St . Laurent - class destroyer The " St . Laurent " class destroyer was a class of destroyers that served the Royal Canadian Navy and later the Canadian Forces from the mid - 1950s to the mid - 1990s . This was the first major class of warship designed and built in Canada . They were similar to the British Type 12 " Whitby " class frigate , but used more American equipment than British . There were seven ships of the class commissioned between 1955 and 1957 . They were originally intended as destroyer escort s ( DDE ) but were later refitted and reclassed as destroyer helicopter escorts ( DDH ) . Construction . The need for the " St . Laurent " class came about in 1949 when Canada joined NATO and the Cold War was in its infancy . The RCN was assigned responsibility for anti - submarine warfare and controlling sea space in the western $ 3 . Design work for a new class of destroyer escorts began that year with the original completion date slated for 1955 . They were designed by Montreal naval architects German and Milne " under the direction of a senior constructor , Sir Rowland Baker , seconded from the [ British ] Director of Naval Construction . . . Baker produced a design basically similar to the Whitby [ Type 12 ] , but incorporating several ideas of his own . . . To flatter Canadian susceptibilities , Baker was careful to make the appearance as different as possible from the " Whitby " , but the ship that resulted was virtually a " Type 12 " specification ( albeit with a different hull form ) translated by a different design team . " The " St Laurent " class were " built to an operational requirement much like that which produced the British Type 12 , and powered by the same machinery plant , she was strikingly different . The rounded deck - edge forward was adopted to prevent ice forming . " She was designed to operate in harsh Canadian conditions . They were built to counter nuclear , biological and chemical attack conditions , which lead to a design with a rounded hull , a continuous main deck , and the addition of a pre - wetting system to wash away contaminants . The living spaces on the ship were part of a " citadel " which could be sealed off from contamination for the crew safety . The ships were sometimes referred to as " Cadillacs " for their relatively luxurious crew compartments ; these were also the first Canadian warships to have a bunk for every crew member since previous warship designs had used hammocks . Other innovative features not found on other ships of its time included an operations room separate from the bridge , from which the captain could command the ship while in combat , 12 separate internal telephone systems , air conditioning , and the latest advances in radar and sonar technology . The " St . Laurent " class originally called for 14 vessels to be commissioned no later than 1955 ; however , changing design specifications due to the rapidly changing Cold War naval environment , as well as Canada ' s wartime priorities during the Korean War , saw only the first 7 completed by 1957 . The remaining 7 vessels were built as the follow - on " Restigouche " - class to incorporate advancements in naval warship design in the preceding years . There were also two essentially similar follow - on classes , the Mackenzie Class ( 4 ships completed 1962 - 63 ) and the Annapolis Class ( 2 ships , completed 1964 ) , the latter completed as helicopter carrying destroyer escorts from the onset , and not converted later as were the seven St Laurent Class ships . Armament . The " St . Laurent " class was fitted with twin 3 inch / L50 guns for engaging both surface and air targets . Her anti - submarine armament consisted of a pair of triple barrelled Limbo ASW mortars in a stern well . The stern well had a roller top to close it off from following seas . " As in the case of the Type 12 , the design included provision for long - range homing torpedo es ( in this case BIDDER [ Mk 20E ] or the US Mark 35 . They were never fitted however . " As built , the twin 3 - inch 50 - calibre anti - aircraft mounts were installed without shields . These were added in 1963 . The gun housings are fibreglass . ( " Jane ' s Fighting Ships 1963 - 64 " shows photographs taken in 1962 and 1963 respectively of " Skeena " and " Assiniboine " with these . ) Machinery . The vessels of the " St . Laurent " class had two Babcock & Wilcox water tube boilers installed providing 600 PSI ( 4 . 1 MPa , 42 kgf / cm² ) at . The steam produced by these boilers was directed at two geared steam turbines which powered two shafts , providing 30 , 000 HP ( 22 MW ) to drive the ship at a maximum speed of . By the early 1990s , the quoted maximum speed was only 27 kt . " Propelling machinery is of British design . Yarrow & Co Ltd , Scotstoun , Glasgow , received an order from Canadian Vickers for the supply of a complete set of machinery for the " St . Laurent " , the other ships being supplied with machinery manufactured in Canada . The main turbines and machinery are of English Electric design . " DDH conversion . The advent of nuclear - powered attack submarines in the late 1950s prompted RCN leaders to assess the new threat they posed . Although these craft were noisier than older submarines and could therefore be detected at longer ranges , they were also capable of while submerged , which was faster than the top speed of the " St . Laurent " s at . Some RCN leaders harbored serious doubts that the destroyers could effectively pursue and destroy such fast vessels , even when operating in pairs . During a 25 February 1959 meeting of the Naval Board , it was decided that the Navy would counter the new threat by outfitting destroyers for helicopter operation . The RCN had examined the feasibility of operating ASW helicopters from small escorts when it modified the " Prestonian " - class frigate in mid - 1956 with a temporary helicopter landing platform fitted the quarterdeck . Trials held in October 1956 using a Sikorsky HO4S - 3 were successful , and a larger temporary helicopter landing platform was installed in the new destroyer escort in August 1957 . Operational trials were conducted using an RCAF Sikorsky S - 58 , a substantially larger and heavier aircraft than the HO4S , and the success of these tests led to approval of the concept . To achieve the goal , the RCN needed a helicopter capable of all - weather day - and - night operations with a heavy weapons load - capabilities the HO4S lacked - and a means to handle and secure the aircraft on the landing platform in rough seas . Trials showed landing was not the major concern : deck handling was . Manpower alone was insufficiently quick or certain in all conditions . During the 1957 trials aboard " Ottawa " , it had taken 30 tense minutes to secure the S - 58 to the deck during nighttime operations in rough seas . The deck handling issue was addressed by the invention of the beartrap . The Navy came up with the solution , and contracted Fairey Aviation of Dartmouth , NS , to produce it . Fairey ' s prototype was installed in HMCS " Assiniboine " during her 1962 - 63 conversion . By keeping the aircraft secure , the beartrap eliminated the need for deck handling from landing to the hangar , or from hangar to takeoff . " In conjunction with the helicopter carrying features and hangar facilities , roll - damping fins were added to the destroyers being so built or converted . These fins reduce the roll of the ship and aid landing and take - off operations during rough weather . " Initial studies identified two helicopters that met the upcoming requirements - the Sikorsky S - 61 ( HSS - 2 ) Sea King and the Kaman K - 20 ( HU2K ) . The Sea King was ultimately chosen in December 1961 . All seven " St Laurent " s were fitted with helicopter platforms and SQS 504 Variable Depth Sonar ( VDS ) . " St Laurent " was equipped with VDS late in 1961 , the helicopter platform to be added later . When ships were fitted with the helicopter platform , the single funnel was altered to twin stepped funnels to permit the forward extension of the helicopter hangar . Stabilizing systems were added to allow for helicopter recovery in any sea conditions , and a single CH - 124 was carried . To make room for the helicopter deck , the aft mount and one of the Limbos were removed . " Assiniboine " was the first in the class to receive the full upgrade , re - commissioning as a DDH on 28 June 1963 . On 27 November 1963 , her new platform was used for the first operational landing of a production CHSS - 2 Sea King , and her beartrap landing system was used operationally for the first time a week later . DELEX program . In the late 1970s , under the Destroyer Life Extension ( DELEX ) program was commissioned to upgrade ten of the " St . Laurent " and " Restigouche " - class ships with new electronics , machinery , and hull upgrades and repairs . The intent of DELEX was to extend the life of these ships for another 15 years of service while the " Halifax " - class frigates were being designed and built as part of the Canadian Patrol Frigate Program . DELEX included the installation of a Naval Tactical Data System ( NTDS ) known as the Automatic Data Link Plotting System ( ADLIPS ) , as well as the Canadian Electronic Warfare System ( CANEWS ) , and a new communication suite . The DELEX program was very successful as it allowed older ships to participate in a modern electronic battle field using tactical data links between ships and aircraft . Ships . Note that pennant numbers were originally prefixed DDE but were changed to DDH in the early 1960s . Significance . In 1997 , the Historic Sites and Monuments Board of Canada recognized the St . Laurent Class as being historically significant to Canadians and in 2000 installed a bronze plaque aboard HMCS " Fraser " which reads :