The Type 2400/Upholder/Victoria-class diesel submarines have been something of an albatross of naval history. The last snorkel boats built in the UK, they were to replace the hard-serving Oberon-class boats for surveillance and coastal special operations but the end of the Cold War found the Admiralty rapidly losing interest in the series. Of the eight planned ships, only four (Upholder, Unseen, Ursula, and Unicorn) reached the Royal Navy between 1990-93. Then these boats, just barely past their shakedowns, were all paid off in 1994.
After a deal fell through to sell them to Pakistan (!) London and Ottawa got to talking and Canada picked up the quartet for a song to replace their own Oberon-class boats in 1998. Then came an extensive refit/rework on these low-mileage boats that only saw them begin to enter Canadian service in 2003.
Since then, the four boats, (now the HMCS Chicoutimi, Victoria, Corner Brook, and Windsor) have had a mixed bag of incidents to include a fairly serious fire at sea (Chicoutimi), “catastrophic damage” to the electrical system of another boat (Victoria) and a sea-floor collision (Corner Brook, followed by a dry dock fire), as well as mechanical issues and hundreds of bad welds that have left them tied up for years at a time.
Nonetheless, they have had periods of good luck, including a 105-day training cruise in 2015 for Windsor followed by a 133-day Atlantic/Med patrol in 2018 (the first time a Canadian submarine was operational in the Mediterranean in more than four decades) and a 197-day West Pac deployment by Chicoutimi in 2018 (the first time a Canadian submarine has visited Japan since HMCS Grisle in May 1968). Now, pushing into their third decade of service, they are getting closer to being right with Victoria recently finishing sea trials and crew training following an extensive refit. Corner Brook, which had been laid up since 2014, is supposed to be repaired enough to return to service sometime late this year. Windsor is reportedly doing the same, recently completing a lengthy Transitional Docking Work Period (TDWP).
Three of the boats so far have ditched their old Type 2040 sonar for a new AN/BQQ-10 A-RCI sonar suite, similar to American submarines. They are also now armed with the Mark 48 MOD 7AT torpedo, an upgrade from the previous Mark 48 MOD 4M that required significant upgrades to the 1990s-vintage weapon handling, weapon discharge, and fire control systems.
The RCN recently released this sizzle reel, planning to keep the quartet around for another decade.