HMS Trenchant (S91)

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Royal Navy Trafalgar-class submarine HMS Trenchant (S91).jpg
HMS Trenchant (2017)
United Kingdom
NameHMS Trenchant
Ordered22 March 1983
BuilderVickers Shipbuilding, Barrow-in-Furness
Laid down28 October 1985
Launched3 November 1986
Commissioned14 January 1989
HomeportHMNB Devonport, Plymouth
Fatein active service
General characteristics
Class and type Trafalgar-class submarine
  • Surfaced: 4,500 to 4,800 t (4,700 long tons; 5,300 short tons)[1]
  • Submerged: 5,200 to 5,300 t (5,200 long tons; 5,800 short tons)[1]
Length85.4 m (280 ft)[1]
Beam9.8 m (32 ft)[1]
Draught9.5 m (31 ft)[1]
  • 1 × Rolls Royce PWR1 nuclear reactor
  • 2 × GEC steam turbines
  • 2 × WH Allen turbo generators; 3.2 MW
  • 2 × Paxman diesel alternators 2,800 shp (2.1 MW)
  • 1 × pump jet propulsor
  • 1 × motor for emergency drive
  • 1 × auxiliary retractable prop
SpeedOver 30 knots (56 km/h), submerged[1]
Electronic warfare
& decoys
  • 2 × SSE Mk8 launchers for Type 2066 and Type 2071 torpedo decoys
  • RESM Racal UAP passive intercept
  • CESM Outfit CXA
  • SAWCS decoys carried from 2002
  • 5 × 21-inch (533 mm) torpedo tubes with stowage for up to 30 weapons:

HMS Trenchant is a Trafalgar-class nuclear-powered fleet submarine of the Royal Navy built by Vickers Shipbuilding, Barrow-in-Furness. Trenchant is in service and is based at HMNB Devonport. She is the third vessel and the second submarine of the Royal Navy to be named for the characteristic of vigour and incisiveness.

The submarine was ordered on 22 March 1983. She was laid down by Vickers Shipbuilding on 28 October 1985, and was launched on 3 November 1986 in the presence of Vice Admiral Sir Arthur Hezlet, who had commanded the World War II T-class submarine Trenchant.[2] She was commissioned into the Royal Navy on 14 January 1989.[3]

Following the Integrated Review of 2020, Trenchant is now scheduled to decommission by the end of 2021.[4]

Operational history


On 22 November 1990, the nets of the fishing vessel Antares were snagged by Trenchant in the Bute Sound in Scotland. At the time the submarine was conducting a 'Perisher' Submarine Command Course exercise in company with the frigate HMS Charybdis. Antares was pulled under with the loss of all four members of the crew.[5][6][7]

In July 1997, the submarine ran aground off the western coast of Australia.[8] While approaching Fremantle, Western Australia, the submarine remained at a depth of 200 metres (660 ft) and grounded when she made contact with the continental shelf, coming to rest on a sloping patch of seafloor.[8] Trenchant was able to free herself, and an inspection by divers reported no significant damage.[8]

Trenchant tested the non-hull-penetrating optronic mast in 1998. She also trialled a camouflage paint scheme comprising jagged shapes of various colours, including pale blue.[citation needed]

2000–present day

HMS Trenchant surfacing through the Arctic ice during ICEX 2018.

On 21 June 2007, the submarine became the first Royal Navy vessel to fire the new Block IV Tomahawk cruise missile in a live-firing trial in the Gulf of Mexico off the United States coast.[9]

In late 2009, Trenchant entered the Devonport submarine refit complex to undertake a 2-year refit and upgrade programme. Upon completion of the programme, the submarine underwent a rededication service on 6 June 2011 to welcome the boat back to active service.[10]

On 22 May 2013, Trenchant completed the longest patrol ever carried out by a Royal Navy SSN. The patrol lasted 335 days (11 months) during which the submarine sailed 38,800nm.[11] During this time the vessel has visited six different ports: Fujairah, UAE; the British Indian Ocean Territory – Diego Garcia; the Kingdom of Bahrain; Aqaba, Jordan; Souda Bay, Crete; and Gibraltar.[12][13]

Following a maintenance period involving a weapon and sensors upgrade, Trenchant returned to service in August 2016.[14]

In March 2018, Trenchant, along with American submarines USS Connecticut and USS Hartford, participated in ICEX 2018, surfacing through the Arctic ice. This was the first time a Royal Navy submarine participated in ICEX since 2007.[15][16][17]

In April 2020 a Royal Navy investigation was opened into videos of sailors having a party while under lockdown.[18] The submarine had returned to Devonport for repairs and the crew were required to stay on board in isolation while repairs were completed because of COVID-19 restrictions.[18] It was confirmed that some sailors were drinking alcohol and it was reported that the captain had approved the party despite being advised that it might be inappropriate.[19] The captain was sent home and later relieved of his command, and moved to another role within the Navy.[20]

On 25 March 2021 she sailed into Plymouth for the last time, flying her decommissioning pennant, ahead of decommissioning later in 2021.[21]


Trenchant is affiliated with the following military and civilian organisations, bodies & individuals:[10]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Bush, Steve (2014). British Warships and Auxiliaries. Maritime Books. p. 12. ISBN 1904459552.
  2. "HMS Trenchant (S91) - Royal Navy". Retrieved 7 August 2016.
  3. Jane's Fighting Ships, 2004–2005. Jane's Information Group Limited. p. 796. ISBN 0-7106-2623-1.
  4. "The Defence Command Paper and the future of the Royal Navy | Navy Lookout". Retrieved 23 March 2021.
  5. "Collision between pelagic trawler Antares and trafalgar-class submarine HMS Trenchant with loss of 4 lives Marine Accident Investigation Branch report - GOV.UK". Retrieved 7 August 2016.
  6. "Kintyre". Archived from the original on 29 January 2008. Retrieved 12 December 2007.
  7. Cusick, James (10 July 1992). "Submarine crew blamed for sinking of Antares". The Independent. London.
  8. 8.0 8.1 8.2 Stewart, Cameron (8 April 2009). "Brits' nuclear sub accident surfaces". The Australian. p. 6. Retrieved 10 April 2009.
  10. 10.0 10.1 "Navy News - Reporting from the Fleet". Retrieved 7 August 2016.
  11. "UK: HMS Trenchant Comes Home from the Longest Patrol Ever". Retrieved 7 August 2016.
  12. "Trenchant completes record-breaking mission- Royal Navy". Retrieved 7 August 2016.
  13. "Royal Navy submarine returns from longest patrol". Ministry of Defence. 24 May 2013. Retrieved 3 October 2017.
  14. George Allison (22 August 2016). "Nuclear submarine HMS Trenchant rejoins the fleet". UK Defence Journal. Retrieved 16 February 2017.
  15. Royal Navy (15 March 2018). "Royal Navy submarine breaks through Arctic ice for major exercise". Royal Navy. Retrieved 29 March 2018.
  16. US Navy (29 January 2018). "ICEX 2018 Welcome Letter" (PDF). US Navy. Retrieved 29 March 2018.
  17. "Nuclear sub breaks ice at North Pole". BBC News (in English). Retrieved 24 April 2018.
  18. 18.0 18.1 "Coronavirus: Royal Navy submarine crew had lockdown party". BBC News. 23 April 2020. Retrieved 24 April 2020.
  19. Haynes, Deborah (24 April 2020). "HMS Trenchant: Nuclear submarine commander holds BBQ for crew during lockdown". Sky News. Retrieved 28 April 2020.
  20. "Navy submarine lockdown party captain sacked". BBC News (in English). 28 April 2020. Retrieved 28 April 2020.
  21. Abel, Stuart; Elmes, Sarah (25 March 2021). "Royal Navy submarine HMS Trenchant sails into Plymouth for the last time".


  • Submarines, War Beneath The Waves, From 1776 to the Present Day, by Robert Hutchinson

External links