The St. Laurent-class destroyer was a class of destroyer escorts 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 analogous to the British Type 12 Whitby-class frigate, intended for the same ASW mission and using the same machinery but used a dramatically different hull form and predominantly American equipment rather than British. There were seven ships of the class commissioned between 1955 and 1957.
They were originally intended as destroyer escorts (DDE) but were later refitted and reclassed as destroyer helicopter escorts (DDH).
Design and description
The need for the St. Laurent class came about in 1949 when Canada joined NATO and the Cold War was in its infancy. The Royal Canadian Navy (RCN) was assigned responsibility for anti-submarine warfare (ASW) and controlling sea space in the western North Atlantic.
Design work for a new class of destroyer escorts began in June 1949 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-class (Type 12) frigate, while incorporating several ideas of his own. Different in appearance to the Type 12 design, the ship that resulted was similar in many respects.
The St Laurent class were built to an operational requirement much like that which produced the British Type 12, and were powered by the same machinery plant. The rounded deck-edge forward was adopted to prevent ice forming. The vessels were designed to operate in harsh Canadian conditions. They were built to counter nuclear, biological and chemical attack conditions, which led 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 to incorporate advancements in naval warship design in the preceding years. There were also two essentially similar follow-on classes, the (4 ships completed 1962–63) and the (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.
As built, the ships were long overall with a beam of and a draught of . The destroyer escorts displaced standard and at deep load. The destroyer escorts had a crew of 12 officers and 237 enlisted.
Armament
The St. Laurent class was fitted with twin /L50 calibre guns in two mounts for engaging both surface and air targets. The guns were capable of 85° elevation and could fire 50 rounds per minute up to . The ships were also fitted with two single-mounted Bofors 40 mm gun| guns. The class's anti-submarine armament consisted of a pair of triple-barreled Mk. NC 10 Limbo ASW mortars in a stern well. The stern well had a roller top to close it off from following seas. As with the British Type 12 design, the provision for long-range homing torpedoes (in this case BIDDER [Mk 20E] or the US Mark 35 were included. However, they were never fitted.
As built, the twin 3-inch anti-aircraft mounts were installed without shields. These were added in 1963. The gun housings are fibreglass.
Machinery
The vessels of the St. Laurent class had two Babcock & Wilcox water tube boilers installed providing , 42 (kgf/cm²) at .