Hobart-class destroyer

The Hobart class is a ship class of three air warfare destroyers (AWDs) being built for the Royal Australian Navy (RAN). Planning for a class to replace the Adelaide class frigates and restore the capability last exhibited by the Perth class destroyers began by 2000, initially under acquisition project SEA 1400, which was redesignated SEA 4000. Although the designation "Air Warfare Destroyer" is used to describe ships dedicated to the defence of a naval force (plus assets ashore) from aircraft and missile attack, the planned Australian destroyers would also be able to operate in anti-surface, anti-submarine, and naval gunfire support roles.

Planning for the Australian Air Warfare Destroyer (as the class was known until 2006) continued through the mid-2000s, with the selection of the Aegis combat system as the intended combat system and ASC as the primary shipbuilder in 2005. In late 2005, the AWD Alliance was formed as a consortium of the Defence Material Organisation, ASC, and Raytheon. Between 2005 and 2007, Gibbs & Cox's Evolved Arleigh Burke class destroyer concept and Navantia's Álvaro de Bazán class frigate competed for selection as the AWD design. Although the Arleigh Burke design was larger and more capable, the Álvaro de Bazán design was selected in June 2007 as it was an existing design, and would be cheaper, quicker, and less risky to build.

Three ships were ordered in October 2007, and will be assembled at ASC's facility in Osborne, South Australia from 31 pre-fabricated modules (or 'blocks'). ASC, NQEA Australia, and the Forgacs Group were selected in May 2009 to build the blocks, but within two months, NQEA was replaced by BAE Systems Australia. Errors with the first hull block and growing delays in construction led the AWD Alliance to redistribute the construction workload in 2011, with some modules to be built by Navantia. An option to build a fourth destroyer was included in the original contract, but has not yet been exercised. Lead ship HMAS Hobart (DDGH 39) will enter service in March 2016 (two years later than originally predicted), HMAS Brisbane (DDGH 41) is due to commission in September 2017, and HMAS Sydney (DDGH 42) should be operational by June 2019.

Planning
The 1992 Force Structure Review contained plans to replace the three Perth class guided missile destroyers and four of the six Adelaide class guided missile frigates with air defence vessels. The initial proposal – to build an additional six Anzac class frigates configured for wide-area anti-aircraft warfare – did not go ahead as the Anzac design was too small to effectively host all the required equipment and weapons. Instead, the RAN began to upgrade the Adelaides in 1999 to fill the anti-aircraft capability that would be lost when the Perths left service between 1999 and 2001. The frigate upgrade was only intended as a stop-gap (only four ships were upgraded, and all four were due to decommission during the mid-2010s), and by 2000, the Australian Defence Force had begun a project to replace the three Perth class destroyers. The acquisition of the dedicated air warfare destroyers was initially identified as Project SEA 1400, then redesignated Project SEA 4000.

The main role of the air warfare destroyer is air defence of a naval task group, in addition to assets ashore and operating in the littoral. Although specifically designed for air warfare, the AWDs also had to be capable of facing other threats, and were to be fitted with ship-to-ship missiles, a gun for naval gunfire support of soldiers ashore, and anti-submarine capability through sonar systems and abovewater-launched torpedoes. The ships had to be able to operate a helicopter for both surveillance and combat duties.

In 2004, the Department of Defence identified that the future air warfare destroyer class would be built around the United States Navy's Aegis Combat System. The use of Aegis was formally approved in April 2005, and Raytheon Australia was brought into the AWD project with the responsibility of integrating the Aegis system into the selected design, along with modifications to accommodate RAN-preferred electronic warfare equipment, underwater sensors, and weapons. In May 2005, the ASC shipyard at Osborne, South Australia was identified as the primary shipbuilder for the project. In late 2005, the AWD Alliance was formed to organise and implement the project. The Alliance is a consortium including the Defence Material Organisation, ASC's project-dedicated subsidiary, and Raytheon.

After receiving tenders from Blohm + Voss, Navantia, and Gibbs & Cox, among others, the Australian government identified Gibbs & Cox's Evolved Flight II Arleigh Burke class destroyer as the preferred design in August 2005. The Álvaro de Bazán class frigate designed by Navantia, was identified as the official alternative, and both designs began further testing and modification as part of a two-year selection process. The two ship designs were equivalent in many areas, including length, speed and weapons outfit, although the Arleigh Burke class was larger with a displacement 2,200 tons greater than the Spanish frigate, and had superior capabilities in regards to range (700 nmi greater), helicopter operations (two embarked helicopters instead of one), primary armament (a 64-cell Mark 41 Vertical Launch System compared to a 48-cell launcher), and close-defence (with a second close-in weapons system). Chief of Navy Vice Admiral Russ Shalders believed the American design would provide the RAN with a greater long-term capability, as there was greater scope for upgrades and modifications later in the ships' careers. Despite the American destroyer being the preferred option, the conclusion of the selection process in late June 2007 saw Navantia's Álvaro de Bazán design selected, as unlike the Evolved Arleigh Burkes, the Spanish ships were a less-risky design as they had been tested and proven, they could be in service four years earlier than the American-designed ships, and they would cost A$1 billion less to build. There were also benefits in ordering the destroyers and the Canberra class landing helicopter dock ships from the same designer.

The contract for the ships was signed on 4 October 2007. The A$8 billion, three-ship deal included the option to order a fourth ship at a later date. This option was due to expire in October 2008. The Australian government sought to extend the offer into early 2009, so as to review the recommendations of the Defending Australia in the Asia Pacific Century: Force 2030 white paper due for completion at the end of 2008, and to enquire about acquiring a fourth Aegis system from the USN, before ordering or cancelling the fourth destroyer. The Navy League of Australia has consistently supported the acquisition of a fourth AWD. According to the Navy League, building a fourth destroyer would be relatively cheap (money for design and other 'start-up' costs would already be spent) and improve RAN capabilities (by offering increased flexibility and redundancy, particularly in the event of a Falklands War-like armed conflict). Along with the Navy League, the Australian defence industry has supported a fourth destroyer, to keep workers employed for longer while reducing the gap to the next major defence construction projects (the Collins class replacement and the Future Frigates).

The Australian Minister for Defence announced on 20 January 2006 that the Air Warfare Destroyers will be named HMAS Hobart (DDGH 39), HMAS Brisbane (DDGH 41), and HMAS Sydney (DDGH 42). The Navy League of Australia suggested several possible names for a possible fourth destroyer; one was to name the ship HMAS Melbourne; another involved taking the HMAS Adelaide name from the second Canberra class landing helicopter dock ship, and renaming the larger vessel HMAS Australia.

Design
Each destroyer will have a length overall of 147.2 m, a maximum beam of 18.6 m, and a draught of 5.17 m. At launch, the ships will have a full-load displacement of 6,250 tonne. However, the Hobarts have been designed to allow for upgrades and installation of new equipment, with a theoretical maximum displacement of 7,000 tonne.

The Hobarts use a more powerful propulsion system than their Spanish predecessors. The combined diesel or gas turbine (CODOG) propulsion arrangement consists of two General Electric Marine model 7LM2500-SA-MLG38 gas turbines, each generating 17,500 kW, and two Caterpillar Bravo 16 V Bravo diesel engines, each providing 5,650 kW. These drive two propeller shafts, fitted with Wärtsilä controllable pitch propellers. The ships' maximum speed is over 28 kn, with a range of over 5,000 nmi at 18 kn; although not fast enough to keep pace with an American carrier battle group, the RAN is happy with the speed/range tradeoff as endurance is more important for Australian operating conditions. For in-harbour manoeuvring, each destroyer is fitted with a bow thruster.

The standard ship's company is 186-strong, plus 16 additional personnel to operate and maintain the ship's helicopter. However, there is accommodation aboard for 31 officers and 203 sailors total. Onboard electricity requirements (the hotel load) are supplied by four MTU prime mover diesel motors connected to Alconza alternators.

Armament
Each ship's main weapon is a 48-cell Mark 41 Vertical Launch System. The cells are capable of firing the RIM-66 Standard 2 anti-aircraft missile or the quad-packed RIM-162 Evolved Sea Sparrow point-defence missile. The Force 2030 white paper indicates that the Hobart's Mark 41 launchers are likely to be equipped (either at construction or through later modification) to fire the RIM-174 Standard 6 anti-aircraft missile and the Tomahawk cruise missile.

The missiles are supplemented by two four-canister launchers for Harpoon anti-ship missiles, and a BAE Systems Mark 45 Mod 4 5-inch gun with a 62-calibre barrel. The 5-inch gun has a maximum range of 23.6 km. Two Babcock Mark 32 Mod 9 two-tube torpedo launchers will be carried, and used to fire Eurotorp MU90 torpedoes at submarines. For close-in defence, the ships will carry an aft-facing Phalanx CIWS system, plus two M242 Bushmaster autocannons in Typhoon mounts sited on the bridge wings.

In November 2006, the Australian Government commissioned research on whether the AWDs should be equipped with anti-ballistic missile capabilities, most likely linked to the United States Department of Defense's Aegis Ballistic Missile Defense System.

The Hobarts will each initially carry a single S-70B-2 Seahawk helicopter. The helicopter will be replaced by the MH-60 Romeo version of the Seahawk once it enters RAN service. Two rigid-hulled inflatable boats are carried.

Sensors and systems
The Hobarts are built around the Aegis combat system, specifically the Aegis Baseline 7.1 Refresh 2 version. The system has been 'Australianised' to be more capable in regards to non-aviation threats. The system feeds into the Australian Tactical Interface; six multi-function consoles that are capable of handling the destroyer's sonar, electronic warfare, and close-defence functions in addition to Aegis. The main radar system is the Raytheon AN/SPY-1D(V) S-band radar. The combination of the AN/SPY-1D(V) radar, Aegis system, and Standard 2 missile will allow each destroyer to fire on enemy aircraft or missiles over 150 km away.

In addition to the main radar, the Hobarts will be fitted with a Northrop Grumman AN/SPQ-9B X-band pulse Doppler horizon search radar, a Raytheon Mark 99 fire-control system with two continuous wave illuminating radars for missile direction, and two L-3 Communications SAM Electronics X-band navigation radars. The ships are fitted with a Ultra Electronics Maritime Systems' Modular Multistatic Variable Depth Sonar System, which included a hull-mounted sonar, a quad directional active-passive receive array, a passive torpedo detection array, and a high-powered towed sonar source. Other sensors include an Ultra Electronics Series 2500 electro-optical director, a Sagem VAMPIR IR search and track system, and Rafael Toplite stabilised target acquisition sights for each ship's Typhoons.

Electronic warfare sensors consist of the ITT EDO Reconnaissance and Surveillance Systems ES-3701 electronic support measures (ESM) radar, a SwRI MBS-567A communications ESM system, an Ultra Electronics Avalon Systems multipurpose digital receiver, and a Jenkins Engineering Defence Systems low-band receiver. Countermeasures include four launchers for Nulka decoy missiles, plus four six-tube launchers for radio frequency, infrared, and underwater acoustic decoys.

Communications equipment includes HF, VHF, and UHF radios, Link 11 and Link 16 tactical data exchange uplinks, ASTIS MCE (Advanced SATCOM Terrestrial Infrastructure System Maritime Communications Elements) terminals, and Inmarsat equipment.

Construction
Each ship is assembled from 31 pre-fabricated modules or 'blocks', averaging 200 tonne in weight and in size. The nine blocks making up the forward superstructure of each destroyer, containing the most sensitive or classified equipment, are assembled by ASC's shipyard at Osborne, South Australia, where the final assembly of each destroyer will occur. The other 22 blocks for each ship were subcontracted out. On 9 May 2009, two companies were selected to fabricate the additional blocks: NQEA Australia (building the twelve blocks of each ship's hull) and Forgacs Group (building the ten aft superstructure blocks per ship). However, during June, NQEA advised the AWD Alliance that the shipbuilder was undergoing restructuring and may have difficulty in meeting its contracted obligations. The Department of Defence went into negotiations with NQEA and BAE Systems Australia (which had been shortlisted during the initial subcontractor selection process), and at the end of June, transferred all of NQEA's work to BAE.

In October 2010, the 20 by central keel block manufactured by BAE for Hobart had distorted, making it incompatible with other hull sections. The cause of the fabrication errors is unknown: BAE blamed incorrect drawings from designer Navantia, while the AWD Alliance claimed the other two shipyards have not experienced similar problems, and believe first-of-kind manufacturing errors were made by BAE. The delay in reworking the keel block was predicted to set construction back by at least six months.

In late May 2011, the government announced that the delay in building Hobart had increased to between one and two years, and would attempt to reduce the workload on BAE (which is also responsible for superstructure work on the Canberra class amphibious ships) by redistributing up to 13 of the 24 hull blocks the company was slated to build for the first two ships to the other two shipyards. In addition, the three blocks containing each destroyer's hull-mounted sonar are being assembled by Navantia in Spain and the United Kingdom, with the possibility another two hull blocks could be assigned to the Spanish shipyard. An additional nine-month delay was announced in September 2012; this was intended to create a better transition of labour from the destroyers to following shipbuilding projects (replacements for the Collins class submarines and the Anzac class frigates), and achieve some savings in the federal budget.

Hobart's keel was laid down on 6 September 2012.

Originally, the Hobart class destroyers were planned to be operational between December 2014 and June 2017. However, the ongoing delays have prompted the Australian government to announce revised entry-to-service dates in September 2012: Hobart will commission in March 2016, Brisbane is due in September 2017, and Sydney in March 2019.