Probably better to stop the bus, back it up a bit, and have a look at the 'big' picture, rather than the dot on the wall.
As has been mentioned here numerous times, there is currently a 'pool' of 12 Phalanx, and it appears that another two will be ordered reasonably soonish(?) for the Future Frigates, have a read of this:
Where to now for naval missiles?
As it stands at the moment there are 3 x FFG's fitted with (or capable of being fitted with) Phalanx, and don't forget they are also equipped with Nulka(?) and ESSM too (and as these three remaining FFG's retire and are replaced by the AWD's, their Phalanx will no doubt go back into the 'pool').
The eight Anzacs, as has been discussed and reported, have top weight issues, so no Phalanx fitted, but have Nulka and ESSM.
So as it appears the 'pool' of 12 is just about sufficient at the moment.
Now moving forward....
The plan is to have the 3 x AWD's fitted with 1 x Phalanx as they enter service, the plan appears to be that the 2 x LHD's will be upgraded/equipped with up to 3 x Phalanx each and also Choules to receive 1 x Phalanx and the two new AOR's (2019 and 2020) 1 x Phalanx each.
So if you add all of that up, it equals 12, and that equals the 12 in the pool too.
so moving forward again.....
Somewhere in around 10 years the first of the Future Frigates should replace the first of the Anzacs to retire.
So lets 'assume' that Phalanx (or another future upgraded version) is still in RAN inventory at that time around the mid 2020's or beyond.
The requirement would possibly look like this:
* 3 x AWD (1 each)
* 2 x LHD (3 each)
* 1 x Choules (1)
* 2 x AOR (1 each)
* 9 x Future Frigate (1 each, the nine will come into service over a long period too)
Added to that is the possibility of the additional AOR or Choules type ship (mid 2020's and beyond), add another mount to the requirement.
If each ship was in commission, and if each was equipped with the appropriate number of mounts that would total 22 mounts.
I would imagine that if the RAN eventually ended up with a 'pool' of around 20 mounts, that would cover all bases, and again not all ships are or will be in service/commission at the one time.
Of course if the 'poo hit the fan', one would hope that we could possibly obtain additional mounts from the USN pool sooner rather than later, and a couple of example could be that the AOR's and Choules might require/end up with a 'second' mount.
Anyway....
Cheers,