BIDDER [Mk 20E] or the US Mark 35) were included. However, they were never fitted. Machinery The vessels of the St. Laurent class had two Babcock & Wilcox water tube boilers installed. The steam produced by these boilers was directed at two geared steam turbines which powered two shafts, providing to drive the ship at a maximum speed of . The ships had an endurance of at . DDH conversion Following successful trials aboard the frigate and sister ship , plans to convert the St. Laurent class took shape. Th development of the beartrap, installed in Assiniboine during her 1962–63 conversion, finalized the concept. By keeping the aircraft secure, the beartrap eliminated the need for deck handling from landing to the hangar, or from hangar to takeoff. In the conversion to a helicopter-carrying vessel, Assiniboine was gutted except for machinery and some forward spaces. The hull was strengthened, fueling facilities for the helicopter and activated fin stabilizers installed. The fin stabilizers were to reduce roll in rough weather during helicopter operations. All seven St Laurents were fitted with helicopter platforms and SQS 504 Variable Depth Sonar (VDS). The single funnel was altered to twin stepped funnels to permit the forward extension of the helicopter hangar. To make room for the helicopter deck, the aft 3-inch mount and one of the Limbos were removed. The two 40 mm guns were also removed. Following the conversion, the displacement remained the same at standard load but at full load, it increased to . DELEX program In the late 1970s, under the Destroyer Life Extension (DELEX) program was commissioned to upgrade ten of the St. Laurent-class ships with new electronics, machinery, and hull upgrades and repairs. However, only enough was done to keep the ships in service into the late 1980s. For the St. Laurents, this meant hull and machinery repairs only. Operational history Assiniboine was laid down on 19 May 1952 by Marine Industries at Sorel, Quebec and launched on 12 February 1954. The ship was commissioned at Sorel into the Royal Canadian Navy on 16 August 1956 and initially carried the hull number DDE 234 as a destroyer escort. After commissioning, Assiniboine was assigned to the east coast as part of the Third Canadian Escort Squadron. From October to November 1956, Assiniboine sailed with the First Canadian Escort Squadron to northern Europe, making a series of port visits. In January 1959, she