Iroquois Class Destroyer Canadian Navy

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 destroyers 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.

HMCS Algonquin (DDH 283)
Iroquois Class Destroyer overview
Name:	Iroquois-class destroyer
Builders:	Marine Industries Ltd., Sorel Davie Shipbuilding, Lauzon
Operators:	Canadian Forces Maritime Command
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

The Iroquois-class destroyers 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 Iroquois-class destroyers 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 helicoper platform most navies followed the approach of the Royal Navy, which only needed to make minor modifications to existing ships to accomodate their small Westland Wasp type helicopters. The advantages of the Canadian approach are two-fold: They allow for multiple helciopters 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 mothership 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 accomodate the larger helicopters.

For other duties the Iroquois-class destroyers 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 Iroquois-class destroyers 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.