Where the German K-class Light Cruisers structurally weak?

[Paul Lakowski]

KM can't compete with RN in ship numbers and they didn't have to either. Most British economy depended on over seas trade so they had to invest heavily in destroyer type ships for escorting capital ships and convoys. Likewise any wartime ship building programme had to build huge numbers of convoy escorts.

With the use of German cruisers for raiding in these wars meant any convoy effort had to include cruisers to counter the surface raiders. In WW-I it was shown that the allies had to deploy 10 longer range warships [mostly cruisers] for every surface raider the Germans dispatched to the southern hemisphere.


With this back drop what can KM do to prep for WW-II?

In the 1920s the governments focused on local navies and ignored the major world navies. That worked until Groner pointed out that a European war would likely erupt out of any military action. But the long term picture was bleak with such a poor economy.

All KM naval leadership agreed that U-Boats were the path to follow....and Donitz argued for a fleet of 300 Atlantic U-Boats to defeat the UK. But such a fleet could not be built in the 1930s since Germany has such a small battery industry..

To support such a U-Boat fleet a dozed enlarged pocket battleships were proposed, but Grand Admiral Raeder objected since he always argued for a balanced 'Tirpitz fleet' . Hitler refused to fund a Tirpitz fleet in the 1930s ,but convinced the armed forces war would not start until the late 1940s....so they would still have time.

[thaddeus_c]

KM can't compete with RN in ship numbers and they didn't have to either. Most British economy depended on over seas trade so they had to invest heavily in destroyer type ships for escorting capital ships and convoys. Likewise any wartime ship building programme had to build huge numbers of convoy escorts.

(thanks Paul)

agree with your point, the KM CANNOT compete in numbers with RN. what I was trying to pose, probably unclear, was that if they could have converted the half dozen or so cruiser size ships used as AA batteries along with overhaul of half dozen light cruisers they operated.

if at all feasible that seems like cost effective strategy, similar to numbers you outlined for upgrade of Emden?

[Paul Lakowski]

http://www.german-navy.de/kriegsmarine/ ... index.html

They already had 7 floating batteries that were hulks & more could be converted but I'm not seeing the purpose of such a conversion?

Historically the KM had thousands of coastal batteries and dozens of ports to cover but those would be better served with the hundreds of 88 flak batteries that were deployed along the Atlantic Wall. Maybe mobile AAA batteries to help hide the " fleet in being " force along the Norwegian coast line?

[thaddeus_c]

They already had 7 floating batteries that were hulks & more could be converted but I'm not seeing the purpose of such a conversion?

Historically the KM had thousands of coastal batteries and dozens of ports to cover but those would be better served with the hundreds of 88 flak batteries that were deployed along the Atlantic Wall. Maybe mobile AAA batteries to help hide the " fleet in being " force along the Norwegian coast line?

to active ships with upgraded machinery

[Paul Lakowski]

The K/L cruisers suffered from structural weakness due to over loaded hull limited by ToV restrictions, while the Emden was limited by similar political reasons and being a WW-I design. In many ways the poor performance of the Zerstroers was an effort to stretch them to fill the void of insufficient/ ineffective cruisers.... so this is an important decision.

Had the resources invested in the Zerstroer programme been spit between completing basic Gross Torpedoboots , then the excess warship construction /propulsion/armaments could have been better invested to build more cruiser warships. Trouble is Germany had only limited large ship yards to build such cruisers and -given the choice- PBS could also be built in such yards and they would be more valuable to the war effort.

Raeder wasted considerable ship building on a line of 6 "Troßschiffe" . These supply ships were built to "warship standards" @ 176m & >20,000t. The yards and much of the resources could have been better used to build more light cruisers....but again what was needed was more PBS type warships not more cruisers.

Having said all that , fixing the K/L cruisers was doable and would require only a 'Karlsruhe mod' to restore the respectable range and fighting strength. That's > 1000 tons reconstruction & > 8 MRM investment for each cruiser...similar to building a "Torpedoboot 1935/37"....which would be worth it in my books. A similar investment in an Emden reconstruction would give it an better gun performance in heavy seas and a director for long range shooting.

With reference to merchant ships, "HSK" 'armed merchant cruisers' would have been a great investment. Prior to WW-II the KM had 15-20 diesel merchant ships large enough to have huge endurance & top speed up to 15-18knots. They also stockpiled >180 WW-I * 6" guns so they could easily arm 15-20 HSK within a year .

[Urmel]

But what would be the point of the light cruisers in the KM line-up?

[Paul Lakowski]

There was little point to most KM warship building except the U-boat program & basic coastal fleet. The rest of the construction should have been focused on building 21 fast pocket battle cruisers.

However the modified CL could escorts capital ships through the North Sea & the Norwegian Sea , as far as Iceland.

[JAG13]

There was little point to most KM warship building except the U-boat program & basic coastal fleet. The rest of the construction should have been focused on building 21 fast pocket battle cruisers.

However the modified CL could escorts capital ships through the North Sea & the Norwegian Sea , as far as Iceland.

Yeah, they needed P-class cruisers, not the over-sized Scharnhorsts that although handsome ships were freaks of nature.

And a bunch of Hilfzkreuzer... you know, the freak fleet the RN was so worried about.

[thaddeus_c]

There was little point to most KM warship building except the U-boat program & basic coastal fleet. The rest of the construction should have been focused on building 21 fast pocket battle cruisers.

However the modified CL could escorts capital ships through the North Sea & the Norwegian Sea , as far as Iceland.

PBs would provoke bad reaction on part of Great Britain? where they might not strike AGNA and have (somewhat) relaxed terms on their fleet building. and real problem they get confronted earlier ON LAND, possibly greater efforts made to keep Italy and/or USSR, even Japan out of German orbit.

my thinking the clandestine raiders cover the role of pocket battleships if they had been better equipped.

for the light cruisers? they could escort u-boats also? with heavy AA defense?

there was planned class of minelayers the size of light cruisers if not as well armed, so that might have been good course, as it was they pressed every variety of ship into minelaying duties.

[Urmel]

I still don't see the benefit of the CLs. What would they add in escort through the North Sea? E.g. would the Bismarck breakout have gone any different if the Emden had accompanied them up to Iceland? What about the then unescorted journey of the CL back into home waters? Why would they escort U-boats out? That makes little sense, risking a 5,000 ton CL each time a 750t submarine tries to break out through Biscay. What would the survival time in those waters be for the CLs? How many missions until Coastal Command gets them?

I can see a lot of reasons to have more DDs and DEs, and then the smaller coastal fleet. More mine layers, sure. But spending money on making the CLs more capable seems a total waste. Lipsticks and pigs come to mind. Although that maybe harsh to pigs.

[thaddeus_c]

I can see a lot of reasons to have more DDs and DEs, and then the smaller coastal fleet. More mine layers, sure. But spending money on making the CLs more capable seems a total waste.

my post was upgrading the CLs the KM inherited, both the half dozen built in the 1920's and the half dozen or so mothballed from WWI. standard size DDs might have been useful but they simply had none.

the other point was that the proposed minelayer class of ships was the size of light cruiser, in addition to 400 mines they could have been well armed, available for other duties.

[Paul Lakowski]

OK the DE aka the F Boot were the worse warships the KM built. No sooner had they finished they were found to be so unstable they were restricted to the Baltic sea. Meanwhile the propulsion unit was so unreliable they were decommissioned to be converted into "fleet tenders"; a role normally reserved for old warships and chartered merchant ships.

The Torpedoboot 1935/37 were reasonable sea boats but had same propulsion problems the F Boot had and were restricted to coastal waters. With only one rear mounted 4" gun they could not attack convoys and were of limited value as convoy escorts.

The Zerstroers were better- being 3 times the size of the F Boot & TB 1935/37 ; but in a effort to make up for lack of CL , they were overloaded with guns and adequate sea keeping for local sea -but were in trouble in heavy seas. Like the previous ships they too had stability problems and poor reliability. The stability problem was partly resolved by limiting fuel consumption to 1/2 tank , but that left this monster with only an endurance of 1500-1800nm @ 19 Kts Vs an required range of 4400nm. Follow on models had bigger hulls but most were still limited to 2000-2500nm and the reliability problems were never completely resolved.

The only small warships that were any good were the TB-1923/24 built in the 1920s and the wartime TB-1939 plus the lesser M-Boot 1935-43 -some times refered to as 'channel destroyers' even though they could only manage 18 knots and had few enough successes to justify such a name.


Generally speaking the bigger the warship they built the better it performed.

[Urmel]

When I say DE, I am thinking of the T-Boote, to avoid the usual confusion with the MTBs which often occurs. I think we all agree that the T-Boote were rather good designs? Sorry for the confusion.

[thaddeus_c]

they had several designs that would at first glance have had more potential than than historical build.

the diesel Bremse, considered for destroyer class http://german-navy.de/kriegsmarine/ship ... story.html would seem a logical escort instead of the F-class for Panzerschiffe?

as already posted they tried to compensate for numbers and straddle a couple of categories with Zerstorers. maybe the high pressure steam systems seemed a reasonable gamble at the time but I wonder why they abandoned they hybrid concept of light cruisers?

what was called 1938 zerstorer class, but technology would have been return to hybrid propulsion used on 1920's K-class http://german-navy.de/kriegsmarine/ship ... index.html

[Paul Lakowski]

Groener puts the range of the D1938Ac as 8000nm @ 17kts mostly due to the diesel which can only manage up to 20 knots. Earlier all turbine version [D1937J1 ] could manage only 4400nm@19kts on 1000ton fuel while the D1938Ac had only 800 tons so could only manage maybe 3600nm@19kts, with no diesel fuel. Perhaps the 8000@19kts is all diesel fuel. D1938Ac did have splinter protection of 10-15mm...likely to amount to a couple of hundred tons armor.

With the diesel /turbine of the K/L class it took 10-15minutes to switch from turbine to diesel or back, although both could run at the same time. So a hybrid may not help. Had the German navy focused on developing the new diesel V design- instead of high pressure turbine- a 76000hp diesel could be installed on a Zerstroer size warship. It thus should also fit into the larger Atlantic Destroyers & Spähkreuzers and still leave space for several turret /barbette/magazine columns .Looking at the designs a 150m 5000 ton warship would be needed. That may mean only the large yards could be used.

If so plans could be put place in the mid 1930s; the first wave of these Spähkreuzers could be completed by 1939, however with the rush to U-Boat mass production, that would have to halt by the early 40s. So no more than two Spähkreuzers from each yard. Historically there were about 9 yards used for large warship construction at this time,so maybe 18 Spähkreuzers built.