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The
St. Laurent class destroyer 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 helicopter destroyer 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, 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 torpedoes (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 850 °F (454.4
°C).
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 28.5 knots (52.8 km/h). 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 30 knots (56 km/h) while submerged, which
was faster than the top speed of the St. Laurents at 28.5 knots (52.8 km/h).
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 HMCS Buckingham (FFE
314) 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 HMCS Ottawa (DDE 229) 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 Laurents 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 3 in
(76 mm) 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.
Conversion / Refit:
DDE / DDH 205 HMCS St. Laurent (DDH - October 1963 / DELEX - never)
DDE / DDH 206 HMCS Saguenay (DDH - May 1965 / DELEX - May 1980)
DDE / DDH 207 HMCS Skeena (DDH - August 1965 / DELEX - November 1981)
DDE / DDH 229 HMCS Ottawa (DDH - October 1964 / DELEX - November 1982)
DDE / DDH 230 HMCS Margaree (DDH - October 1965 / DELEX - November 1980)
DDE / DDH 233 HMCSFraser (DDH - October 1966 / DELEX - May 1982)
DDE / DDH 234 HMCS Assiniboine (DDH - June 1963 / DELEX - November 1979)
source: wikipedia
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