Mackenzie-class destroyer

The last two hulls were completed to the post DDH conversion St. Laurent-class design (which included helicopter hangars); they were designated as the Annapolis class instead. The four Mackenzie-class destroyers spent most of their service in the Pacific Ocean, used primarily in a training role. Their only significant update was the DELEX (destroyer life extension) program, which was completed between 1982 and 1985 and updated their navigational radar and their sonar. The initial design for what became known as the Mackenzie class was for an enlarged version of the St. Laurent class. 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. They would also have improved radar and sonar installed. Instead, budget issues forced a repeat of the previous Restigouche class, with changes intentionally minimized. Four ships were ordered in 1957, two more in 1958.