What was the most powerful CA and CL in a straight duel, December 1941? (1 Viewer)

[renrich]

Janes has a rather lengthy write up on the Kent class and it mentions the fact that increased armor protection was added in 1935-38 and that originally a considerable amount of weight was devoted to structural strength and internal protection. Also states that main guns were given an exceptional elevation ability and because of improved ammunition supply a rate of fire of four rounds per gun per minute can be maintained under director control. Sounds like a pair of Kents would do nicely against a PB. Kents could carry 3400 tons of fuel which gave them a rad. of action of 10400 miles at 11- 14 knots.

 

[renrich]

I still say that if I were designing the Scheers I would give them a twin or if possible a triple 5.9 gunhouse(not turret) superimposed over each 11 inch turret with a third (Q) 5.9 gunhouse somewhere amidships. I know that would add topweight but intuitively it looks like the ship could handle it and she would be much more dangerous in a fight like the Plate.

 

[Glider]

The problem with the County class is the thin (negligable) armour on the turrets and CT which means that a near miss will cause a huge amount of damage.
At least with the vessels mentioned above, the GS would have to actually hit you to cause significant damage.

 

[delcyros]

Renrich, I have forwarded the range question to a friend from the US naval institute but it looks very suspicious to me. The Kent´s didn´t had such a range by many accounts. My preliminary guess is that radius of action is meant as range (e.g. You use a point in the middle of the ocean and draw a circle around it with the max. range of the ship. This is the radius of action, but it doesn´t mean that the ship has enough fuel to return to the starting point).

I have filed down an older discussion we had with Nathan Okun on the subject of the splinter effect of 11" projectiles. Perhaps You will find this interesting:

The amount of armor a naval gun projectile can penetrate by sideways-blasted fragments from the middle body (not counting the heavy nose pieces or base plug) depends somewhat on the filler (detonating high explosive (HE) filler assumed; not black powder or guncotton) used and a lot on the percentage weight of explosive. For a first approximation, I simply use an "average" HE (circa TNT in power), rather than try to adjust for the individual type of filler (there were many), since for gun projectiles the explosive power usually only ranged from 0.9-1.4 (TNT = 1.0), with only the WWII "RDX" or "Cyclonite" filler mixtures being above 1.1 and they were not used except for US AA guns projectiles very much during WWII and very rarely against ships).

My MISCELLANEOUS FORMULAE artcle uses roughly 0.08 caliber as the maximum plate thickness of US WWII STS (or equivalent in another metal using its "effective" plate quality against penetration) for the small-fillerAP projectiles blowing up 5 calibers away to the projectiles' sides from the target that any of these sideways-mpoving fragments can penetrate (barring the rare fluke), 0.095 caliber STS for Common/SAP medium-size filler projectiles, and 0.11 caliber STS for large-filler ("Bombardment"/HE/HC/CPC) projectiles. Thus, at 5 calibers to the side, the 11.1" GRAF SPEE shells can penetrate 0.89" STS with its APC shell, 1.05" STS with its base-fuzed HE shell (SAP), and 1.22" STS with its nose-fuzed HE shell.

This linearly ramps up to 0.156 caliber of STS for the nose-fuzed HE shell in contact with the shell's middle side (1.73" for the 11.1" gun) ("zero caliber distance"), and, proportionally, 0.156 x (0.08/.11) = 0.113 caliber STS on contact for an AP round (1.26" for the 11.1" gun) and 0.156 x (0.095/0.11) = 0.135 caliber STS on contact for an SAP shell (1.5" for the 11.1" gun).

Going away from the target from the 5 caliber distance starting point, the penetration ability drops off with distance, with the heavier fragments having the least loss in penetration before they simply fall down to the ground/ocean surface rather than hit the target as distance increases (as expected), and the small fragments slowing down faster, reaching less and less distance and with less and less penetrating power for those that do make it to any given distance.

Even at 1000 calibers (11,100" or 925' or 308.33 yards for the 11.1" shells), some fragments can still penetrate, as follows:

(1) Only 40% of the original fragment weight thrown in a direction that could reach the target are still there. Those thrown in other directions of course do not matter and the conical spread of fragments reduces the hits per presented area of the target using the same inverse square law used with light and gravity. The rest thrown at the target were so small that air resistance essentially stopped them and they fell down with no real velocity (they could injure people, but that it about it).

(2) Of this 40% left, 62.5% of it (25% of the original weight portion thrown at the target) can still penetrate 0.0064 caliber STS (HE shell) (0.071" for the 11.1" gun), 0.095/0.11) x 0.0064 = 0.0055 caliber STS (SAP shell) (0.061" for the 11.1" gun), and (0.08/0.11) x 0.0064 = 0.0047 caliber STS (AP shell) (0.052" for the 11.1" gun).

(3) Similarly, a further 25% of the 40% (10% of the original weight thrown at the target) can penetrate, for HE/SAP/AP, resepctively, 0.012/0.01/0.009 caliber STS (0.133"/0.111"/0.1" for the 11.1" gun).

(4) A further 2.5% of the 40% (1% of the original weight thrown at the target) can still penetrate 0.023/0.02/0.017 caliber STS (0.255"/0.222"/0.189" for the 11.1" gun).

(5) The rest of the 40% that is still "in play" (100 - 62.5 - 25 - 2.5 = 10% of the 40% or 4% of the original thrown fragment weight at the target) fall in-between the three values given here -- none are below the 62.5% lowest-penetration value or above the 2.5% value (give them random penetration values in this range of possible penetration values).

In reality there would be a smooth spread in fragment penetration ability from the minimum given to the maximum given, but the above fractions, if used in a step-based Monte Carlo probability system, will usually give "good-enough" estimates of the chances of damaging the target.

Thus, even at 1000 calibers miss distance, if the GRAF SPEE had an 11.1" nose-fuzed HE shell hit near one of the British cruisers, there is some chance for up to 0.25" NCA plate (British STS equivalent) to be penetrated by a fragment or two. You of course have to work out how few fragments per unit area of that penetating power there were left, which is pretty thin, and how big the target ship's vulnerable area is, but it is possible, though rare, to hit something -Nathan Okun

It appears that the standart side plating of a County class CA (not it´s belt) is subject to become riddled when straddled by 11"ers even from considerable distance. Theoretically spoken, the very first salvo fired by GS, beeing 300 yards short does fall in the category to potentially impair EXETERs waterplane vy splinterdamage. This may add a lot of flooding in heavier sea!
Furtherly, neither the CT nor the turrets are splinterproof! The rapid loss of turrets ship controll, as experienced by HMS EXETER during River Plate, won´t be the exception but the rule in such an encounter.

 

[renrich]

Janes gives the armor of Kent class in 44-45 as 3-5 inch at WL(side) 4 inch deck over vitals. 2-1 1/2 gunhouses. 3 inch CT, bulges. This additional weight added in 1935-38 was compensated for in Cumberland and Suffolk by the cutting down of one deck aft. The rest of the County class apparently had the same armor arrangement. London was so changed after reconstruction that she was hardly recognizable as a County cruiser. It sound to me that their armor was fairly complete. Am I in error?

 

[renrich]

Del, the SLC was staddled many times by 8 inch shell fire at the Komondorskis. None of her guns were put out of action. Her gunhouses had one and one half inch armor. The action was fought mainly at 18000 yards. Is the 11 incher that much more destructive? I know the projectiles are much heavier, perhaps 700 pounds versus 250-300 pounds but would the shrapnel from a miss be any larger or have any more velocity and thus more energy? I don't have much info on the Cathedral class but I have to believe they carried as much armor as the Kent class, probably better. Am wondering about the damage caused by near misses from GS?

 

[delcyros]

Janes gives the armor of Kent class in 44-45 as 3-5 inch at WL(side) 4 inch deck over vitals. 2-1 1/2 gunhouses. 3 inch CT, bulges. This additional weight added in 1935-38 was compensated for in Cumberland and Suffolk by the cutting down of one deck aft. The rest of the County class apparently had the same armor arrangement. London was so changed after reconstruction that she was hardly recognizable as a County cruiser. It sound to me that their armor was fairly complete. Am I in error?

You are not in error, the main belt of the Kent-class is indeed partially that strong. But it´s a to narrow belt, at deep combat load its upper edge is barely a ft. above the wl and once the ship engages any speed, the ships own induced wavelength will cover the belt completely except amidships so that the NCA plating in some areas (fore aft) is the only side protection in a number of conditions. The gunhouse has 1-2" faces, 1" sides and roofs. The deck over machinery spaces is 1.375" thick, again not thick enough to stop the heavier fragments of the nose base pieces but it will provide some protection against lateral fragmanetation, except the projectile burst close to or at contact with the deck.

Del, the SLC was staddled many times by 8 inch shell fire at the Komondorskis. None of her guns were put out of action. Her gunhouses had one and one half inch armor. The action was fought mainly at 18000 yards. Is the 11 incher that much more destructive? I know the projectiles are much heavier, perhaps 700 pounds versus 250-300 pounds but would the shrapnel from a miss be any larger or have any more velocity and thus more energy?

There is a substantial difference in the splinter problem caused by 8" and 11" projectiles (and for that matter real BB rounds, too). According to Nathan Okun, whom I do thrust in this, an 8" HE round will defeat .88" STS if burst 5 cal. away or 1.248" STS if burst directly in contact with the plate with means of lateral fragmentation, only. Thus, 1.5" armour as such installed in the gunhouses of SLC are perfectly capable to make the gunhouses splinterproof vs. 8" AP and -HE rounds. Even an 11" HE round would have it´s problems defeating that much armour with it´s lateral fragmentation, altough it will be able to do so if the burst happens close to the plate (less than 4 cal. or 3.5ft. distance to the plate is required).

 

[renrich]

Watched "Pursuit of the Graf Spee" last night again and was struck again by it's authenticity in spite of using a Baltimore class CA as GS. Interestingly(because of my emotional attachment to the SLC) in one scene Langsdorff is demonstrating to a captured British merchant captain how they are disguising the GS as an American CA by adding a dummy second funnel. He is showing him a picture of the American CA in a Janes and it is the Pensacola class. Easy to identify because of the wide spread between funnels. If I read you properly an 11 inch round exploded 3.5 feet from the gunhouse the fragments would penetrate. Doesn't that mean the round exploded on or in the ship not in the sea?

 

[Freebird]

Renrich, I have forwarded the range question to a friend from the US naval institute but it looks very suspicious to me. The Kent´s didn´t had such a range by many accounts. My preliminary guess is that radius of action is meant as range (e.g. You use a point in the middle of the ocean and draw a circle around it with the max. range of the ship. This is the radius of action, but it doesn´t mean that the ship has enough fuel to return to the starting point).

It appears that the standart side plating of a County class CA (not it´s belt) is subject to become riddled when straddled by 11"ers even from considerable distance. Theoretically spoken, the very first salvo fired by GS, beeing 300 yards short does fall in the category to potentially impair EXETERs waterplane vy splinterdamage. This may add a lot of flooding in heavier sea!
Furtherly, neither the CT nor the turrets are splinterproof! The rapid loss of turrets ship controll, as experienced by HMS EXETER during River Plate, won´t be the exception but the rule in such an encounter.

The County class were designed with endurance as a major factor. A point to remember is that the County's were 1920's designs, and were at a distict disadvantage vs. the newer Zara's Hipper's {which were heavier too}

Del, how does the armour protection scheme compare on the newer "Southhampton's" "Fiji's"

I think that the Southamptons were like CA's except that they had to fit 6" guns instead of the 8" because there was no more 8" tonnage available. They could have had the 4 x triple 6" switched for twin 8" guns, just as the plan for the Japanese Mogami's

 

[Glider]

The Southampton Class cruisers were made up of three distinct versions sometimes called the Southamptons, Gloucesters and Edinburgh of which the Edinburgh and her sistership Belfast were clearly different vessels and to be honest I would consider them to be a different class.

Armour improved a little on each version, all had quite a good belt of 4.5 in and unusually for a British Vessel the DCT was well protected. Turret varied considerably with 1in on the first Group increasing to 4in on the Edinburgh.

I have no doubt that Del can add a lot more to this

 

[delcyros]

Sorry, I can hardly add something, Glider. I personally regard the 12 x 6" gunned CL´s highly, they are perhaps the best CL´s to see action and showed an remarkable service log. And they are protected accordingly!

If I read you properly an 11 inch round exploded 3.5 feet from the gunhouse the fragments would penetrate. Doesn't that mean the round exploded on or in the ship not in the sea?

This is correct. It shows that HE-rounds will be very, very dangerous to Exeter. My primary concern was hull damage by splinters against the NCA hullplating from even considerable distance (not necessarely the thin armour belt, which was difficult to hit) by "shorts" but a single deck hit with an HE-round between the turrets/barbettes may knock out both by lateral splinters and this should be considered as a major concern.

 

[parsifal]

This is an interesting thread guys. As usual I didnt read all of the posts as carefully as I should have, however I thought I might have my "two cents" worth

From all that I have read, the Pocket Battleships were actually described as Panzerschiff in German, which literally means "armoured ship". They were designed and built in the pre-nazi era, in accordance with the special clauses of the Versailles Treaty which limited the future capital ships of the KM to 10000 tons and a calibre not exceeding 11". In actual fact the ships exceeded the tonnage limits by a wide margin. Deep Load displacement was 16200 t, even standard displacement was 11700 t. By comparison, the british treaty cruisers like the Achilles had a deep load displacement of 9280 t, whilst the Exeter had a deep load of 10490 t. In 1941 (I think), they (the surviving PBs) were re-classified to the standard of CA.

The PBs were clever designs, but they had their limits. As substitute capital ships that could not compete with proper capital ships they worked on the theory of being able to overpower any ship with the speed to overtake them, and to be able to outrun any ship that could overpower them. By 1939, there were just a handful of ships that could overpower and out run her. The ships that I can think of a the Hood, the Repulse and Renown, and the two French Battlecruisers. They could also not compete with the Japanese Kongos or the Italian rebuilt BBs, but this is kind of academic.

I dont agree with the reasons that have been given for the loss of the Spee. i believe that it was a case of the Spees commander losing his nerve at the critical moment. According to Corelli Barnett (Engage the Enemy More Closely- the Royal Navy in WWII Cox Wyman 1991, 1029 pages, "the german warship had 6 11" and 8 5.9" guns. In weight of shell her armament completely outclassed the british force. Moreover Graf Spees armour scheme protected her from anything except direct hits from the six 8" guns of the Exeter. The 6" guns could only inflict damage to the control positions and upper works of the German ship".

The course of the battle went something like this. Battle was joined at about 0630. The two British CLs operated as one division, whilst the Exeter operated as the other. The British forces split , so as to split the German fire. Spee concentrated her main guns on the Exeter, whilst the 5.9s engaged and kept at bay the Ajax and the Achilles. Exeter obtained hits on the Spee, but none were vital, whilst Spees reply knocked out the Exeters, fire control, and all but one of turrets, which continued to fire under local control. Exeter gallantly remained in the battle until the last possible moment, but was eventually forced from the battle, limping away at about 10 knots. However, I believe the Germans were shocked to see the two CLs continuing to close, and seek further engagement with the raider. they evidently had not read the British traditions to engage the enemy more closely, wherever, and whenever they presented themselves. However, both CLs began to take damage, as the Spees main armament swung round onto these new adversaries. The end result was that the RN was forced to adopt a shadowing role.

It is at this point that I believe Langsdorf (the german commander) lost his nerve. Reportedly badly shaken by the dead and wounded and the damage to his ship (Which post war accounts by the German surivors suggests was not nearly as extensive as claimed), Langsdorf apparently shrugged off all pleas by his senior officers to make for open sea, or try to deal with the now shadowing cruisers. I believe this is what he should have done. A retreat to nightfall would in all probability have seen the Spee escape (similar to Bismarcks achievement 18 months later), and beyond that who knows. There was a supply ship, the Altmark, not so far away, and if the British could be shaken, I believe that emergency repairs could have been effected at sea, and the ship returned to Germany.

Instead, Langsdorf ran for Montevideo, where he fell victim to a very clever propaganda war which suggested that the Ark Royal and the renown were waiting for him. The rest is history as they say.

The point I want to make is that the Spee won the battle, in a technical sense, but allowed that victory to slip though her fingers. The Spee lived up to all her design parameters.

So why was she ultimately defeated. I believe it was because of the different traditions that existed in the two navies, but more importantly the make up of langsdorf. The British navy tradition was to keep on fighting despite the odds. It was a fighting spirit based on 300 yearsof tradition. Whilst fighting and suffering off Crete, ABC (Cunningham) signalled the fleet...."stick it out, the army expects our help. ....it takes three years to build a destroyer and three hundred years to build a tradition....such traditions helped the british to pull them through the hard bits. The Germans did not have nearly such deep traditions for their navy to call on in the hard times, moreover, the standing orders for all german ships at the time was to avoid combat against equal or superior forces. Faced with a hard bit, Langsdorf chose to run for cover, and to comply with his standing orders. It was the sensible, logical thing to do, but it was still the wrong thing to do. I have often asked myself what might have happened if the Spee was a British ship?

 

[delcyros]

From all that I have read, the Pocket Battleships were actually described as Panzerschiff in German, which literally means "armoured ship". They were designed and built in the pre-nazi era, in accordance with the special clauses of the Versailles Treaty which limited the future capital ships of the KM to 10000 tons and a calibre not exceeding 11". In actual fact the ships exceeded the tonnage limits by a wide margin. Deep Load displacement was 16200 t, even standard displacement was 11700 t. By comparison, the british treaty cruisers like the Achilles had a deep load displacement of 9280 t, whilst the Exeter had a deep load of 10490 t. In 1941 (I think), they (the surviving PBs) were re-classified to the standard of CA.

Parsifal, the Panzerschiffe were conforming to their treaty limits within acceptable tolerances.
standart displacement is what counts. The PB Deutschland had a std. displacement of 10.600t. and a light displacement considerably below 10.000t. The deep load was 14.290t., altough this increased after the Atlantic bow had been refitted (long after the treaty of Versailles and London expired). Follow on ships were a tad bit heavier due to refits and modifications undertaken after war broke out but thats true for all combattants (additional AAA, updated firecontroll...).
Any comparison has to take care of contemporary CA´s. The Exeter was a 6 x 8" CA, basically the smallest possible design with 8" and cruiser abilities.
The comparable Kent-class CA averaged with 10.400t. stdt. and 14.150t. avg. deep load, very much like PB Deutschland / Lützow.
The italian Zara class CA had a displacement of 11.870t. std. and 14.530t. deep.
The french Algerie CA was perfect 10.000t. std. and 13.900t. deep, the only modern CA to fullfill the requirements of the treaty.
The US Cleveland class light cruiser had a standart displacement of 11.800t. and a deep load of 14.183t.

The Panzerschiffe were thus conforming to their displacement limits but this was not without some notable risks in protection.

 

[timshatz]

The Panzerschiffe were thus conforming to their displacement limits but this was not without some notable risks in protection.

Delc, can you go further and explain what those risks were? Curious more than anything else?

 

[delcyros]

Hi Del

Your figures are slightly lower than those quoted in Conways, Janes and one other reference I have for the KM. But not enough to get excited about.

Except when you say that Deutschlands Std Disp is below 10000. Conways lists it as 11700, whilst the German Warships of WWII lists it as 11700 also. My Encyclopaedia of ships lists the same displacement. Factsare the Germans exceeded treaty limits, and broke the rules. Oh, and the Treaty of versailles was repudiated by Hitler, it did not "expire". Same with the Anglo-German Naval Treaty

The germans exceeded the treaty limits, as did the british, US, japanese and italian. Virtually all except France. The Panzerschiffe were nothing special in this regard.

Conway lists the std. Displacement belonging to post refit times. The original displacement (std.) as comissioned was 10.600t. for Deutschland, matching the official "10.000"t. displacement. Light displacement was below 10.000t. (note that "light" does not refer to standart). The std. displacement of Scheer and Graf Spee was slightly larger. And if You carefully read the articles of Versailles, You won´t find a definition of "displacement". Unlike in the Washington Treaty, where the displacement was precisely defined, the Treaty of Versailles leaves this open. Hard to argue that they broke the rules then from a juristical point of view...

I dont believe that they were conforming. They were 1700 tons over maximum at the very least, and in the case of the Spee, at least 2200 tons over weight. That represents the potential to put a lot more effort into the defensive schemes than the ships she faced in 1939. The CLs were much less well protected, and the Exeter, also could not withstand the 11" guns in anything like a comparable state to the way Spee could withstand her broadsides
I am not saying the PBs were invulnerable, but the odds against the three British ships on that December morning were heavily weighted in favour of the Spee, at least on a theoretical level

I think You are in error here. Note that almost all modern CA´s commissioned as "Washington Cruiser" were in fact overweight. The PB´s had no substantial advantage in weight which could be devoted to protection compared to the other contenders. They traded speed and protection for firepower, that´s it.
I mean, 50-80mm armour belt is not going to stop a properly capped APC at any realistic fighting range. Some CA had up to 152mm belt armour!
It´s equal whether this is 6" or 8", it will overmatch the belt. The Panzerschiff cannot dictate the range, unlike the faster CL and CA. In the end Graf Spee was rather lucky to find herselfe confronted with british opposition instead of french.
The Royal Navy by then was only using CPBC, soft capped projectiles for the 6"ers and SAP for the 8"ers, both are only dangerous at close to medium distances. All other navies, however, supplied their cruiser guns with a hard capped, true APC projectile, which would make short work out of the belt.
The only true chance a PBB has when facing multiple cruisers (one on one, the PB wins due to it´s greatly enhanced offensive capabilities and battleship scale firecontroll) is to keep distance. The River Plate engagement showed this. Had the british CL force pressed home harder their attack, they could well overwhelm Graf Spee.

 

[parsifal]

I mean, 50-80mm armour belt is not going to stop a properly capped APC at any realistic fighting range. Some CA had up to 152mm belt armour!
It´s equal whether this is 6" or 8", it will overmatch the belt. The Panzerschiff cannot dictate the range, unlike the faster CL and CA. In the end Graf Spee was rather lucky to find herselfe confronted with british opposition instead of french.


The 6 in BL Mk XXIII had armour penetration characteristics as follows:

At 22000 yds it could penetrate 2in say 45 mm, whilst at 12500 yds it was 3 in, say 68 mm. This is using the CPBC ammunition that you mentioned. My source says that at 22000 yds the majority of hits will be deck penetrations, whilst at 12500 it will be mostly belt impacts

By comparison the SKC 28 cm has penetrations of between 291mm and 335 mm at ranges 16000-19000 yds, for side armour penetrations. According to Wiki the deck penetrations at those ranges are between 41 and 48 mm (but I strongly suspect that figure to be too low).

Conways lists the belt armour for the Panzerschiff as between 2.25 and 3 in. I havent checked the distribution of this armouring scheme. The deck armouring was 1.5 inches (about 35 mm), but there was additional protecive bulkheads below deck that would largely contain the effects of any deck penetrations.

You may be right, in a general sense about the panzerschiff not being able to dictate the range, but at River Plate, it certainly looks like they did, the German ship managed to keep the ranges at between 16 and 19000 yds from memory, by various means (constant changes of course and smoke mostly), which was the optimum range for her main armament to pentrate the RN cruisers defences, whilst at the same time maximising her own protection. At the engagement ranges mentioned (16000-19000 yds) the majority of British fire is going to be hitting the belt, and not the deck. Depending on how extensive the belt protection is of course.

I want to make something very clear. I agree that the armour protection scheme of the Panzerschiff was far from fullproof in its protection, however it SUBSTANTIALLY protected them from damage from the Light cruisers on that day, due to the ranges of the engagement, the characteristics of the British 6in guns and the protective scheme of the german ship itself


The Royal Navy by then was only using CPBC, soft capped projectiles for the 6"ers and SAP for the 8"ers, both are only dangerous at close to medium distances. All other navies, however, supplied their cruiser guns with a hard capped, true APC projectile, which would make short work out of the belt.


I think i agree with this, although the 6in ammunition worked well enough against the Italians and even the Germans later in the war, using the same ammunition


The only true chance a PBB has when facing multiple cruisers (one on one, the PB wins due to it´s greatly enhanced offensive capabilities and battleship scale firecontroll) is to keep distance. The River Plate engagement showed this. Had the british CL force pressed home harder their attack, they could well overwhelm Graf Spee.

But I dont think that they could, thats the point. They tried repeatedly to close the range during the battle, but each time the Spee managed to evade them (as evidenced by the range being maintained). The speed difference that you keep mentioning did not seem to provide the British the required advantage on this occasion. Even by closing the range, as you say, far more damage would be inflicted on the brit ships (probable loss in fact) in comparison to the german ship, whose protection, whilst far from perfect, was far superior to that of the British ships.

 

[delcyros]

The 6 in BL Mk XXIII had armour penetration characteristics as follows:

At 22000 yds it could penetrate 2in say 45 mm, whilst at 12500 yds it was 3 in, say 68 mm. This is using the CPBC ammunition that you mentioned. My source says that at 22000 yds the majority of hits will be deck penetrations, whilst at 12500 it will be mostly belt impacts

By comparison the SKC 28 cm has penetrations of between 291mm and 335 mm at ranges 16000-19000 yds, for side armour penetrations. According to Wiki the deck penetrations at those ranges are between 41 and 48 mm (but I strongly suspect that figure to be too low).

We have a basic agreement that any comparison of armour piercing abilities will be in decisive advantage for the 28cm gun, using APC or Common:

Nathan Okun wrote with regard to the 11.1"/52 SAP of the Panzerschiffe:
" (...) These guns also had a very blunt-nosed SAP-type Common projectile (Spgr.m.Bdz) with only light AP penetration ability, though the blunt nose shape gave it good thin-deck (British and French 'Treaty' cruisers) penetration at long range, which was probably what it was for."

The british 6" BL was an extraordinary poor armour piercer in comparison. The principal reason was the CPBC round supplied. You might argue that the Panzerschiffe were protected according to their prime adversary but the Panzerschiffe, however, were not designed to counter british CL but instead were meant as a naval measure against France, primarely.

The 6" gun of Emile Bertin, La Galissonnière and De Grasse-class french CL are a much more severe test to Deutschlands armour scheme. Supplied with an SAP and true armour piercing projectiles, the 152mm/55 is estimated to achieve a penetration of 122mm KC at 10.900 yards. This shows what the british 6"/55 could achieve if it had only been supplied with a proper AP-projectile. Basically an improvement in order of 40 to 45% over the RN 6"BL! The US 6"/47 and 6"/50, if supplied with an AP, projectile was only little short of french performances. The 155mm / 152mm and 150mm of japanese, italian and german guns repectively were markedly superior to these performances.

Conways lists the belt armour for the Panzerschiff as between 2.25 and 3 in. I havent checked the distribution of this armouring scheme. The deck armouring was 1.5 inches (about 35 mm), but there was additional protecive bulkheads below deck that would largely contain the effects of any deck penetrations.

Breyer (the new 1993 one, not the 70´s old one) is probably the best source for the Panzerschiffe. The belt armour was made of 80mm above the waterline and 50-60mm below (Graf Spee and to a lesser degree Scheer had wider distribution of the 80mm belt in respect to protected height covered) and inclined 15 degrees, the deck armour was a single deck (no slopes or protected decks!) of 40mm thickness, which in Graf Spee only was covering the whole distance between both belts. On Scheer and Lützow -at least theoretically- a projectile may strike over the belt and on the 40mm longitudinal torpedo bulkhead (the bulwark ways were not protected by a deck here- a serious gap in their protection). This even a 6" CPBC may achieve from considerable distance. The pocket battleships were protected in a manner known better as "all-or-nothing".

I want to make something very clear. I agree that the armour protection scheme of the Panzerschiff was far from fullproof in its protection, however it SUBSTANTIALLY protected them from damage from the Light cruisers on that day, due to the ranges of the engagement, the characteristics of the British 6in guns and the protective scheme of the german ship itself

The results of River Plate proof that You have a reasonable position. I only want to add that british 6" CL showed little effect at the conditions of River Plate, but these are not to compare with french CL´s of the period or with what they could achieve at closer distance.

They tried repeatedly to close the range during the battle, but each time the Spee managed to evade them (as evidenced by the range being maintained). The speed difference that you keep mentioning did not seem to provide the British the required advantage on this occasion. Even by closing the range, as you say, far more damage would be inflicted on the brit ships (probable loss in fact) in comparison to the german ship, whose protection, whilst far from perfect, was far superior to that of the British ships.

Agreed. One of the big miracles of this battle. Perhaps the 5.91"ers secondary guns of Graf Spee kept them on distance (a secondary gun don´t needs to hit in order to be successful here) or skillful helm or multiple aspects. Graf Spee could hardly exceed 24-25 Kts with the state of that date (engine problems and fouled bottom) while the british cruisers matched 30 Kts.
At closer distance, the CLs would hit more often and harder, the CL´s could also easily overwhelm Graf Spee with pure volume of fire.

best regards,

 

[renrich]

Another factor in this engagement to consider is that in the early part the GS used her two eleven inch turrets to engage the more dangerous adversary, Exeter, which left the CLs confronted only by 4-5.9s behind nothing more than splinter shields. When Harwood closed the range with the CLs , the Britich 6-inchers did do some damage.

 

[parsifal]

We have a basic agreement that any comparison of armour piercing abilities will be in decisive advantage for the 28cm gun, using APC or Common:

Nathan Okun wrote with regard to the 11.1"/52 SAP of the Panzerschiffe:
" (...) These guns also had a very blunt-nosed SAP-type Common projectile (Spgr.m.Bdz) with only light AP penetration ability, though the blunt nose shape gave it good thin-deck (British and French 'Treaty' cruisers) penetration at long range, which was probably what it was for."

The british 6" BL was an extraordinary poor armour piercer in comparison. The principal reason was the CPBC round supplied. You might argue that the Panzerschiffe were protected according to their prime adversary but the Panzerschiffe, however, were not designed to counter british CL but instead were meant as a naval measure against France, primarely.

The biggest single problem with the french cruisers were the limited endurance that they possessed. They were unable to mount the sustained patrols far from home that the British cruisers were able to do.


The 6" gun of Emile Bertin, La Galissonnière and De Grasse-class french CL are a much more severe test to Deutschlands armour scheme. Supplied with an SAP and true armour piercing projectiles, the 152mm/55 is estimated to achieve a penetration of 122mm KC at 10.900 yards. This shows what the british 6"/55 could achieve if it had only been supplied with a proper AP-projectile. Basically an improvement in order of 40 to 45% over the RN 6"BL! The US 6"/47 and 6"/50, if supplied with an AP, projectile was only little short of french performances. The 155mm / 152mm and 150mm of japanese, italian and german guns repectively were markedly superior to these performances.

British 6" guns were undoubtedly hampered by the ammunition they used, however, IMO you are overstating the advantages of SAP rounds. British CPBC were very effective at damaging upper works, and disabling other parts of the enemy ship, without necessarily penetrating the belt. SAP ammunition often had the unfortunate habit of passing right through the target. Italian SAP ammunition also seems to have suffered from poor metallurgical treatment. Certainly on a number of occasions when it struck British armour rather than penetrating, it simply shattered. Many Italian guns also suffered from poor accuracy because of closeness of the two barrels. I have also read that the Italian turrets often were insufficiently strong, and/or the guns too closely spaced together, to permit proper salvo fire. In any event, trying to put aside the operational limits that the Italians were forced to work under, I still think that ship for ship, the British even with their inferior guns achieved better success, and inflicted more damage, even before the full impact of radar. A good example is perhaps Cape Spada

There ar very few instances of german 5.9" engaging British 5.9s. at least in cruisers. The German Narviks used them, and there is the Koromoran vs Sydney (and a couple of othe raiders as well. Without having looked at all the examples all that carefully, I dont know that it can be said that the British were all that badly disadvantaged.

The reason I think is because the disabling of a ship is not so much linked to the penetration of the belt, as the destruction of the control positions and the like. This was certainly how the Bismarck was silenced so quickly, and was the general pattern of events in many engagements, particulalry the Pacific

Breyer (the new 1993 one, not the 70´s old one) is probably the best source for the Panzerschiffe. The belt armour was made of 80mm above the waterline and 50-60mm below (Graf Spee and to a lesser degree Scheer had wider distribution of the 80mm belt in respect to protected height covered) and inclined 15 degrees, the deck armour was a single deck (no slopes or protected decks!) of 40mm thickness, which in Graf Spee only was covering the whole distance between both belts. On Scheer and Lützow -at least theoretically- a projectile may strike over the belt and on the 40mm longitudinal torpedo bulkhead (the bulwark ways were not protected by a deck here- a serious gap in their protection). This even a 6" CPBC may achieve from considerable distance. The pocket battleships were protected in a manner known better as "all-or-nothing".


Thanks

I will look him up


The results of River Plate proof that You have a reasonable position. I only want to add that british 6" CL showed little effect at the conditions of River Plate, but these are not to compare with french CL´s of the period or with what they could achieve at closer distance.

I agree that the French CLs would have had a better chance of penetrating the GS belt and deck, with their SAP ammunition, although I hesitate when you describe it as "easy". The superficial damage inflicted by the Brit cruisers was not insignificant, but I am not convinced that it was lethal either, despite certain reports that I have read to the contrary (you mention them yourself, but i sense you are a bit doubtful as well, perhaps i am mistaken)


Agreed. One of the big miracles of this battle. Perhaps the 5.91"ers secondary guns of Graf Spee kept them on distance (a secondary gun don´t needs to hit in order to be successful here) or skillful helm or multiple aspects. Graf Spee could hardly exceed 24-25 Kts with the state of that date (engine problems and fouled bottom) while the british cruisers matched 30 Kts.

I have read that GS during the battle managed to reach just short of 26 knots during the battle. Does that not correlate to our understanding??? Also, you over-estimate slightly the speed of the British cruisers. They too, were all in need of refit, and could not exeed 28.5 knots maximum sea speed

My earlier post about the ranges was in error. Without checking I had thought the battle was fought at ranges 16-19000 yds. This is not actually the case, now that I have checked. Sometime after 0643 (ie, after the Exeter had retired), , I believe about 0646, the British cruisers had managed to reduce the ranges to 13800 yds. Battle had commenced at 0619, at 19200 yds. This means that in 27 minutes, the British had closed the range 5400 yds, which is an average closure rate of 6 knots. This tends to support, very precisely your contention that there was a 6 knot difference in their effective sea speeds

There are, of course many variables at play that might wreck thi otherwise simple comparison


At closer distance, the CLs would hit more often and harder, the CL´s could also easily overwhelm Graf Spee with pure volume of fire.

How then do you explain the british reluctance to close in the stern chase that followed the battle. It was not confirmed until 1915 that the raider was definately making for port, yet the British made several attempts at closing the range, each time they broke off and resumed shadowing range. Harwood knew that help was still a long distance from the scene at that time

 

[renrich]

The closing of the range during the battle was, I believe, not a result of difference in the ability of the ships to make speed or not. Rather, it was the choice of Harwood to close the range in order to be more effective with his 6 inchers. He closed the range until it got too hot and then reopened it. The reason he did not close again and "overwhelm" the GS was that his heaviest ship, Exeter, was out of action, he had two turrets on one of his CLs out of action, he probably was short of ammo and shadowing the GS until help arrived seemed a more prudent option for the time being. If the situation changed, he could always change his tactics.