WI earlier Type XXI

The reich designed and built the Type XXI U-boat in response to the heavy losses of May 1943. "Black May" was a wake up call; a new sub was needed to function under conditions of allied air superiority--to the mid Atlantic--and better overall ASW assets.
But the Type XXI program turned out to be worse than futile. Consuming vast resources, it availed nothing since the war was over just as the XXIs were becoming operational.
But what if the setback of March 1941, in which the ubootwaffe lost its three best skippers, was taken as the wake up call to build a better boat? What if the Type XXI became operational in large numbers beginning in May 1943 (note in the OTL it also took about two years after the decision to build/mass produce for craft to be operational in significant numbers)? What might a Type XXI fleet have achieved from May '43 onward?
 
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Earlier construction might have fixed the quality-control problems and produced an effective weapon - maybe...
 
Earlier construction might have fixed the quality-control problems and produced an effective weapon - maybe...

If the XXIs worked like they were supposed to, what would've been the effect on allied shipping and the war overall? Had U-boats remained effective after 5/'43, so that the performance of '42 was maintained, I'd assume additional shipping losses would've slowed allied progress. D-Day might've been delayed, or if it had priority, something else.
 
... Had U-boats remained effective after 5/'43, so that the performance of '42 was maintained, ...

The effectiveness of 1942 depended more on operational conditions. Reading the Allied convoy code, The USN inability to provide escorts for convoys off the US east coast and Caribbean & Gulf, the ramp up and execution of Operation TORCH diverting escorts from the UK bound convoys in the last three months of 1942, the Brits being shut out of the encryption used by the submarine fleet, less than optimal use of aircraft for ASW.

Faster longer diving subs have a tactical advantage, which may translate to a operational advantage if there are enough of them. But, the ability of the Brits to read the daily radio traffic to and from the subs, the Germans losing the ability to read the convoy route/location details off their radio traffic, the results of a revamped escort construction program (reflecting decisions made a year or more earlier), improving the ASW aircraft, ect... weighed considerably.
 
The effectiveness of 1942 depended more on operational conditions. Reading the Allied convoy code, The USN inability to provide escorts for convoys off the US east coast and Caribbean & Gulf, the ramp up and execution of Operation TORCH diverting escorts from the UK bound convoys in the last three months of 1942, the Brits being shut out of the encryption used by the submarine fleet, less than optimal use of aircraft for ASW.

The bulk of the successes in '42 resulted from long range operations like Drumbeat and Eisbar. This was still possible in '43 as Luth's experience demonstrates, and newer boats could've improved operations against Atlantic convoys.

Faster longer diving subs have a tactical advantage, which may translate to a operational advantage if there are enough of them. But, the ability of the Brits to read the daily radio traffic to and from the subs, the Germans losing the ability to read the convoy route/location details off their radio traffic,

From what I've read (Blair Hitler's U-boat War) despite a failure of communications discipline in 5/'43, which cost the Germans their ability to read allied codes, they were still able to keep track of allied convoys.

the results of a revamped escort construction program (reflecting decisions made a year or more earlier), improving the ASW aircraft, ect... weighed considerably.

Type XXIs were supposed to stay submerged throughout their patrols (either moving on battery power or recharging via schnorkel) which would in theory have negated the value of ASW aircraft, and a lot of the value of escorts, which used radar as a means of location. Even sonar may have become less effective due to new coatings IIRC.
 
The reich designed and built the Type XXI U-boat in response to the heavy losses of May 1943. "Black May" was a wake up call; a new sub was needed to function under conditions of allied air superiority--to the mid Atlantic--and better overall ASW assets.
But the Type XXI program turned out to be worse than futile. Consuming vast resources, it availed nothing since the war was over just as the XXIs were becoming operational.
But what if the setback of March 1941, in which the ubootwaffe lost its three best skippers, was taken as the wake up call to build a better boat? What if the Type XXI became operational in large numbers beginning in May 1943 (note in the OTL it also took about two years after the decision to build/mass produce for craft to be operational in significant numbers)? What might a Type XXI fleet have achieved from May '43 onward?
As much i love to see this happening, i doubt i will change much.

What if: Battle of Atlantic and the Type XXI

type21.jpg
 
My conclusions appear similar--an earlier XXI (by itself) would've probably meant a longer war instead of a draw or victory.
 
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From what I've read (Blair Hitler's U-boat War) despite a failure of communications discipline in 5/'43, which cost the Germans their ability to read allied codes, they were still able to keep track of allied convoys.

Not really. The ability to intercept declined drastically. Huge and Costello examine this closely convoy by convoy. Ships departure information from spies in the US, residual air reconnaissance, and signals analysis were not enough to consistently place the intercept lines. On top of this the Brits started altering the convoy courses after breaking back into the submarine fleets communications, to dodge the suspected locations of the intercept lines.



Type XXIs were supposed to stay submerged throughout their patrols (either moving on battery power or recharging via schnorkel) which would in theory have negated the value of ASW aircraft, and a lot of the value of escorts, which used radar as a means of location. Even sonar may have become less effective due to new coatings IIRC.

The trade off is the area visible to the submarine from the periscope is drastically reduced over surface watch. Acoustic sensing supplemented visual search but was not a substitute with the same level of efficiency. As for new technology that give one or another advantage, that apples to the Allied side too, perhaps with better odds of actual application.
 
Yes the type 21 required complete rethinking of tactics and training which considerably delayed deployment late in the war. It of course didn't help that allied bombers could range over Europe to interdict construction , ports and training efforts.

Like most of these techs they were mostly post war weapons.

Prewar examinations anticipated the failure of Donitz U-Boat strategy, but lack of independent review [operations research etc] frustrated any evolution of the existing U-Boat designs and tactics.
 
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