Another U-boat thread.

[Naval Aviation Fan]

Got tired of trying to keep up with the other two U-boat threads, as they seem to be getting much in the way of replies, but little progress on the topic of more, faster U-boats getting built.

In this thread, I'd really just like to take a look at what was being built (or attempting to be built) and then look at what might have been, using the historical types, had the sectional construction method been a thing starting back in 1933, instead of being tried only in 1943.

This will not be a fast paced thread, as my health as always is messing with my head, but just a few points I'll be wanting to go over and at least touch upon.

Type XXI, 9 sectional construction, potential Type VII and type IX, as sectional construction, and construction times for these three notional classes.
The Number of slipways that Germany will need to have, in order to make a serious number of U-boats, starting no later than mid 1940, and how we get there after Sep 1st, 1939.
What kind of stockpiling of materials, and prefabricated sections stockpile can be had, before the war begins?

More once my head stops feeling like the room is spinning.

 

[Gudestein]

Of course it Can be gone, but it will take organization, practice and persistence. Requires a POD to work as an island of sanity and foresight in the Nazi rearmament.
Something like, we want to overwhelm the unprepared world of opponents when war suddenly breaks out. It’s entirely possible, but needs a decision and consistent backing from within and outside the Navy.

 

[Naval Aviation Fan]

Ok, so first I'd like to talk and ask thoughts others have on the WWI U-boat campaign, on what it accomplished, failed to accomplish, what it achieved, and what it cost.

Part of the experience of Germany in and leading up to WWI should include the Anglo-German naval arms race, it's origins and progress, and outcome. Mainly, I'm interested in what the Germans could learn by what the British did to counter the German buildup. Armed with that experience, that should inform any future conflict with Britain, namely, how to gain an advantage, short term, over what the British are expecting, and what the Germans can try to do, to achieve this.

 

[Pangur]

Very doable. Start of with something small, not even necessarily uboats n build a handful. Find the issues and gotchas, fix and continue until its working as you want. Meanwhile work on the uboats designs that are going to be built that way (by doing that if a modification to the design is required it's very early on and can be absorbed time wise)

 

[NoMommsen]

Very doable. Start of with something small, not even necessarily uboats n build a handful. Find the issues and gotchas, fix and continue until its working as you want. Meanwhile work on the uboats designs that are going to be built that way (by doing that if a modification to the design is required it's very early on and can be absorbed time wise)

... what about ... the Kriegsfischkutter (war fishing trawler)?
Programatically started alreadyd during the weimarian time to foster/booster german fishing in general.
The Nazis - almost the whole lot - were kinda 'fans' of Fordism and similar production practises but ... 'bowed' to the perceived/assumed expertise of then top brass who favored - for whatever rfeasons - hand-dengeled one-by-one-piece making of their assests (i.e. like tanks).

Let ITTL someone pick up the idea - of rationalisieng also of shipbuilding at least - and push the idea.
Then start for reasons of further improving ofc 'only civilian' fishing even further dsign and produktion of such fish trawlers in - to determine the most reasonable ways - section building as well as construction from prefab parts from all over the Reich.
Possibly already shortly after taking power as part of the vigorization of the german economy.


Therewith in ~ 1935 there shoould be quite a corpus of experience of organisation, using what standards and standard controls, etc. which would come in handy in planning further sub-models and their produktion. That way 'designed' - with prefab in mind to 'overcome' the limitations of the AGNA when time would come - the first might be 'finished in the numbers allowed though more or less to iron out ev. remaining flaws of the production method.
That way aside the 'allowed' numbers of sub in spring 1939 there might be some additional numbers 'stored' in sections or modules all over the Reich to be assembled in ... a rather short time.

Not ot forget:
The first six subs of class U II A were actually - to some degree - prefabricated to be launched only a couple of weeks after signing of the AGNA

 

[Pangur]

... what about ... the Kriegsfischkutter (war fishing trawler)?
Programatically started alreadyd during the weimarian time to foster/booster german fishing in general.
The Nazis - almost the whole lot - were kinda 'fans' of Fordism and similar production practises but ... 'bowed' to the perceived/assumed expertise of then top brass who favored - for whatever rfeasons - hand-dengeled one-by-one-piece making of their assests (i.e. like tanks).

Let ITTL someone pick up the idea - of rationalisieng also of shipbuilding at least - and push the idea.
Then start for reasons of further improving ofc 'only civilian' fishing even further dsign and produktion of such fish trawlers in - to determine the most reasonable ways - section building as well as construction from prefab parts from all over the Reich.
Possibly already shortly after taking power as part of the vigorization of the german economy.


Therewith in ~ 1935 there shoould be quite a corpus of experience of organisation, using what standards and standard controls, etc. which would come in handy in planning further sub-models and their produktion. That way 'designed' - with prefab in mind to 'overcome' the limitations of the AGNA when time would come - the first might be 'finished in the numbers allowed though more or less to iron out ev. remaining flaws of the production method.
That way aside the 'allowed' numbers of sub in spring 1939 there might be some additional numbers 'stored' in sections or modules all over the Reich to be assembled in ... a rather short time.

Not ot forget:
The first six subs of class U II A were actually - to some degree - prefabricated to be launched only a couple of weeks after signing of the AGNA

A trawler is a neat idea, the exercise could posed as a way to bring work to economically deprived areas and freeing up most ship yards to build merchant ships. No military involvement etc, nothing to see here and other such lies.

 

[Naval Aviation Fan]

Since we already have mention of the first WWII U-boats being constructed, I feel the need to post a bit about this portion of things here, so this will be posted out of chronological order, but needs doing anyway, so here goes.

I'm going to be drawing heavily forms this page of Wiki.

In 1935, Britain sought to control the increasingly apparent breaches of the Versailles Treaty and it concluded in 1935 the Anglo-German Naval Agreement. This ended officially the limitation of the Versailles Treaty and allowed Germany to build ships in a 100:35 tonnage ratio to the British fleet. For submarines the Germans obtained a parity in tonnage, but promised a 45 percent limit unless special circumstances arose.

I have no reservations about the text of the AGNA allowing the Germans to build 100% of RN submarine tonnage in pre-war Europe, but with the caveat that Germany needs a plan, already underway, that will allow Germany to far exceed this tonnage, if and when it is needed. Now let's look at what was initially done under this historical agreement.

In 1937 Britain announced it would expand its submarine fleet from 52,700 to 70,000 tons.

I don't find the figure for the submarine fleet in 1935, but the above tells me it is 52,700 and that 45% of that is 26,350 - 2635, so 23,715 tons, but...

This allowed 24,000 tons for U-boat building. Only one week after the signature of the agreement, the first of six Type II U-boats, U-1 was commissioned in the German Navy, which changed name from Reichsmarine ( State Navy ) to Kriegsmarine ( War Navy )

So we have now covered the very first WWII U-boats joining the German navy, further...

Within the year, the Germans commissioned a total of 36 U-boats for a total of 12,500 tons.

• Twenty-four small 250 tons Type II U-boats
• Ten medium 500 tons Type VII U-boats
• Two large 750 tons Type I U-boats, based on the design of the Spanish submarine.

Again, I'm fine with these numbers and types of initial submarines, it this next part that I differ from the historical;

Karl Dönitz was appointed as head of the submarine section of the kriegsmarine. He believed firmly that in spite of the Anglo-German Naval agreement and Hitler's policy of avoiding conflict with Britain, the next war would be with Britain. Based on these views he requested that the remaining 11,500 tons be used for building twenty-three medium submarines, which were in his opinion the ideal type for the commerce war against British convoys.

Raeder however did not share these beliefs and opinions and opted for a more balanced expansion of the submarine fleet:

• Eight small 250 tons improved type II U-boats
• Seven medium 500 tons U-boats. The type VII was designed with a single rudder and this had two drawbacks : as the rudder was not in the wash of the two propellors, the rudder response was not good. The stern torpedo tube had also to be mounted externally as the rudder obstructed the exit of an internal tube. As a consequence, this tube could not be reloaded. Hence the type VII was upgraded to type VIIB with dual rudders to improve manoeuvrability and to fit an internal stern tube with a reload.[26]
• Eight large 750 tons U-boats. The Type I was found to be unsatisfactory: not only had it the same single rudder manoeuvrability problems of the type VII but it had also a very poor diving time. The gravity center of the U-boat was too forward so on surface the type I had its propellors exposed when she was pitching. Whilst submerged there were problems with depth keeping and stability as air bubbles in fuel tanks wobbled back and forth.[26] Hence a new Type IX design for a large U-boat was made.

In other words, Raeder gave the lowest priority to what Donitz wanted. Both of these decisions are based upon Germany going into WWII with just 45% of British submarine strength, whereas in TTL, we are going for a Germany that has planned and prepared for the possibility of mass construction of U-boats. With that in mind, I'd venture a divergence from historical to have the Germans build 46 additional small U-boats, bringing their total small (training) U-boat numbers up to 70, but barring that, I would still advocate that 41 new small, and only 1 each of the medium & large U-boats be built under this program, so as to keep up with historical prototyping, while still expanding the training fleet at near maximum speed.

At some point, probably prior to 1936 (or even more likely, before that), we need to figure out when all bigger German subs are going to have designs that take advantage of sectional construction.

This is way ahead of time, and I apologise for that, but we needed to get this covered and start thinking in terms of how (and what) to build instead of historical.
Not even all of these 23 U-boats were ready in time for the start of the war historically, and that won't due.

Twenty-one of these twenty-three U-boats were commissioned before the start of World War II. In 1937 Britain announced it would expand its submarine fleet from 52,700 to 70,000 tons. Again, Raeder decided that the extra 7,785 tons would be divided between medium and large U-boats:

• Seven medium 500 tons type VIIB U-boats
• Five large 750 tons of the improved type IXB U-boats.

I personally would want at least 2 of each of these, but would prefer that they be constructed as the first sectional constructive of larger U-boats, but given that the Germans are already well versed in non-submarine sectional construction methods by this point in time in this notional ATL.

Further historical development/construction plans...

During 1938 Hitler changed his attitude towards Britain. Whilst he still hoped that Britain would not interfere in his foreign policy it became clear to him that he needed a Navy that could act as a deterrent. Hitler wanted to invoke the escape clause of the naval agreement and to have 70,000 tons of submarines. Between May 1938 and January 1939 Raeder ordered 52 more U-boats, to be completed by 1942:

• Twenty-one medium 500 tons type VIIB U-boats
• Eleven large 750 tons type IXB U-boats
• Three very large type XB minelaying U-Boats
• Four huge type XI U-cruisers

This portion needs to be known, but 1938 is far too late to commit to building a large U-boat force.

Included below is plan Z, for whatever value that may have (if any):

In 1939, the ambitious Plan Z was launched. It called for the construction of a German Navy capable of challenging the Royal Navy. The plan included 249 U-boats for a total of 200,000 tons. But when World War II broke out only months after the plan was announced, only a handful of the planned U-boats ended up being built.

When World War II started, Germany had 56 U-boats commissioned, of which 46 were operational and only 22 had enough range for Atlantic operations, the other 24 were limited to operations on the North Sea.

Plan Z

Total	230	82
Type	Projected	Completed
Battleships	10	4
Battlecruisers	3	0
Aircraft carriers	4	0
Panzerschiffe	15	3
Heavy cruisers	5	3
Light cruisers	13	6
Scout cruisers	22	0
Destroyers	68	30
Torpedo boats	90	36

Now obviously, in this thread we will not be seeing any such thing as "Plan Z" (from outer space), but maybe a submarine construction plan could take it's place?

Anyway, tired out again, so naptime for me.

 

[Naval Aviation Fan]

Ok, I needed to hit the sack earlier, but went and spent more time online, and I may as well make the effort of the only historical build program we can draw on for the time period, and that is the type XXI.

These things were fairly big as subs went at the time, being 1,621 some odd tons on the surface, and 1,819 tons submerged. I'm going to impose some rough numbers, in order to get a discussion going on sectional construction of U-boats.

the type XXI were built of 9 sections, and were supposed to be built in 6 months or less AFAIK. So, 9 sections of an overall 1,800 some odd ton submarine, and a 6 month construction time, we should see 1.5 sections joined a month, and another rough guess would have about a 200 ton section, so applying 3 sections over two months, or roughly 20 days each, what would the Type VII and Type IX likely come in at, section and construction/assembly time wise?

Some type VII came in at ~800 tons more or less, so I would guess 4 sections, and an 80 day construction time/assembly time if built with sectional construction.
Initial Type IX came in at ~1100+ tons, more or less, so I would guess 6 sections, and at 20 days a section, a 120 day construction time/assembly time, if built with sectional construction.

If we can achieve a 20 day/section construction/assembly rate, then:
600 ton, (3 sections) subs should be a 60 day project.
800 ton, (4 sections) subs should be an 80 day project.
1,000 ton (5 sections) subs should be a 100 day project.
1,200 ton (6 sections) subs should be a 120 day project.

While the OTL type XXI would be
1,800 ton, (9 section) subs should be a 180 day project.

So food for thought, and more later on about building the slipways/drydocks needed for mass production of subs in this time lines Germany.

 

[NoMommsen]

... Raeder ... and the monstrance but strategical NONSENSE of a 'balanced fleet' when your're the dwarf against a giant.
Asymetrical warfare should (have) be(en) looked after. ... as i.e. submarines focusing IMHO constitute

 

[Pangur]

... Raeder ... and the monstrance but strategical NONSENSE of a 'balanced fleet' when your're the dwarf against a giant.
Asymetrical warfare should (have) be(en) looked after. ... as i.e. submarines focusing IMHO constitute

Not sure if I should bring this up however just how good were the mines uboats laid? The asymmetrical warfare comment brought that to mind

 

[The Tai-Pan]

In this thread, I'd really just like to take a look at what was being built (or attempting to be built) and then look at what might have been, using the historical types, had the sectional construction method been a thing starting back in 1933, instead of being tried only in 1943.

But why? In 1933 and through till his death, Hitler's biggest concern was the USSR. U-Boats won't help him with that.

 

[Naval Aviation Fan]

But why? In 1933 and through till his death, Hitler's biggest concern was the USSR. U-Boats won't help him with that.

Because this timelines Hitler goes down a different path, perhaps because he takes advice from those who know naval warfare?

 

[The Tai-Pan]

Because this timelines Hitler goes down a different path, perhaps because he takes advice from those who know naval warfare?

If Hitler views the UK as the most serious threat to his world vision, doesn't this change everything about the Nazi state, ideology and war plans?

 

[Naval Aviation Fan]

If Hitler views the UK as the most serious threat to his world vision, doesn't this change everything about the Nazi state, ideology and war plans?

Perhaps, perhaps not. But if this Hitler just realizes he cannot attack the USSR with an unbroken UK at his back, and decides to finish the job on the UK first, then we get exactly the thread that we are looking for, right?

 

[Post]

Perhaps, perhaps not. But if this Hitler just realizes he cannot attack the USSR with an unbroken UK at his back, and decides to finish the job on the UK first, then we get exactly the thread that we are looking for, right?

That would require some remarkable foresight from him. Because OTL he didn't expect Britain to declare war, France to fall and when France did fall he expected Britain to give up.

 

[Naval Aviation Fan]

That would require some remarkable foresight from him. Because OTL he didn't expect Britain to declare war, France to fall and when France did fall he expected Britain to give up.

Perhaps, and perhaps not.
If we need Hitler to be the same bullheaded goy we know and hate, who makes all the same decisions as historically, and doesn't take advice from any more than historically, then yes, that would require quite the change, but then, that is what we are on about in this thread.

Now on the note of why Germany goes down the patch of more submarines, let us start off with the very first attempts at getting around the ToV, shall we?

 

[Naval Aviation Fan]

Should have made this post first, so apologies, and let's get to this then...

The first thing that Germany did to get around the Treaty of Versailles restrictions about 'no submarines' had nothing to do with either Hitler, nor the Nazi's. So any and all talk about Hitler should be sidelined until we explore what was done historically, and then we can see where we need to incorporate some good old "Alternate History" to get to our goal of a Germany that is going to go down the path of more U-boats.

Now historically, we need to account for the subterfuge used to initially circumvent the Treaty (which was not limited to just submarines, afterall), and the best example of this is going to be the dummy corporation IvS, which was setup to allow Germany to maintain it's submarine design skills. IvS was created on July 21, 1922 (and thus predates both Herr Hitler, and the Nazi's), to get German submarine designers the ability to work on and get submarines built to their designs.

Some groundwork for this post can be found here at this wiki page:

Background information
At the time of IvS, the Germans were bound by the Treaty of Versailles, signed in 1919. This treaty, among other terms, demanded that all German U-boats be destroyed or given to other nations. Thus the Reichsmarine was left without a submarine capability, and IvS was created to work around these restrictions. The work of the company was a major factor in the foundation of the Kriegsmarine of World War II.

So, as we can see, Germany historically began violating the "no subs" clause of the ToV a decade before Hitler came to power, so our PoD is not going to depend upon him, but rather decisions made before he came to be in charge.

History
NV Ingenieurskantoor voor Scheepsbouw (IvS) was founded on 21 July 1922 and initially was led from the Germaniawerft in Kiel, Germany. During this time the company gradually built up a team of skilled and experienced German and Dutch engineers that were led by technical director Hans Techel, the former director of U-boat design at Germaniawerft. In 1925, after resolving their legal technicalities with the Dutch government, IvS finally opened its office in The Hague and the eleven-man staff that were leading the firm from the office in Kiel moved to the Dutch office. This office at the corner of the Wagenstraat and Gedempte burgwal would be used by IvS till its dissolution in 1945.

At first IvS used the old UB III and UC III boats of the Imperial German Navy as starting point for their new submarine designs.

So, we have the basis for German submarine designs and development already in play by 1925. In a thread where Germany does more for U-boat construction, we need to improve of what history provides, but more on that a bit later...

I was going to list all the various shenanigans that IvS got up to historically, but won't for two reasons;
1) Anyone that wants to read up on that can just do so by going to the Wiki site I am quoting from for themselves, and
2) We in this thread are not bound by what was historically done, and so can unleash our creativity in augmenting to suit our needs.

For some context, another page over on Wiki has this:

In December 1931, the Reichswehr finalized a second rearmament plan that called for 480 million Reichsmarks to be spent over the following five years: this program sought to provide Germany the capability of creating and supplying a defensive force of 21 divisions supported by aircraft, artillery, and tanks. This coincided with a 1 billion Reichsmark programme that planned for additional industrial infrastructure that would be able to permanently maintain this force. As these programs did not require an expansion of the military, they were nominally legal. On 7 November 1932, the Reich Minister of Defense Kurt von Schleicher authorized the illegal Umbau Plan for a standing army of 21 divisions based on 147,000 professional soldiers and a large militia. Later in the year at the World Disarmament Conference, Germany withdrew to force France and Britain to accept German equality of status. London attempted to get Germany to return with the promise of all nations maintaining an equality in armaments and security. The British later proposed and agreed to an increase in the Reichswehr to 200,000 men, and for Germany to have an air force half the size of the French. It was also negotiated for the French Army to be reduced.

So, it wasn't just the Nazi's that were responsible for German rearmament (and not just restricted to submarines), nor did these kind of actions have to wait for Hitler to come to power.

feeling the need for another nap.

 

[gatordad699]

IMHO I just don’t see being able to use those techniques in the 30s. Submarines are very complicated machines. There are so many air, electrical, hydraulic, ventilation, and other systems. All of those have to be mounted in perfect alignment to the adjacent block. They all have to be connected perfectly as well. Then you have to weld the pressure hull perfectly with all that equipment in the way. Every single inch of every single weld has to be perfect. The heat from the weld cannot have changed the properties of the surrounding metal or you could have soft or brittle material. I would not want to ride a boat whose welds had not had radiography done on them. I was on the last submarine to be Shock tested (USS Jacksonville SSN 699 in 1988). It was nuts. I would not want to do that on a boat built in sections in the 30s.

 

[Post]

My recent posts about the efficiency of U-boats against the north Atlantic convoys in the other thread are also relevant.

Warsailors says "According to Arnold Hague's "The Allied Convoy System" the 377 HX convoys lost a total of 206 ships. Of these, 110 were lost in convoy, 60 were stragglers and 36 were losses out of convoy. (The HXF convoys were run to accommodate ships whose speed was sufficiently high to require special convoys, but not high enough to justify inclusion in the independent category. A total of 17 were run - this number is included in the 377 above)"

The Arnolds Hague convoy database gives 364 HX convoys, with 18,740 ships.

The HX convoys were the main convoys from North America to the UK. The overall losses in these convoys are very low.

There's a slight difference between the number of convoys, partly because Warsailors include HXF convoys, while these are on a separate page in the Hague database. Hague also has some convoys listed that are listed differently on the linked page at Warsailors (for instance HX119A and HX119B are combined to HX119 on the latter). The 17 HXF convoys had 199 ships according to Hague. 206 losses out of 18,939 (18,740+199) is about 1%.

Also from Warsailors: "According to Arnold Hague's "The Allied Convoy System" the 177 SC convoys lost a total of 211 ships. Of these, 145 were lost in convoy, 54 were stragglers and 12 were losses out of convoy. "
According to the Hague database these convoys had 7,598 ships. So a lossrate of about 3%. These were slower convoys, so they would be easier to catch for U-boats.

This however is aggregate data over the course of the war. It's likely most of the losses were in 1940-1942. But still even then the vast majority got through.
It's also important to note that these aren't all the losses: as I posted earlier, most ships that were sunk travelled out of convoys.
Also note that these aren't the only losses in convoys in the north Atlantic: there were also return convoys which got attacked. These are also mentioned on the same page on Warsailors.

Overall the losses in the convoys seem to be very low. Which to me means that the UK wasn't as much in peril as is usually suggested. There was a steady stream of supplies.

This site shows the losses per convoy on the route from North America to the UK. But where usually only the losses are shown, it also shows what got through, and it has a summary per year.

Nordamerika - Großbritannien

It's in German though. I combined the data from the HX and SC convoys, and then you get what I was looking for:


If you see a list of only convoys with losses, you think "argh, that's horrible"*, but if you see what gets through it paints a completely different picture. Because then you see the losses aren't nearly as bad as they seem.**

*Like here: https://www.uboat.net/ops/convoys/battles.htm?convoy=ONS-154***
** and again the disclaimer that ships sailing solo had worse chances.
*** It's also interesting to see that in 1942 and 1943 when convoys (that got attacked) often got attacked by dozens of U-boats, but still usually the losses were well below 1 ship per U-boat, and again the table at U-boat.net doesn't tell the whole story, because it doesn't tell how many weren't sunk. For instance one of the last convoybattles was ONS-5, in which 55 U-boats attacked a convoy of 42 ships and sunk 13 (and 6 U-boats were sunks, which the table also leaves out). I guess most would have thought the whole convoy should have been sunk with that many U-boats attacking.

TL;DR: they were not efficient at all against convoys.

 

[Post]

Perhaps, and perhaps not.
If we need Hitler to be the same bullheaded goy we know and hate, who makes all the same decisions as historically, and doesn't take advice from any more than historically, then yes, that would require quite the change, but then, that is what we are on about in this thread.

Now on the note of why Germany goes down the patch of more submarines, let us start off with the very first attempts at getting around the ToV, shall we?

It's not just about being bullheaded, it's also because of his goals. He wanted Lebensraum in the east. You don't get that by building submarines. His best way to get his goals was to not antagonise the UK. The more I look at the data, the more I get convinced that it's better for Germany not to bother with the navy at all. What they had in 1940 was sufficient for their wareffort (it got them Norway), they don't need more and it just cost them resources that were of better use elsewhere. Everything they commissioned afterwards basically just got sunk with little gain. Yes, I know it tied up British forces, but that helped the Japanese more than the Germans.