German Battleships and convoy hunting.

Mr. Delcyros:

When you say the internal design of the french main cuadruple turret worked well in the Strasbourg -saying that when it got hit only half the turret got knocked out- to what combat you be referring to?

The action against the British in Mers-el-Kebir?

Strasbourg, was the only large vessel anchored there that managed to escape -it was, with not doubt, a test of seamanship and guts: manouvering in the chaos of the small harbor, with the enemy fleet firing from the distance speaks a lot for itself- and if i recall correctly, the British scored no hits on her. Her twin, Dunkerque was heavily damaged and got beached.

So when was it that the design proved its worth? Just a question, I might be unaware of another combat where she got involved.

While theoretically interesting as a design, I have my doubts as to how it would actually work once put to test in real combat.

Putting an armor plate dividing the big turret into two sections... it seems highly unlikely that in the event of a heavy shell hitting the turret on any side only half turret would get knocked out.

A smaller shell hitting it, well, even without the internal armor plate fitted, any major turret would have no problem in resisting the impact and continue in operation.

Or say, that depending on the exact place and angle of the oncoming shell, at least the rotating mechanism of the turret would get thrashed.

My mistake. It was Richelieu, not Strassbourg, which suffered main turret damage. It was hit by a 15 inch shell either from HMS Barham or HMS Resolution at Dakar which knocked her main gun #2 and #1 out of action. #3 and #4 remained intact (minor damages by shock effects, some injured crew members as well), so the subdivision of the quadruple turret is battle proofed.
It´s all a question at what impact angle the shell hits and what striking force it has (weight, speed, design of AP-cap). A 15" hit is anyway a heavy hit.
However, since the Richelieu has face hardened armor on it´s turret face (and sides), the effect is different:
A slow moving, heavy shell with soft cap will ricochet off(at high obliquities), break (at the holing limit) or make it´s way through (at direct impact angles). A faster, lighter AP shell (let´s take 8 inch) won´t make it through at most but close distances but it will plug out a lot of armor, which in most cases will knock the turret out of action (repairable), since the face hardened armor is more resistant but more brittle also than homogenoius.
Designs differ to counter these effects.
One of the reasons why Bismarck had so little turret armor is that design crews found out that a turret cannot be safed even by heavy armor at almost all distances (thanks to shock effects and damage caused by armor punched out) from 14" and heavier projectiles.
Take Bismarcks 15" for example: It will reach partly penetration (upper body at low obliquity) even at distances of 18000 yrds against 22 inch of face hardened armor! The non penetrating damage caused by this projectile weighting 3/4 of a ton, travelling at speeds between Mach 1.5 and Mach 4 will knock out a 22 inch covered turret even at 30000 yrds...
Realizing this they decided to protect against smaller, high velocity shells, like 8 inch even at 0 distance. However, in order to provide sufficient protection against heavier projectiles a second, very ductile layer of approx. 45-50 mm armor (US-"B" or Ww) would be neccessary behind a more thicker face hardened armor (around 20 inch and more). This was partly executed only in the Yamato turret design. It should be noted that such a turret would weight almost a destroyers full weight!
The US replaced face hardened with homogenoius armor on their turret mainly because of the worrisome scaling effects of their class"A" face ardened armor. This is very reasonable. The resistence of "B" is little less compared to face hardened but the good elongation qualities more than offsets this. The problem was to make homogenoius in such a thickness (20 inch +) without making it brittle (thus reducing the elongation advantage). I don´t believe that they succeeded in this, but there are no confirmations avaiable. Even with this in mind, The turret is only partly protected against heavy shells (against Richelieus 15"/50 at distances further away than 17.000yrds) and not protected against non penetrating hits (at any distance). With this in mind, the subdivision of the Dunkerque/Richelieu-class turrets should be considered as advanced.

Just theoretically, the Prinz Eugen might have done the fatal hit on Hood. But this is very theoritcally.
Let´s assume it is a deck penetrating hit (as most scholars believe), the abilities to penetrate the deck (calculated with british homogenious armor) are the following at 16.000 yrds distance (around the distance where Hood suffered conflagration):

Bismarck:
15"/52: 2.2 inch at 1816 ft/sec.
5.9"/55: 1.3 inch at 1019 ft/sec.
4.1"/65: neglectable, the angle of fall would indicate no deck penetration

Prinz Eugen:
8"/60: 1.2 inch at 1551 ft/sec.
4.1"/65: neglectable, the angle of fall would indicate no deck penetration (deflected)

-surprise! The deck penetrating abilities of Bismarcks main and secondary guns are better than the CA´s main artillery (thanks to a very flat trajectory) The deck armor of Hood over aft magazine are 67mm + 51 mm weather deck + splinter deck (may have been hit also) 17mm.
With this in mind, there is no justification for the claim that Prinz Eugen did the fatal blow directly. A indirect may be caused by a fire set up by a 8 inch hit (which could in theory set off the secondary ammo stored there), which in the end led to the main ammo burning (unprobable because of the armor subdivision there, it must have been "open" in some kind).
However, let´s think it was a 15" hit - the deck armor penetration makes it improbable:
Penetarting the weatherdeck (projectile is losing windscreen and AP-cap, no nose damage, speed reduced to 1345 ft/sec., deflection down by 5.4 degrees), the projectile is getting weaker and would be rendered "ineffective" by reaching the armor deck (nose shattered, partly penetration). Could the non penetrating damage set off the powder?
Hard on the explainable limit, if you ask me.

Now let´s assume it was a belt penetrating hit (against british cementated, which is a little better than that used on Hood:

Bismarck (penetration must be "effective" with intact shellbody):
15"/52: 17.6 inch
5.9"/55: 2.2 inch
4.1"/65: 1.6 inch

Prinz Eugen:
8"/60: 7.5 inch
4.1"/65: 1.6 inch

The armor layout of Hood there is 305 mm main belt(slightly inclined) + 54mm (sloped 45 degrees)+ 19 mm, so the 15" of Bismarck is the only gun to place a projectile in this distance into Hoods vitals via belt (without any problems).
Lets assume a last possibility: The ship was doing a turn left , there is some probability that the ship rolls a bit in the sea.
I have a diving shell in mind (right side of Hood is briefly lifted due to rolling sea), the armor here is 76m plus 19mm, so under this circumstance, both, Bismarcks 15" and Prinz Eugen´s 8" could make it´s through. Anyway, a belt penetrating hit is more reasonable for the destruction of Hood than any thinkable deck penetration.

Whilst I agree with Delc that it is certain to have been a 15in that sank the Hood. I think everyone will recognise that the Prinz Eugen did remarkably well hitting the Hood hard as well as scoring damaging hits on the POW. It certainly shows up the performance of our CA's in the battle

Gentlemen though providing for a rather nice disortation nothing has been proven with regard of the P.E. destroying the Hood or not. Since we have no living eye witnesses to say a Bismarck big boy shell or one of smaller caliber hit the Hood to cause the fatal damage nothing can be said except conjecture. The P.E. remarked in their log-books, sadly nothing can be said for the Bismarks ill fated crew as to witness, they ahving their own problems during the battle obviously. We of course in this day and age could not admit the pride of the Royal Navy being sunk by a lesser craft so it would of had to been the Hood.

Mr. Delcyros:

Thanks for the info again.

Now, if a heavy shell of either Barham and Resolution knocked out 2 of the 4 guns in one of the turrets of Richelieu, it is kind of natural to assume -in accordance with the info on Bismarck´s 15in. shells you provided here- that an impact in the same point of the cuadruple turret fired from the German battleship would have knocked out the complete turret.

The guns of Bismarck, as well as the shells, were better and more powerful than those fitted to the vintage battleships of the Royal Navy.

I think we can agree on this can´t we?

Not neccessarely. The hit was a turretroof hit. It must be considered as a horizontal "deck" penetration. Obviously the british 15"/42 has more deck penetrating capabilities than the high velocity, flat trajectory 15"/52 of Bismarck. In this very case, I would suspect that the probability to ricochet off or deflect the projectile would be higher for a Bismarck´s shell.
Nethertheless non penetrating damage would be worrisome and knock out half a turret. In the end Richelieu would suffer less damage (because repairable in most cases).
Even a direct hit would knock out one half turret completely, but fragmentation and blast effects are contained by the additional dividing heavy armor plate, so I suspect that only non penetrating damage occurs in the second turret half at all but very close distances (when the shell penetrates both plates intactly). This doesn´t mean that the intact half turret can continue to fire (I already mentioned the problems to mount vital cables at the armor plate, this probably would silence the whole turret), but it would be repairable.
The german AP shells in general were superior in armor penetration but more a subject to projectile damage than contemporary US or british shells. The british shells in particular have a more pointed AP-cap design, increasing the amount of non penetrating damage (armor punched out, called "discs" by the RN).

According to the post battle report of PoW and (more important) Norfolk, the Hood blew up just at the time when it was staggled by 15" impacts. It might be reasonable to think there is a causal relation. However, this doesn´t exclude the PE, as you pointed out correctly, Erich.
What seems more interesting to me is that at these distances deck penetration is a very rarely thing to happen, whatever gun is involved. Belt penetration could be a (better?) explenation. The wreckage analysis showed that the ship indeed turned (in order to bring all main guns into firing position) port prior to impact (while all three survivers state that the ship did not executed the turn). If we factor longitudinal impact angles properly, we can assume that this turn sealed the ship´s fate, showing the belt and making belt penetration possible (without there would be deck penetration only, no chance to hit the belt from these angles). Of course, failed armor plates might make deck penetration possible, also. The wreckage gives some valid informations that two conflagrations happened, the first to seperate the stern from amidship and the second (not noticed before) seperating the bow. I could imagine that the latter is caused later, even may have little to do with the battle.

Del I would be curious if there is a ship to ship map showing the angle of the 3 ships in reference to one another during teh final engagement with the Hood. I have about 3-4 books on the Eugen so will look if something is there. Still with the choas and the smoke, clarity was not at a premium. Still many unsolved questions

...many of them cannot be answered in detail, agreed.
The position can be extrapolated if you plot the headings for each ship in correspondence with the time, speed and the distance to each other. Not all details are known but here are some:

Hood/PoW heading:

until 05:37: 240, 28 kts
05:37: Bismarck and PE spotted
05:37-05:49: 280
05:49-05:55: 300
05:52: Hood opens fire, distance is ~25.000 yrds
05:53: PoW opens fire
05:55-06:00: 280
06:00-06:01: 260
06:01: Hood sinks, distance is ~16.000 yrds
06:01-06:02: 160 (PoW only)
06:02-06:05: 210 (PoW only)
06:05-06:23: turn left to 110 (PoW only)

Bismarck heading:
until 06:03: 220, 30 kts
05:55: Bismarck opens fire, distance is ~23.000 yrds
06:03: toprpedo evasive action (turn right, then left, Bismarck overtakes PE)
06:09: Bismarck fires last half salvo, distance to PoW: ~18.000 yrds
06:09: turn to new heading 270 (PE accelerates to 32.5 kts and overtakes Bismarck)

So with a little math and added informations from Suffolk and Norfolk (Norfolk stayed out of the battle, Suffolk joined later PoW) as well as those provided by Bismarcks artillery director Müllenheim-Rechenberg (checked for the british CA), there is good chance to reconstruct each ships position +- 200 yrds. That sounds pretty much but it is sufficiant to check the longitudinal impact angles from Bismarck and Hood. I am pretty sure somewhere in the web are more detailed informations avaiable.

Erich said:

Del I would be curious if there is a ship to ship map showing the angle of the 3 ships in reference to one another during teh final engagement with the Hood. I have about 3-4 books on the Eugen so will look if something is there. Still with the choas and the smoke, clarity was not at a premium. Still many unsolved questions

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If you watch the video "The Discovery of the Bismark" it has some nice computer simulations showing the angles and where the shells hit.

At the reported distance the angle of fall for Bismarck´s vaunted 15" AP shell is indicated with only 14 degrees. A deflection at this very high obliquity (on horinzontal armor) is very probable.
In order to get back with the topic I will post some aspects with advantages for KM using heavy surface forces in the Atlantic:

1.) While beeing totally outnumbered, the Atlantic is a large field to operate in. As long as the KM ships posses the speed advantage, they may dictate the terms of engagement (as Scharnhorst%Gneisenau did)

2.) The use of carrier based air forces in the Atlantic is less effective than in the Pacific due to bad weather conditions (KM usually preferred bad weather conditions for their raids)

3.) The existence of Raiders would press the RN in the uncomfortable situation to protect their convois against both, submarines and raiders. And while the older BB would perfectly fit into the escort´s role, they would be more exposed to submarine attacks also

4.) KM ships usually had the advantage of a better range, while the RN did not need an effective higher range because of their innumerous bases, the chase for the Bismarck proved that their range was insufficiant even at this short journey (all involved ships were in the end very low on fuel)

5.) Raiders proved to be effective against merchants if properly deployed (evading battles)

6.) The binding of RN forces in the Atlantic theatre would benefit the other theatres, esspecially the axis in the Mediterannean, later less BB could support the allies in the coastal bombardments neccessary for amphibous/invasion campaigns in northern Africa, Sicily, Italy and France.

7.) it could be argued (not sure), that the heavy ships would attract more concentration than the submarines, thus making each other´s task easier.

It should be noted that extensive battles of heavy forces would always benefit the RN.

1.) While beeing totally outnumbered, the Atlantic is a large field to operate in. As long as the KM ships posses the speed advantage, they may dictate the terms of engagement (as Scharnhorst%Gneisenau did)

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Are you reffering just to the North Atlantic or the whole Atlantic ocean?

2.) The use of carrier based air forces in the Atlantic is less effective than in the Pacific due to bad weather conditions (KM usually preferred bad weather conditions for their raids)

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Land based airpower is available from Iceland and Scotland. The German raiders would not be able to operate past the mid Atlantic as the US had a zone of exclusion for the German navy.

3.) The existence of Raiders would press the RN in the uncomfortable situation to protect their convois against both, submarines and raiders. And while the older BB would perfectly fit into the escort´s role, they would be more exposed to submarine attacks also

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The raiders would also be exposed to the RN submarines. In fact, the anti submarine zig zagging the German raiders would have to perform as a normal course of defense would mean far higher fuel consumption.

4.) KM ships usually had the advantage of a better range, while the RN did not need an effective higher range because of their innumerous bases, the chase for the Bismarck proved that their range was insufficiant even at this short journey (all involved ships were in the end very low on fuel)

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Agreed

5.) Raiders proved to be effective against merchants if properly deployed (evading battles)

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Agreed, but what happens when all of the merchant ships are in convoys? You will have to do battle then.

6.) The binding of RN forces in the Atlantic theatre would benefit the other theatres, esspecially the axis in the Mediterannean, later less BB could support the allies in the coastal bombardments neccessary for amphibous/invasion campaigns in northern Africa, Sicily, Italy and France.

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By the time the invasions of North Africa occured, the USN had been in the war for 10 months. The RN was not going to operate alone. Beginning in 1943, the first bunches of cruisers and battleships ordered under the 1940/1941 ship building programs were beginning to join the fleet, so in just sheer numbers the German navy was going to be overwhelmed. Plus Pearl Harbor and the Repulse/POW debacle off of Malaya proved that the operation of surface ships in the threat of air power was a recipie for disaster.

7.) it could be argued (not sure), that the heavy ships would attract more concentration than the submarines, thus making each other´s task easier.

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Clarify that for me. I dont understand.

It should be noted that extensive battles of heavy forces would always benefit the RN.

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The allies would win a battle of attrition.

One other thing to remember is the operation of large fleets requires extensive logistics. Battleships alone use up oil by the kiloton. I'm not sure that Germany could afford to operate more than a couple of raiders at one time without impacting other area's of its war economy.

Fine You´re back again, Syscom.

While I am not qualified enough to give proper answers to all I may have some points (starting with the latter ones):
According to the operations conducted by the KM 1945 in the Baltic, the KM never was short on fuel nor had logistical problems of any kind. This isn´t much surprising since both, the number of their ships as the use and deployment was very limited. Fuel shortness became critical in late 44 for all units which depended on HIGH GRADE FUEL (bombers for example), the KM only depended on low grade fuel (e-boats), Diesel or simple oil.
(of course from mid march 45 on general technical and logistical problems were overwhelming)

The Kriegsmarine had never been used in extensive operations though, and the actions in the Baltic were extremely close to home ports. This wouldn't use up many resources. Using surface raiders across the Atlantic couldn't be further from the Baltic actions of 1944-1945.

Surface raiders in ones or pairs would be able to attack singular or small convoys, but they would not be able to choke Britain. The major convoys from the Americas to Britain would be defended by the BBs and BCs of the Royal Navy - this would force the Kriegsmarine into a desicive conflict which they would be best to avoid.

On top of that, the long operation times and distances covered would be a drain on Germany's resource. Capital ships would be all around the Atlantic continually if they wanted any chance of starving Britain out and this would cost a lot in oil.

Air strike in ETO at freely moving big ships actually did not that well. Tirpitz was attacked by torpedo bombers and could evade untouched, Bismarck was attacked also and only a fluke hit doomed her (one of three hits, the others showed nothing), Ark Royal was attacked by Luftwaffe and could evade succesfully. As far as I remember only the Roma was destroyed by level bombing with the help of guided X-1 bombs (which also severely damaged the BB Italia and Warspite). Air attacks were very succesful against ships in their harbour (Tarento, Tirpitz, Gneisenau, Casablanca, Sevastopol).
It is very questionable if land air forces could do much more than screening and patrol dutys against lonely Raiders.
Some thought´s about submarines. The UK and SU subs regularly patroled in norwegian waters which was efficient, since they stayed there but without any succes. Zigzagging would (and did) only take effect in proximity to the harbours and coasts (where these ships have been screened by DD´s also), while in the open Atlantic the ships high cruising speed (28-30 Kts) would make it very difficult for submarines to get a shot.

The KM never was in the position to choke Britain with it´s capitolships but staying in the Atlantic would make the whole convoijob a lot nastier for the allies.
I remember that PQ-17 was dispersed (and therefor doomed) just after they got the info that Tirptz left it´s anchorage despite the heavy screening with Washington and Duke of Yorck.

It's agreed then, the surface raiders couldn't choke the British Isles. What then, would be the point in them? The U-boats with more resources and bigger numbers would have a much bigger strategic impact on the war than the surface vessels.

Syscom this zone of exclusion that the US had did not cover the whole Atlantic. It was just the immediate coast lines surrounding the US and its interests. The Germans were free to go past the mid atlantic all they wanted and did so throughout the war before the US entered. The KM operated from the N. Atlantic to the S. Atlantic to within a couple hundred miles of the US, which we know the Germans broke once the US started escorting convoy even before they entered the war.

German U-boats generally operated in U.S coastal waters too. The U.S had no effective coastal defence until 1942.