Armidale-class patrol boat

The Armidale class is a class of patrol boats built for the Royal Australian Navy (RAN). Planning for a class of vessels to replace the fifteen Fremantle class patrol boats began in 1993 as a joint project with the Royal Malaysian Navy, but was cancelled when Malaysia pulled out of the process. The project was reopened in 1999 under the designation SEA 1444, with the RAN as the sole participant. Of the seven proposals tendered, the Austal Ships/Defence Maritime Services proposal for twelve vessels based on an enlarged Bay-class patrol boat was selected. The first vessel, HMAS Armidale (ACPB 83), commissioned into the RAN in June 2005. Two more patrol boats were ordered in 2005 to provide a dedicated patrol force for the North West Shelf Venture, bringing the class to fourteen.

The Armidales are longer and heavier than their Fremantle class predecessors, with improved seakeeping ability and increased range, allowing them to reach Australia's offshore territories. The ships are multi-crewed, with three ship's companies available for every two vessels; this allows the patrol boats to spend more time at sea without cutting into sailors rest or training time. However, during their early service life, there were problems with the fuel systems across the class, and a 20-bunk auxiliary accommodation compartment has been banned from use after toxic fumes were found in the compartment on at least two occasions.

All fourteen vessels were constructed by Austal Ships at Henderson, Western Australia, with the last entering service in February 2008. The Armidale class ships are operated by the Australian Patrol Boat Group, and based in Cairns and Darwin. They are primarily tasked with border protection, fisheries patrols, and the interception of unauthorised arrivals by sea, although two vessels are permanently assigned to protecting the oil and gas production facilities of the North West Shelf Venture. A fictional Armidale class boat, HMAS Hammersley, appears in the Australian military drama series Sea Patrol from the second season onwards.

Development and tendering
Planning for the Armidale class began in 1993, as a plan to replace the Fremantle class, which was due for retirement in 1998. This evolved into a joint program with Malaysia to construct an offshore patrol craft. When Malaysia pulled out, the plan was scrapped, and the Fremantles underwent a life-extending refit. The cost of maintaining the aging vessels prompted the Department of Defence to create the Replacement Patrol Boat program, which received the procurement project designation SEA 1444.

SEA 1444 marked several departures from the Department's standard acquisition requirements. Instead of specifying a number of vessels, the coverage of 3,000 ship-days per year (with 1,800 to be spent on border protection operations, and a surge capability of 3,600 days) was given, with the producer to determine how many ships were needed to meet this. The ships had to meet specific performance parameters, such as the ability to conduct boarding operations in conditions up to Sea State 4, and to maintain surveillance capability up to Sea State 5. The producer was also required in the contract to provide support and maintenance for the ships, for fifteen years after construction completed.

Nine companies expressed interest in the project; of these, seven had the required capability to build the ships. These seven were narrowed down to three based on each tender's merit, competitiveness with the other tenders, and successful meeting of Australian industry involvement targets for both construction and long-term support. Austal Ships and Defence Maritime Services (DMS) partnered to offer twelve ships based on an expanded version of the latter's Bay class patrol boat, in use with the Australian Customs Service. The companies submitted two proposals for a 56 m vessel, one with a steel hull, and one with an aluminium hull; the latter offering a 21% reduction in fuel consumption. Australian Defence Industries (ADI) tendered a design based on the Royal Danish Navy's Flyvefisken class patrol vessel. The vessel was to be built with a glass-reinforced plastic hull, similar to ADI's Huon class minehunters. The Tenix proposal was a variant of the 56 m search and rescue vessel constructed for the Philippine Coast Guard. The tender was awarded to the Austal/DMS partnership in December 2003. The contract was valued at A$553 million, with each ship costing between A$24 million and A$28 million to construct.

During the 2004 federal election, the Coalition promised to acquire two more patrol boats to provide a dedicated patrol force for the oil and gas producing facilities located off the north-west coast of Australia. These were ordered in 2005.

Design and construction
All fourteen ships were constructed by Austal at their shipyard in Henderson, Western Australia. Lead ship HMAS Armidale (ACPB 83) was commissioned into the RAN in June 2005. Two other patrol boats were delivered to the RAN in 2005, six in 2006, and five in 2007, with the final ship in the class, HMAS Glenelg (ACPB 96), delivered in October 2007 and commissioned in February 2008. At one stage, six vessels were being constructed simultaneously.

Each patrol boat has a length of 56.8 m, a beam of 9.5 m, a maximum draught of 2.25 m, and a displacement of 270 tons. The hull is of the semi-displacement vee type, and is fabricated from aluminum alloy. The ship is designed to a combination of Det Norske Veritas standards for high-speed light craft and RAN requirements: a lot of effort went into avoiding attempts to overengineer the Armidales or turn them into 'miniature warships'.

The Armidales can travel at a maximum speed of 25 kn, and are driven by two propeller shafts, each connected to an MTU 16V M70 diesel. The ships have a range of 3000 nmi at 12 kn, allowing them to patrol the waters around the distant territories of Australia, including the Cocos (Keeling) Islands and Christmas Island. The Armidale class has demonstrated an improved seakeeping ability over the preceding Fremantle class: the Armidales are 15 m longer, 85 tons heavier, and have hydraulic stabiliser fins and trim tabs incorporated into the design, allowing them to survive conditions up to Sea State 9. The vessels are designed for standard patrols of 21 days, with a maximum endurance of 42 days.

Weapons and systems
The main armament of the Armidale class is a Rafael Typhoon stabilised 25 mm gun mount fitted with an M242 Bushmaster cannon. This cannon has a rate of fire of 200 rounds per minute, and is controlled remotely from the bridge. Two 12.7 mm machine guns are also carried.

Boarding operations are performed by two 7.2 m, waterjet propelled rigid-hulled inflatable boats (RHIB), which carry ten people (a fully equipped, eight-strong boarding party, and two boat crew). The RHIBs are larger and more powerful than the single RHIB aboard a Fremantle, are capable of operating independently of their mothership, and carry their own communications, navigation, and safety equipment. Each RHIB has a dedicated cradle and davit, the boats can be launched and recovered easily, and a centralised 'dressing room' incorporated into the ship's design has streamlined the deployment and return of personnel.

The patrol boats are fitted with S band and X band surface search radars, a Toplite electro-optical detection system, and a Warrlock direction finding system. A Prism III radar warning system was fitted to the last two boats during construction, and refitted to the rest.

Complement
Each patrol boat has a standard ship's company of 21 personnel, with a maximum of 29 (not including use of the austere compartment). Unlike the Fremantle class patrol boats, the Armidales do not have a permanently assigned ship's company. Instead, there are 21 crews established for the 14 Armidale class patrol boats, which are divided up into four divisions: Attack, Assail, Ardent, and Aware. The first three of the Divisions are assigned six crews for four ships, while Aware has three crews for two ships. The ships are continually manned, with two out of three crews actively deployed while the third undergoes leave or training, or prepares to transfer into a ship: a handover can be accomplished in less than six hours. The intention of multi-crewing is to allow the ships to spend more time at sea, without compromising sailors' rest time or training requirements.

Junior sailors are housed in four-berth cabins, as opposed to the central sixteen-berth mess deck of the Fremantles, while senior sailors and commissioned officers either have individual or share two-berth cabins. Personnel have access to e-mail and satellite television, and the galley is better equipped than that on a Fremantle class vessel and better suited to use in heavy seas. The comfort of personnel is also significantly improved over the Fremantles, with air conditioning throughout the entire ship (excluding engine and machinery compartments).

Introduction into service
The introduction of the class into service has not been without problems. Since June 2005, all active Armidales have undergone operating restrictions on two occasions, both due to water contamination of the main fuel systems. The first occurrence, in September 2006, led to the suspension of operations by the patrol boats for a month, and the engineering controls were redesigned. The problem occurred again in January 2007, and led to an 'operational pause' while Austal redesigned the fuel system, engineering procedures were altered, and fuel quality criteria were tightened. The five ships yet to be completed were fitted with the modified fuel system during construction, while the active ships were refitted over the course of 2007. As of December 2007, no further fuel problems have occurred.

A 20-berth auxiliary accommodation compartment was included in the design, for the transportation of soldiers, illegal fishermen, or unauthorised arrivals; in the latter two cases, the compartment could be secured from the outside. However, a malfunction in the sewerage treatment facilities aboard HMAS Maitland (ACPB 88) in August 2006 pumped hydrogen sulfide and carbon monoxide into the compartment, non-fatally poisoning four sailors working inside. Use of the compartment as accommodation was banned across the class. In 2009, a sailor working in the compartment on a different vessel was also gassed with hydrogen sulfide, and carbon monoxide was regularly detected in the enclosed space.

Operations
The Armidale class ships are operated by the Australian Patrol Boat Group and are primarily tasked with border protection and fisheries patrols. As of 2009, up to seven Armidale class boats are assigned to patrols of Australian waters at any given time as part of Operation Resolute, with an increase to nine of the fourteen vessels when required.

Ardent Division and four ships are based at HMAS Cairns in Cairns, while the other three divisions and ten ships are located at HMAS Coonawarra in Darwin. Up to two ships (typically HMA Ships HMAS Glenelg (ACPB 96) and HMAS Maryborough (ACPB 95), plus Aware Division) can be forward-based at Dampier, Western Australia, facilitating patrols of the oil and gas producing facilities located off the north-west coast of Australia.

Appearances in fiction
From the second season onwards of Sea Patrol, an Australian military drama series, the fictional Armidale class patrol boat HMAS Hammersley (pennant number 82) is used as the main setting. In 2008, two ships were conflated to represent Hammersley: 42 of the 86 days of filming were spent aboard HMAS Broome (ACPB 90), with later pick-up filming aboard HMAS Launceston (ACPB 94).

Replacement
Defending Australia in the Asia Pacific Century: Force 2030, the 2009 Department of Defence white paper, proposed replacing the Armidales, along with the RAN's mine warfare and hydrographic vessels, with a single class of multi-role offshore combatant vessels (OCVs). The new vessels, which could displace up to 2,000 tonnes and be equipped for helicopter or unmanned aerial vehicle operations, will use a modular mission payload system to change between roles as required.

Although the 2013 White Paper committed to the OCV as a long-term plan, it announced that an interim patrol boat class based on an existing design would be acquired as a short-term replacement.