I think he means "Australian waters" exactly how you explained it. The RAN will use them for disaster relief in their proverbial backyard a port visit here and there and some token military exercises to show that it actually is a warship. But the RAN unlike the USN is not designed for major transoceanic operations, so they will probably operate mostly in and around South East Asia.
I have a problem with your point about the escorts though! Dodger67 said "An LHD has no business paddling around in hostile water without an escort of at least a frigate" and he's right, so are you when you say they will have escorts. But the issue I have with this and with a lot of the discussion in this thread is that it's all very... academical. It's like a lot of the air force debates, this stat versus that anecdote.
And we're not wrong to do it because that's how defense theory is made. But ultimately things never go as planned. The Canberra ships are major national assets, more importantly they are warships. They should at least be able to protect themselves, even if they're protected a missile or an aircraft could penetrate and they would be defenseless. What's more is by the nature of their operations, amphibious assault assets are often in vulnerable positions close to shore.
We've been through this a thousand times on this site. Feel free to read the RAN thread...
The Canberra Class are armed according to threat level they are expected to encounter in PEACE TIME operations and Humanitarian Support support missions. If they are to be deployed to a combat area, they will be appropriately armed to address the threat, just as Kanimbla and Manoora were when they went to the Gulf.
In addition, they will only operate inside the defensive air, surface and sub-surface 'umbrella' just as any other 'capital' ship does.
What I mean to say is that you never know how useful a weapon will be until you actually use it, but also that you can never completely plan out how you are going to use it. For example I personally think the type of 1-on-1 slugging match scenario described here earlier is more plausible than a lot of you are willing to admit. I don't think we'll see a lot of massive battles on the high seas anymore, because no way any nation will ever throw a fleet or carrier group against another. The risk is too high and the assets too expensive, that's why we build submarines and missile boats.
So IMHO there's a good chance that navies will be fighting in littorals and archipelago's and the like. I'm not an expert but it seems to me that this makes things more complicated. When you don't have interstellar engagement ranges and a carrier battlegroup. But enemies that are hiding or taking potshots, low flying aircraft making strafing runs etc... I know I know it's not as exiting as shooting down hypersonic cruise-missiles and whatnot but for a lot of surface combatants it is a likely scenario. I think we should conceptualize CIWS more as an all round weapon than something that shoots down incoming missiles. Even if a FFG or DDG doesn't need a Phalanx to shoot down a ASM in a battlegoup, Sir Galahad and Sir Tristam ( or their escort) could have used it to shoot down skyhawks.
And those lessons have been learnt. Why do you think Manoora and Kanimbla were equipped with Phalanx when they went on Operations? Canberra Class ships will do likewise, I'm sure. As would Choules if we were to deploy it anywhere.
Finally (super ontopic now) I like the bigger guns for air defense. Mostly because 76mm rapid fire is hella cool! With the smart airburst ammunition and all the computers and sensors you can put on a ship I'm sure that they will be effective at air defense. I don't like those hybrid gun/missile systems though. I think they're perfect for smaller ships to give them organic air defense at different engagement ranges. But for a bigger ship I think CIWS should be more compact. I also like guns more than missiles because they are more versatile. You can't fire a missile at a skiff, but you can put a CIWS on a patrol boat as a main gun and give it a secondary air defense capability.
Of course you can fire a missile at a skiff. Assuming you have the right weapons. Sea Sparrow, SM-2, Rolling Airframe Missiles all have a secondary anti-surface capability. Or you can simply add ship-launched Hellfire, Griffin, Brimstone whatever you would like and then you get a very capable, layered anti-surface capability. But what is the threat you're trying to address?
It therefore depends on what you want your 'patrol boat' to do. Our Armidale Class with a 25mm Typhoon gun and a pair of 12.7mm guns, already 'out guns' any light skiff in the world. So the argument becomes, why add a far more expensive weapon system, even if it is possible with top weight issues, real estate issues and so on? A Phalanx CIWS isn't cheap and we don't have enough in the entire Navy to fully equip our major surface combatants, let alone the entire Armidale Class.
On a big ship 6000+ tonnes I would put 3 gun CIWS and 1 SeaRAM. Then I would have 1 CIWS at the front with the main gun and VLS battery and at the back I would have 2 CIWS and SeaRAM. I don't think I would put SeaRAM together with guns, also when my CIWS was knocked out I could still use my RAM. Another thing about gun systems is you can put them in a little nook or corner on the superstructure, with missiles you always need some blast shielding so you can't place them to close to the superstructure.
Again, real estate management. If you have a vessel that big, it's primary anti-air is going to be bigger more capable SAM systems (Sea Sparrow, SM-2/6, Aster 15/30 and so on). CIWS becomes a 'last ditch' defence all the way behind EW, decoy systems, longer range SAMS, air coverage and so on.
Finally I have questions. First, I haven't seen anything to indicate it, but is there an autoloading SeaRAM system? If not, why not? Too complex? Too expensive? Not enough space/ compactness of design? Or is it just a bad idea? It would be something like the Mk 26 launcher with a magazine underneath.
My second question is a bit offtopic but someone mentioned big guns and I was wondering just theoretically. What kind of cool things you could do with some 16 inch hardware? How far could you make a 1 tonne projectile go with modern technology? And when you get it there you could make a cluster shell an airburst shell maybe a thermobaric shell a nuclear shell. What I mean to ask is could you use modern technology to make the 16 inch gun a good and useful weapon in these times?
My final question is also about the 16 inch gun. Can you really use a little 20mm cannon to shoot down a 1 tonne cannon shell? Do you aim for the fuse or do you knock it off its path (seems implausible)?
With regards
the Rolling airframe missile system is a small, lightweight self-defence system. Not a major air defence system, if you need more capability than RAM provides, you probably need to assess whether you need a more capable system, rather than just more missiles. RAM provides a 21 round launcher and most users employ 2 per ship, giving 42 missiles at full load. SeaRAM 'only' offers 11 rounds per launcher, but it is a standalone system akin to Phalanx. It's whole purpose is minimum impact on the vessel and zero to no deck penetration.
If you are expecting your vessel to require more than this, you are considering high threat environments and RAM is probably not going to be your first choice weapon system anyway.
As to the larger guns, I'll leave someone else to address this if they want. You may have noticed a significant trend away from large guns towards medium calibre, fast firing guns and missiles in modern navies.
This is for good reason...