What if the Type 21 U-Boats became operational in 1940?

[JAG13]

The Type XXIII, for all it's benefits, is an overpriced way of delivering two torpedoes to a target. The Seehund, for example, was a much cheaper option.

I'm not following why it was one or the other? The Germans were building both.

That's okay, I'm still not clear on how 1944 technology gets transferred to 1940? Time machine? Or how single examples of the Typ XXI and XXIII completed in June 1944 and barely operational in 1945 could effect D-Day?

Some solutions could have been available with a bit more foresight in 1940, others were borne out of the war and thus unavailable.

[JAG13]

Seehund is worthless. It's like all midget subs. It lacks a fire control system for firing torpedoes meaning if the target's moving, even slowly, you need to be close to get a hit, or you need very good luck. The conning tower is so low that you can't really open it in any sort of sea other than near calm. The vessel is slow, cramped, and noxious in design.
It also lacks communications and navigation gear so it's really even just luck getting to an operational area to begin with. If you add in that visibility from the low conning tower limits one to about 5 to 8 miles of range, finding targets is even a matter of luck. No sonar is fitted, so you are all but blind submerged.

This is the later model with Plexiglas bubble on the conning tower to allow the commander to try and see around him when surfaced in a seaway and not sink the boat:

Midget Submarines of WW2, pp. 102.

[T. A. Gardner]

seeh.png

Midget Submarines of WW2, pp. 102.

This is like saying the Yugo is the most sophisticated motor car produced in Yugoslavia... It's meaningless.



There were 285 Seehund produced by the end of the war. Not all were actually used. Of those that went on patrol, they sank 8 merchant ships (17,301 tons for an average of 2162 tons each meaning they sank only small intercoastal freighters) while losing 35 Seehund or about 4 Seehund per success. That's not a very good ratio.

Most of the losses were clearly self-inflicted. Carbon monoxide in the boat was a major issue and probably caused many of the losses. Some might have simply gotten lost trying to navigate and the crew succumb to exposure and time at sea.

Basically, the Seehund was one of those self-defeating weapons that got produced out of desperation.

[JAG13]

Basically, the Seehund was one of those self-defeating weapons that got produced out of desperation.

Yep...

...and had it been made in 1940 far better care would have been invested in the design with far better results for both damage to the enemy and crew safety, that was the point, right? 1940 subs instead of a rushed 1944 ones? Technologically the Seehund was no breakthrough, it was a simple and cheap mass produced machine, had the KM identified the need pre-war they would have had a very potent weapon in their hands.

As the RN officer said, they were really lucky...

Or as someone put it:

[T. A. Gardner]

Yep...

...and had it been made in 1940 far better care would have been invested in the design with far better results for both damage to the enemy and crew safety, that was the point, right? 1940 subs instead of a rushed 1944 ones? Technologically the Seehund was no breakthrough, it was a simple and cheap mass produced machine, had the KM identified the need pre-war they would have had a very potent weapon in their hands.

As the RN officer said, they were really lucky...

Or as someone put it:

seeh2.jpg

That's speculation. A "better" Seehund is a Type VII U-boat. A 300 km range, two-man, two torpedo submersible is a waste of time and materials. You need a fire control system, a good sonar / hydrophone system, ability to operate for longer periods at sea to lower rotation rates and times, and basically you need a real submarine of the sort the Type VII or IX represented.

The Seehund as demonstrated by results, along with every other midget sub made by every other combatant, is nearly worthless as a weapon system.

[JAG13]

Yep...

...and had it been made in 1940 far better care would have been invested in the design with far better results for both damage to the enemy and crew safety, that was the point, right? 1940 subs instead of a rushed 1944 ones? Technologically the Seehund was no breakthrough, it was a simple and cheap mass produced machine, had the KM identified the need pre-war they would have had a very potent weapon in their hands.

As the RN officer said, they were really lucky...

Or as someone put it:

seeh2.jpg

That's speculation. A "better" Seehund is a Type VII U-boat. A 300 km range, two-man, two torpedo submersible is a waste of time and materials. You need a fire control system, a good sonar / hydrophone system, ability to operate for longer periods at sea to lower rotation rates and times, and basically you need a real submarine of the sort the Type VII or IX represented.

The Seehund as demonstrated by results, along with every other midget sub made by every other combatant, is nearly worthless as a weapon system.

No...

Seehund is a midget sub, Type VII is a full 700t medium sub that can operate for weeks in the high seas, the midget can do it for a few days operating basically as a smart mine but, if employed in large numbers could have shut down the UK east coast traffic.

Funny thing, a couple RN officers thought they were dangerous, including one who wrote about a dozen books on submarines... you know, the one speculating.

[T. A. Gardner]

What we do know with historical hindsight is that 238 were produced, 142 patrols were made. They sank just 8 merchant ships for small tonnage and damaged 3 more losing 35 boats doing that. That's almost a 30% loss rate. I'd say that's probably not sustainable economically.

They could do 7 knots surfaced, and 3 knots submerged. That's too slow to do much more than hoped some target runs them over.

They are just too limited in capacity to be worth building other than as a desperation measure.

[JAG13]

What we do know with historical hindsight is that 238 were produced, 142 patrols were made. They sank just 8 merchant ships for small tonnage and damaged 3 more losing 35 boats doing that. That's almost a 30% loss rate. I'd say that's probably not sustainable economically.

They could do 7 knots surfaced, and 3 knots submerged. That's too slow to do much more than hoped some target runs them over.

They are just too limited in capacity to be worth building other than as a desperation measure.

Nope, that is misleading info, 20 of those were lost to bad weather and not enemy action. Understandable since:

- They were a rushed design.
- Built by people unrelated to the shipbuilding industry.
- Crewed by volunteers with no U-boat experience.

And YET, in spite of all THAT, the few operational but very unreliable craft were able to attack and cause damage to an experienced and numerous enemy, sinking 18.000t and damaging a further 18.000t of shipping.

Make a similar sub available to the KM pre-war, with proper design, testing, production and training and set it against the poor early war RN ASW adn see how the scenario changes really fast...

People far more knowledgeable saw it as a real threat and were relieved to have been spared the experience.

[T. A. Gardner]

Nope, that is misleading info, 20 of those were lost to bad weather and not enemy action. Understandable since:

- They were a rushed design.
- Built by people unrelated to the shipbuilding industry.
- Crewed by volunteers with no U-boat experience.

And YET, in spite of all THAT, the few operational but very unreliable craft were able to attack and cause damage to an experienced and numerous enemy, sinking 18.000t and damaging a further 18.000t of shipping.

Make a similar sub available to the KM pre-war, with proper design, testing, production and training and set it against the poor early war RN ASW adn see how the scenario changes really fast...

People far more knowledgeable saw it as a real threat and were relieved to have been spared the experience.

Actually, most of the losses are attributable to either enemy action or poor navigation (eg., running aground).

https://weaponsandwarfare.com/2019/09/1 ... nd-part-i/

https://weaponsandwarfare.com/2019/09/1 ... d-part-ii/

https://weaponsandwarfare.com/2019/09/1 ... -part-iii/

Seehund also mostly operated at short ranges from their base at Ijmuiden Netherlands. They had frequent issues with machinery and components, but most of these seem routine rather than due to shoddy manufacturing. The limitations of having just 2 crew, few or no spares and tools making this a more serious problem than it otherwise might be.

On the whole, given better resources early in the war the Seehund would be a waste of time and effort compared to building a more efficient coastal submarine like the Type VII or some of its predecessors.

[JAG13]

Actually, most of the losses are attributable to either enemy action or poor navigation (eg., running aground).

https://weaponsandwarfare.com/2019/09/1 ... nd-part-i/

https://weaponsandwarfare.com/2019/09/1 ... d-part-ii/

https://weaponsandwarfare.com/2019/09/1 ... -part-iii/

Seehund also mostly operated at short ranges from their base at Ijmuiden Netherlands. They had frequent issues with machinery and components, but most of these seem routine rather than due to shoddy manufacturing. The limitations of having just 2 crew, few or no spares and tools making this a more serious problem than it otherwise might be.

On the whole, given better resources early in the war the Seehund would be a waste of time and effort compared to building a more efficient coastal submarine like the Type VII or some of its predecessors.

Ibid, pp. 107

Type VII wasnt a coastal sub, Type II was, why keep repeating something so blatantly wrong?

Again, problems were due to the rushed nature of the design, which is why you usually have prototypes to iron out defects and unreliability problems, they skipped all of that for obvious reasons and with the usual consequences, same with the crew, read your own sources.

If weather can sink a SUB, there is something wrong with the design, construction and/or training...

Larger subs could be picked up by sonar, these were pretty much invisible and the few that attacked demanded a HUGE allied response to fight them.

[T. A. Gardner]

You obviously didn't read the three part article I posted links to. In it is detailed the operations and losses of Seehund. For example (summarizing from the article):

5309: Damaged in a naval action, intentionally grounded and abandoned
5024: Seriously damaged by depth charging, intentionally grounded and abandoned
5377: Lost cause unknown
5339: Depth charged, sunk
5332: Ran aground off Calais, lost.
5327: Ran aground, abandoned.

Others are listed by crew without reference to the boat number. For instance, a boat manned by Paulsen and Huth (listed in more detail within the article) hit a mine and sank.
Another was sunk by HMS Ekins
Another was damaged by ramming by HMS Puffin. The Seehund sank but the crew was rescued.
Another was sunk off Dover by ML 102
Several were sunk by aircraft either by strafing or rocket fire.
Probably the most unusual was one boat where the crew went crazy. The commander killed the engineer in a suicide pact, then tried to take his own life but failed and was later court martialed for murder.

The Germans also figured out PDQ that the boat was visible on late model Allied radar when surfaced, and could be found with sonar as the numerous depth chargings of these boats attest to. Yes, they were hard to kill with depth charges, but that doesn't mean they were immune either.

Almost no mention is made of them being sunk by weather on the other hand.

They had serious limitations in design as I pointed out. The crew of just 2 required a high level of skill for both to successfully operate the boat. Only experienced U-boat crew were assigned after an initial disastrous start to operational use with less skilled crews was tried. The lack of spares and ability to fix problems while on patrol was an issue. The boats also had navigation problems when not in sight of land where the use of a chart, compass, and basic coastal navigation skills were sufficient for operation.

Running on the surface was just as dangerous for a Seehund as for any German sub. Allied aircraft did find and attack a number of Seehund, usually successfully when they did.

There was no way a large group of Seehund were going to coordinate an attack. They lacked radios and other forms of communication like signal lamps, semaphore, or the like. They couldn't even coordinate an operation off the Scheldt near their base, instead individual boats tried as best they could to attack targets of opportunity since they were too slow and had too limited a search range to go hunting targets down. Their usual MO was to sit off a port and wait for traffic to come in or out.

[glenn239]

Says a lot about how successful these Type XXIIIs will need to be...If the Allies are intentionally sinking 50 merchant vessels. Right there is 75 Type XXIIIs worth of sunken ships.

Does anyone know what the effect on a Mulberry would be if it were torpedoed?

[glenn239]

Some solutions could have been available with a bit more foresight in 1940, others were borne out of the war and thus unavailable.

I can't say what other posters were thinking of, but for myself it would be more the idea that D-Day was delayed into 1945 or 1946 rather than 500 Type XXI operational in 1940. For something earlier, in 1940, I've never pictured the Type XXI, but something more like a heavier and better streamlined Type VII with more batteries and a snorkel.

Does anyone know if any study was ever done on an iteration of the Type VII or IX to this end?

[JAG13]

Some solutions could have been available with a bit more foresight in 1940, others were borne out of the war and thus unavailable.

I can't say what other posters were thinking of, but for myself it would be more the idea that D-Day was delayed into 1945 or 1946 rather than 500 Type XXI operational in 1940. For something earlier, in 1940, I've never pictured the Type XXI, but something more like a heavier and better streamlined Type VII with more batteries and a snorkel.

Does anyone know if any study was ever done on an iteration of the Type VII or IX to this end?

Not that I am aware of, but simple common sense should have pushed the KM towards a true sub ala Type XXI pre-war, than the mere submersible Type VII, why?

Radar.

Dönitz was trying to keep the Uboote arm alive and made several night attack exercises to try and support his wolf-pack thesis but... he left radar off them since radar would have immediately killed the concept.

Had someone in the KM realized this (and a junior Lt. aboard a radar-equipped cruiser did), either the Uboote arm would have died or been forced into designing a true sub since surface attack would have been dead on arrival.

[JAG13]

You obviously didn't read the three part article I posted links to. In it is detailed the operations and losses of Seehund. For example (summarizing from the article):

5309: Damaged in a naval action, intentionally grounded and abandoned
5024: Seriously damaged by depth charging, intentionally grounded and abandoned
5377: Lost cause unknown
5339: Depth charged, sunk
5332: Ran aground off Calais, lost.
5327: Ran aground, abandoned.

Others are listed by crew without reference to the boat number. For instance, a boat manned by Paulsen and Huth (listed in more detail within the article) hit a mine and sank.
Another was sunk by HMS Ekins
Another was damaged by ramming by HMS Puffin. The Seehund sank but the crew was rescued.
Another was sunk off Dover by ML 102
Several were sunk by aircraft either by strafing or rocket fire.
Probably the most unusual was one boat where the crew went crazy. The commander killed the engineer in a suicide pact, then tried to take his own life but failed and was later court martialed for murder.

The Germans also figured out PDQ that the boat was visible on late model Allied radar when surfaced, and could be found with sonar as the numerous depth chargings of these boats attest to. Yes, they were hard to kill with depth charges, but that doesn't mean they were immune either.

Almost no mention is made of them being sunk by weather on the other hand.

They had serious limitations in design as I pointed out. The crew of just 2 required a high level of skill for both to successfully operate the boat. Only experienced U-boat crew were assigned after an initial disastrous start to operational use with less skilled crews was tried. The lack of spares and ability to fix problems while on patrol was an issue. The boats also had navigation problems when not in sight of land where the use of a chart, compass, and basic coastal navigation skills were sufficient for operation.

Running on the surface was just as dangerous for a Seehund as for any German sub. Allied aircraft did find and attack a number of Seehund, usually successfully when they did.

There was no way a large group of Seehund were going to coordinate an attack. They lacked radios and other forms of communication like signal lamps, semaphore, or the like. They couldn't even coordinate an operation off the Scheldt near their base, instead individual boats tried as best they could to attack targets of opportunity since they were too slow and had too limited a search range to go hunting targets down. Their usual MO was to sit off a port and wait for traffic to come in or out.

Read it, it made a PARTIAL detail of losses, so?

Depth charge attack doesnt mean a sonar contact, something quite hard against such a target in coastal waters...

You only need to swamp the defenses with a large number of attackers, no need to coordinate in detail.

At least you are no longer calling the Type VII a coastal submarine...