Duty done – farewell HMS Trenchant

HMS Trenchant returned to Devonport for the final time on 25 March. She will be formally decommissioned before joining the long list of submarines awaiting disposal. Here we take a brief look at her career and the current status of the Royal Navy’s SSN fleet.

HMS Trenchant was laid down at Barrow Shipyard in October 1985, the fifth of the seven Trafalgar class submarines constructed for the RN. The highly successful T-boat programme delivered 7 boats to the RN over an 8 year period, in stark contrast to the troubled Astute programme, which will take about 18 years to deliver the same number of boats. The Trafalgars are also widely acknowledged to be the best SSN design of the Cold War and are still proving to be effective well into the 2020s.

Trenchant was commissioned in 1989 but her early career was marred by an accident when she became ensnared in fishing nets and sunk the trawler Antares with the loss of 4 lives. The accident led to a major change in operating procedures which have been effective at preventing any further collisions between fishing vessels and submerged RN submarines.

There is limited information about Trenchant’s career in the public domain for obvious reasons but she has been deployed all over the world. In the 1990s this still involved tracking the diminishing Russian submarine fleet in the High North and North Atlantic but as time went on, RN submarines were increasingly deployed further afield, particularly to the Middle East. In 1998 the Tomahawk Land Attack missile entered service with the RN and for many years, at least one SSN was permanently deployed East of Suez as the ‘duty TLAM boat’, ready to respond to events in the region.

In June 2007, Trenchant conducted the RN’s first live firing trial of the new Block IV TLAM in the Gulf of Mexico. Between 2009-11 she underwent a major refit and Devonport. In 2013 she conducted a patrol that lasted 335 days, covering 38,000 nm while operating in the Mediterranean, Gulf and the Indian Ocean, a record that still stands for the longest continuous patrol ever carried out by an RN SSN.

Delays to the delivery of the Astute class vessels ensured Trenchant would have her life extended. She was subject to the largest and most complex SSN refit and upgrade package ever undertaken at Devonport from 2014-16, involving about 650,000 man-hours of work. Not for the first time, problems emerged with cracks in the ageing pipework in the reactors of the Trafalgar class and in early 2017 some media outlets were even predicting Trenchant would never sail again. Given their critical importance to the defence of the nation and protection of the deterrent, there could be no question of decommissioning the three remaining boats and the reactors were repaired. HMS Trenchant returned to sea in April 2017 and has had an exceptionally busy final four years in service.

The majority of her time would appear to have been spent in the NATO area as the Russian submarine threat has increased dramatically again in the last decade. In April 2018, she broke through the ice at the North Pole, joining the USS Connecticut and USS Hartford at the conclusion of joint under-ice exercises.

She briefly hit the headlines in April 2020, when her CO was relieved of command after allowing a dockside Barbeque at Devonport against advice from his superiors. After intense patrols in a confined space, it’s important for morale to allow submariners to let off steam, something difficult to manage while adhering to strict pandemic lockdown rules. Trenchant conducted her last major deployment in 2020, returning home in November. During more than 4 months away she operated with vessels from 13 nations and covered 18,000 nautical miles. Her final few months in service were mostly spent operating out of Faslane.

Decommissioning a nuclear submarine is not as straightforward as de-storing the boat and then leaving it tied up in a basin, pending a trip to the scrapyard. A small duty watch has to be maintained on board to oversee the reactor as it comes offline for up to 2 years. Trenchant will eventually go into afloat storage and join the 12 other hulks awaiting dismantling at Devonport. (Assuming HMS Courageous is preserved as a museum). 8 of the 12 boats are currently awaiting nuclear de-fuelling but the facilities to remove fuel from retired boats are not yet ready at Devonport. There is now such a backlog and the process will be so slow that under current plans it will be well into the 2040s before the hulk of Trenchant is dismantled and fully disposed of.

Tribute should be paid to the hundreds of submariners who have served on board and the engineers that have supported her during her 32 years of duty. The submarine service tends to be in the headlines when things go wrong while their achievements are often overlooked or misunderstood. For submariners, the line between peacetime and wartime posture is small and they operate in a hostile environment that leaves little room for error. The SSN force is the gatekeeper for the nuclear deterrent, the first line of defence and the most potent threat to surface ships. Whether it is gathering intelligence, trailing adversary submarines or supporting special forces there is a very long task list for the RN submarine service. HMS Trenchant will be effectively replaced by HMS Audacious but the force will number just 6 boats until the arrival of HMS Agincourt by the end of 2026 brings the total to 7.