Iroquois-class destroyer

HMCS Algonquin (DDH 283)
Class overview
Name	Iroquois-class destroyer
Builders	Marine Industries Ltd., Sorel Davie Shipbuilding, Lauzon
Operators	Royal Canadian Navy
Preceded by	Annapolis-class destroyer
Succeeded by	Canadian Single Class Surface Combatant
In commission	29 July 1972
Completed	4
Active	Iroquois, Athabaskan, Algonquin
Retired	Huron
General characteristics
Displacement	5,100 t (5,100.0 t)
Length	129.8 m (425.9 ft)
Beam	15.2 m (49.9 ft)
Draught	4.7 m (15.4 ft)
Propulsion	COGOG - 2 shaft 2 x Allison 570-KF cruise gas turbines (5.6 MW) 2 x Pratt & Whitney FT4A-2 boost gas turbines (37 MW)
Speed	29 kn (53.7 km/h)
Range	4,500 nmi (8,334.0 km)
Complement	280
Sensors and processing systems	Signaal AN/SPQ 501 DA-08 radar Signaal LW-08 AN/SPQ 502 radar SQS-510 hull sonar SQS-510 VDS sonar
Armament	32 x VLS, Standard SM-2MR Block IIIA SAMs 1 x 76 mm/62 OTO Melara 6 x 12.75 in tubes firing Mark-46 Mod 5 torpedoes 1 x Phalanx CIWS (Block 1) 2 x M2 Browning machine guns
Aircraft carried	2 x 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 Canadian Forces. 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. HMCS Huron was paid off and later sunk in a live-fire exercise, leaving three ships in the class. Except for the Swedish Spica class fast attack craft, the Iroquois-class were the first military ship design to employ gas turbines exclusively, using two turbines for cruise power, and another two fast starting "boost" turbines for speeds of up to 29 knots (such an arrangement is known as COmbined Gas Or Gas, or COGOG). The design was highly influential, and had a major impact on the design of the US Navy's first modern post-war destroyers, the Spruance-class.

Original design

The ships were originally intended for long-range anti-submarine warfare. Their primary weapon for this role was their complement of two CH-124 Sea King helicopters, which could be launched in even high sea states due to their "bear trap" winch system. The ships included a hangar that provided an enclosed working space for both helicopters at the same time. The helicopters were 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. The use of large helicopters on destroyer-sized ships makes an interesting contrast to the approach favoured by most navies of the time. Where the Canadian ship design has effectively turned half the ship into a helicopter platform most navies followed the approach of the Royal Navy, which only needed to make minor modifications to existing ships to accommodate their small Westland Wasp type helicopters. The advantages of the Canadian approach are two-fold: They allow for multiple helicopters aboard one ship and allow for far more capable helicopters to be used: The CH-124 Sea King can effectively operate on its own, whereas the Westland Wasp was not much more than a remote weapons platform that needed the sensors of the mother-ship to find its target. The larger size of the Canadian helicopters also allows for flight operations in heavier weather. The disadvantage of course is the sacrifice of a significant part of the ships own abilities to accommodate the larger helicopters.

For other duties the ships also mounted a Otobreda 127/54 Compact 5" multi-purpose gun and two four-round Sea Sparrow launchers for point anti-aircraft defence. The two four-round missile batteries were located in a protected box on the deck just in front of the bridge area. For firing, the box opened and the battery extended to the sides, requiring some time for them to unlimber.

The ships were powered primarily by two Pratt & Whitney FT12-AH3 of 7,400 shp each, backed up by two more FT4-A2 gas turbines of 50,000 shp each for boost. The power from these turbines was used to run the twin shafts through a series of helical gears. One unique feature was the distinctive Y-shaped "Playboy Bunny" funnels, which were designed to exit the exhaust gasses to either side of the helicopter deck.

The ships were 425 × 50 × 14 feet (129.8 × 15.2 × 4.4 metres) and 4,700 tons displacement. The normal crew complement was 285.

Gulf War modification

HMCS Athabaskan (DDH 282) was deployed on Operation FRICTION, the Canadian Forces contribution to the international coalition naval task force serving in Operation DESERT SHIELD and Operation DESERT STORM (the Gulf War).

Athabaskan was the flagship of the Canadian Naval Task Group and was hurriedly modified at CFB Halifax in August 1990 prior to the deployment. These modifications included a new mine-avoidance sonar, a Phalanx 20mm CIWS (mounted over the Limbo mortar well, which was made inoperative) and shoulder launched Blowpipe and Javelin missiles.

TRUMP modifications

The entire class underwent major retrofits as a part of the Tribal Class Update and Modernization Project (TRUMP) in the early 1990s. 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. In order to provide room for the VLS, the original 5" 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 Sea Sparrow system was removed.

The modernization also replaced the original Pratt & Whitney FT-12 cruise turbines with newer 12,788 shp 570-KF engines from Allison. The speed remained the same, however, as the weight had increased to 5,100 tons full load. The original split funnel was replaced by a simpler single one, as the exhaust proved not to be a problem.

The TRUMP was intended to be a stop-gap measure since the radar systems on these ships are outdated. Following TRUMP, the Iroquois-class were intended to be decommissioned by 2010. Defence budget cuts during the mid-1990s resulted in Huron being left without a crew. Huron was paid off in 2005, and sunk in a live-fire exercise in 2007 by her sister ship Algonquin.

There has been some preliminary work on a replacement design, known to Canadian naval-observers as the Province-class destroyer however 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. Current speculation is that the ships themselves would be similar to an enlarged Halifax-class frigate. Such a design would have similar capability to the Iroquois but only embark one helicopter. There appear to be no current plans to actually build such a class.

General characteristics

• Length: 129.8 m
• Beam: 15.2 m
• Draft: 4.7 m
• Displacement: 5100 tonnes full load
• Power plant:
  • two shaft COGOG system
  • two Allison 570-KF cruise gas turbines, 5.6 MW at the shaft total
  • two Pratt & Whitney FT4-A2 boost gas turbines, 37 MW at the shaft
• Speed: 29+ knots (54 km/h)
• Aircraft: 2 CH-124 Sea King helicopters
• Complement: 280
• Armament:
  • four 8-cell VLS, Standard SM-2MR Block IIIA surface-to-air missiles
  • one 76 mm/62 OTO Melara (Super Rapid) dual-purpose gun system
  • one Phalanx 20 mm Close-In Weapons Systems
  • two triple Mark-46 12.75 in (324 mm) torpedo tubes firing Mark-46 Mod 5 torpedoes
  • 0.5 in (12.7 mm) machine guns
• Radar: AN/SPQ 501 (Signaal DA-08), AN/SPQ 502 (Signaal LW-08)
• Sonar: SQS-510 hull, SQS-510 VDS

Ships in class

HMCS Iroquois (DDH 280)

Iroquois heads into the Mediterranean passing Gibraltar.

• Builders: Canada (Built at Marine Industries Ltd., Sorel)
• Laid down: 15 January 1969
• Launched: 28 November 1970
• Operator: Royal Canadian Navy
• Commissioned: 29 July 1972
• Status: In active service
• Modifications: 3 July 1992 TRUMP - addition of Mk.41 VLS SM-2 Block III, Phalanx CIWS and Otobreda 76 mm gun; removal of Sea Sparrow SAM
• Operations: 6 month deployment to the Arabian Sea as a part of Operation Enduring Freedom.

HMCS Huron (DDH 281)

File:HMCS Huron being towed to sinking.jpg

Huron being towed to her mooring for Operation Trident Fury.

• Builders: Canada (Davie Shipbuilding, Lauzon)
• Laid down: 1 June 1969
• Launched: 9 April 1971
• Operator: Royal Canadian Navy
• Commissioned: 16 December 1972
• Paid off: 31 March 2005
• Status: Sunk on 14 May 2007 100 km west of Vancouver Island as part of a SINK-EX named exercise Trident Fury 2007.
• Modifications: 25 November 1994 TRUMP - addition of Mk.41 VLS SM-2 Block III, Phalanx CIWS and Otobreda 76 mm gun; removal of Sea Sparrow SAM
• Operations:

HMCS Athabaskan (DDH 282)

HMCS Athabaskan

• Builders: Canada (Davie Shipbuilding, Lauzon)
• Laid down: 1 June 1969
• Launched: 27 November 1970
• Operator: Royal Canadian Navy
• Commissioned: 30 November 1972
• Status: In active service
• Modifications: 4 June 1994 TRUMP - addition of Mk.41 VLS SM-2 Block III, Phalanx CIWS and Otobreda 76 mm gun; removal of Sea Sparrow SAM
• Operations:

HMCS Algonquin (DDH 283)

Algonquin at Rim of the Pacific Exercise (RIMPAC) 2004

• Builders: Canada (Davie Shipbuilding, Lauzon)
• Laid down: 1 September 1969
• Launched: 23 April 1971
• Operator: Royal Canadian Navy
• Commissioned: 3 November 1972
• Status: In active service
• Modifications: 4 June 1994 TRUMP - addition of Mk.41 VLS SM-2 Block III, Phalanx CIWS and Otobreda 76 mm gun; removal of Sea Sparrow SAM
• Operations:

External links

• Canadian Navy
• Tribal Class