They were pitched over the side by a modified depth charge thrower. Improved Restigouche Escorts (IRE) As part of the 1964 naval program, the Royal Canadian Navy planned to improve the attack capabilities of the Restigouche-class. Unable to convert the vessels to helicopter-carrying versions like the St. Laurents due to budget constraints, instead Restigouche-class ships were to receive variable depth sonar (VDS) to improve their sonar range, placed on the stern, and the RUR-5 anti-submarine rocket (ASROC). The destroyers also received a stepped latticed mast. Called the Improved Restigouche Escorts (IRE), Terra Nova was the first to undergo conversion, beginning in May 1965. The conversion took ten months to complete, followed by sea trials. The sea trials delayed the conversion of the next ship for four years. By 1969, the budget for naval programs had been cut and only four out of the seven (Terra Nova, Restigouche, Gatineau and Kootenay) would get upgraded to IRE standards and the remaining three (Chaudière, Columbia, and St. Croix) were placed in reserve. The ASROC launcher replaced the 3 in/50 cal twin mount and one Mk 10 Limbo mortars aft. The ASROC was rocket-propelled acoustically-guided Mk 44 torpedo that had a minimum range of and a maximum range of . Destroyer Life Extension (DELEX) The Destroyer Life Extension (DELEX) refit for the four surviving Restigouche-class ships was announced in 1978. An effort by Maritime Command to update their existing stock of naval escorts, the DELEX program affected 16 ships in total and came in several different formats depending on the class of ship it was being applied to. On average, the DELEX refit cost $24 million per ship. For the Restigouches this meant updating their sensor, weapon and communications systems. The class received the new ADLIPS tactical data system, new radar and fire control systems and satellite navigation. They were also fitted with a triple torpedo tube mounting to use the new Mk 46 torpedo. The ships began undergoing their DELEX refits in the early 1980s. However, by the time the ships emerged from their refits, they were already obsolete as the Falklands War had changed the way surface battles were fought. Gulf War refit With the advent of the Gulf War in August 1990, Maritime Command was asked to have a fleet of ships available to send to the Persian Gulf, preferably three ships. The and the replenishment ship would be made part