The Upholder/Victoria class is a four-boat Type 2400 diesel-electric submarine line designed in the United Kingdom as the Royal Navy's late-Cold-War successor to the Oberon class. The Vickers Shipbuilding and Engineering design was ordered for HMS Upholder in 1983, followed by three Cammell Laird-built boats, but the Royal Navy withdrew the class in 1994 as it moved to an all-nuclear submarine force. Canada acquired the reserve boats in 1998, renamed them as the Victoria class, and rebuilt them around Canadian fire-control, communications, and Mk 48 heavyweight-torpedo requirements. Current Royal Canadian Navy and National Defence material frames the class as Canada's covert underwater-surveillance and deterrence force while Victoria Class Modernization keeps the boats in service into the mid-to-late 2030s.
All four completed Type 2400 boats entered brief Royal Navy service as Upholder-class submarines before Canada accepted them into the Victoria-class program.
| Royal Navy boat | Builder | RN service | Canadian name |
|---|---|---|---|
| HMS Upholder S40 | Vickers/VSEL, Barrow-in-Furness | Commissioned June 9, 1990; paid off April 29, 1994 | HMCS Chicoutimi SSK 879, commissioned RCN September 3, 2015 |
| HMS Unseen S41 | Cammell Laird, Birkenhead | Commissioned July 20, 1991; paid off April 6, 1994 | HMCS Victoria SSK 876, commissioned RCN December 2, 2000 |
| HMS Ursula S42 | Cammell Laird, Birkenhead | Commissioned May 8, 1992; paid off June 16, 1994 | HMCS Corner Brook SSK 878, commissioned RCN June 29, 2003 |
| HMS Unicorn S43 | Cammell Laird, Birkenhead | Commissioned June 25, 1993; paid off October 16, 1994 | HMCS Windsor SSK 877, commissioned RCN October 4, 2003 |
Sources: Royal Canadian Navy ship histories for HMCS Chicoutimi, Victoria, Corner Brook, and Windsor.
The Upholder/Victoria class has documented torpedo-tube weapon relationships in both British and Canadian service, with the Canadian fit centered on Mk 48 heavyweight torpedoes.
| Carried item | Item type | Carriage evidence |
|---|---|---|
 | Heavyweight torpedo | Royal Canadian Navy history says the Canadianization package covered in-service Mk 48 heavyweight torpedoes and that HMCS Victoria fired a warshot Mark 48 torpedo in 2012. Later Canadian sources describe the Victoria-class upgrade path from Mk 48 Mod 4M to Mk 48 Mod 7AT. Sources: Canadian submarine history, Canada's most modern submarine returns to the water, Maritime Engineering Journal 114: Heavyweight Torpedo Upgrade |
 | Submarine-launched anti-ship missile family | Naval Technology describes the Upholder-class missile-firing system for Sub-Harpoon; this is treated as historical British-service compatibility, separate from the later Canadian Mk 48-centered fit. Sources: Naval Technology: Victoria class |
The class's weapon fit is best read in two periods: the original Royal Navy Upholder configuration and the later Canadian Victoria-class configuration. Canadian service centered the boats on Mk 48 heavyweight torpedoes, then began moving the fleet from the older Mk 48 Mod 4M to the Mk 48 Mod 7AT through the Heavyweight Torpedo Upgrade project.
Canada's 2021 Navy article says Corner Brook became able to fire the Mk48 7AT, while Windsor had equipment installed for Mk48 7AT firings and Chicoutimi was scheduled to receive the same torpedo capability.
The 2025-2026 Maritime Engineering Journal describes the Mod 7AT work as replacing the legacy Weapon Data Converter with a Weapon Control Manager that links the torpedo to the submarine fire-control console.
Canada's Corner Brook update says the boat received the BQQ-10 sonar suite, improving processing and displays compared with the previous 2040 sonar suite.
Sources: Canadian submarine history; Canada's most modern submarine returns to the water; Maritime Engineering Journal 114: Heavyweight Torpedo Upgrade.
The Journal of Naval Engineering Type 2400 paper says the Naval Staff Requirement was endorsed in early 1980 after outline and naval-staff target work in 1978 and 1979.
Sources: JNE: Type 2400 Upholder Class
The Type 2400 paper says HMS Upholder was ordered in November 1983; Royal Canadian Navy ship history records the lead boat as laid down at Vickers/VSEL Barrow-in-Furness on November 2, 1983.
Sources: JNE: Type 2400 Upholder Class, Royal Canadian Navy: HMCS Chicoutimi
Royal Canadian Navy ship history records the former HMS Upholder as commissioned into Royal Navy service on June 9, 1990, before later becoming HMCS Chicoutimi.
Sources: Royal Canadian Navy: HMCS Chicoutimi
A 1991 Hansard debate described the Upholder class as the first new British-designed SSK in 30 years, introduced to replace Oberon-class submarines.
Sources: Hansard: The Royal Navy 1991
In 1993 the UK government told Parliament that the class's primary role had been GIUK-gap patrol against Soviet submarines, but that the reduced former-Soviet submarine threat made the Upholder requirement subject to review.
Sources: Hansard: Royal Navy 1993 Upholder role
Hansard later recorded that withdrawal of the Royal Navy's most recent conventional submarine class, the Upholder class, was completed in 1994.
Sources: Hansard: Conventional Submarines 1997
UK and Canadian parliamentary records describe an eight-year lease-to-purchase arrangement for the four reserve Upholder-class boats, with Canada gaining unrestricted use and later purchase options.
Sources: Hansard: Upholder Class Submarines 1998, Canadian Parliament Victoria class acquisition report
The former HMS Unseen was accepted by Canada as HMCS Victoria on October 6, 2000 and commissioned into Canadian service on December 2, 2000.
Sources: Royal Canadian Navy: HMCS Victoria
The RCN history page says HMCS Victoria was the first boat of the class to reach high readiness and successfully fired a warshot Mark 48 torpedo in 2012.
Sources: Canadian submarine history
Canada's Victoria-class modernization page says the 2017 defence policy announced continued operation and modernization of the class into the mid-2030s.
Sources: Victoria class modernization
An RCN Maple Leaf article says Corner Brook's extended docking work period included grounding repairs, a Universal Modular Mast, BQQ-10 sonar suite, and the ability to fire the Mk 48 7AT torpedo.
Sources: Canada's most modern submarine returns to the water
The Maritime Engineering Journal says HMCS Windsor fired exercise Mk 48 Mod 7AT torpedoes at AUTEC in August 2022 during first-of-class trials for the Victoria-class upgrade.
Sources: Maritime Engineering Journal 114: Heavyweight Torpedo Upgrade
The Maritime Engineering Journal reports successful Corner Brook Mk 48 Mod 7AT firing trials at Nanoose in July 2025 after the boat emerged from an extended docking work period with BQQ-10 sonar and Mod 7AT capability.
Sources: Maritime Engineering Journal 114: Heavyweight Torpedo Upgrade
National Defence's Victoria Class Modernization page lists the Safran Trusted 4D Canada periscope-modernization contract award and states first delivery is planned for 2026, with initial operational capability in 2031 and full operational capability in 2034.
Sources: Victoria class modernization
