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Arming the Arafura Class 

First published in Australian Warship  magazine and reprinted here with the generous consent of the author Steve Chaplan. - Thank you Stever.

Some possible options reports Steve Chaplin.

Recent announcements from the Department of Defence have indicated further progress with the $3.6B Arafura class offshore patrol vessel (OPV) program as the $95B naval shipbuilding plan gathers steam.

The keel for the first of twelve Arafura units has been laid down on time and on budget, using more than 50 tonnes of Australian steel assembled at ASC’s Osborne Naval Shipyard in South Australia. SEA 1180 Phase 1 OPVs will replace and improve upon the capability offered by the 13 Armidale class patrol boats (ACPBs) when the larger ships enter service from 2022.

With work now well underway, the decision makers involved in the outfitting of these new vessels need to get it absolutely correct when it comes to the proper types of weapons to be fitted to the class.

Armed for their roles

The primary role of the Arafura class will be constabulary missions and the OPV will be the primary ADF asset for these maritime patrol and response duties. Following the December 2018 sale of HMA Ships Hawkesbury and Norman from the minehunter squadron, references made by Defence indicate these OPVs “may” replace some of the Huon class mine hunters or act as mother ships for future hydrographic missions.

In stating that, should we ensure the outfitting of weapons for these vessels is correct from the start and not have to spend millions of dollars attempting to upgrade these systems which should have been done properly in the first place?

After all, it is the Australian taxpayer who is purchasing these vessels and I am in no doubt they would mandate value for their hard-earned dollar!  Defence must seriously consider military movements and happenings to Australia’s northern borders and the missions and taskings that will be undertaken by these OPVs, as they will be on most occasions, operating as an independent asset.  If, in the event of becoming actively involved in a naval engagement or awaiting the arrival of a larger RAN or RAAF asset, these vessels MUST have the right equipment to ensure they can properly defend themselves.

Primary armament

ADF as well as media reports indicate that the Leonardo Oto-Marlin 40mm Naval Gun will be the OPV’s principal armament. The gun mount operates with a high fire rate; its 40mm cannon fed through a 72 round magazine capable of managing a dual feed ammunition system. The system can be set up according to three different configurations based on customer requirements:

Type A - remote control mode - this system is married to the shipboard Command Management System (CMS), and the short reaction time in conjunction with the high accuracy, provides excellent performance.

Type B - local emergency control - when this is required, in addition to the remote control mode, it is possible to adopt the coaxial configuration (Type B) that employs a high-performance daylight camera installed on the gun mount. This camera allows control in emergency autonomous mode if the CMS is not available.

Type C - completely autonomous mode - in this scenario it is possible to adopt a Stand Alone with Micro Fire Control System (MFCS) configuration (Type C) based on an independent line of aim Sensor Suite equipped with a daylight sensor, a cooled IR sensor and an LRF (Laser Range Finder). The system integrates a predictive ballistic calculation based on muzzle velocity radar installed on the gun mount.

An auto tracking module, capable of identifying and aiming at an acquired target is optional. The fully CMS slaved mode is still available and selectable. If required, an optional ballistic calculation system is available for Type A and Type B configuration.

The Oto-Marlin 40mm gun system provides all the expected 40mm ammunition performance with the advantage of a compact, versatile and flexible structure typical of a smaller calibre system. Furthermore, the modern design fulfils the increasing need for easy maintainability and management.

Under the specifications, it would appear the Type B system would be the more appropriate installation for the OPVs, supported by the intended integrated electro-optic targeting system.  With crew numbers estimated at approximately 40 personnel, a fully autonomous supply/loading system would allow for an enhanced limited systems manpower and not having to rely upon several much-needed crew members being taken away to maintain an ammunition supply line to the weapon whilst firing.

Secondary armament - preliminary selection

Previous announcements regarding the support weapons indicate at least two 12.7mm machine guns will be fitted to each OPV. However, that reveals that the class will be extremely vulnerable and weak in the event of multiple attacks from either surface or airborne platforms.

To counter this possible scenario, the Mini-Typhoon could be added to the armament. This weapon is a lightweight, naval, stabilised and remote operated machine gun system utilising the .50 calibre Browning Quick Change Barrel (QCB)heavy machine gun. The MiniTyphoon could provide perimeter protection for larger or smaller sized vessels.

See details in the table hereunder:

Function - Close-In Weapon System Manufacturer - Rafael and General Dynamics

Action - Short recoil-operated Feed - Belt-fed (up to 230 rounds on mount)
Weight - 140-170 kilograms Rate of fire - 450-575 rounds per minute
Ammunition - 12.7mm x 99mm NATO rounds Calibre - 12.7mm (.50 cal) Barrel length - 1,143mm Range - 1,800 metres

Whilst the 12.7mm machine guns are considered an inexpensive support weapon to a ship’s main armament, their selection for fitting aboard the OPVs could be considered ill-chosen for the intended task. Another consideration in the selection of this size weapon is the inadequate Maximum Effective Range (MER) of only 1,800 metres. In a combat environment the Commanding Officer would surely seek something that not only has a MER greater than 1,800 metres, but also offer a serious deterrent against incoming threats at much more than arms reach.

Secondary Armament - optimum selection

With the selection of the OPV 80 design would it not make financial logic to recycle and upgrade the Armidale’s existing Mk38 25mm M242 Bushmaster weapon systems and fit them aboard the new OPVs?

Although each Armidale is fitted with only one mounting, this proposition suggests two of the M242 25mm guns be mounted onto each OPV. To install and link two of these gun systems will require some additional expenditure to upgrade and incorporate them onto the twelve OPVs. Consideration must be given in selecting a weapon that is not crew intense, so the M242 Bushmaster would make the ideal support weapon.

The weapon is mounted on a stabilized deck mounting which allows it to remain on target as the platform beneath it moves. The mounting does not penetrate the platform, making it relatively simple to install the weapon. The Bushmaster can use sights attached to the weapon mount or it can receive inputs from an independent Electro-Optical Detector (EOD) or Fire Control Radar (FCR). Using its own sight, the gun system can provide firing solutions entirely without outside assistance, allowing it to function fully independently.

The Bushmaster mount can traverse 120° to either side and elevate between -12.5° and 40.5°. The weight of a complete system is between 690 kg and 750 kg without ammunition, depending on the guns and sensors mounted. Its effective firing range is 3,000 metres, with a maximum firing range out to 6,800 metres. The 25mm round also enjoys greater range and terminal effectiveness, coupled with lethality in both the anti-surface and anti-air roles than the smaller 12.7mm ammunition.

The gun can destroy lightly armoured vehicles and aerial targets (such as helicopters and slow-flying aircraft). It can also suppress enemy vessels such as exposed personnel, vessel superstructures,and electronic/communication domes and fittings.

Its standard rate of fire is 200 rounds per minute. With over 10,000 units sold worldwide, it is one of the most successful autocannons.  Such systems could be installed and set up on each OPV to be operated from the Operations Room via the Combat Management System (SAAB 9LV Mk4) or from the independent remote operating consoles, also located in the Operations Room.

As for 25mm ammunition, it is significantly cheaper and currently being manufactured by ADI at Benalla. Bushmaster location

In the initial fit-out of the OPV’s weapon system, a missile point defence system was not included in the package.  Therefore, to accommodate the two 25mm weapons systems, the rear of the bridge deck towards the funnel could be extended to ensure enough space to mount these weapons.

In summary

Despite the fact that Navy is known not to be keen on introducing another class of gun into service, cost is far and away the principal driver to produce savings wherever practicable. Thus, would it not be logistically and financially appropriate to encapsulate the ammunition requirements for both the RAN and Army with a locally manufactured calibre for the respective 25mm and 30mm weapon systems for the OPVs, Hunter class guided missile frigates (FFGs) and the Boxer MPVs?

Deliberating on the unsettling times to the north of Australia and the dependence of these new OPVs in supporting Australia’s interests, reaffirms the argument to outfit these new vessels with capable, reliable and powerful hardware in which to either attack or defend.

The argument could exist in why you would want to ‘under-gun’ an OPV which could be operating against similar sized hostile platforms but fitted with a superior weapon system. Not an ideal situation to provide comfort and reassurances to the ship’s company, that’s for sure.

Whichever way Defence considers an outfit of weapon operating systems, the adage of “don’t even think of taking a knife to a gunfight” should be of foremost concern. Overall, the Government today cannot consider cheaper options or cost savings when it comes to provisioning the warships that protect Australia and are placed in harm’s way - they must be able to robustly defend themselves and their crews with the appropriate and the correct weapon systems.