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 escorts (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 North Atlantic.

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, Rowland Baker, seconded from the [British] Director of Naval Construction... Baker produced a design basically similar to the [Whitby class frigate| 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." ["Conways", p44.]

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." [Friedman, "The Postwar Naval Revolution" p161.] 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 prewetting 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.

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. ["Janes Fighting Ships 1963-64", p35]

Armament

The "St. Laurent" class was fitted with twin 3 inch .50 calibre 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 the case of the Type 12, the design included provision for long-range homing torpedoes (in this case BIDDER [Mk 20E] or the US Mark 35. They were never fitted however." [Friedman, "The Postwar Naval Revolution" p.161]

Machinery

The vessels of the "St. Laurent" class had two Babcock & Wilcox water tube boilers installed [ [http://www.hazegray.org/navhist/canada/postwar/stlauren/ Canadian Navy of Yesterday & Today: "St. Laurent" class destroyer escort] ] providing 600 PSI (4.1 MPa, 42 kgf/cm²) at convert|850|°F|°C|1 ["Janes Fighting Ships 1992-93"] .

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 convert|28.5|knot|km/h|1. ["Janes Fighting Ships 1963-64", p35] By the early 1990s, the quoted maximum speed was only 27 kt. ["Janes Fighting Ships 1992-93"]

"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." ["Janes Fighting Ships 1963-64", p35]

DDH conversion

The RCN acquired a fleet of 41 CH-124 Sea King anti-submarine warfare helicopters in 1963. At this time it was decided to refit and reclass the "St. Laurent" vessels from Destroyer Escort (DDE) to Destroyer Helicopter (DDH).

"The 3-inch, 50 calibre anti-aircraft twin gun mountings were originally installed without shields , but gun shields have now [1963] been fitted. The gun housings are of fibre glass." ["Janes Fighting Ships 1963-64" shows photographs of "Skeena" and "Assiniboine" with these taken in 1962 and 1963 respectively.]

In advance of modifying the "St. Laurent" vessels, the RCN had experimented with operating helicopters from small warships when it modified the "Prestonian"-class frigate warship|HMCS|Buckingham|FFE 314 in 1957 "with a pre-fabricated helicopter platform fitted above the quarter deck, for ASW helicopter reconnaissance and to test the feasibility of operating helicopters from anti-submarines escort vessels of this size." ["Janes Fighting Ships 1963-64" p37.] "Trials were successfully carried out, using a Sikorsky HO4S-3 helicopter." [ [http://www.readyayeready.com/timeline/1960s/beartrap/index.htm "Crowsnest Magazine - Vol 17, Nos 3 and 4 March-April 1965"] ] "The deck was subsequently removed and installed in the new destroyer escort warship|HMCS|Ottawa|DDE 229" ["Janes Fighting Ships 1963-64" p37.]

The prefabricated helicopter platform "was fitted over the after well in "Ottawa" in August 1957 to test the feasibility of operating helicopters from anti-submarines escort vessels of this class; but this experimental flight apron was subsequently removed." ["Janes Fighting Ships 1963-64" p35.] "Further trials were conducted, using an RCAF Sikorsky S-58. On the basis of the trials, the concept of operating helicopters from destroyers was recommended and received approval in principle." [ [http://www.readyayeready.com/timeline/1960s/beartrap/index.htm "Crowsnest Magazine - Vol 17, Nos 3 and 4 March-April 1965"] ]

"Two things were needed. One was a helicopter capable of all-weather day and night operation (the HO4S-3 was not). The other was a system for handling and securing a helicopter on a small flight deck in rough seas."

"The former was found, in the 9.5 ton Sikorsky CHSS-2 Sea King. The landing-handling problem was solved by the beartrap."

"During the trials, it was found that landing was not so much a problem as was the handling of the helicopter after it had landed. Manhandling was neither quick enough nor certain enough to establish the measure of control necessary to ensure that, in certain circumstances, the helicopter will not take charge, and go over the side."

"The Navy went to the drawing boards and came up with a scheme that promised to make the concept practicable. Conceived by the RCN, the haul-down and beartrap system was engineered by Fairey Aviation, Dartmouth, N.S. A prototype was designed and built by Fairey, under RCN supervision, and was installed in HMCS "Assiniboine" during her 1962-63 conversion" (see below).

"Trials with a newly-acquired "Sea King" began late in 1963. By mid-1964 the daytime trials were completed and pronounced successful. 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."

"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." [ [http://www.readyayeready.com/timeline/1960s/beartrap/index.htm "Crowsnest Magazine - Vol 17, Nos 3 and 4 March-April 1965"] ]

With the advent of the nuclear submarine, it became apparent that the ships needed to be further upgraded. [ [http://www.hazegray.org/navhist/canada/postwar/stlauren/ Canadian Navy of Yesterday & Today: "St. Laurent" class destroyer escort] ] all seven ships of the "St Laurent" class were fitted with helicopter platforms and SQS 504 Variable Depth Sonar (VDS).

The "St Laurent" was fitted with VDS late in 1961, 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. ["Janes Fighting Ships 1963-64" p35.] Stabilizing systems were added to allow for helicopter recovery in any sea conditions, and a single CH-124 Sea King was carried. [ [http://www.hazegray.org/navhist/canada/postwar/stlauren/ Canadian Navy of Yesterday & Today: "St. Laurent" class destroyer escort] ] To make room for the helicopter deck, the rear 3 inch gun mounting and one of the Limbos were removed. [ [http://www.hazegray.org/navhist/canada/postwar/stlauren/ Canadian Navy of Yesterday & Today: "St. Laurent" class destroyer escort] ]

"Assinibione" was the first vessel in the class to receive the full upgrade, re-commissioning as a DDH on 28 June 1963. ["Janes Fighting Ships 1963-64" p35.]

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.

hips

Note that pennant numbers were originally prefixed DDE but were changed to DDH in the early 1960s ["Janes Fighting Ships 1963-64"] ["Conways", "Janes Fighting Ships 1963-64"] [ [http://www.hazegray.org/navhist/canada/postwar/stlauren/ Canadian Navy of Yesterday & Today: "St. Laurent" class destroyer escort] ] .

References

* [http://www.hazegray.org/navhist/canada/postwar/stlauren/ Canadian Navy of Yesterday & Today: "St. Laurent" class destroyer escort]
* Chumbley, Stephen and Gardner, Robert (Ed.) "Conway's All the World's Fighting Ships, 1947-1995". Conway Maritime Press, 1995. ISBN 0-85177-605-1.
* Couhat, Jean Labayle, "Combat Fleets of the World 1978-79" Arms and Armour Press, 1978.
* Janes Fighting Ships 1963-64
* Sharpe, Richard "Janes Fighting Ships 1992-92", Janes Information Group, 1992. ISBN 0-7106-0983-3.
* Friedman, Norman, "The Postwar Naval Revolution", Naval Institute Press, 1986. ISBN 0-87021-952-9.
* [http://www.readyayeready.com/timeline/1960s/beartrap/index.htm "Crowsnest Magazine - Vol 17, Nos 3 and 4 March-April 1965"]