Yes and guess what Lurssen is the main contractor for the German K130 Braunschweig class corvettes, as well as being involved in the SAAR6 class evolved from the K130 for the Israeli navy. Should the need arise it may well be a better option to just build something similar rather than up gun the OPVs.
Get these OPVs built and in service and determine what they can and can't do, over and above the contracted requirements, from there, then if it is deemed that a more capable platform is required they can then be built by the thriving industry that has resulted from the shipbuilding plan. The OPVs can then either all continue as is, as modified or be cascaded into Hydro, MCM or to BPC, roles the design is already suitable for in its baseline form with the addition of containerised systems.
The bit I am concerned about, and this to an extent is based off how the RNZN's
Protector-class OPV's turned out, is just how much flexibility has been incorporated into the design? For example, if it were to turn out that a 40 mm/L70 Bofors became insufficient due to changes in operational tasking or the security situation, could a 57 mm or 76 mm gun mounting be installed? Or would structural work need to be done first? The old FCPB's were fitted with surplus 40 mm/L60's, but the mounting location was designed to take a 76 mm gun. OTOH the RNZN's
Protector-class OPV per the design drawings would need to have significant structural work done to put any deck penetrating mount in place of the 25 mm Typhoon, or to install a magazine beneath the gun mounting.
A similar situation exists with respect to helicopter operations. A lack of permanent helicopter facilities could make long duration helicopter operations more difficult or untenable in the future. While there are no current plans to get more LUH's at this time, it is likely the OPV's would see service until ~2050 and there will likely be plenty of opportunity for things to go pear-shaped in the next 30 years.
Not aimed at Raven but a general comment ref the 40mm, there is a very wide range of capable modern munitions available in that calibre, including some that provide a CWIS capability. As for replacing 25mm on all and sundry I don't know, the LPHs are getting Phalanx but the Hobarts will likely be keeping theirs and I am pretty sure they will be in the running for the new frigates which will need 18 mounts. Also with the MCMVs being upgraded and life extended 25mm may well find its way onto them as well.
With respect to a CIWS capability, I am less concerned about the munitions fired than the gun itself. For a small-calibre gun that has an effective range of ~4 km in a CIWS role, a practical ROF 100 rounds in 20 seconds seems insufficient. The Italian DARDO CIWS for instance uses variants of the Bofors 40 mm/L70, but in a twin-mounting, or twin rapid fire variant which can provide two to three times the volume of fire as a single gun mount can.
With the larger calibre guns, the significantly larger size of the shell and what the munitions can do offset the much lower ROF. To put things into perspective, the 35 mm AHEAD projectile is 0.75 kg with 152 tungsten sub-projectiles and 40 mm projectile from the L70 is ~0.96 kg. While a 57mm Mk 295 Mod 0 3P-HE projectile is ~2.4 kg with 8,000+ preformed tungsten fragments and 76 mm DART projectiles are ~4 kg and guided
Between the ROF, stock of munition in the mounting, and weight of the munition, a gun like the Mk 4 40 mm/L70 can deliver a smaller weight of shot in a given period of time, or before running out altogether, than guns like the Millennium Gun, or the Mk 110 57 mm and Mk 75 76 mm.
Australia does seem out of step with other countries in that there are no plans for light frigate corvette sized warships.
While I agree that large surface combatants like the Hobart and SEA 5000 frigate represent huge capability boost, ship numbers do have a quality all of their own.
I would hasten to add that this should not be at the expense of any of Australia's planned new fleet of frigates but perhaps it could be combined with Australia's requirement for a new MCM fleet in the 2030s.
This is largely due to Australia's location an area or breadth of naval interests. Corvettes tend to be either very lightly armed with some sea-keeping and endurance like an OPV, or well-armed like a scaled down frigate or destroyer but with a much shorter endurance and less seakeeping. Australia sends the main fleet units all over the world, but IMO it would be risky to attempt to do the same with a corvette.
As a side note, does anyone see potential value to the RAN/ADF for a few (2-4) multi-role support ships in the 3,000 to 4,500 ton range? I have in mind something like a smaller version of the Danish
Absalon-class support ship or perhaps Singapore's
Endurance-class LPD. A vessel able to perform some patrolling functions, but also capable of self-defence in moderate threat environments and able to land and then support platoon+ sized detachments for HADR and insurgency responses.
