The KM changes their U-boat construction

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T. A. Gardner
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The KM changes their U-boat construction

#1

Post by T. A. Gardner » 06 Sep 2016, 02:08

This “what-if” proposes that the KM recognizes that in a war, their commerce raiding strategy for U-boats needs to take a much wider area of operations right from the start. Historically, the KM built boats with the intent of commerce raiding in waters near Britain, their most likely opponent. These boats were the Type II to VII. Construction of larger, Atlantic capable boats didn’t start until very close to the war’s beginning leaving the Germans with limited ability to hunt outside the North Atlantic, North Sea, and Channel.
Here, the Germans go for construction of three types of boats early:

A Type VII for use as they historically did.
A Type IX for use as they historically did.
A Type “USN/IJN” boat. This is a much larger boat than the other two. It has a cruising range on the order of 15,000 + miles. These boats include air conditioning and have room for provisions to stay at sea much longer times and far further from Germany.
To support them the KM prepositions a number of merchants in places where they can do so. Several of these merchants are in Japan when the war breaks out and proceed to remote Japanese islands, or elsewhere to resupply the U-boats. Surface raiders are trained to work with these boats in assisting them in finding targets and in keeping them resupplied.
To further this, the KM enthusiastically adopts electronic sensor technology rather than a serious command structure with rigid control. Boats get seetakt radar early on. They have RDF on board on a folding or retractable mast. Improvements to ESM and radar are pursued aggressively. Countermeasures to enemy radar are sought as well.
The result is, as the war widens the Germans are hunting merchant ships worldwide. The Allies have to escort everything and have ASW assets everywhere.

So, when the war starts, the British / Commonwealth now have a few U-boats off India, Singapore, Australia, Canada, and elsewhere sniping at shipping. The RN has nowhere near the ASW assets to deal with such a far flung guerre de course of merchant raiding. Losses in places like the Indian Ocean rise precipitously as there are few, if any, escorts to be had. The two or three merchants with fuel and supplies sitting in Italian East Africa keep the boats operating.
Areas like Singapore and French Indochina have their merchant shipping hit hard. The French and British having little or no ASW assets there to stop that. Even the Australians would be forced to begin building some ASW ships to protect their merchant traffic.
This in turn would have forced Britain to put more resources into ASW than they did. That would detract from either the buildup of the RAF or army in turn.
With a much wider plan of merchant raiding the U-boat force might well have made it too expensive for Britain to continue in the war. It certainly would have complicated things for them greatly.

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Re: The KM changes their U-boat construction

#2

Post by pugsville » 06 Sep 2016, 03:00

wended they start building these boats and how many?

what reaction do the British have to increased U boat construction?

what others things that the Germans built historically are they now not building?

The germans stumbled into war with Britain it was not their aim. so how do they complete this program had just the right time rather than aim for a date like 1944?


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Re: The KM changes their U-boat construction

#3

Post by T. A. Gardner » 06 Sep 2016, 04:28

pugsville wrote:wended they start building these boats and how many?
Assume the original 57 boats only the distribution now is 33 Type VII, 12 Type IX, and 12 Type USN/IJN.
what reaction do the British have to increased U boat construction?
Probably none. The numbers don't change and there really is no way for Britain to respond to Germany building what would appear to be the equivalent of a US Fleet boat or Japanese I class large submarine. The numbers initially don't need to be larger, as the big change is Germany is no longer looking at primarily a commerce war against Britain and France in European waters.
what others things that the Germans built historically are they now not building
This scenario doesn't require any significant changes to other programs.
The germans stumbled into war with Britain it was not their aim. so how do they complete this program had just the right time rather than aim for a date like 1944?
Not so for the KM. They recognized Britain, then France as their opponents well before WW 2. While they may still be looking to complete their build up later, here they start with a different assumption: They assume that their commerce war will go worldwide immediately rather than be concentrated in European waters. Thus, they build some U-boats specifically for operations in distant oceans and provide support for that.

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Re: The KM changes their U-boat construction

#4

Post by pugsville » 06 Sep 2016, 07:46

12 boats. 12. it's not a huge number.

Supplying U boast at very long ranges is going to hard. Torpedoes are very costly having merchants wandering around with large numbers of torpedoes sounds a bit much. The supply ships would be rapidly run down. there is no way of protecting them.

increasing the U boat tonnage would break the anglo-german naval agreement. The building of long range submarines would be noted.

There is also advances in a number of technologies. This requires highly specialised , highly trained manpower which must be pulled from other projects. What projects would suffer?

The KM was not expecting war with Britain in 1939. So the point remains why should they ready in 1939 lacking the benefit of hindsight.

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Re: The KM changes their U-boat construction

#5

Post by T. A. Gardner » 06 Sep 2016, 17:19

pugsville wrote:12 boats. 12. it's not a huge number.
The Germans started the war with 57 active boats. Here, they have more capable of action in the open Atlantic and elsewhere. One boat operating off Africa and the Red Sea could have made a huge dent in Commonwealth traffic going to or from the Middle East for example. One or two off Canada would have created a massive problem for trans-Atlantic shipping.
Supplying U boast at very long ranges is going to hard. Torpedoes are very costly having merchants wandering around with large numbers of torpedoes sounds a bit much. The supply ships would be rapidly run down. there is no way of protecting them.
Why? The Germans had a considerable number of merchant ships overseas when war broke out. There were at least three in Italian East Africa. They moved into what was then a "neutral" port out of British and French reach. Others were in ports in Mexico, Japan, etc. Two German liners in Japan ended up being turned into aircraft carriers (Hiyo, Junyo). So, these supply ships could still have been in foreign ports in neutral nations as "Merchant" ships. All they need do is slip out to resupply a sub then run into another neutral port.
For example, the Germans might send a tanker and a merchant for this purpose, with Japan's tact agreement, to the Bonin Islands. Excellent port, Japanese controlled, and no foreign prying eyes to report on anything.
Britain hardly has the resources to mount standing blockades of neutral ports around the world. The best they could manage would be having someone ashore keeping an eye on known Axis shipping in those ports... Where possible. For example, the British relied on US observers of Mexican ports where Axis merchant ships were trapped. When a few of these tried to make it home, the British were notified and these were intercepted usually within a few days well into the Caribbean or Atlantic.
In this scenario, such a merchant could put to sea, rearm and fuel a U-boat, and return to a neutral port before the British or French could have responded. Sure, the British (or French) could then put more resources into trying to stop that but that takes ships away from other priorities.
increasing the U boat tonnage would break the anglo-german naval agreement. The building of long range submarines would be noted.
This doesn't require a huge increase in tonnage. The Germans would still be within treaty limits as they hadn't come close to filling them. They could legally build to 35% of RN tonnage. The size of the subs isn't part of the agreement. A larger sub isn't going to draw that much attention either. A US Gato class sub displaces about 1,500 tons. A Type IX was 1,000. A 500 ton increase is hardly a major step forward when the Japanese, US, even the Italians have boats close to that tonnage.
There is also advances in a number of technologies. This requires highly specialised , highly trained manpower which must be pulled from other projects. What projects would suffer?
None. This change requires nothing different technologically than was available to the Germans pre-war. That a particular U-boat requires four diesels versus two, or other design changes doesn't impact it's technology. That remains the same. Seetakt is available in 1939 and the KM could have simply ordered more sets early on for installation in their ships. The same goes for RDF equipment. None of this has any significant impact on German production.
The KM was not expecting war with Britain in 1939. So the point remains why should they ready in 1939 lacking the benefit of hindsight.
The KM certainly was. The Wehrmacht and Luftwaffe might not have been, but the KM saw Britain, then France, as their primary opponents. The U-boats, merchant raiders, and even their cruisers and panzerschiffe, were all built with a commerce war against Britain in mind. The Dithmarschen supply ships were built specifically to support a raiding war at sea with Britain.
So, this isn't hindsight either. It is foresight on Germany's part. The KM here simply intends to expand the U-boat area of operations on entry to the war to worldwide rather than primarily focus on the North Sea, Channel, and Atlantic off Britain and France as they did historically. They historically did do some of that anyway with surface raiders and ships like the Graf Spee. Here, they are adding a submarine component.

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Re: The KM changes their U-boat construction

#6

Post by BDV » 06 Sep 2016, 22:39

It cannot be done. It should not have been attempted; never ever, in a 1000 years.
Nobody expects the Fallschirm! Our chief weapon is surprise; surprise and fear; fear and surprise. Our 2 weapons are fear and surprise; and ruthless efficiency. Our *3* weapons are fear, surprise, and ruthless efficiency; and almost fanatical devotion

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Re: The KM changes their U-boat construction

#7

Post by pugsville » 07 Sep 2016, 00:57

T. A. Gardner wrote:
Why? The Germans had a considerable number of merchant ships overseas when war broke out. There were at least three in Italian East Africa. They moved into what was then a "neutral" port out of British and French reach. Others were in ports in Mexico, Japan, etc. Two German liners in Japan ended up being turned into aircraft carriers (Hiyo, Junyo). So, these supply ships could still have been in foreign ports in neutral nations as "Merchant" ships. All they need do is slip out to resupply a sub then run into another neutral port.
For example, the Germans might send a tanker and a merchant for this purpose, with Japan's tact agreement, to the Bonin Islands. Excellent port, Japanese controlled, and no foreign prying eyes to report on anything.
Britain hardly has the resources to mount standing blockades of neutral ports around the world. The best they could manage would be having someone ashore keeping an eye on known Axis shipping in those ports... Where possible. For example, the British relied on US observers of Mexican ports where Axis merchant ships were trapped. When a few of these tried to make it home, the British were notified and these were intercepted usually within a few days well into the Caribbean or Atlantic.
In this scenario, such a merchant could put to sea, rearm and fuel a U-boat, and return to a neutral port before the British or French could have responded. Sure, the British (or French) could then put more resources into trying to stop that but that takes ships away from other priorities.
So German ships leaving Germany for some years before the war starts are going to be carried large numbers of torpedoes just in case war breaks out? Without torpedoes rearming is not possible, without rearming the resupply is useless. The U Boats will have to return to Germany. long round trip, much time not on Station, much reduced effect.

The germans were not expected world war in 1939. The did not expect Britain to fight. War with Britain was unexpected in 1939. Your repeated claims otherwise are completely and utterly wrong. While the Navy was focused on Britain it was not prepared for war when war with Britain unexpectedly broke out.

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Re: The KM changes their U-boat construction

#8

Post by thaddeus_c » 07 Sep 2016, 01:20

something not too different from Type X? http://german-navy.de/kriegsmarine/ship ... index.html

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Re: The KM changes their U-boat construction

#9

Post by Graniterail » 07 Sep 2016, 04:33

T. A. Gardner wrote:
pugsville wrote:wended they start building these boats and how many?
Assume the original 57 boats only the distribution now is 33 Type VII, 12 Type IX, and 12 Type USN/IJN.
what reaction do the British have to increased U boat construction?
Probably none. The numbers don't change and there really is no way for Britain to respond to Germany building what would appear to be the equivalent of a US Fleet boat or Japanese I class large submarine. The numbers initially don't need to be larger, as the big change is Germany is no longer looking at primarily a commerce war against Britain and France in European waters.
what others things that the Germans built historically are they now not building
This scenario doesn't require any significant changes to other programs.
The germans stumbled into war with Britain it was not their aim. so how do they complete this program had just the right time rather than aim for a date like 1944?
Not so for the KM. They recognized Britain, then France as their opponents well before WW 2. While they may still be looking to complete their build up later, here they start with a different assumption: They assume that their commerce war will go worldwide immediately rather than be concentrated in European waters. Thus, they build some U-boats specifically for operations in distant oceans and provide support for that.

Why would the British have 'No reaction'? If German re-armament is greater there's going to be a greater call for re-armament in Britain. The debate in Britain over rearmament was over who would pay for it through increased taxation (Labour or Capital), not so much if it could be done.

Britain also doesn't face the industrial limitations Germany does if it decides to spend the money, Canadian/American production can be sourced. It can point out to members of the British Commonwealth that historically spent trifling proportions of their GDP on rearmament like Australia that Germany is building boats for the express purpose of preying on shipping in their waters.

It might also draw earlier attention to sourcing the type of VLR aircraft for long range patrols that wound up helping to close the mid-Atlantic gap OTL. After all, if building 10,000tns more of destroyers just lets the Germans have an excuse to build 3,500tns of U-Boat under the Anglo-German naval treaties, why not build aircraft instead?
T. A. Gardner wrote:
None. This change requires nothing different technologically than was available to the Germans pre-war. That a particular U-boat requires four diesels versus two
Will they have the fuel for this? The best opportunity for U-Boat warfare opens opens up after the fall of France, the question is rather moot by the time America declares war & fuel was already considerably short in 1941.

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Re: The KM changes their U-boat construction

#10

Post by pugsville » 07 Sep 2016, 06:47

There its also relying Japanese co-operation is pretty questionable.

About half of all soviet lend lease just sailed across the pacific to Vladivostok straight past Japan protected by nothing there than the soviet flag. The Japanese did almost nothing for the Germans.

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Re: The KM changes their U-boat construction

#11

Post by antwony » 07 Sep 2016, 10:25

Graniterail wrote:
T. A. Gardner wrote:
pugsville wrote:wended they start building these boats and how many?
Assume the original 57 boats only the distribution now is 33 Type VII, 12 Type IX, and 12 Type USN/IJN.
what reaction do the British have to increased U boat construction?
Probably none. The numbers don't change and there really is no way for Britain to respond to Germany building what would appear to be the equivalent of a US Fleet boat or Japanese I class large submarine. The numbers initially don't need to be larger, as the big change is Germany is no longer looking at primarily a commerce war against Britain and France in European waters.

Why would the British have 'No reaction'? If German re-armament is greater there's going to be a greater call for re-armament in Britain. The debate in Britain over rearmament was over who would pay for it through increased taxation (Labour or Capital), not so much if it could be done.

Britain also doesn't face the industrial limitations Germany does if it decides to spend the money, Canadian/American production can be sourced. It can point out to members of the British Commonwealth that historically spent trifling proportions of their GDP on rearmament like Australia that Germany is building boats for the express purpose of preying on shipping in their waters.

It might also draw earlier attention to sourcing the type of VLR aircraft for long range patrols that wound up helping to close the mid-Atlantic gap OTL. After all, if building 10,000tns more of destroyers just lets the Germans have an excuse to build 3,500tns of U-Boat under the Anglo-German naval treaties, why not build aircraft instead?
Seems to be a perennial issue with this forum's "What if?" threads that only one side is allowed to do something different.

I'd also add that, to me, the British Commonwealth efforts in re-armament in the late 1930's were a bit misdirected. i.e. what money the services got could have been better used.

A more realistic "What if?" thread could have been what if the Flower and Hunt classes of escort vessels had been ordered in 1938, or even earlier.

From what I understand, the British Army had some serious, never fully resolved, issues about whether their budget should go to modernising the Territorial Army or upgrading Regular Army units.

RAF was still going to win the next war through strategic bombing and Bomber Command was getting the lions share of the funding and, of relevance to this thread, Coastal Command didn't have a seat at the big boys table.

And, as I understand, RN had decided to go with battleships over carriers, which was the wrong answer and more importantly wasn't even the right question in regards to what's going to be their role in the upcoming war.
T. A. Gardner wrote:Historically, the KM built boats with the intent of commerce raiding in waters near Britain, their most likely opponent. These boats were the Type II to VII. Construction of larger, Atlantic capable boats didn’t start until very close to the war’s beginning leaving the Germans with limited ability to hunt outside the North Atlantic, North Sea, and Channel.
Pretty sure it would be more accurate to say that pre WW2, Germany manufactured the biggest, most advanced submarines they were capable of. Neither the Japanese nor, debatably more surprisingly, the Italians were helping them out. The early U-boats were a collaborative project involving Nationalist Spain, who were pretty busy at the time and Finland, who were sort of neutral.
T. A. Gardner wrote:Even the Australians would be forced to begin building some ASW ships to protect their merchant traffic.
This in turn would have forced Britain to put more resources into ASW than they did. That would detract from either the buildup of the RAF or army in turn.
Australia only launched a handful of "fleet" destroyers during WW2. Well, not even a handful. I'm not going to Wiki it up but Australian shipyards made maybe 3/4 destroyers. They made over 50 corvettes, sloops and other vessels which were pretty much purely for ASW work.

To go along with your premise, a fleet of U-boats operating out of Truk from 1939, would have been a bit of game changer.

Wiki tells me the The Tripartite Pact was signed in Sept. 1940. As has been pointed, even after all the major nations were fully involved, Japan didn't render much assistance to Germany.

Are you aware of the Monsoon Group of U-Boats operating out Malaysia/ indonesia in 1944? The situation in 1944 was very different from early war, but of the original deployment to the Indian/ Pacific theatre only 4 of the U-Boats got through, 9 being sunk and 2 turning back. Those 4, plus later reinforcements, didn't account for much even when operating for ports that would have been unavailable pre 1942.

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Re: The KM changes their U-boat construction

#12

Post by thaddeus_c » 07 Sep 2016, 13:35

with hindsight (of WWI) they should have desired a long range blockade runner? a more developed version of Type X http://german-navy.de/kriegsmarine/ship ... index.html (that could be same platform for raider)

they could carry same number of mines as large destroyer, my understanding that was considered mundane task, so another wasted opportunity.

of course any development of u-boat force probably requires different leader of KM? instead of someone desiring to recreate High Seas Fleet?

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Re: The KM changes their U-boat construction

#13

Post by pugsville » 07 Sep 2016, 14:56

thaddeus_c wrote:with hindsight (of WWI) they should have desired a long range blockade runner? a more developed version of Type X http://german-navy.de/kriegsmarine/ship ... index.html (that could be same platform for raider)

they could carry same number of mines as large destroyer, my understanding that was considered mundane task, so another wasted opportunity.

of course any development of u-boat force probably requires different leader of KM? instead of someone desiring to recreate High Seas Fleet?
but the entire Nazi regime made the assumption that all of their wars would be short share wars. They were always going to win the war in the next 6 months. Why would you need a blockade runner in such a short war?

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Re: The KM changes their U-boat construction

#14

Post by BDV » 07 Sep 2016, 15:55

pugsville wrote:but the entire Nazi regime made the assumption that all of their wars would be short share wars. They were always going to win the war in the next 6 months.


Then one needs to make sure the opponent cannot afford (in the wide sense of the word) a war that lasts longer than 6 months. Things can be done on the UBoat front to help with this. But setting on a path of direct confrontation with GB-US partnership is obviously (to me) a non-starter.

Why would you need a blockade runner in such a short war?
As if blockade without shooting war was unheard of; especially between Great Britain and the Deutsches Reich ... :roll:
Nobody expects the Fallschirm! Our chief weapon is surprise; surprise and fear; fear and surprise. Our 2 weapons are fear and surprise; and ruthless efficiency. Our *3* weapons are fear, surprise, and ruthless efficiency; and almost fanatical devotion

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