Designed in 1957, they were to be 1,000 tonnes (980 long tons) heavier, 50 feet (15 m) longer and have engines that were 20,000 horsepower (15,000 kW) stronger than those installed in the St. Laurents.

Instead, budget issues forced a repeat of the previous Restigouche class, with changes intentionally minimized.

[7][note 1] The class was powered by two Babcock & Wilcox boilers connected to the two-shaft English-Electric geared steam turbines creating 30,000 shaft horsepower (22,000 kW).

[8] These torpedoes were installed in order to provide more distance in their attack on a submarine, with a range of 4,500 yards (4,100 m) at 15 knots (28 km/h; 17 mph), compared to the relatively close-in nature of the Limbo mortar.

Encompassing all the classes based on the initial St. Laurent (the remaining St. Laurent, Restigouche, Mackenzie, and Annapolis-class vessels), the DELEX upgrades were meant to improve their ability to combat modern Soviet submarines,[13] and to allow them to continue to operate as part of NATO task forces.

This meant that the ships would receive the new tactical data system ADLIPS, new radars, new fire control and satellite navigation.

[1][16] The Mark 46 torpedo had a range of 12,000 yards (11,000 m) at over 40 knots (74 km/h; 46 mph)[16][18] with a high-explosive warhead weighing 96.8 pounds (43.9 kg).

Mackenzie was laid down by Canadian Vickers of Montreal on 15 December 1958, followed by Yukon on 25 October 1959 by Burrard Dry Dock of Vancouver, Saskatchewan on 29 October 1959 by Victoria Machinery Depot Co. of Victoria, British Columbia, and Qu'Appelle from Davie Shipbuilding of Lauzon, Quebec, on 14 January 1960.

[20] They commissioned in a different order, beginning with Mackenzie on 6 October 1962, Saskatchewan on 16 February 1963, Yukon on 25 May 1963 and Qu'Appelle on 14 September 1963.

[9] Mackenzie spent the better part of her service life on the west coast of Canada, with the exception of her first year based at Halifax.

Mackenzie had an uneventful career, spending most of her time as a training ship or performing general duties, such as port visits and naval exercises.

The ship was paid off on 3 August 1993 and sunk as an artificial reef off Rum Island, near Sidney, British Columbia.

In February 1970, she transferred back east and acted as the flagship for STANAVFORLANT, the standing NATO fleet during the Cold War.

She spent the majority of her career acting as a training ship and performing general fleet duties, such as port visits.

However, before the ceremonial scuttling could take place, ex-Yukon flooded in bad weather and sank the day before at the site.