Gneisenau vs. Strasbourg

[Udet]

Strasbourg:

8-13 in. guns (two quadruple turrets)
16- 5.1 in. guns

Gneisenau:

9-11 in. guns (three triple turrets)
12- 5.9 in guns

These are two of my favorite ships of the war.

What if...these two vessels had clashed during the war?

Although I like the quadruple turret layout of the Strasbourg very greatly, it seems kind of clear that once entering combat with a fast enemy such as Gneisenau (30.7 knots) there could certainly be moments when the french vessel could find herself in a critical blind arc of fire -all main guns located forward of the main tower, leaving only secondary guns aft-.

Given the difference in the caliber of the main battery, Gneisenau can certainly surpass the french ship in the rate of fire department.

Keeping in mind once the duel is accepted anything can happen, who would you see (or wish) emerging as victor?

 

[Glider]

This one I suspect is to close to call. The 13.1 was a good modern gun but the 11in lacked punch. My suspicion is that it would be down as is often the case, to luck as to where the shells hit and the training of the crews.
The layout I believe would be to the Strabourg's advantage. The problem with a rear turret is that the ship has to stay broadside on to fire all her guns. When the rear turret can bear again their is an inevitable time delay before the accuracy picks up again. The Strasbourg would have more options as long of course, she doesn't turn away.

 

[delcyros]

That´s a particularly interesting match. I suppose we do have a 1940 timeframe and while my two cents would be that Gneisenau runs away (which was the official option against BC and BB) we can have a closer look.
I will check the guns first, followed by the armor and do some calculations regarding each others immune zone, can take some hours...

 

[delcyros]

Ok-let´s start with the main battery:
The french 13"/50 is a very high velocity, flat trajectory gun:
(using 1235 lbs AP (1087 lbs body weight)):
max. elevation: 35 degrees
max. range: 45.000 yrds (sources differ from 44.401 yrds to 45.450 yrds)
muzzle velocity: 2854 fps
theoretical RoF: 3.0 rpm
elevator capacity: 12-16 rounds per minute
practical RoF: 1,5-2.0 rpm
main battery output: around 72 rounds in 5 minutes (at 15.000 yrds)
loading angle: gun can be loaded at any elevation under 20 degrees
rate of elevation: 6 degrees/sec.
AP qualities (against KCN and in [ ] Wotan hard), not included ranges over 30.000 yrds:
0: 30.3"; 2Kyrds: 28.6"; 4Kyrds: 27.0"; 6Kyrds: 25,5"; 8 Kyrds: 24.0"[0.98"]; 10Kyrds: 22.5"[1.2"]; 12 Kyrds: 21,1"[1,4"]; 14 Kyrds: 19.8" [1.7"]; 16 Kyrds: 18,5"[1.9"]; 18 Kyrds: 17,2"[2.2"]; 20 Kyrds: 16,0" [2.4"]; 22 Kyrds: 14.8"[2.7"]; 24 Kyrds: 13.9"[2.9"]; 26 Kyrds: 12,5" [3.2"]; 28 Kyrds: 11.1"[3.5"]; 30 Kyrds: 9.9" [3.9"]
Keep in mind that I neglected deck penetration under 8000 yrds, it would
deflecte anyway rather than penetrate.
The gunhouse is divided by a 1.6" armored bulkhead into two twin mounts. The guns are sleeved in pairs due to weight considerations.
According to what I know the gun has a wide shell distribution pattern, gun preciseness was good with brand new guns only. The shell pattern openes very quickly with even little gun wear.
There is little record avaiable about the shell reliability, rate it as average.

Lets check the Gneisenau´s main guns.
The 11"/54 was an improvement over the older 11"/52 of the pocket battleships, as the Dunkerque´s were, are the 11"ers flat trajectory, high velocity guns (using a lighter 727 lbs AP shell (640 lb body weight))
max. elevation: 40 degrees
max. range: 45.500 yrds (sources differ from 44.760 -46.749 yrds)
muzzle velocity: 2920 fps
theoretical RoF: 3.5
elevator capacity: 28-30 rounds per minute
practical RoF: 3.1 at loading angle
main battery output: 126 rounds in 5 minutes at 15.000 yrds
loading angle: + 2 degrees
elevation rate: 8 degrees / sec.
AP qualities (hard to estimate, I calculate against US "A" for face hardened and Wotan hard for homogenious. There are little datas known for french pre ww2 armor but I expect the early 30´s armor is a little worser in the end: )
0: 24.4"; 2 Kyrds: 22.7"; 4 Kyrds: 21.0"; 6 Kyrds: 19.4"; 8 Kyrds: 17.8" [0.8"]; 10 Kyrds: 16.3" [1.0"]; 12 Kyrds: 15" [1.2"]; 14 Kyrds: 13.7" [1.4"]; 16 Kyrds: 12.9 "[1.6"]; 18 Kyrds: 11.8" [1.8"]; 20 Kyrds: 10.9 " [2.0"]; 22Kyrds: 9.9" [2.2"]; 24 Kyrds: 9.2" [2.4"]; 26 Kyrds: 8.5" [2.6"]; 28 Kyrds: 7.8" [2.9"]; 30 Kyrds: 7.2" [3.3"]
The 11 " ers are reputated for the very close shell distribution pattern and high preciseness (which reduced gradually with heavy gunwear).
In terms of pure armor penetartion the french gun wins by a mile advance! Indeed it is surprising that it has such a good striking power. The french gun also has more destructive potential once it delivered it´s load beyond the armor plates.

 

[delcyros]

How well are Gneisenau´s chances to penetratethe main armor zone of Dunkerque? It´s 11.200 t. of armor are well placed. I will take vital hits first:
1.) It isn´t possible to penetrate it´s decks with 11" plunging fire, no chance. The main armor deck is 115 mm (4.5") thick, over the magazines even 130 mm (5.1"). At 30.000 yrds distance the 11" angle of fall is 26 degrees, the shell will went through the two deck deep upper unprotected zone (loosing windscreen) and fail to penetrate. Non penetrating damage will be contained by the 40 mm (1.6") second armor deck.
2.) The 11 " projectile will succesfully penetrate the main armor belt at any distance up to 20.000 yrds. Actually this will not automaticly lead to damaging the vitals. There is a sloped 50 mm (1.9") armor deck behind it. The projectile will deflect downwards around 3 degrees by passing the 11.2 degrees inclined 241 mm (9.5") main belt and still hit the sloped deck at very high obliquity and around 1.700 fps. But it already lost windscreen and AP-cap with the impact. Calculating the lower shell body weight the projectile will pass the sloped deck and deflect sownwards by another ~ 2 degrees and keep 1.584 fps striking velocity. Enough to pass the 30 mm (1.2") armored torpedo bulkhead and detonate inside the vitals. However, the immune zone of Dunkerque is rather large. At distances under 8.700 yrds (+-) a main belt penetrating hit will most probably ricochet off or be deflected by the sloped armordeck.
3.) The armor scheme is very vulnarable against diving shells. There is virtually no protection beside of the 30 mm main torpedo bulkhead. Even slow striking velocitys (around 450 fps at 25 degrees) will pass through the torpedo bulkhead. The main belt is inclined and allows all high obliquity shells to pass the hull without hitting the water or the main belt. However the 11"ers are flat trajectory guns and chances for diving shells are little under 15.000 yrds distance.
Lets conclude:
0- 9.000 yrds: belt penetrations only
9.000- 11.000 yrds: belt penetrations, vitals most probably safe (ricochet off)
11.000-19.500 yrds: vitals vulnarabel to belt penetrations at certain impacts
15.000-30.000+yrds: vulnarable to diving shells
all distances: immune against deck penetrations
Don´t take these numbers for sure -so little data is known, it´s rather speculation. Beside of this if You factor longitudinal impact angles (which are important for any belt penetrations), then the immune zone is much wider and it is becoming very difficult for the 11"ers to penetrate into Dunkerques vitals...They did a good job with the armor placement there.

 

[delcyros]

What about Gneisenau?
It´s 14.000 t of armor are differently placed.
It´s 350 mm (13.75") KCN main belt is tough. At B and C turret it is inclined by 10, at the A turret at 16 degrees. At the centre of the ship it is vertical. This means that the main belt will be pierced at distances up to 24.500 yrds at the centre, 21.000 yrds at B and C turret and 20.500 yrds at A turret.
Complicated.
1.) The heavy weatherdeck can be pierced by plunging fire at all distances over 18.000 yrds. In this case it will loose AP cap and windscreen and have a remaining striking velocity of ~1400 fps (it will travel 14-18 m and detonate in case the fuze works properly) but it hasn´t enough deflection to reach the main armor deck. At 18.000-(have to calculate) yrds it will detonate inside the Zitadell but above the main armor deck. If the fuze is a crap or extra long, the shell WILL penetrate the main armor deck as well and reach the vitals.
2.) The vitals cannot been reached by belt penetrations. The belt itself can be penetrated (see above): At 6.000 yrds with a striking velocity of 2450 fps the shell looses windscreen and AP-cap (and 200 fps striking velocity) and will then have to pierce the 105 mm (4.12") sloped deck at extreme high obliquity. It would require a striking velocity of 3.800 fps+ for penetration under these circumstances. The projectile will brake or ricochet off and always be ineffective as well.
3.) There is little chance for diving shells. The main belt covers a larger area under the waterline (the actual waterline was higher due to the overload of Gneisenau and Scharnhorst) Even if a shell at high obliquity gets under the belt it will have to pass 1.) a 20mm secondary torpedo bulkhead -possible- and the main 45 mm torpedo bulkhead afterwards. The distance would be too much for a diving shell, the fuze would detonate the projectile before it reaches the main bulkhead or if it is a dud will be stopped by the main belt at such low striking velocitys.
Lets conclude:
1.) The main belt is piercable up to 20.500-24.500 yrds (depending on area) but the vitals will always be safe from 13" belt penetrations
2.) 13" deck hits may pierce the weather deck at longer distances than 18.000 yrds and WILL ALWAYS reach the main armor deck in case the shell is a dud at distances longer than 20.000 yrds. In such cases the vitals are vulnarable
3.) diving shells from 13"ers can be excluded to reach the vitals
again- just rough estimations for now

 

[Udet]

Mr. Delcyros:

Excellent information. Thank you very much.

You are right: if we take precedents into account, Gneisenau might avoid engaging the Strasbourg.

Just try to imagine she enters the battle, where would you put your money?

Now, do you have any data as to the reliability of the quadruple turrets?
The British never found the way to solve the problems in the quadruple turrets of the King George V class. Did the french experience any sort of trouble here?

More questions:

What exactly is "plunging fire"?

Cheers and thanks!

 

[delcyros]

plunging fire is fire with high angle of fall (at attached images always 1.)= deck hits.
I recalculated dek hits against Gneisenau more precise:
under 18.000 yrds: immune (angle of fall would indicate deflection instead of penetration)
at 18.000 yrds: penetration of the weather deck. remaining striking velocity: 1663 fps, angle of fall: 11.3 degrees (fuze will detonate the shell after ~17.5 m), it will pass the 20 mm vertical splinter bulkhead (afterwards angle of fall 11.4; striking velocity 1655 fps) and most probably detonate before it reaches the main armor deck* (*= in case the fuze delay is 0.035 s.) In case of a dud the shell will suffer base first impact/penetration which render the shell ineffective (plug velocity 150 fps)
at 20.000 yrds: penetration of the weather deck. Remaining striking velocity: 1566 fps and AoF: 14.1. Penetration of the splinter bulkhead (AoF:14.2; V: 1555 fps), shell will detonate before it reaches the main armor deck*, In case of a dud the shell WILL penetrate the main armor deck in nose first condition with Velocity of 1183 fps
at 22.000 yrds: penetration of the weather deck. Remaining striking velocity: 1466 fps (AoF: 16.2); penetration of the splinter bulkhead: AoF: 16.3, V: 1457 fps. that´s still not enough to ensure reaching the main armor deck. In case of a dud the shell WILL penetrate the main armor deck in nose first condition with Vel. 1064fps
at 24.000 yrds: Weatherdeck passed at 1421 fps and AoF 19.5. (shell will move 15 m before detonates = 3.75 m in height) Splinter Bulkhead passed with 1411 fps and AoF 19.6. Still not enough to reach the main armor deck. A dud WILL penetrate the main armor deck with remaining vel. of 1012 fps
at 26.000 yrds: Weatherdeck passed (1381 fps, AoF: 22.5), shell will move 14.5 m before detonating, splinter bulkhead passed (1370 fps, AoF: 22.7). Shell still not reaches main armor deck. A dud WILL penetrate and remain 1017 fps
at 28.000 yrds: Weatherdeck and splinterbulkhead passed. Shell will detonate before hitting the main armor deck, a dud WILL pnetrate (1030 fps)
at 30.000 yrds: As before, with the exzeption that the shell will get very, very close to the main armor deck before detonating (half a meter), a delayed fuze will cause the shell to penetrate with 1079 fps and reach the vitals.
It should be noted that during ww2 fuzes often delayed between 0.035 and 0.045 sec. Only the japanese diving shell had an extra long fuze delay (0.07s.)
To conclude: The gneisenaus vitals are exposed from 19.000 yrds on to deck hits. A dud WILL always (as estimated before) also penetrate the main armor deck and cause some minor (dud) damage there. Long delay fuzes may also allow the shell to detonate while penetrating the main armor deck. A normal fuze delay doesn´t present any danger for the vitals. A 13" deck hit would need between 34.000 and 35.000 yrds distance to penetrate all armordecks and detonate inside the vitals at normal fuze delay. That´s pretty much the SAME DISTANCE at which Gneisenau´s 11"ers (in theory) will penetrate Dunkerque´s deck armor:
At 35.000 yrds they WILL penetrate Dunkerques main armor deck (remaining striking velocity 374 fps, AoF 60 degrees. The shell will move 3.95 m before detonating but only reachs partly or full penetration of the 40 mm splinter deck (striking velocity is 374 fps, 381 fps are necessary for Navy ballistic limit). Blast effects and fragmentation may reach the vitals. At ANY longer distance than 35.000 yrds Dunkerque´s vitals are exposed to 11" deck hits, except for the 5.3" armored deck over the magazines, which are reachable from 37.000 yrds on by Gneisenaus 11"ers .

 

[delcyros]

For all who want to know more simplified:

Immune zones of Dunkerque and Gneisenau (using their guns against each other) in Kiloyrds:

0: immune, no penetration possible
1: fluke hit: Longer than usual fuze delay (or a diving shell)
2: penetration possible at certain points (small areas have to be hit)
4: Penetration will occur

ship/area----2K--4K--6K--8K-10K-12K-14K-16K-18K-20K-22K-24K-26K-28K-30K-(32K)-(34K)-(36K)-(39K)-(40K)

Dunkerque:--0---0----0---0----2----2---2----2----2----2----1-----1----1----1---1-----(1)----(1)----(4)----(4)-----(4)-

Gneisenau:--0----0----0---0----0----0---0----0----0----1----1-----1----1----1---2----(2)-----(2)----(4)----(4)----(4)-

Actually both ships are widely immune against each others main weapons. Keep in mind that any longitudinal influence in impact angle (Dunkerque turns) would make it very difficult for belt penetrations of 11"ers against Dunkerque. I expect that another factor would decide the outcome of the battle. Such as duds (the Gneisenau can suffer from deck penetrating duds at all distances over 19.000yrds) or diving shells (Dunkerque is exposed to even flat trajectory diving shelles at all distances over 15.000 yrds). Again: longest ever gunfire hit against a ship: 26.450 yrds

 

[Udet]

From these numbers it´d appear the Gneisenau has a slight advantage over the french ship.

This is totally brilliant Mr. Delcyors, from where are you getting all these data?

Finally, which vessel has the award for the longest gunfire hit ever attained?

26,450 yrds= 24.18 kilometers. Outstanding.

 

[delcyros]

From these numbers, sure. But I have to point out that secure penetration at usual distances into each others vital is not possible for both (note that "4" begins at very, very long ranges). A Firecontroll hit /bridge hit or non penetrating damage will decide it but Gneisenau also has the advatage of better sinking resistence/ metacentric height. This undoubtly would led to extensive punishment without decisive advantages for any side. Pure luck, if you ask me.
I use to calaculate the penetrations with Nathan Okuns computerprograms for face hardened and homogenious armor. The datas for the guns are avaiable at the naval technical board (there also is a link to Okuns pages, including a comprehensive analysis of Bismarck´s armor scheme and his programs),
try:
www.navweaps.com

The homogeniuos armor penetration program also is useful for calculating penetrations on tank armors if anyone needs (some armor specifications have to be modified).

The longest gunfire hit on a ship was by Scharnhorst against the RN CV Glorious. You may find an article about this as well at the Naval technical board.
A close second is the longest gunfire hit on an enemy BB: Warspite achieved a hit on the italian BB Guilio Ceasare (26.000yrds).
It´s interesting that the navies with emphasis on short range engagement achieved the long range hits while the US and japanese navies with special emphasis on long distance engagements did not.

 

[Udet]

Delcyros:

Thank you very much for the prompt reponse.

So it was the Scharnhorst. I of course knew of the episode when the German twins caught the Glorious and simply destroyed her with all escorts. I just did not know of this particular feat.

Was Admiral Lütjenz in command of the twins when they sunk the Glorious?


Also if we take into account the experience gained by both Gneisenau and the Strasbourg I put my money on the German machine.

By the time France surrendered -June 25, 1940-, it´d appear the crews of the Gneisenau were far more seasoned than the french guys on board Strasbourg.

They had raided the Atlantic, and had sunk the Rawalpindi in 1939. Of course the clash with Rawalpindi was overkill, but the vessel was destroyed and sent to the bottom. Efficient work.

The twins also participated in Weserübung. They had sent -as you pointed out- the carrier Glorious and her escorts to the bottom as well. Overkill again. But, again, efficient work.

This were the fundamental events of Gneisenau before the french surrender in late June, 1940.

It´d appear that other than escorting some convoys during the Phony War, the french twins did not see any action. Oddly, the real -and only- combat these excellent french ships ever saw was against their British "allies" until meeting their sad ends in Toulon in November, 1942.


Also I agree German heavy surface vessels in general had better sinking resistance: the Bismarck being the clearest and cleanest example.

I wonder how long would any of the British capital ships have lasted if it had been subjected to shelling by Bismarck, Scharnhorst and Gneisenau together -well, HMS Hood blew up in only a few minutes, very bad resistance-.

Also the dramatic end of both HMS Prince of Wales and HMS Repulse when they were destructed by Japanese planes.

If I recall correctly the HMS Prince of Wales took one, repeat ONE, torpedo hit aftwhich flatly doomed the vessel. Unlike Bismarck, the Prince of Wales was a poor damage resisting creature.

The PoW took more hits. But that particular hit aft implied her end.

 

[Jabberwocky]

Prince of Wales took an unlucky torpedo hit to the aft quarter which lead to some loss of steerage and flooding. It also cut power to some of her main batteries.

However, even after the hit, she fought on for another 2 hours before being hit by 6 more torpedos and sunk.

I don't know of the sinking of the Glorious was necessarily that "efficient" either. Her escort consisted of just two destroyers, both of which landed torpedo hits on the German battle cruisers and put them out of commision until late 1940. A little more luck on the British side and both battlecruisers might of been the ones who ended up on the bottom.

 

[Henk]

The PoW was poorly designed if you take that her guns failed quite a lot and she had all her life boats fitted in the center of the ship. All in all it is not a great ship. All her main guns ceaced to work after she lost power.

I think the Gneisenau is the best of the two, allthough the Strasbourg is a lovely ship and also well equiped.

Henk

 

[delcyros]

I rate both ships as about equal in key factors. This is interesting, since the Dunkerque´s were a lot lighter. If it really comes on pounding the luck is most probable to decide who will sustain.
In terms of the damage taken from BC Scharnhorst during torpedo attacks I have to point out that it was both, efficient (longest distance hit is something efficient, average shell/hit ratio was far better than average against small, fast and couragious maneuvering DD in the weathers) and Jabberwocky- it had little to do with luck. The damage on Scharnhorst was to the latest because of the torpedo hit but because of the crappy HPT engine. The battle reports show this clearly (one turbine ran out of calibration due to the impact shock, another because of a design failure). Even if both DD could have landed 4 torpedo hit´s each the, Scharnhorst would not necessarely have sunk. Crippled, yes. Sunk, not necessarely.
The torpedo hit was outside the TDS of Scharnhorst. The Byouncy reserve and metacentric reserve of the BC would allow a lot of flooding (it took 12+ to sink her in 1943).
The ship stayed so long in drydock because the HPT showed some difficulties, partly from worse materials, partly from design failures. The whole turbines had to be reworked and this takes a lot of time. The torpedo damge was significant (flooding, speed loss) but never serious or close to serious.

 

[Glider]

The fact though that two destroyers on their own were able to land such hits on the German vessels implys to me anyway that the Ships were not as well manned as they should have been.
Also their poor performance off Norway when the Renown on her own met both the Scharnhorst and Gneisenau together would also make me question how effecient these ships were.
I don't think there was anything wrong with the ships but early in the war I believe the crews were not as effective and they could or should have been.

 

[delcyros]

Actually Scharnhorst and Gneisenau evaded a total of 11 torpedos against both Destroyers. They were capable to evade all had they noticed them properly. The torpedo launched to hit Scharnhorst wasn´t detected according to the battle report otherwise evasive actions would handle it.
A single BB or BC has little to stop a DD. And it should be noted that both DD were excellently handled by their crews. They took evasive actions like hell to avoid the 11"ers, 5.9 "ers and 4.1"ers of the twins. Both DD´s were knocked out pretty quickly if we compare these fights with Guadacanal or Leyte.
The thing with Renown is another one. It was decisive battle order to avoid any contacts with enemy BB or BC. Renown was escorted by two DD as well and a Rodney class BB was in close proximity. The weather was extremely bad and both german ships suffered in bad weather from a wet bow which rendered turret A useles. So they had only 4 triple turrets to use against Renown and the 15"ers of Renown had a reputation for a good deck penetrator. As we know, the Scharnhorsts are vulnarable from deck penetrations and even a significant damage was a too high a prize. The DD could use their torpedo´s and once the twins are slow, Nelson can close in and Game over. It was a fully correct decision to disengage. A BC is a raider, not a battleship. In each Battle were BC fought BB (Denmark Street, Guadacanal, North cape, the BC lost. In a one on one comparison the Renown was a very vulnarable ship. The heavy 15" armement led to the wrong decision to use it as BB. The twins however, were fully recognized as BC and always disengaged when the enemy carries heavier guns (the initiative advantage of these fastest capital ships of their time).

 

[lesofprimus]

Excellent reading gentlemen... Hats off to u delc for jumping into it so wholeheartedly...

 

[Glider]

Not often I would disagree with you Delc but on this occaision we will have to differ.
Two fast modern Battlecruisers in daylight with good weather each with a broadside of 9 x 11in 6 x 5.9 ad 8 x 4.1 plus I think one of them carried their own torpedos should have been able to handle two destroyers on their own without support without being hit by torpedo's.

As for the meeting with the Renown, remember she was also a BC from WW1 with very thin armour, often half that on the German ships.
The weather was very poor and ranges low. Even with two turrets each your left with 12 x 11 in against 6 x 15in with the 11 in having a much faster rate of fire and able to penetrate the Renown's armour with ease plus the 5.9s capable of doing damage at that range. Bearing that in mind I believe they should have done better. I admit that I thought the Renown was without her escort and no capital ship would want to mess about in bad weather with destroyers about, its asking for trouble. With that in mind the Germans action was more understandable
That said, even with the action that took place, with the German Ships running and the action fleeting, the two German ships did no effective damage to the Renown and the Renown did a decent job working over the Gneisenau causing significant damage to her Turret and Fire Control. As there was nothing wrong with the German ships, I would put the difference down to the crews.

I don't believe that the Rodney Class was an issue, for the simple reason that the Germans didn't know they were there.

 

[delcyros]

If the BC can concentrate on a DD...yes. The problem is to stop them (disable them) before they reach torpedo launching distance. And moreso becuase both DD were between the twins and their prey. So either they loose contact to the Glorius or they take the risk of a DD in torpedo launching distance. They did the latter, while one BC attacked Glorius and the other the closest DD (the other effictively build a smoke screen to cover Glorius).
In such a gunnery duel the DD´s fate is inevatible. The qustion is what the DD can do in it´s last minutes and how it will be used. The captian of both DD were great and highskilled skippers, they used their ships far beyond the point when others had long given order to abandon the ship because it suffered too much critical damage.
It may be easy to seal the fate of a DD by a single 11"hit but it is hard to sink the DD before it comes into torpedo range under such circumstances. This is what I meant with a single BC has little to stop a DD on their own.
While the point with the Renown is a different one. I totally agree with You that the Renown is inferior in such situations on a paper battle.
However, Gneisenau had, according to the war diary of its operation, short visible contact to Nelson/Rodney the previous night. So they knew about a BB in that region. Plus the weather forced all ships to under 20kts (makes Nelson theoriticly as fast as Gneisenau)- and the problem was they did not knew where Nelson exactly was.
But beside of this I wouldn´t blame the crew for disengaging. It was naval doctrine to disengage heavier guns in order to prevent damage. The KM unlike the RN had no naval doctrine to engage under all circumstances (alike Glowworm against Hipper), they simply had too few ships. Each was worth too much to risk it.
The damage caused by the 15" hits from Renown contributes to her reputation for excellent gunnery training. The uneffective fire from the twins may be explained partly by the use of a single (rear) turret by each ship because they were fleeing. It´s quite hard to hit anything with 3 guns per ship only. But beside of this it´s record stays in contrast to the other recorded actions (Glorius, Rawalpindi, North Cape), when they got a reputation for early hits in the battle. Still the numbers are not that weak for the twins: Renown managed to land one 15" hit and Gneisenau got two 11" hits on Renown in return.
It should be noted that Scharnhorst suffered a boiler breakdown earlier.
The identification of Renown was unclear from german side. According to the battle report they knew about enemy firing 15" rounds, probably Hood or Repulse/Renown.
Ammo spendid:
Scharnhorst&Gneisenau: 182 11"AP; 13 11" HE; 91 5.9"------2 11" AP hits
Renown:54 15"AP; 72 4.47"--------1 15" hit, 2 4.47" hits
The damage caused by Renown was not, I repeat, not significant:
15" hit:
AP penetrated the unarmored upper superstructure under the forward FC rooms, cutting some cables and left through the other side. It detonates outside the superstructure and some of it´s splinters killing four and injuring two more in the forward FC. FC was fully repaired on sea.
4.47" hit:
Shell hits turret A (already not active due to heavy seas) and cuts of one of it´s rangefinders (compare attached picture)
4.47" hit:
Shell hits the rear 4.1" DP without major damage. turret still operational.