[1][note 3] The ships were powered by two Babcock & Wilcox boilers connected to the two-shaft English-Electric geared steam turbines providing 30,000 shaft horsepower (22,000 kW).

[4] The ships were initially armed with two 3-inch (76 mm)/50 calibre[note 4] dual-purpose guns mounted in a single turret forward.

[7] The two Annapolis-class destroyers were built late enough to incorporate the helicopter hangar retrofitted to the St. Laurent class and the "Beartrap" haul-down device.

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,[8] and to allow them to continue to operate as part of NATO task forces.

The Annapolis class received the same sensor and communications upgrades that others in the St Laurent family of ships received, including the installation of a new tactical data system (ADLIPS), updated radars and sonars, fire control and satellite navigation.

[12] Both ships spent the majority of their career split between Canada's Pacific and Atlantic coasts with the Annapolis being at Esquimalt and Nipigon at Halifax.

They spent most of their careers participating in training exercises, such as Ocean Safari '87[4] or representing Canada at ceremonial situations, such as commemorating the Battle of the Atlantic in May 1993 at Liverpool.

[4] In 1995, after illegal fishing had taken place in Canada's exclusive economic zone, Nipigon was sent to support Canadian Coast Guard and Fisheries vessels in apprehending the perpetrators, in what became called the Turbot War.

[13] Nipigon remained in the fleet until 1998 as a trials ship for the ETASS Mod 5 towed sonar system which was a precursor to the CANTASS that is currently fitted on the Halifax class of frigates.

[13] After years of court battles, Annapolis was sunk as an artificial reef off Gambier Island, British Columbia in 2015.