Maybe I am being dense. I get it that corvettes are more capable than OPVs. What I don't get are what are the situations where this additional combat capability - greater than an OPV but less than an FFG/DDG - is the right answer? Where that capability is not overkill, and also not overmatched, and sufficient to justify a rumoured $6bn price tag?A Corvette is going to have a range of capabilities that an OPV never will. Take a look at the K130 seeing as though it was mentioned as a possible in context for the RAN Corvette discussion.
It comes with a combat management system, 3D /4D AESA radar system, active and passive EW / SIGINT, passive starring IRST, EO /IR capabilities, 76mm gun system, a pair of self-defence surface to air missile launchers with 42 missile rounds full integrated into the combat system and cued by radar / IRST, an anti-ship / land attack missile capability again integrated fully into the combat system, a pair of anti-surface auto-cannons, a torpedo decoy system. a mine laying system and aviation facilities for an 11t class maritime helicopter.
Compared to an Arafura with a 57mm gun, there is day and night between the 2 in terms of combat capability.
The K130 however is very short-ranged. If it were imposed upon RAN politically (which I suspect it would have to be) it would likely be used for local patrolling and defensive operations and escort tasks at most.
I don't understand the CONOPS for dealing with grey zone incursions but I would think the OPVs would be sufficient. But I may be wrong.
I would think the logical course of action would be to:
1) Complete the OPV build as planned. Use them as planned to patrol our EEZ. If a Chinese fishing boat or coast guard vessel wants to ram the OPV, put a 57mm sized hole in it. If something that wants to do more than ram shows up, the OPV should phone a friend (DDG / FFG / P-8).
2) Use the extra cash that would have otherwise gone on the corvettes to build more FFGs (accelerate Hunter if possible) or DDGs (call Navantia if their offer is credible) so that the OPV is more likely to have a friend to call when it needs it.
The only way I can see building covettes being an optimal solution would be if:
a) corvettes provide an appropriate amount of capability that an OPV can't in a situation the RAN are likely to face (possibly escort duty or commerce raiding?)
b) we have no options to accelerate the availability of FFGs / DDGs (which doesn't seem to be the case).
So the nub of my question is not what can corvettes do that OPVs can't, it's what are the situations likely to emerge in the next few years where having the additional capability a corvette offers is the right answer?