Royal Australian Navy Discussions and Updates
- Thread starter icelord
- Start date
- Status
Aussie optimist
Member
I’m no ship builder but I would not want to go down that track. The risk would be massive, essentially it would require the ship to be cut in half. There would be concerns regarding stability and overall integration of pretty much most systems. The risk would be that if it was unsuccessful, we loose one frigate and a tonne of $$$.
Also if this was a viable option, I would assume that it would have been done a long time ago as space has always been an issue with the Anzac’s.
Last edited:
Boagrius
Well-Known Member
Will defer to others on the viability of a hull plug, but I agree that we needed the Hunters yesterday. If I was a betting man I'd wager that the drum beat will need to be sped up. Given the current strategic trajectory in our region, I'm not confident that a dozen MFUs will still cut it by the end of the Hunter build, so perhaps a subsequent valley of death isn't a given? Just my 2c.
Not as easy as it may seem ... and it will be expensive and time consuming and may ultimately make things worse.
Firstly .... if you are adding a plug into the ship then it is going to have to be close to amidships where the hull form is at its widest. if you go anywhere else then the fact the beam is diminishing in either direction means that you would mess with the hull form and water flow and structural strength (as the flow of stress will not be linear. Draw a line of the hull form water line and try putting a plug in forward while maintaining that shape. It does not work.
Extension to the bow (meaning a replacement ... again to have an uninterrupted hull form) or the stern may be possible but of limited utility. Merchant ships are easier to plug as they have a consistent hull shape for quite a bit of their length.
Coefficients of Form - Ship's Waterplane, Block, Midship and Prismatic Coefficient (cultofsea.com)
looking at a handy size bulker you can see from the design about a third of the length of the ship has a consistent form. This is not true of destroyers and frigates noting they have a small block coefficient there is very little length with the same shape. Have a look at the T26 being joined up as an example.
design-of-30000-dwt-and-53000-dwt-bulk-carriers-using-advanced-computer-design-softwares.pdf (longdom.org)
Finally messing about with weights is fraught with danger. Useful example below.
History and Technology - Understanding Block Coefficients - NavWeaps
Thanks for the detailed post and links
Much appreciated.
The ANZAC's have been placed up on the blocks a number of times already for refits, so maybe if an extension could of been done it would have.
With computer modeling so good now days I would of hoped there was some scope for this option.
Was the main challenge financial or engineering?
The former we can fix, the later looks like the deal breaker.
From the link
I liked the challenged example of the Iowa Class and also the fowl water from toilet discharge following the ship in stagnant water.
Certainly don't want that !
Cheers
Regards S
Another possibility might be, is there a technical way to claw back some margin (even if it is extremely expensive and under less stringent “strategic” circumstances perhaps not worth the cost…) in the existing design so that the SWAP originally intended for a 2x 8 cell Mk.41 VL system and other enhancements (Phalanx, ESSM Block II, medium calibre guns, towed sonar array, new EW capability, new UAV capability, new RHIB boats, new type of ASM etc) might be able to be employed?
I am aware there are stability issues, centre of gravity and so on with this design, but if these vessels are to serve another 20 + years and potentially be pitched into a level of conflict they were never really conceived for, such enhancements may be necessary?
I wonder how much it would cost to build a virtual ANZAC Class frigate? It would then be possible to undertake the enhancements including a hull plug to determine what the actual impacts upon the ship's stability, safety, sea keeping etc., using the virtual ship. This would enable most problems to be discovered and rectified before any decisions are made to start cutting hulls.
Actually it probably wouldn't be that expensive or even time consuming. You can easily digitise existing blueprints. Come to think of it even if you haven't got access to the blue prints you could digitally scan sections of the ship.
In fact when it come to projects such as the LOTE for the Collins class you would almost certainly need to create a digital twin if you were to have even the slightest chance of completing the job in two years.
Last edited:
They certainly are for the Hobarts, with the planned upgrade to AEGIS Baseline 9.0 and addition of ESSM Block II, SM-2 Block IIIC and SM-6 Block 1A already in the planning stages. With us having joined the development program for Mk.54 Mod 2 torpedo and approved acquisitions for future ASM and “strategic strike“ weapons I’d suggest the upgrade program will be a lengthy, on-going process with significant new capabilities intended over the next decade to make these truly formidable vessels.
But there is and only ever will be 3 of them and the ANZAC Class for better or worse due to current Government choices, will comprise the bulk of our surface combatant force for potentially up to the next 20 years… Given improvements such as towed sonar arrays and (apparently) ESSM Block II are already approved, I and I guess others wonder what else might be able to be done to them, to ensure they remain a viable combat capability during those years?
Todjaeger
Potstirrer
Not sure that answering the question would really simplify matters, as there are quite a few guns/mountings which have non-deck penetrating versions.
You do it by suffering from sleep deprivation, causing your logics circuits to begin misfiring, while you are operating a calculator...
Going back through the numbers, I might have been listing a hypothetical ESSM loadout for a Flight II Arleigh Burke-class DDG, as 384 ESSM could (in theory) be quad-packed into the 96 Mk 41 VLS cells in the later builds of that USN destroyer. Otherwise, I have NFI or recollection of where I got the number from.
Yep it's a numbers game.
ANZAC's a big part of the fleet for many many years to come and their relevance as a front line unit must be maintained.
A big challenge that want go away.
Like it or not we need to find an answer over and above bringing the Hunters online and putting the Hobart Class through refits.
The reasons for purchasing the MEKO 200 design and what we wanted for them back in the day are now irrelevant.
The constant is the parameters of the ship and an increasingly challenging world they will sail in.
Regards S
Todjaeger
Potstirrer
IIRC the issue with the RAN's ANZAC-class FFH displacement is not 'just' what the total displacement is, but also where some of that displacement is, namely topweight. As I understand it (@alexsa and others jump in when I get it wrong) if one were to take two different vessels, of the exact same dimensions and displacement, but one of them had a goodly portion of their displacement located a significantly greater distance above the waterline than the other, then that vessel would have a much higher centre of gravity and would be more inclined to have the hull roll. It could also be more prone to capsizing under the right (or wrong) conditions
Also, I looked at some of the images of the Valour-class (MEKO A200) frigates in S. African service and I noticed that elements of the layout were quite different between the RAN and SAN. For example, while both designs have a main gun in the 'A' position, the SAN frigates have their SAM VLS cells on the same level as the main gun, immediately aft of the gun. The RAN's ANZAC-class frigates appear to have their Mk 41 VLS located immediately aft of the funnels, two decks higher their where the SAN has their VLS located.
All good points and I don't disagree.
Remember going to an open day for one of the ANZAC's when just entering service.
Climbed lots of internal stairs to the void where the future second cell VLS was to be installed.
At the time a big open space of opportunity!!!!!!!
Not sure what's there now.
Certainly many MEKO's across various navy's with various combinations of weapons / sensor fit out.
Anyway will watch this space.
Regards S
Indeed. As I understand it, some of the RAN ANZAC displacement increase is ballast to balance added topweight. Perhaps some additional equipment could be added low down without increasing displacement, by removing an equivalent weight of ballast. I'd not dare venture an opinion on how much or where, though, or even if it's possible, rather than just 'perhaps'. Way outside my competence.
These additions for the Hobarts are what really make me wonder about the magazine size, as well as the commentary about strike from RAN. I have no knowledge on what will be the mix the RAN choose, but let’s guess with a hypothetical load of about 16 TLAM, 10 SM-6, 14 SM-2 and 8 Quad packed ESSM cells. That’s decent, but IMO a little short for high intensity war fighting on the TLAM and long range SAM side, particularly given the inability to reload at sea. The problem is magnified for the Hunters with only 32 cells.
Boagrius
Well-Known Member
I think it's a real dilemma, because if your Hobart is in range to shoot a Tomahawk salvo at a given target, it is also in range of any number of hostile anti-ship weapons lurking in the neighbourhood of said target (DF21/26, H6 + YJ100, DF100... etc.). Obviously you are going to deploy your Hobarts in a task force (ideally under cover of the USN, its airpower and that of the USAF/RAAF) using defence in depth to deny the bad guys their targeting data, but I still think there's likely to be a premium on those AAW weapons in a peer conflict.
It would be interesting to find out how much range you can get out of the SM6 when used in its MRC land-attack role. If it can rival the Tomahawk here as has been suggested elsewhere, it might prove to be a safer and more versatile weapon than the Tomahawk on the Hobarts, albeit at the expense of warhead mass.That way if it starts raining ASBMs you've still got interceptors ready to go, and if it's safe to do land attack or ASuW that option is there too.
Last edited:
Git_Kraken
Active Member
Comment on general shipbuilding concepts: Ref for stability physics found here.
Weight up high does change the center of gravity and changes the "righting arm" of a ship thus affecting stability. You can have a fast energetic recovery from a roll or a slow languid recovery, and everything in between depending on the weight distribution (given everything else being equal in a hull). In warship design in particular you can have "wasted tonnage" (there is probably a Nav Arch term for it but this will suffice for our discussion).
For a modern warship, the most critical warfighting dimension is available topside space. (no longer is it tons -WW1 thru 1950's, or guns- Nelsonian parameter, or internal space - Cold War parameter). You need a plethora of sensors, radios, ECM, weapons all topside. To compensate one places a bunch of these to the mast giving you more available space. But modern radars, in particular, are heavy and required lots of cooling. All the weight from the sensor/cooling means lots of weight up high above the center of gravity.
There is a calculation for each ship design that relates how much weight "X" feet above the designed CoG and how much ballast that equals to compensate for ship stability. So placing a ton of weight in the mast might equal four tons of weight below the CoG to compensate. If that weight below decks does not come from equipment already designed into the ship you need ballast. And ballast is "wasted tonnage" because it doesn't do anything but counterbalance weight up high.
This is really important in AOR's as ballast is the weight they can't carry in fuel/stores. But it also leads to weight inflation on frigates like Hunter and CSC. Those radar weights up high are often 5 times or more than the actual weight of the radar. Because of lead ballast to compensate. Add in everything else on the mast, multiple VLS systems, a bigger gun, a bigger helicopter, etc. and you suddenly get the weight inflation you see in both programs above the original design specifications.
Yep, sad that RAN didn’t get it’s way reportedly, when it wanted the 64x cell equipped ‘Baby Burke’ but it’s what they have to live with, given they have little other option. ANZAC‘s have the current pathetic 8x cell VLS launcher and Hunter will be an upgrade on that, but will still have among the smallest VLS cell number of any modern fighting ship, weighing 10,000t or more in the world…
I do wonder who within ADF and RAN in particular envisages we need these massive, uber-expensive, high end fighting ships, but conversely such light armament to equip them?
- Thread Starter Thread Starter
- #29,880
The ANZACs were top heavy when the VLS was installed before they went through major upgrades to the tower.
Packing anymore behind the bridge has been discussed for many years including closing the GDP for increased EW. Since they haven't it is perhaps to much on top of what has always been an "oversized patrol boat"
Packing anymore behind the bridge has been discussed for many years including closing the GDP for increased EW. Since they haven't it is perhaps to much on top of what has always been an "oversized patrol boat"
- Status