Trading an Anzac for a Hobart class type ship I get. You get way more firepower and capability for slightly more crew. We have only 3 hobarts, we need more than 3 hobarts. 48+ VLS, Aegis, 5" blah blah, it make sense. It aint perfect, but it has a clear niche to fill.
Trading an Anzac for a Corvette I don't get.
Modern Corvette/small frigate has a crew of about 100.
Anzac has a crew about 160.
So for two Anzacs you get three Corvettes in terms of crewing.
- But the corvette is smaller
- But the corvette has less range
- But the corvette has an inferior and smaller radar and a lower radar mast
- But the corvette has less than half the helo capability
- The the corvette has a smaller gun
- The corvette has worse sea keeping capability.
- The corvette ties up a naval yard and costs ~500-1b...
- Corvettes typically don't have a layered defence.
Not sure this is the trade off we are looking for. The Anzac are old, but they sport the very latest radars, ESSM, soon NSM, and two helos.
Can't help but look at 4000-6000t class, where you could get similar manning and a whole lot more capability. Unless the corvette is super fast to build....