Yep, and the reality is that if the desire is for a new build you have to have a yard to build them that is familair with the design before you start construction. Look at the fun and games with the Hobart Class where the designer and yard were pushed together. In this context I suggest running off to Korea with a design and saying 'build this' is not practical in the time frame being mooted. It is going to require time to assess the design and integrate that into the build programme of the yard (the need for comprehensive scheduling of the build programme connot be underestimated).Look we can all agree on that. Of course it would be great if we could magic up a couple of new Frigates. But this is not going to happen Naki for all that we wish for.
But a lease of say for example Arunta or Warramunga (or whatever the first OZ Anzac ships crew becomes the commissioning crew of the Hunter were assigned to ) which we take over, operate and crew for a further 5 years until the first of our Anzac replacements happen is the only other solution unless 1. We can find another 2nd hand Frigate like a Type 23 or a mothballed and tarted up OHP or 2. We want to go through the period of 2025-2032 with still just two Frigates in commission.
At this stage the NZ DoD have not even agreed the requirements for the next class of major fleet unit and it is almost 2019. A 2022-3 build start is really not practical unless someone stands up and makes a decision now and even then it is almost impossible as the the contractural arrangements will chew up a year and I doubt long lead items will be purchased until that is done. Lets face it .... you cannot walk up and ask for a combat system or sensors off the shelf ...same goes with GT's, DA's and gearboxes and a myriad of other gear.
So there are a few options:
1. Piggy back off someone elses build ... which means living with someone elses decisions
2. Develop your requirements and then go out with an RFT ........... and this is going to take a while and I suspect you are not going to see a new hull in a hurry and 2025 would be a real stretch.
3. Look at an interim solution.... if considered necessary
If the political environment changes and there is an urgent need for another ship then an ANZAC (assuming one is available) is a good option as the ship design and a number of the systems are the same or similar and training can be done on an in service ANZAC with joint manning by RAN and RNZN service personnel (noting this has been done in the past).
However ..... this is all semantics unless there is a change in the political and regional environment. If that happens and things going pear shaped the Hunter Class or the T26 may be their best option... who knows. The critical issue is NZ need to determine what they require first.