Armoured Cruiser Vs Treaty Cruiser

Since the ACR were almost all long dead in WW2, we have to force things a bit to get one into action, but I've allways wondered how would one of the later armoured cruisers fare against a treaty cruiser.
So lets get them into the ring. Say in late 40 a group of Italian Ships bringing high priority cargo to Africa is being chassed by a RN county cruiser. San Giorgio (in as new condition from her 37 refit) sorties and manages to place herself btw the british cruiser and the convoy. The RN captain decides to engage.
4x10''+4x7.5'' vs 8x8'' broadsides. The RN cruiser is a lot faster but needs to decide the matter qickly or loose the interception chance. No other ships are in a position to intervene and there are no aircraft in the area. Its a clear day with fine weather. Who would win?

WNIT_10-45_M1908_San_Giorgio_pic.jpg
 

sharlin

Banned
Hmm...a good question, one thats caused no end of debate. An AC was a fairly well armoured opponent but the armour scheme is built for fighting at fairly close quarters with lots of horizontal fire yet her deck protection is lacking against plunging fire, and an 8 inch shell could punch through her relatively thin decks with ease.

The AC would also have issues with spotting her gun splashes. A 10 inch shell splash is verrry similar to an 8 inch one and unless the italians had a special system worked out to time their gun salvos so they could spot for the splashes of the different caliber guns accuracy would be an issue.

A County with its 8 more rapid firing guns (much more modern mounts) would be more accurate through sheer rate of fire but the British ship would be vulnerable to the 8 inch rounds and a 10 inch hit would be VERY painful as unless its one of the Countys that got a belt (the later batches) there's nothing to stop the shell apart from light armour.

I'd say it would be the County class ship but her Commander would have to fight smart and basically dance around at long range, if it got into a close quarters brawl then the Italian AC would be in a better position to absorb the hits than her RN opponent.
 
an in this case...

Thats why I set it up this way. The RN ship would have limited time to "dance around". But even at long range, the destructive power of a 10'' shell on a cruiser might offset the reduced number of probable hits.
 

sharlin

Banned
The RN ship could quite happily sit at 24k yards and pump out 5 rounds per minute per gun and those shells would eat through the 2 inch deck of the San Giorgio with relative ease and use her speed to control the engagement but you are very right. One hit from a 10 incher would cause significant damage but salvo firing 4 guns accurately at long range is a bugger, you ideally need more guns and the 10 inch guns are let down by their slow rate of fire.
 
The AC would also have issues with spotting her gun splashes. A 10 inch shell splash is verrry similar to an 8 inch one and unless the italians had a special system worked out to time their gun salvos so they could spot for the splashes of the different caliber guns accuracy would be an issue.
For what its worth, Italian rangefinders were known to be extremely high quality (surpassing their RN counterparts conventionally iirc), but it was offset by lack of radar for them (which the RN did have) and crew inadequacies (which probably isnt a factor if we're making both the RN and RM crews equal in this scenario).
 

sharlin

Banned
Italian rangefinders were by all accounts good (yet they never scored many hits in the war) but we don't know if the San recived an update of the latest versions of the range finders. We can establish that she did get new rangefinding equipment but you can bet your bottom dollar its not the most modern.

If this battle's taking place in 1940 the RN didn't have gunnery radar so its a pure optical gun fight.
 
I would almost consider this scenario a repeat of Rio de la Plata, where there was a clash between British cruisers and a German armoured cruiser.
 

CalBear

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Monthly Donor
The Treaty cruiser has a two mile range advantage and can put anywhere fron 50-100% more rounds out per minute. It is also at least 10 knots faster and carries ten 533mm torpedoes.

Assuming both ships are properly handled, the Country will be able to dodge its opponent, prevent pursuit with judicious use of its torpedoes once it has gotten between the AC and its charges, and rip up the merchies.

If it goes to straight up fight, the Treaty cruiser has a huge speed advantage, maneuverabity advantage, main battery range advantage, and it has torpedoes that it can make use of if it manages to disable either the forward or aft 10" turret.

Not a good day for the AC.
 
Maybe I'm confused. Weren't armored cruisers slow, 22-25kt predreadnought ships, armed with turn of the century vintage guns, that would have suffered from major armor and compartmentalization deficiencies when faced by a modern heavy cruiser? Couldn't a modern 33 kt Italian heavy cruiser armed with 8 modern 8" guns have sailed circles around a 1905 vintage armored cruiser and pepper her with plunging 8" gun fire coming at 3 times the ROF of four old 10" guns of the British ship? How would this even be close, and in true Eyeteye fashion, if the Italian ship took some damage, couldn't she break of the battle and escape very easily with her almost 10 kt speed differential?

Help me out.

Oops. I just re-read this and realized the WI referred to an Italian AC fighting a British treaty crusier protecting a convoy. No wonder I was confused. Nevermind.
 
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The Treaty cruiser has a two mile range advantage and can put anywhere fron 50-100% more rounds out per minute. It is also at least 10 knots faster and carries ten 533mm torpedoes.

Assuming both ships are properly handled, the Country will be able to dodge its opponent, prevent pursuit with judicious use of its torpedoes once it has gotten between the AC and its charges, and rip up the merchies.

If it goes to straight up fight, the Treaty cruiser has a huge speed advantage, maneuverabity advantage, main battery range advantage, and it has torpedoes that it can make use of if it manages to disable either the forward or aft 10" turret.

Not a good day for the AC.

Oops. I can see wasted time with my response.
 
A few points

I have deliberatedly helped the old lady by giving the treaty cruiser an intercept mission that precluded playing long range games all day. But:
The range advantage of the 8'' guns is 28 to 25km max. But as anybody ever heard of a cruiser hitting a manouvering ship at that range? PE hit while supporting Bismarck but I think it was much closer. A BB yes, for a cruiser realistic fighting range would be smaller. The 10'' guns might have been old, but would they be less accurate at extreme ranges? The old 15'' guns on warspite still hold the ship on ship record and were pushing thirty at the time.
Closing the range means the 7.5'' guns of the San Giorgio get in the action and weight of fire is now clearly on the Italian side. Plus, if the RN ship chooses to pull away to extend range, the Italian one needs only retreat a bit, staying btw the County and it's intended prey and it's out of rang with the job done.
Someone mentioned radar. It's 1940 and radar ranging in clear weather isn't an advantage of good optics yet. Torpedoes. Only an option if the San Giorgio is no longer firing, no treaty cruiser could survive a few salvos of 10'' or even 7.5'' at torpedo range ( 24'' long lance torpedoes at maximum range being a possible exception)
 
The CA should win this fight most of the time, assuming her captain handles his ship properly.

Incidentally, the USN actually studied a somewhat similar problem and gamed out a series of engagements between a CA & and ACR during the 1920s, both of which are detailed in Friedman’s book on US cruisers. After the WNT was signed, the USN looked at the possibility of modernizing its remaining armored cruisers in 2 separate studies, as they were not only effectively exempted from the treaty, but were bigger, more heavily armored, and in the case of the 3 surviving Tennessees, carried bigger guns than any cruiser legal to build under the treaty.

The second series of studies included an analysis of the modernized ACRs retaining their original main battery [based on BuOrd's assumption that replacing them with the 8"/55 of the treaty cruisers was impractical; the 8"/45 of the Californias could be increased to 30 degrees giving a max range of 28k yards; the 10"/40 of the Tennessees could be increased to 40 degrees, giving a range of 31k yards] albeit with increased elevation, pitted against Pensacola.

According to the resulting calculations, the 10" of the Tennessees could penetrate Pensacola’s side armor at any range it could hit, and the deck from 18k yards out, Pensacola would actually be immune to the California’s 8"/45 between 15-18k yards. On the other hand, Pensacola’s 8"/55 , as calculated, not only could penetrate the decks of the ACRs [the proposals studies included no changes to their side or deck armor] from 18k yards out, and the side armor out to 20k (a bit optimistically; revised penetration tables based on service data suggest about 17-18k), but also enjoyed a range advantage, being capable of firing out to 35k yards. Nor were the 6" guns the armored cruisers could also bring to bear considered to offset the 6 extra heavy barrels Pensacola had.

Operational studies suggested that even with new engines, assuming they increased the speed as promised, [the second studies proposed replacing the engines of the ACRs with the powerplant used on the carrier Ranger, which was expected to increase their speed to ~26 kts] the reconstructed ships would be too slow to operate independently, or with the carriers or new cruisers. They would have to be used in squadron strength screening the battle line or convoys against enemy cruisers, and supporting destroyer attacks carried out in the face of a cruiser screen in order to be effective.

These results, combined with concerns over what weapons the cruisers might be up against at the end of their post-modernization lives in the 1940s when they already weren't up to facing existing weapons, and the political issues inherent trying to rebuild 25-30 year old ships after a difficult political fight to buy new cruisers for the first time in over a decade, half of which were intended to replace the ACRs in question scuttled the modernization plans.

Back to the scenario in the OP, assuming that the County-class CA in question has a belt & is loaded with full-tilt AP shells in the magazines, then the engagement should go in a way similar to the studies of the modernized ACRs vs Pensacola.
 

CalBear

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Long range gun duels were extremely rare, but the same question can be asked about the AC. Did an AC even make a 25,000 yard hit on a maneuvering 33 knot warship? The 15" on Warspite were, well, 15" guns of 42 calibers, firing a shell that had been redesigned in the interwar years for better long range performance. The 8" guns on the Country Class were 50 calibers in length and were also using shells that had been designed in the interwar years to take advantage of the longer ranges available in the Country gun mount design.

The 10" was a 45 caliber design (actually a British Elswick Pattern design very similar to the main battery found on HMS Swiftsure) was, as far as I have been able to determine using the same shell design as the day the ship was launched, placing her at a serious disadvatage. I have also found references that indicated that during her 1937/38 rebuild, San Giorgio had her power plant substantially changed resulting in the loss of 1,300 shaft HP and a drop in max speed to 18.6 knots.

Overall, the scales seem to tilt ever farther toward the Treaty Cruiser.

http://navypedia.org/ships/italy/it_cr_san_giorgio.htm

http://www.regiamarina.net/detail_text_with_list.asp?nid=73&lid=1&cid=3


I have deliberatedly helped the old lady by giving the treaty cruiser an intercept mission that precluded playing long range games all day. But:
The range advantage of the 8'' guns is 28 to 25km max. But as anybody ever heard of a cruiser hitting a maneuvering ship at that range? PE hit while supporting Bismarck but I think it was much closer. A BB yes, for a cruiser realistic fighting range would be smaller. The 10'' guns might have been old, but would they be less accurate at extreme ranges? The old 15'' guns on warspite still hold the ship on ship record and were pushing thirty at the time.
Closing the range means the 7.5'' guns of the San Giorgio get in the action and weight of fire is now clearly on the Italian side. Plus, if the RN ship chooses to pull away to extend range, the Italian one needs only retreat a bit, staying btw the County and it's intended prey and it's out of rang with the job done.
Someone mentioned radar. It's 1940 and radar ranging in clear weather isn't an advantage of good optics yet. Torpedoes. Only an option if the San Giorgio is no longer firing, no treaty cruiser could survive a few salvos of 10'' or even 7.5'' at torpedo range ( 24'' long lance torpedoes at maximum range being a possible exception)
 
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