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|Operators:||Royal Canadian Navy|
|Preceded by:||Annapolis class|
|Succeeded by:||Single Class Surface Combatant|
|In commission:||29 July 1972 - present|
|Type:||Guided missile destroyer|
|Displacement:||5,100 t (5,000 long tons; 5,600 short tons)|
|Length:||129.8 m (425.9 ft)|
|Beam:||15.2 m (49.9 ft)|
|Draught:||4.7 m (15.4 ft)|
|Speed:||29 kn (54 km/h; 33 mph)|
|Range:||4,500 nmi (8,300 km; 5,200 mi)|
|Aircraft carried:||2 × CH-124 Sea King helicopters|
Iroquois-class destroyers, also known as Tribal class, are a class of four helicopter-carrying, guided missile destroyers of the Royal Canadian Navy. Launched in the 1970s, they were originally fitted out for anti-submarine warfare, but a major upgrade programme in the 1990s overhauled them for area-wide anti-aircraft warfare. One was sunk in a live-fire exercise in 2007, two more were decommissioned in 2015 leaving one active ship in the class. The ships are named to honour the First Nations of Canada.
Design and description
The call for a new class of destroyers came on 22 December 1964 when then Minister of National Defence Paul Hellyer announced them as part of the government's plan to refit the Royal Canadian Navy. Following the cancellation of the General Purpose Frigate Project, the navy hoped to create an improved version of that design. However, at Hellyer's insistence, the focus for the new ships was to be anti-submarine warfare. The estimated cost for the vessels was initially $35 million each, which was similar to the Annapolis class.
It took four years to settle on a final design, partly due to the requirements for space to accommodate a large helicopter, variable depth sonar and the improved habitation standards brought in by the same government. In 1968, contracts were awarded to Marine Industries Ltd. of Sorel and Davie Shipbuilding of Lauzon.
Designed in the late 1960s, the Iroquois class were originally designed as a unique solution for long-range anti-submarine warfare. Their primary weapon for this role is their complement of two Sikorsky CH-124 Sea King helicopters, which are supported on a large flight deck with a two-helicopter hangar that collectively takes up roughly half of the ship's available area. The helicopters can be launched even in high sea states due to their "bear trap" winch system.
The Iroquois class represents a different implementation of anti-submarine warfare compared to its contemporaries. Most ships of the same general size and role, like the Royal Navy's Type 22s or the United States Navy's Oliver Hazard Perry class, had much smaller helicopter support areas, typically only the rear ¼ of the ship. These supported a single, small, short-range helicopter, the Westland Lynx or Kaman Seasprite. Such small helicopters were incapable of operating independently of the ship's sensors, and were effectively a system for extending the range of the weapons by carrying them away from the ship before launch. In contrast, the Iroquois class' much larger Sea Kings are able to carry a complete sensor suite and operate at much longer ranges independently of the launch ship. The two Sea Kings would operate in tandem to hunt submarines, with one helicopter employing its dipping sonar to locate and track potential targets, while the second helicopter engaged the target with its torpedoes. This allows a single Iroquois to control a much larger area of the ocean, using both its own sensors and those of its helicopters, combining together to scan larger areas. The downside to this design is that the area taken up by the helicopters would normally be given over to other weapon systems.
For anti-submarine use, the helicopters are backed up by two triple-mount torpedo launchers firing Mk.44 and Mk.46 Mod 5 torpedoes and a Limbo Mark 10 depth charge mortar. For other duties, the ships also mount an Oto Melara 5-inch (127 mm) multi-purpose gun and two four-round RIM-7 Sea Sparrow launchers for point anti-aircraft defence. These launchers are located in a protected box on the deck just in front of the bridge area (behind the gun). For firing, the box opens and the battery extends to the sides, requiring some time for them to unlimber.
The ships were originally powered by two Pratt & Whitney FT12-AH3 of 7,400 shp (5,500 kW) each, backed up by two more FT4-A2 gas turbines of 50,000 shp (37,000 kW) each for boost. They were the first large combat ships to be powered entirely by gas turbine. The power from these turbines is used to run the twin shafts through a series of helical gears. One unique feature was the distinctive Y-shaped split funnels, which were designed to exit the exhaust gases to either side of the helicopter deck.
The Iroquois class influenced the design of the Spruance-class anti-submarine warfare destroyers, which were the first large U.S. Navy ships to use gas turbine propulsion (known as COmbined Gas And Gas, or COGAG), and the first U.S. Navy destroyer/cruiser class to have a enclosed hanger, with space for up to two medium-lift helicopters, which was a considerable improvement over the basic aviation facilities of earlier U.S. cruisers and frigates.
Gulf War modification
HMCS Athabaskan was deployed on Operation Friction, the Canadian Forces contribution to the international coalition naval task force serving in the Gulf War. She was hurriedly modified at CFB Halifax in August 1990 prior to the deployment. These modifications included a new mine-avoidance sonar, a Phalanx 20 mm CIWS (mounted over the Limbo mortar well, which was made inoperative) and shoulder-launched Blowpipe and Javelin missiles.
As a modernization concept, origins of TRUMP date back to early 1980s. By mid-1980s the Canadian Federal Government had decided on the necessity of upgrading of Iroquois-class ships and released a RFP foreseeing complete refurbishment. The phrase "update and modernization" essentially meant stripping down of the vessels to the bare hulls and entire re-equipping with modern technologies, mechanical or otherwise. Litton Systems Canada was selected as Prime Contractor and Project Manager.
The entire class underwent major retrofits in the early 1990s as a part of the Tribal Class Update and Modernization Project (TRUMP). These refits had the effect of re-purposing the ships for area air defence; following TRUMP the Iroquois class were referred to as air defence destroyers. Their former anti-submarine role was largely transferred to the Halifax-class frigates.
The main weapon of the new design is the Mk.41 VLS, firing 29 SM-2 Block III long-range anti-aircraft missiles. To provide room for the VLS, the original 5-inch L54 gun was replaced with the smaller, but much faster firing, OTO Melara 76 mm gun, relocated from the deck to the bridgework above it. A Phalanx CIWS was also added for self-defence. The torpedo tubes were retained, but the Limbo and Sea Sparrow systems were removed.
The modernization also replaced the original Pratt & Whitney FT-12 cruise turbines with newer 12,788 shp (9,536 kW) 570-KF engines from Allison. The speed remained the same, however, as the weight had increased to 5,100 tonnes (5,000 long tons) full load. The original split funnel was replaced by a simpler single one, as the exhaust proved not to be a problem.
Ships in class
|Name||Pennant Number||Builder||Laid down||Launched||Commissioned||Fate|
|Iroquois||DDG 280||Marine Industries, Sorel, QC||15 January 1969||28 November 1970||29 July 1972||Awaiting disposal|
|Huron||DDG 281||Davie Shipbuilding, Lauzon, QC||1 June 1969||9 April 1971||16 December 1972||Sunk in live fire exercise off Vancouver Island, 14 May 2007|
|Athabaskan||DDG 282||27 November 1970||30 September 1972||Active in service|
|Algonquin||DDG 283||1 September 1969||23 April 1971||3 November 1973||Sold for scrapping, 27 November 2015 at Liverpool, Nova Scotia|
All of the Iroquois class was laid down in 1969, Iroquois on 15 January, Huron and Athabaskan on 1 June and Algonquin on 1 September. Their names were chosen both to honour the First Nations of Canada, but also to perpetuate the names of destroyers that served during the Second World War. Iroquois was the first to commission, on 29 July 1972, followed by Athabaskan on 30 September, Huron on 16 December and Algonquin on 3 November 1973.
By the early 1980s, the Iroquois class were the only surface vessels in the Canadian navy that were capable of fighting a modern war. The destroyers underwent the TRUMP modifications beginning in 1987, with Algonquin being taken in hand on 26 October to 11 October 1991; Iroquois, 1 November 1989 to 3 July 1992; Athabaskan, from October 1991 to 3 August 1994; and Huron, from July 1993 and 25 November 1994.
From the onset of their careers, the Iroquois-class ships were deployed to NATO naval missions such as STANAVFORLANT, performing search and rescue missions, such as Algonquin rescuing the crew from the fishing vessel Paul & Maria in 1974 or Athabaskan in 1981 when she sailed to rescue the crew of MV Euro Princess. They also participated in many major naval exercises.
On 24 August 1990, Athabaskan, after a refit to add several advanced weapons including a close-in weapon system (CIWS), sailed to the Arabian Sea as flagship of the naval component of Operation Friction, the Canadian contribution to the Gulf War. The task group served in the central Persian Gulf, with other coalition naval forces, through the fall of 1990. After Operation Desert Storm began in January 1991, the task group undertook escort duties for hospital ships and other vulnerable naval vessels of the coalition. When the Ticonderoga-class cruiser USS Princeton detonated two Iraqi bottom-moored influence mines (MANTAs) at the north end of the Persian Gulf and was seriously damaged, her commanding officer specifically requested the assistance of Athabaskan. Athabaskan could simultaneously operate two large CH-124 Sea King helicopters, originally for anti-submarine warfare, which proved useful in searching out mines for long periods until a U.S. Navy minesweeper arrived. Athabaskan returned to her task group and remained on station in the Persian Gulf until after the war ended. After the hostilities were complete she was relieved by her sister ship Huron. 
In September 1999, Huron, carrying Canadian immigration officials, intercepted a ship trafficking 146 Chinese migrants. Royal Canadian Mounted Police boarded the vessel from Huron while the destroyer escorting the vessel into Nootka Sound. On 3 August 2000, Athabaskan sent her helicopter to board GTS Katie, a cargo vessel carrying Canadian military equipment whose charterer refused to deliver them.
On 17 October 2001, as part of Operation Apollo, Iroquois led the Canadian Task Group to the Arabian Sea. Eventually, Algonquin and Athabaskan also took part in the War in Afghanistan. In 2003, while readying for deployment to Operation Apollo, Iroquois's Sea King crashed on deck and the ship was forced to return to Halifax.
Despite Huron being the most recently refitted Iroquois-class destroyer, she was placed in mothballed status in 2000, due to a personnel shortage following defence cutbacks during the late 1990s. Huron was paid off in 2005, and sunk in a live-fire exercise in 2007 by her sister ship Algonquin.
In August 2013, Algonquin was involved in a collision with HMCS Protecteur during a naval exercise. Algonquin suffered significant damage along her port side hangar. The vessel was laid up following the collision. In May 2014, while visiting Boston, Massachusetts, severe cracks were discovered in the hull of Iroquois requiring her immediate return to Canada and lay up for inspection. The inspection determined the hull was compromised and would require the ship to be laid up indefinitely. On 19 September 2014, the Royal Canadian Navy announced that these two ships were to be paid off along with the Protecteur class, leaving only Athabaskan active.
On 27 November 2015, Algonquin, along with Protecteur, was sold for scrapping to R.J. MacIsaac Ltd. of Antigonish, Nova Scotia. They will be towed to Liverpool, Nova Scotia where the work will be done.
There was some preliminary work on a replacement design that was informally termed the Province class. This was confined largely to studies of a much-improved phased array radar system being developed for the Royal Netherlands Navy and German Navy known as APAR. Speculation had been that these new ships would have been similar to an enlarged Halifax-class frigate. Such a design would have had a multi-role capability similar to the Arleigh Burke-class destroyer.
The replacement for the Iroquois class is now known to Canadian naval observers as the Single Class Surface Combatant Project and this project has been included in the National Shipbuilding Procurement Strategy, announced in October 2011. The new vessels will eventually replace the Halifax class, as well as the capabilities previously provided by the Iroquois class, beginning in about the mid-2020s. Under the NSPS, the federal government has awarded the combat vessel package to Irving Shipbuilding which will include the construction of up to 15 Single Surface Combatant warships.
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