There are lots of questions with this announcement, but not many answers, other than if the
Fairfax media report is correct in that the ship mentioned by the Def Min will be 'large' and 'new'.
New build is reasonably clear, large is more of, how long is a piece of string?
If the new ship is built overseas, then yes it can be any size we want and any design we want (money is the only limiting factor), but in the current political climate (a new Morrison Government and an election a max of six months away), I'd suggest that the new Government will want to maximise all the potential benefits from this project.
If things don't change around dramatically between now and the next election, then Shorten will be the next PM (God forbid), so I would think that the current Government will not only want to be seen as good neighbours for our Pacific friends, but also want to provide employment in Oz (Jobs! Jobs! Jobs! winning one or two marginal seats in critical electorates could be the difference of being in Government or Opposition for the next three years).
Assuming that the new HMAS
Pacific Reach (for a better name) is built here in Oz, then that will certainly limit the ship size and build location.
Using HMAS
Choules as an example of 'displacement/size' (she is approx. 16,000t), with the current infrastructure at both Osborne SA and Henderson WA, the max displacement that is able to be launched is somewhere between 10,000t and 12,000t.
Here is some info on the current (and planned) capabilities of both the facilities:
Henderson PDF:
https://www.australianmarinecomplex.com.au/sites/default/files/inline-files/1.1-AMCCUF-eBrochure_2016_Web_0.pdf
Osborne PDF:
https://www.asc.com.au/assets/downloads/CD4067_ShipbuildingCapability_A4_4pp_CMYK_%C6%92_LR_FINAL.pdf
Osborne upgrade:
https://www.youtube.com/watch?v=_nUZZBG0KXA&t=41s
Henderson upgrade:
https://www.youtube.com/watch?v=eQHhZ8o7YvI&t=2s
So even with all of the above upgrades (which are focused on Frigates and OPVs in their respective build locations), I would imagine that at the very least there would have to be a further enlargement of hardstands and transfer systems, which of course also cost more money and to stay within the limits of the capacities of the shiplift in SA and floating dock in WA. A ship of the size of HMAS
Choules (16,000t) would also require the shiplift and floating dock to be increased in capacity too.
If the new ship (built in Oz) was to be something along the lines of a Damen Enforcer, it would have to be one of the smaller designs, LPD 7000, 8000 or probably the 9000 at the max.
Landing Platform Dock for strategic transport and amphibious operations
Anyway, all speculation on my part, but if the new ship is built here, then there will be limitations as to size without spending buckets on money on substantial infrastructure upgrades too.
Cheers,