AHC: Best possible German performance in the Battle of the Atlantic

BlondieBC

Banned

Thanks for the chart. With hindsight, we know that German Navy victories have substantially change the war in roughly 18 months after France falls but before the USA falls. In this time period, the Germans get around 7 million tons of shipping. If things go great for the Germans, then a 50% increase is good place to begin discussion of possible impacts.

Out of curiosity, do you happen to easily know how many tons of shipping arrived in the UK in these 18 months?

Thanks
 
Thanks for the chart. With hindsight, we know that German Navy victories have substantially change the war in roughly 18 months after France falls but before the USA falls. In this time period, the Germans get around 7 million tons of shipping. If things go great for the Germans, then a 50% increase is good place to begin discussion of possible impacts.

Out of curiosity, do you happen to easily know how many tons of shipping arrived in the UK in these 18 months?

Thanks
http://www.ibiblio.org/hyperwar/USN/rep/ASW-51/ASW-8.html

This gives the annual shipping capacity and how each type of attack effected the total supply capability. Typical WALLIE , they can't seem to use calendar years.
 

Ian_W

Banned
Regarding the British reaction to a buildup of German marine naval patrol aircraft, I refer you to the bottom of page 4.

"Pargraph 10. Aircraft carriers. That the effect on naval warfare, especially in the narrow seas,
of the very recent developments in the range and power of aircraft referred
to in the memorandum by the Secretary of State for Air (CP. 27
(36)), should receive early consideration, but that in the meantime the
proposals for the construction of four new carriers (some of a smaller type) within the
period 1936-42 should provisionally be approved.
It would be advisable to limit the reference in the White Paper to. the numbers of aircraft carriers to the one small carried to be included in the 1936 programme."


http://filestore.nationalarchives.gov.uk/pdfs/small/cab-23-83-cc-10-36-10.pdf

Note this is not only OTL, this is OTL in February 1936 under the government of Stanley Baldwin.
 
That sounds about correct. Seems like 60 or so was enough to give Pearl Harbor reasonably good coverage. Or Midway during the battle. And we basically need two or three times this number. Probably one group out of Norway searching SW to North. One group out of NW France search NNW to West. And probably one group in reserve for training or other opportunities. An example might be one squadron is task with search patrols, second squadron tasked with keeping eyes over big convoys as wolf pack approaches. Or maybe second squadron has some attack ability. I figure of 60 planes in or near Brest France, about 20 head out most days of good weather.

So lets talk about the ramp up. The air frame production is not too bad. You start out with a planned strength of 60 patrol aircraft to patrol the North Sea and Baltic. Start planning about 1934, first delivery of air frames about 1936, full planned strength in late 1938. This should not seem to alarming to the UK, and requires a production peak rate of maybe 4 planes a month. This is the likely shorter range, model A. As this line winds down, you now are coming out with the better range second batch. Call it Model B. Probably planned for completion about 1941 as a part of Plan Z. The double orders once war starts. Production peak of 10 per month is all that will be needed. Minor note, these planes may carry some anti shipping weapons, but are more for search than kill.

I did the calculation/planning about a half decade or so ago, but that is the way I recall it.
Yes, this is the way for a more bloody start of the Battle of the Atlantic. But as it is pointed out, losses will soar when countemeasures are implemented.
And unless some thinking is done to prevent it, this problem will be countered before there are enough U-boats to act on the Intel.
 
Point 2 is why I never would invest in battleships , surface raiders are good enough and just needs to be some kind of AGS size raider with a Transom stern to boost sprint speed to 30 knots. But to have any sizable impact there needs to be many of them.

Just a random thought. The chart above is great but lacks the number of raiders/subs etc deployed. There were never that many warship raiders in service so they might not be doing too badly per unit. Unfortunately I don't have the resources to check.


but RN sources lament over the convoy escorts being to few and many convoys had trawlers as escorts.

RN officers are a whiny bunch. They always complain that they don't have enough and the enemy has it better... and then they win. I even take Churchill's quote about "The only thing that ever really frightened me during the war" with a serious grain of salt. Anything serious on the topic I have ever read makes it clear that even though things were frightfully tough at a tactical level the Allies would really have to stuff up to lose at a strategic level.
 
Garbled POV .

In 1939 -40 there were 375 convoys sailed North Atlantic and 11 were attacked , but RN sources lament over the convoy escorts being to few and many convoys had trawlers as escorts. When U-Boats often attacked 4 ships per convoy in the first couple of years , after that there were enough WALLIE ASW platforms to limit convoy attacks to 1 per U-Boat. This is why that was called the 'first happy time'.


BTW LRMP was demanded from the start and the choice of a converted airliner into patrol in 1939/40- was brilliant compromise...since LW didn't want to give the KM anything. Best KM could do was to order Condors in a ton tor ton exchange with the other sea planes they historically ordered.
Exactly. The effect of submarines, AMCs, mines, E-Boats and aircraft wasn't just in the number of ships sunk but the disruption to shipping caused by the slowing due to convoying, the requirement for escorts that could otherwise be used elsewhere (or have the construction/running resources and crews used elsewhere).
It's all about the opportunity costs.
 

BlondieBC

Banned
Yes, this is the way for a more bloody start of the Battle of the Atlantic. But as it is pointed out, losses will soar when countemeasures are implemented.
And unless some thinking is done to prevent it, this problem will be countered before there are enough U-boats to act on the Intel.

Presumably, the navy who plans the planes better plans the shipyard construction better. But yes, if skippy the ASB give the Germans 180 PBY plus two replacements per month, the impact is limited.
 
This is also from Volume I of Roskill

I added the U-boats sunk in the previous quarter column. I had to swap the U-boats completed in the quarters ending 1st October 1941 and 1st December 1942 because if I hadn't -2 U-boats would have been sunk in the quarter ending 1st January 1942.

German U-boat Strength, 1939-41.Mk 3.png
 
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Just a random thought. The chart above is great but lacks the number of raiders/subs etc deployed. There were never that many warship raiders in service so they might not be doing too badly per unit. Unfortunately I don't have the resources to check.
Will this help?

M = moored mines
G = ground mines

Enemy Surface Commerce Raiders, 1939-41 Mk 2.png
 
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Deleted member 1487

With a POD of 28th June 1919 could Germany have developed better naval radars than the ones it had 1939-41 IOTL?
Develop the cavity magnetron...
https://en.wikipedia.org/wiki/Hans_Hollmann
https://en.wikipedia.org/wiki/Cavity_magnetron#History
While radar was being developed during World War II, there arose an urgent need for a high-power microwave generator that worked at shorterwavelengths, around 10 cm (3 GHz), rather than the 50 to 150 cm (200 MHz) that was available from tube-based generators of the time. It was known that a multi-cavity resonant magnetron had been developed and patented in 1935 by Hans Hollmann in Berlin.[3] However, the German military considered the frequency drift of Hollman's device to be undesirable, and based their radar systems on the klystron instead. But klystrons could not at that time achieve the high power output that magnetrons eventually reached. This was one reason that German night fighter radars — which never strayed beyond the low-UHF band to start with for front-line aircraft — were not a match for their British counterparts.[23]:229

Or have the Japanese office that was touring Germany in 1940-41 to gain info about their radio/radar developments share his own development of the magnetron:
https://en.wikipedia.org/wiki/Yoji_Ito#Magnetron
 
the E-boats or S-boats were pressed into service as minelayers, there is no way to determine how much of that total they were responsible for?

always my first suggestion on this and similar threads would be for larger S-boats, the immediate post-war version Jaguar-class https://en.wikipedia.org/wiki/Jaguar-class_fast_attack_craft could deploy about two dozen mines vs. wartime model's six.


Its just that the 1/2 of all diesel engine construction went to U-Boat construction, while the rest went to thousands of MFP/AFP S-Boat/R-Boat tenders & tankers. The bulk of these boats had small diesel engines similar in size to Type II diesels, while the TYPE-VII U-Boats each had a pair of diesels smaller than the ones on the wartime S-Boot diesel.

Some 700 plus larger diesel engines were in the 2000-7000hp region. The 14,000-16,000t PBS each had 8 such engines, while the Bremse had 8 x of the lighter end engines. There were dozens of fleet fenders & seaplane tenders with two to four such lighter diesels, while three of the massive Dithmarschen each had 4 of the bigger diesels each.

By far the biggest consumer of these engines were the over 200 S-Boot, that ought to have been used to power the 200+ M-Boot.

Like WW-I , most of the coastal defence fleet should have been coal powered.
 
the E-boats or S-boats were pressed into service as minelayers, there is no way to determine how much of that total they were responsible for?

always my first suggestion on this and similar threads would be for larger S-boats, the immediate post-war version Jaguar-class https://en.wikipedia.org/wiki/Jaguar-class_fast_attack_craft could deploy about two dozen mines vs. wartime model's six.

Its just that the 1/2 of all diesel engine construction went to U-Boat construction, while the rest went to thousands of MFP/AFP S-Boat/R-Boat tenders & tankers. The bulk of these boats had small diesel engines similar in size to Type II diesels, while the TYPE-VII U-Boats each had a pair of diesels smaller than the ones on the wartime S-Boot diesel.

By far the biggest consumer of these engines were the over 200 S-Boot, that ought to have been used to power the 200+ M-Boot.

Like WW-I , most of the coastal defence fleet should have been coal powered.

my view an enhanced S-Boat would have been worthwhile and the U-boat program was not starved for diesel engines or overall numbers. rather the U-boats did not receive some evolutionary changes that might have been expected in series production of over 700 boats?

think the KM could have scratched the R-boats entirely in favor of more (and earlier) M-Boats, all coal powered. some of the latter day KFK projects were to use coal as well? NOT having to equip 300 odd R-boats with diesels should free up some capacity?

MFP/AFP, if better planned, could have probably used coal? once they moved beyond landing craft to transport role
 
https://www.alternatehistory.com/forum/threads/diesel-kriegsmarine.440313/

This showed how much difference a diesel fleet could have made for the KM. Its the surface fleet that needs the diesel engines and fuel, which in-turn can limit the need for the turbine /bunker-oil and provide more for the Italian fleet or allow more fuels of other types to be made INSTEAD. Jet fuel can be combinations of diesel & kerosene.


I compiled a list of small KM vessels and found every single diesel vessel could be substituted for a coal powered warship except the S-Boot . There was just enough VTE engine production and petrol engine production industry to fill similar roles. There was just enough maritime sheet metal & steel framed wooden vessels industry to also to build these ALT warships.

Now U-Boat production could alternative have been boosted -but the whole maritime industry lacked the electric motor & battery industries to enable this increase . Furthering of U-Boat effectiveness, could only come from earlier schnorkel combined with higher submerged U-Boat speed through the kind of streamlining Dr Walther had been advocating since 1934..... like eliminating flooding slits and installing stream lined sails with retractable schnorkel

While the turbine industry could provide the thrust, Germany had only a fraction of the alloyed steels needed for such high temp/pressure engines programmes and even less of the needed peroxide fuel. The alloying industry and aural fuel industry was sufficient to enable AIP to run diesels by 1943...

Four of these S-Boot diesel engines geared to a central screw- could provide 315 ton -10,000hp diesel to drive Zerstroers @ 19-21 knots top cruise speed for about 5000nm on 550 ton diesel oil . That should still leave 930 tons for two medium boilers/turbines /screw [each 20,000hp -260ton turbine/boilers] plus 410 tons of bunker oil. At top speed that could provide 500nm @ 27 knots or 18 hours @ 27 knots.
 
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perfectgeneral

Donor
Monthly Donor
120 Squadron RAF was setup in July 41 - but the close blokade of the uk had already been defeated by Coastal Commands other shorter ranged aircraft - it was only the 'Black Gap' a fairly large area in mid Atlantic where land based MPAs could not cover where Uboats could operate with impunity and so that is where the battle moved - however 120 Squadon with a handful of VLR Liberators could cover much of this area but this remained the only unit thus equipped operating in the Black Gap until early 43. US Units thus equipped where carrying out ASW patrols everywhere the Uboats were not!

It was only when increasing numbers of U-Boats bagan to surge this area and losses increased in late 42/early 43 that more VLR Liberators where prised away from bomber command in March 1943 and those USAAF squadrons where assigned at the same time, that any further VLR Liberators where made available.

A mere 50 additional VLR Liberators by May 43 helped turn the tide (along with an alignment of additional escorts, the RCN and USN escort groups coming of age, improved tech and intellegence methods).

So an earlier upsurge of Uboat numbers and effectiveness is going to elicit an earlier and more robust response from the allies because they cannot lose the BotA and throwing aircraft at the problem is a relatively easy and effective response for them to make at the expense of a small % drop in heavy bombers reaching the Strategic Airforces.

Also snorkles while allowing a submarine to remain submerged while using the deisels are not the be all and end all to that particular problem

Firstly in anything but calm weather the snorkle can become swamped and when this happened the engines sucked air from the submarine - a highly unpleasent ear popping experiance for the crew

Secondly while submariners are tough and all that - travelling at periscope depth at speed for any period would be exhausting for the crew as the surface wave effect would be moving the boat all over the place in anything but calm conditions.

Thirdly unless designed as a underwater sub its hull form would be less efficient than motoring on the surface and so use up its fuel and speed was limited to about 6 knots anyway because anything faster would deform and damge the snorkle.

Lastly - you cannot see anything - visabile horizon from a perisope is 2-3 miles - although depending on speed of the boat and conditions hydrophones could probably hear further than that?

A surfaced boat would be able to travel faster and see further than a submerged one using a snorkle.

The snorkle only makes sense as an 'improvement' in improving a submarines ability to traverse an area where enemy ASW airpower is strong - so until that happens why bother?
I realise that any answer to the challenge must be realistic and that your scepticism is probably founded on this, but I feel you are starting to argue against the thread rather than the realism of the posts. The challenge is for the "best possible", not the winning performance of the KM in the BotA. Having said that you could argue that the best possible is none. Although you would have to do that, rather than just shoot down other posters.

Germany had gone to war in September 1939 with 57 U-boats, but only 26 of them were long-distance ocean going boats. That OTL circumstance will not successfully blockade the British Isles or reduce merchant tonnage to the point that blockade is moot. The test here, I feel, is to get closer to that point. More U-boats both for training and ocean going blockade bring up that tonnage, if they can engage successfully. "Happy Time"s reflect periods of the U-boat war where the KM were engaging with some degree of success. So an increase in U-boats available, of the correct sort, at those times, might be thought of as increasing performance.

Had Germany gone to war with 200+ ocean going boats, with the manufacturing that implies, and the training fleet and air forces to support a campaign on that scale, it is far more likely that they would have been successful. Although in WW1 far more ships were hit without capitulation, so look for a huge early improvement before a tipping point is reached.

uboats-ships-hit.gif


Many of the counter-measures wouldn't have time to enact before a tipping point in the fighting capability of the British Isles would be reached. Anticipating some of these counter measures only puts back the deadline for reaching that tipping point. It seems to me that 1939-1941 with sustained losses of over 5,000 ships per year might do it. How many U-boats would that require, given counter-measures in place during the early war and proportional response to losses?

Any measures later than March 1941 start to fall foul of the counter-measures improving to a deadly degree.By 1945 the Allies are running out of targets.

uboats-losses.gif
 
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The problem with streamlining your uboat to make it faster is there are some unfortunate side effects.

First, the faster hull shape makes the boatmore difficult to handle on the surface (which is from where so many u-boat attacks were made)

But the second is that the biggest speed advantage is removing or streamlining all the openings used to sink the boat (its quite difficult to sink a boat quickly). They cause a surprising amount of resistance. The RN experimented with doing this, and found that indeed it raised underwater speed by some knots. But the problem was, this meant it could take up to 3 times as long to submerge.

There isnt much point in a faster boat if it gets sunk by the incoming aircraft first.
 

perfectgeneral

Donor
Monthly Donor
The problem with streamlining your uboat to make it faster is there are some unfortunate side effects.

First, the faster hull shape makes the boatmore difficult to handle on the surface (which is from where so many u-boat attacks were made)

But the second is that the biggest speed advantage is removing or streamlining all the openings used to sink the boat (its quite difficult to sink a boat quickly). They cause a surprising amount of resistance. The RN experimented with doing this, and found that indeed it raised underwater speed by some knots. But the problem was, this meant it could take up to 3 times as long to submerge.

There isnt much point in a faster boat if it gets sunk by the incoming aircraft first.
Either you fight on the surface or you don't it seems. It might be possible to pump air out of the ballast tanks through the roof of the conning tower. Powered pumping would be inefficient, but helpful for a crash dive. Gates for the inlet of sea water into ballast tanks could have covers, like torpedo tubes. Extensible outriggers or stabilizing fins would make a boat more stable on the surface. These are examples of how what the RN found was not definitive and that solutions could have been developed before the war. Jury rigged adaption of existing boats is not good development research.

Putting on my tin-foil hat for a moment, I'd like to propose a conspiracy theory. Admiral King deliberately sabotaged the escort of Atlantic shipping in order to hurt the UK. No convoys seems very fishy. /hat off

Fig8-2_sm.jpg


Gotta sink 'em all. 40 million gross tons will take a lot of sinking.
 
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With a POD of 28th June 1919 could Germany have developed better naval radars than the ones it had 1939-41 IOTL?
In 1929 Rudolf Kuhnhold of the German Navy Signals Research Division began work on an air 'echo sounder' and in 1933 was suggesting research on centimetric waves to detect aircraft and ships. He was using Phillips magnetrons and Yagi directional antenna with a 13cm wavelength. The experiments were promising so he went to Telefunken in 1934. He spoke to mid-level manager Wilhelm Runge who was working on decimeter wavelengths. Knowing no one at Telefunken was working on centimetric waves Runge told Kuhnhold that he had neither the funds nor staff to spare to collaborate with the Navy. Kuhnhold took this as a rejection by the whole company and so left the navy and went off to form GEMA, a company to continue radar work for the navy. This took some years to set up and produced the early Seetakt radars but an early opportunity to collaborate on powerful radar systems was missed by a misunderstanding.
 
Either you fight on the surface or you don't it seems. It might be possible to pump air out of the ballast tanks through the roof of the conning tower. Powered pumping would be inefficient, but helpful for a crash dive. Gates for the inlet of sea water into ballast tanks could have covers, like torpedo tubes. Extensible outriggers or stabilizing fins would make a boat more stable on the surface. These are examples of how what the RN found was not definitive and that solutions could have been developed before the war. Jury rigged adaption of existing boats is not good development research.

Er, no. Just no....

Just for a start, pumping masses or air up through an opening your trying to close, through the control room, isn't the best idea...
 
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