The Kriegsmarine's Double Whammy: Monitors and Carrier Conversions

[Kantai Kessen]

Hello everyone!

So this is my first time ever posting on AH.com, and I wanted to start with a subject that has always interested me: the Kriegsmarine.

I know there have been a lot of threads on this website about this navy, and I know that it has not a chance in hell of winning the Second World War short of a POD before 1900. However, I have often considered ways in which the Kriegsmarine could have done significantly better, and so posed a worthier challenge to the Royal Navy.

Now I was watching a Drachinifel Drydock the other day in which he discusses the Battle of Drøbak Sound, and what ship would have done best to replace the Blücher in that battle. Apparently, a monitor-type ship would have done the job: lots of anti-torpedo protection, decent armour and heavy guns, perfect for forcing the coastal defences.

I was also reading Wikipedia on the Deutschland-class cruisers, and found that around 1943 there was a proposal to convert them into aircraft carriers: https://en.wikipedia.org/wiki/Deutschland-class_cruiser#Possible_conversion

So I began considering two things:

(1) Could the Kriegsmarine have converted the three Deutschland-class ships to carriers instead of attempting to build the Graf Zeppelin-class? If so, what do you think their projected airgroup would be (taking Goering into account), and how effective do you think they would have been? Bonus points if you can get them completed by 1940 and worked up by, say, March 1941.

(2) Could the Kriegsmarine have used the spare 28cm triple turrets and 15cm guns from these conversions to construct six 20-knot monitor type ships, for use in coastal operations? I think that this is relevant to their strategic thinking since they were worried about an attempted French or Polish amphibious landing, and also since they would be useful in the Baltic or on the Norwegian coast. If they could build them, do you think they could have been used well in Norway, or indeed in the war as a whole?Bonus points if you can get at least two completed by Operation Weserübung.

And, on a related note:

(3) How would German battleship and heavy cruiser construction be impacted by this, since Graf Zeppelin's and Peter Strasser's slipways are not being used?

Looking forward to your replies!

 

[naraic]

The torpedo protection you want is from massive bulging. This will make the monitor slow. I don't think you will get a 20 knot monitor and get the benefits Drancinifel is suggesting a monitor would have. You can build 14-16 knot ships maybe. If you want this I'm sure you can do it.

As to the effect on German ship building of carrier conversions I would suggest that converting 3 Panzer ships and building six monitors would consume more resources than Peter Strasser and Graf Zeppelin. Even if slipways are conserved. I doubt anything major will be laiddown in those slipways as the naval resources are being consumed anyway.

In terms of size the Panzer ships were basically equivalent to HMS Hermes. I'd say performance will be similar enough in terms of airgroup size.

 

[Monk78]

Personally I feel any kind of aircraft carrier /capital ships for KM is an enormous waste of resources, they should focus on making licensed copies of https://en.wikipedia.org/wiki/Nakajima_B5N armed with decent aerial torpedoes and AP bombs
They had the range and weapons and if given fighter escort could dominate Baltic , North sea and Norwegian sea and could be perfect sea denial weapons.

Even 300 of these bombers probably would be cheaper than any of the big carriers / battleships and will give them a lot of flexibility as well even if the fear factor is much lower.
But just imagine the effect on British morale if Hood and Prince of Wales are sunk in early 1941 by such bombers ?

 

[Monk78]

spare 28cm triple turrets and 15cm guns from these conversions to construct six 20-knot monitor type ships, for use in coastal operations? I

and would really come in handy for shore bombardment as well to support advancing Wehrmacht

 

[CV(N)-6]

Hello everyone!

So this is my first time ever posting on AH.com, and I wanted to start with a subject that has always interested me: the Kriegsmarine.

Welcome!

(1) Could the Kriegsmarine have converted the three Deutschland-class ships to carriers instead of attempting to build the Graf Zeppelin-class? If so, what do you think their projected airgroup would be (taking Goering into account), and how effective do you think they would have been? Bonus points if you can get them completed by 1940 and worked up by, say, March 1941.

I mean, I guess, but why? Before WW2, the KM's larger than CL fleet was just the Deutschlands, the Twins, and if you want to count them the pre-dreads, which are worthless outside of shore bombardment. The KM was planning on having Graf Zeppelin in service in the next couple of years before WW2 got in the way, and it seems unlikely that the KM would sacrifice its second most powerful ships and only heavy cruisers until the Hipper's came into service in '39-'40 in favor of carriers, which were not proven in combat, and that would be lucky to carry 20 planes considering the size of the ships and the inefficiency of a conversion of a completed warship to a carrier. In terms of wartime conversions, the KM needs those ships and doesn't have the resources to spare.

(2) Could the Kriegsmarine have used the spare 28cm triple turrets and 15cm guns from these conversions to construct six 20-knot monitor type ships, for use in coastal operations? I think that this is relevant to their strategic thinking since they were worried about an attempted French or Polish amphibious landing, and also since they would be useful in the Baltic or on the Norwegian coast. If they could build them, do you think they could have been used well in Norway, or indeed in the war as a whole?Bonus points if you can get at least two completed by Operation Weserübung.

For the reasons outlined above, I don't see them complete by 4/40, and after that the KM wasn't building much. Coastal defense ships go against the Kriegsmarine's doctrine because it was mainly planned to be a combination of a raiding fleet and a balanced battlefleet, when given a chance to build similar ships instead of the Deutschland's, the Kriegsmarine didn't despite the risks of an Allied landing being much higher given the force disparities. The guns would likely go to Hitler's coastal defenses. As for amphibious landings, the Polish Navy wasn't bad for a minor power in 1939, but the Kriegsmarine was quite easily the dominant fleet in the Baltic. A flanking Allied amphibious landing in the North Sea would run into minefields, airpower and submarines, and would likely fail or at least be a pyrrhic victory, and the Germans would detect it in time to stop it.

(3) How would German battleship and heavy cruiser construction be impacted by this, since Graf Zeppelin's and Peter Strasser's slipways are not being used?

The only battleships and heavy cruisers built during wartime were Bismarck(completed 8/40), Tirpitz(completed 2/41), Blucher(8/39) and Eugen(8/40). The Z-Plan ships were all cancelled soon after the war began. As a prewar conversion is impractical, meaning this would happen during the war, there would be plenty of slipways to work on the ships without delaying anything. The bigger problem for the Germans is that the conversions wouldn't be likely to be finished. Look at Seydlitz, she was fairly close to completion before she was ordered to be converted, and she wasn't finished, the KM just didn't have the resources available to build major surface combatants after 1941 unless it delayed a good number of U-Boats.

 

[Dorknought]

Use a decoy - suitably tarted up of course:

 

[Talwar]

The torpedo protection you want is from massive bulging. This will make the monitor slow. I don't think you will get a 20 knot monitor and get the benefits Drancinifel is suggesting a monitor would have. You can build 14-16 knot ships maybe. If you want this I'm sure you can do it.

As to the effect on German ship building of carrier conversions I would suggest that converting 3 Panzer ships and building six monitors would consume more resources than Peter Strasser and Graf Zeppelin. Even if slipways are conserved. I doubt anything major will be laiddown in those slipways as the naval resources are being consumed anyway.

In terms of size the Panzer ships were basically equivalent to HMS Hermes. I'd say performance will be similar enough in terms of airgroup size.

Generally agreed.

Seydlitz was guesstimated to have an airgroup of 20 once completed, which is probably a best case scenario for the smaller panzerschiffe.

 

[Kantai Kessen]

Thanks all!

The consensus seems to be that the monitor/carrier duo isn't going to work. Then, 2 further questions:

(1) Which ship would you slam into the Drøbak Sound instead of a valuable heavy cruiser? Perhaps a pre-dread? (Dunno how well-protected they were underwater.)

(2) Blücher survives as a result of (1), and the Kriegsmarine avoids a brain fart so they complete Seydlitz as a CA. How do subsequent raiding operations go? (Especially considering that Seydlitz would probably be ready for Bismarck's wild ride, considering Prinz Eugen's building times).

 

[Kantai Kessen]

The torpedo protection you want is from massive bulging. This will make the monitor slow. I don't think you will get a 20 knot monitor and get the benefits Drancinifel is suggesting a monitor would have. You can build 14-16 knot ships maybe. If you want this I'm sure you can do it.

As to the effect on German ship building of carrier conversions I would suggest that converting 3 Panzer ships and building six monitors would consume more resources than Peter Strasser and Graf Zeppelin. Even if slipways are conserved. I doubt anything major will be laiddown in those slipways as the naval resources are being consumed anyway.

In terms of size the Panzer ships were basically equivalent to HMS Hermes. I'd say performance will be similar enough in terms of airgroup size.

Would it? Each PS takes 2,000 tonnes, and a monitor is, say, 10,000 tonnes. That's 66,000 tonnes overall, and GZ is about half that.

 

[thaddeus]

Use a decoy - suitably tarted up of course:

they had a large number of WWI-era ships that could have be equipped as AA flak batteries (up to 10.5 cm guns) with some greater armor, and use them as escorts, planned for commercial shipping, but they could have screened Blucher?

as far as carriers my suggestion has always been start with ocean liner SS Columbus which had been eclipsed by newer liners.

edit. the above are revamps of secondary vessels and would not remove any of their scarce fleet from service.

 

[marathag]

Monitors won't give the French and British heartburn, like the Pocket Battleships did

 

[Gudestein]

Personally I feel any kind of aircraft carrier /capital ships for KM is an enormous waste of resources, they should focus on making licensed copies of https://en.wikipedia.org/wiki/Nakajima_B5N armed with decent aerial torpedoes and AP bombs
They had the range and weapons and if given fighter escort could dominate Baltic , North sea and Norwegian sea and could be perfect sea denial weapons.

Even 300 of these bombers probably would be cheaper than any of the big carriers / battleships and will give them a lot of flexibility as well even if the fear factor is much lower.
But just imagine the effect on British morale if Hood and Prince of Wales are sunk in early 1941 by such bombers ?

They already made the Fi-167 with even greater range, but yes, a reasonable investment could have had a good impact on their home turf

 

[tigercat]

How about reinvent the bomb vessel

Mount Morser Karl on a ship and use for shore bombardment

 

[Monk78]

They already made the Fi-167 with even greater range, but yes, a reasonable investment could have had a good impact on their home turf

did it have the same survivability though? they only need enough range to cover all the approaches to north sea

basically making no place around british isles safe for RN

 

[Gudestein]

did it have the same survivability though? they only need enough range to cover all the approaches to north sea

basically making no place around british isles safe for RN

None of these planes were safe from enemy Fighters and would need to stay clear or get help.
The Fi-167 did score the worlds last biplane kill against a P-51 though

 

[Kantai Kessen]

None of these planes were safe from enemy Fighters and would need to stay clear or get help.
The Fi-167 did score the worlds last biplane kill against a P-51 though

The Fi-167 is a pretty good plane, but who's going to cover it? The Bf-109 doesn't have the range and using twin-engined fighters is not a good idea, as the Battle of Britain showed. Bearing in mind these will probably be Luftwaffe planes as this is Goering we are talking about.

 

[HMS Warspite]

Basically the major issue would be politics, not the technical part, even though this was equally a difficult thing in Germany in the time period of consideration. Converting a ship is one thing, making it an efficient new sort of vessel is another issue, which both were not in favour of the German schemes of how to reconstruct ships into aircraft capable ships in the first place. Besides this, the time is a major issue as by the time the war actually was a mere fact, the shipbuilding of major warships, as well as conversion and rebuilding warships collapsed due to more urgent needs, especially for lighter forces and submarines, rather than cruiser sized warships.

The Oslo and Norway campaign was major gamble in the first place, where the young Kriegsmarine could have been lost completely with ease, at least as a fighting force of some value. No mater what sort of vessels were deployed the losses would have been heavy, even with monitor type vessels, which would have been at the expanse of the other units present. Tactically the outcome would have been the same though the whole of the Kriegsmarine's nature would have been altered to get other sorts of ships in the first place. Perhaps a different Luftwaffe would have been a more logical option, especially in who was in charge.

 

[thaddeus]

Basically the major issue would be politics, not the technical part, even though this was equally a difficult thing in Germany in the time period of consideration. Converting a ship is one thing, making it an efficient new sort of vessel is another issue, which both were not in favour of the German schemes of how to reconstruct ships into aircraft capable ships in the first place. Besides this, the time is a major issue as by the time the war actually was a mere fact, the shipbuilding of major warships, as well as conversion and rebuilding warships collapsed due to more urgent needs, especially for lighter forces and submarines, rather than cruiser sized warships.

The Oslo and Norway campaign was major gamble in the first place, where the young Kriegsmarine could have been lost completely with ease, at least as a fighting force of some value. No mater what sort of vessels were deployed the losses would have been heavy, even with monitor type vessels, which would have been at the expanse of the other units present. Tactically the outcome would have been the same though the whole of the Kriegsmarine's nature would have been altered to get other sorts of ships in the first place. Perhaps a different Luftwaffe would have been a more logical option, especially in who was in charge.

agree, the carrier "proposition" always seems doubtful to me, they had years of experience with seaplane handling, and could have built some type of vessel for that?

my suggestion instead of monitors was a "down and dirty" revamp of the WWI-era ships, but with lighter armament, would not think they would want to risk large naval guns (maybe some leftovers?)

 

[muskeg13]

The Germans were expecting to arrive in Oslo without any serious opposition, so heavy bombardment forces really were not needed. They counted on surprise, confusion and the weak pacifist government to take no action even if the invasion flotilla was discovered in time for defenses to mobilize. Arriving in Oslo harbor around first light with an overwhelming display of force, the Germans hoped the government would capitulate and offer up both the city and the entire country without a shot being fired. The decision to lead with heavy warships was probably more for visual intimidation than out of military necessity. The Germans knew about Oslofjord coastal defense forts, chief among these being Oscarsborg Fortress at the Drobak Narrows, with its three old 280mm cannon, since it was the home of the Norwegian Coastal Artillery school and had been a coast defense fort since 1644. However, none of the forts were operationally manned or were in any way prepared to fight. The Germans expected to be able to glide by the forts in the darkness and confusion without having to fight their way up the fjord. The Germans did suspect the Norwegians had mined the approaches to Oslo. In fact, there were extensive plans for minefields, and mines stockpiled, but not a single mine had been emplaced when the Germans arrived. The main "ace in the hole" was the secret hidden Oscarsborg torpedo battery. Unlike the torpedo battery defending Bergen with its above ground launching tubes, the Oscarsborg battery, with below water tubes, was not readily detected for what it was and was a complete surprise for the invaders. There were also at least 2 Norwegian submarines based in Oslofjord.

Going back to your question about what to lead the force with: I'd lead with a small group of minesweepers, followed by a destroyer or possibly a gunboat to provide overwatching rapid gunfire support if any coastal defense forces fire on the minesweepers and be in position to begin ASW operations if the subs make an appearance. I'd have the heaviest warships, particularly the one carrying the General Staff and Oslo occupation troops, follow in the rear of the formation. My make up of the Oslo invading force would largely be the same as was used historically with the addition of a destroyer if the gunboat had no ASW capability.

 

[McPherson]

Hello everyone!

So this is my first time ever posting on AH.com, and I wanted to start with a subject that has always interested me: the Kriegsmarine.

I know there have been a lot of threads on this website about this navy, and I know that it has not a chance in hell of winning the Second World War short of a POD before 1900. However, I have often considered ways in which the Kriegsmarine could have done significantly better, and so posed a worthier challenge to the Royal Navy.

Now I was watching a Drachinifel Drydock the other day in which he discusses the Battle of Drøbak Sound, and what ship would have done best to replace the Blücher in that battle. Apparently, a monitor-type ship would have done the job: lots of anti-torpedo protection, decent armour and heavy guns, perfect for forcing the coastal defences.

I was also reading Wikipedia on the Deutschland-class cruisers, and found that around 1943 there was a proposal to convert them into aircraft carriers: https://en.wikipedia.org/wiki/Deutschland-class_cruiser#Possible_conversion

So I began considering two things:

(1) Could the Kriegsmarine have converted the three Deutschland-class ships to carriers instead of attempting to build the Graf Zeppelin-class? If so, what do you think their projected airgroup would be (taking Goering into account), and how effective do you think they would have been? Bonus points if you can get them completed by 1940 and worked up by, say, March 1941.

(2) Could the Kriegsmarine have used the spare 28cm triple turrets and 15cm guns from these conversions to construct six 20-knot monitor type ships, for use in coastal operations? I think that this is relevant to their strategic thinking since they were worried about an attempted French or Polish amphibious landing, and also since they would be useful in the Baltic or on the Norwegian coast. If they could build them, do you think they could have been used well in Norway, or indeed in the war as a whole?Bonus points if you can get at least two completed by Operation Weserübung.

And, on a related note:

(3) How would German battleship and heavy cruiser construction be impacted by this, since Graf Zeppelin's and Peter Strasser's slipways are not being used?

Looking forward to your replies!

1. It took/takes 20 years to learn aircraft carrier warfare and three generations of shipbuilding to get the ship/plane interface "right". NOBODY in 1939 knew what they were doing. It will be 1941 when the Japanese finally get a clue and 1944 before the Americans catch up to them. The British will get there, sort of, by August 1942.

Graf Zeppelin I | Weapons and Warfare

That piece of junk, was designed with the elevators in the approximate correct position as illustrated, but we have no idea what the Germans intended as seen here:

What can be discerned...(data from wiki)

General characteristics
Class and type:	Graf Zeppelin-class aircraft carrier
Displacement:	33,550 long tons (34,088 t) (full load)
Length:	262.5 m (861 ft 3 in)
Beam:	36.2 m (118 ft 9 in)
Draft:	8.5 m (27 ft 11 in)
Installed power:	200,000 shaft horsepower (150,000 kW)
Propulsion:	4 geared turbines
Speed:	33.8 knots (62.6 km/h; 38.9 mph)
Range:	8,000 nmi (15,000 km; 9,200 mi) at 19 knots (35 km/h; 22 mph)
Complement:	1,720
Armament:	16 × 15 cm SK C/28 guns 12 × 10.5 cm SK C/33 guns 22 × 3.7 cm SK C/30 guns 28 × 2 cm FlaK guns
Armor:	Belt: 100 mm (3.9 in) Flight deck: 45 mm (1.8 in) Main deck: 60 mm (2.4 in)
Aircraft carried:	Proposed complement of 42[1] 1930 proposal: 30 fighters & 12 dive bombers[1] 1939 proposal: 12 fighters & 30 dive bombers[1]

Source: United States Navy

is that whatever the Germans thought they were doing with their first generation flattop was wrong, wrong, wrong as even the Curiosities carried more aircraft and AAA and were arguably better sea-keepers. Compared to a similar sized and armed Lexington? This is horrible.

So a buzzcut and flattoping a Hipper is contra-indicated.

Personally I feel any kind of aircraft carrier /capital ships for KM is an enormous waste of resources, they should focus on making licensed copies of https://en.wikipedia.org/wiki/Nakajima_B5N armed with decent aerial torpedoes and AP bombs
They had the range and weapons and if given fighter escort could dominate Baltic , North sea and Norwegian sea and could be perfect sea denial weapons.

The RAF will eat that platform alive. The Mosquito is a thing.

Even 300 of these bombers probably would be cheaper than any of the big carriers / battleships and will give them a lot of flexibility as well even if the fear factor is much lower.

The expense in dead aircrew and resources would be... about the money cost of a Graf Zeppelin.

But just imagine the effect on British morale if Hood and Prince of Wales are sunk in early 1941 by such bombers ?

Use submarines.

The Fi-167 is a pretty good plane, but who's going to cover it? The Bf-109 doesn't have the range and using twin-engined fighters is not a good idea, as the Battle of Britain showed. Bearing in mind these will probably be Luftwaffe planes as this is Goering we are talking about.

See remarks about Mosquito.