Hi everyone, and welcome to my series which I’m entitling “Canada’s Cold War Cadillacs”. This series aims to create a definitive series of drawings that depict Canada’s Cold War destroyer escorts through various stages of their service histories, beginning with the St. Laurent – class destroyer escorts, and eventually continuing with the Restigouche, Mackenzie, and Annapolis – classes. This is a work in progress, so stay tuned for updates in the future!
Part One: St. Laurent - class Destroyer Escorts
The impetus 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. The St. Laurent - class was the first class of warships designed for the post-war Royal Canadian Navy.
Design work for a new class of destroyer escorts began in June 1949, with the original completion date planned for 1955. They were designed by Montreal naval architects German and Milne, under the direction of a senior constructor, Sir Rowland Baker, who was seconded from the British Director of Naval Construction. Baker produced a design basically similar to the Whitby - class (Type 12) frigates while incorporating several ideas of his own. The St. Laurent - class destroyer escorts ended up being significantly different in appearance than the Type 12 frigates, but internally, they were much the same, sharing the same powerplant, among other features.
Unlike the Whitby - class, the St. Laurents featured a rounded deck edge that was designed to prevent ice from forming. The vessels were designed to operate in harsh Canadian conditions. They were built to counter nuclear, biological, and chemical (NBC) 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" that could be sealed off from contamination for the crew's safety. The ships gained the affectionate nickname of "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.
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The lead ship of the class, HMCS St. Laurent (DDE-205), was laid down on 24 November 1950 by Canadian Vickers at Montreal. She was launched on 30 November the following year and was commissioned into the Royal Canadian Navy on 29 October 1955. Initially, HMCS St. Laurent and her sister ship, HMCS Saguenay (DDE-206) were painted in the two-tone post-war paint scheme of the Royal Canadian Navy.
Armament included two 3-inch Mk. 33 twin guns in open mounts, two 40mm "Boffin" single mounts, two A/S Mk 10 "Limbo" anti-submarine mortars, and two Mk IV torpedo throwers - an intriguing and little-known Canadian invention that used a converted Mk IV depth charge launcher to fire a single lightweight torpedo. Unlike the Mk. IV depth charge launcher, the cradle was permanently attached to the launcher, and only the torpedo was thrown clear of the ship. The cradle was angled to ensure that the torpedo entered the water nose-first.
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By the late 1950s, the St. Laurent - class frigates lost their two-tone scheme, instead being painted in the RCN's new single-colour haze grey scheme which was heavily inspired by the Royal Navy's Light Admiralty Grey.
By this time period, advances in Soviet submarine technology, specifically the development of nuclear-powered submarines, had caused the RCN to begin earnestly studying the employment of the helicopter in an anti-submarine warfare role. In 1957, HMCS Ottawa (DDE-229) was used as a test ship for helicopter landing trials, with a newly constructed flight deck installed over the rear of the ship and her "Limbo" mortar well temporarily covered over. A Sikorsky S-58 (S/N 9633) of No. 108 (Comm.) Flight Detachment RCAF was loaned to the Royal Canadian Navy for this purpose. With her embarked helicopter, HMCS Ottawa took part in NATO exercises in the eastern Atlantic in the fall of 1957, which validated the use of the helicopter in the anti-submarine warfare role.
The helicopter landing trials on HMCS Ottawa 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, in one particular instance, it took 30 tense minutes to secure the S-58 to the deck during nighttime operations in rough seas. The deck handling issue would eventually be addressed by the invention of the "beartrap", otherwise known as a Helicopter Haul-down and Rapid Securing Device (HHSRD), one of the most significant Canadian innovations of the Cold War period.
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In the early 1960s, the RCN began retrofitting its 3-inch Mk. 33 twin guns with fibreglass shields. Because the St. Laurent - class was not designed with a separate gun director for fire control, the RCN fitted its Mk. 33s with the SPG-48 tracking radar, which was coupled with the Mk 64 Gun Fire Control System (GFCS). The antenna for the SPG-48 was located between the gun barrels on the mounting. Early variants of the SPG-48 used a parabolic antenna, while later versions used a Cassegrain-type antenna.
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By the early 1960s, the Royal Canadian Navy was fully convinced of the future of the helicopter as the ultimate anti-submarine warfare weapon - nothing else in their inventory could effectively counter the fast and deep-diving November - class nuclear submarines of the Soviet Navy. The St. Laurents were being seen as increasingly obsolete against this new threat, thus the RCN embarked on a radical program of converting their destroyer escorts to helicopter-carrying destroyers (DDHs).
In 1962, HMCS Assiniboine (DDE-234, renumbered to DDH-234) began the conversion process - she was to serve as the prototype for the conversion of her six sister ships. Emerging from drydock in 1963, Assiniboine was radically different from before the conversion process. In the conversion to a helicopter-carrying vessel, Assiniboine was gutted except for machinery and some forward spaces. Her 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. She was also fitted with the AN/SQS-504 "Diver" Variable Depth Sonar (VDS), another radical new invention that would also be adopted by the Royal Navy and Royal Australian Navy.
The single funnel of the St. Laurent - class 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 40mm guns were also removed. Because Assiniboine was the prototype for the DDH conversion process, she featured some notable differences from her sisters - her twin funnels were raked at an angle, and her hangar was of a somewhat different configuration.
The most important feature of HMCS Assiniboine's conversion was the installation of the new "beartrap" haul-down device. Conceived by the RCN, the haul-down system was designed and engineered by Fairey Aviation in Dartmouth, Nova Scotia. A prototype was designed and built by Fairey, under RCN supervision, and was installed in HMCS Assiniboine during her 1962-63 conversion. After re-entering service, Assiniboine quickly went to work validating the "beartrap", along with CH-124 Sea Kings from Experimental Air Squadron Ten (VX-10). By mid-1964 the daytime trials were completed and pronounced successful, and VX-10 moved on to validating the "beartrap" during night operations. Using the new system, no manhandling was needed to get the helicopter on the deck and in or out of the hangar. The helicopter was solidly secured on landing and remained so until the next take-off.
![[ img ]](https://i.imgur.com/QBWeUOI.png)
In the late 1970s, the Destroyer Life Extension (DELEX) program was commissioned to upgrade the St. Laurent - class ships with new electronics, machinery, and hull upgrades and repairs. Unlike on later classes, such as the Restigouche - class, upgrades were fairly limited and focused primarily on basic capability enhancements, along with hull and machinery repairs. The St. Laurents received the AN/WLR-1C electronic countermeasures system (ECM), along with TACAN systems to enhance the navigation capability of their CH-124 Sea King helicopters. Their rudimentary Mk IV torpedo throwers were replaced by the new Mk 32 Surface Vessel Torpedo Tubes (SVTT), along with new Mk 46 Mod 5 lightweight torpedoes.
![[ img ]](https://i.imgur.com/Ge8FxWf.png)
By the 1980s, the St. Laurent - class helicopter destroyers were beginning to get quite long in the tooth. The namesake vessel of the class, HMCS St. Laurent, had been decommissioned in 1974, following an incident in which she was run aground and her keel substantially damaged, leaving her six sisters to soldier on. In the mid-1980s, HMCS Fraser (DDH-233) was designated the fleet test ship. In 1986, Fraser landed her AN/SQS-504 Variable Depth Sonar, becoming the testbed for the Experimental Towed Array Sonar System, which would later evolve into the Canadian Towed Array Sonar (CANTASS) that equipped the Halifax - class frigates. In 1987, Fraser was the first Canadian ship to carry and was the first to test the NIXIE torpedo decoy system. HMCS Fraser followed that with testing the TACAN antenna, installed on a unique lattice mast which was unlike the pole masts on her sisters.
The St. Laurent - class helicopter destroyers began decommissioning in the early 1990s as the new Halifax - class frigates began to enter service, with HMCS Fraser being the last to be paid off on 5 October 1994. The St. Laurent - class holds the distinction of being one of the most influential Canadian military achievements, being closely tied to several advances in anti-submarine warfare over their service lives, such as the development of the variable depth sonar and the ship-borne anti-submarine helicopter.
If you're still reading by now, thank you so much for taking the time to do so! As always, comments, constructive criticism, and feedback of all kinds are warmly welcomed. A big thanks to BCRenown for his Annapolis - class drawing, which was instrumental in me being able to create this series of drawings. Stay tuned for Part Two - the Restigouche - class destroyer escorts!
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