be extended in service by up to 18 months to cover gaps caused by delays to the replacement Astute-class program. HMS Talent will now serve an addition year beyond her planned retirement date in 2021 and HMS Triumph will have to serve an additional 18 months beyond her previously 2022 out of service date.

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Page last modified: 22-09-2021 12:59:33 ZULU