Could the Type XXI U-boat have won the war?

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
alecsandros
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Re: Could the Type XXI U-boat have won the war?

Post by alecsandros »

RF wrote:
alecsandros wrote:

I think this is opinion rather than fact.
This has been discussed before,
And I am rather surprised you do not have the knowledge about it .. ?
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Re: Could the Type XXI U-boat have won the war?

Post by Dave Saxton »

LeopardTooth wrote: If Type XXIs had appeared in large numbers in, say, 1943, and convoys across the Atlantic started taking unacceptable losses, developing such technologies would have been the highest, emergency-level national priority for Allied scientists, and would presumably have been introduced before too long..
I think that its quite a stretch to assume that Allies could have and therefore would have developed effective counter measures in a matter of months. It still took them years to tackle the problem of the Type XXI even after they had examined and tested actual Type XXI's directly.

Another assumption is that these hastly developed counter measures would prove to be highly effective against operational German Type XXI's during war operations, which would themselves be further developed.

The problem for Allies in the context of convoy battles is still overcoming the U-boat's stealth. APS-20 radar is airborne early warning radar designed to pickup low flying aircraft. Even if the range that it can detect (non Stealth) schnorkels is improved (which didn't happen until the 1950s); the basic problem of radar pulses being picked up by a radar detector at greater range than the radar can register a return echo remains. The Type-XXI will have been warned by the enemy's own radar emissions, or by active radar detection of the AEW aircraft, and will have disappeared before the airborne radar can detect the schnorkel or the trimmed down sub.

Passive sonar technology will not be useful among thirty or forty noisey ships making 8-10 knots. Even in the 60s it required deploying this technology to known bottle necks that the Soviet subs had to transit such as the Bear Island gap or the Iceland Faroes gap. If I read the article correctly it required a quiet listening platform in the form of a quiet and relative non mobile submerged submarine to be effective. Once, that submarine submerges and goes into listening mode it has lost its own tactical mobility and the ability to communicate. The Allies will need an SSK that is both faster and quieter than the Type XXI. I don't see that happeneing for years-even in a war emergency. The development of Allied eqivilents to the Type XXI took years even using the Type XXI as template.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.
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Re: Could the Type XXI U-boat have won the war?

Post by Siegfried »

If the TypE XXI could have been advanced two years, by which we mean entering trials service in early 1943, being debugged by mid to late 1943 with a large wave of production line u-boats entering service at that time it is in my opinion that the Arctic routes to Murmansk as well as the US to UK Atlantic trade route could have been sealed of to all but the very fastest turbine merchant ships; those able to cruise at over 20 knots.

It is certainly conceivable as the Type XXI contained no radical propulsion advances: it merely optimized the submarine for greater underwater performance by increasing the space and weight of Lead Acid Batteries. The Type XXI itself was delayed by the Allied bombing campaign and had the idea of a submarine that designed to operate primarily underwater had of been advanced only 1 year earlier the Type XXI might have entered service 1.5 years earlier minus some of the radical advances in stealth and navionics.

The possibility of the Type XXI winning the war is certainly so if the full complement of other technologies intended for the Type XXI were ready.

One of the technologies entering service on type XXI was the UKW-D or rewirable reflector for the enigma machine. Amazingly UKW-D was in limited use in 1943. Had it been widely deployed Bletchley park would have gone blind for years. When a new rotor or reflector came into use it might take weeks to reconstruct it or break it. The reconstruction required a long crib or known message. These were obtained from broken code groups and used to track a message into an unbroken one. If all enigmas were equipped with UKW-D then the source of cribs would disappear and the whole Bletchley park system collapse as it would not be possible to reconstruct the daily UKW-D rewiring or even to get the short cribs necessary to find the rotors and key settings used when there was no new rotor or reflector or rewiring for that matter. On top of that the German navy was planning to add a 5th rotor enigma.

The security of the enigma codes itself is regarded as shortening the war two years. If secured by 1943 the Scharnhorst likely would have evaded sinking, U864 would not have been sunk etc. The Luftwaffe’s supply routes to North Africa would have continued as would have German and Italian shipping. There would be no massacre of German paratroopers in Sicily and D day would have gone far worse.

Of course the Type XXI with only vastly greater under water range and speed was much better than a standard u boat I suggest it might need some of the other technologies ready around late 44 or early 1945 and intended for the Type XXI. For instance how much of an advantage could a Type XXI have if it lacked a Schnorkel or suitable radar detector?

Here are a list of them, all were either in advanced trials or in full use.
1 Radar Detector “Athos” for waves down to as low as 2.5cm to warn the u-boat of allied aircraft.
2 Flamingo-II, Infrared warning device that sat on top of the Athos to provide warning in the case of allied aircraft using non radar methods.
Both the above devices were captured at the end of the war and investigated by CIOS committees.
3 Schonsteingfehger (Chimney Sweep) mast head stealth program. This consisted of a broadband jaumann absorber wrapped around the mast which absorbed 96% of microwaves at 10cm and 80% at 3cm. Jaumann absorbers consisted of a dielectric material of exponentially increasing conductivity (eg impregnated semiconducting paper). Another material called “Wesch” was made of a Ferrite laden PVC better suited for moulding around 3 dimensional curved positions of a mast head.
4 “Albrecht” the anechoic anti sonar coating. This was in use as early as 1940 but tended to delaminate and cause noise as it ‘flapped’. The 1944 version saw service in several Type VII u-boats overcame these issues. It consisted of a metallic mesh with at least two different hole sizes inside a rubber like matrix. The hole sizes determined a particularly strong absorption point through resonance.
5 The Type XXI had retractable Hohtenweil PPI radar (FuMO 63u). However a water proof version of the Berlin 9cm radar which could be used underwater was to be used. This radar which saw some use on Torpedo Boats (very small German destroyers), e-boats as well as Prinz Eugen used dielectric rod radiator arrays in a disk shaped antenna perfectly suited for encapsulation in a streamlined lenticular antenna for extension while the submarine was underwater.
6 FuMO-391 Lessing radar was a slim low visual profile ‘whip’ style antenna that radiated a 125kW Omni directional pulse to check up to a range of 30km for anti submarine aircraft before surfacing, snorting or occasionally during snorting. It was based on the Freya radar (wavelength 1.8m) and so optimal for aircraft detection. Such a system could ‘clear’ the air with only a few pulses difficult to direction find. Freya was capable of phase modulation and variable frequencies and so it is possible that the radar’s short pulses, of variable frequency would further be able to avoid the direction finding methods of the day which lacked computer memory and used the ‘maximum’ strength method of direction finding.
“Ballspiel” was a microwave radar for automatically directing guns. The FuG 246 night fighter radar was adapted to the FLAK 38 Vierling 2.0cm gun known in this form as the AEG FMG 45 RETTIN.

It should be noted that the Luftwaffe had already demonstrated automatic track locking in late 1943 with the FuG “Mannheim” radar (operating at 53cm with a 3m dish) so the essentially much of the technology had already been developed.
The Type XXI apart from having conventional passive sonar also had the “GHG” passive array low frequency sonar, able to locate a ship to within 1 degree at up to 30km.

Integrated with this was active ‘pencil beam’ sonar which could be used to aim the torpedos under water. The sonar could with only three pulse not only accurately range but direction find. Moreover its Doppler capability gave closure rates thereby providing a critical parameter as far as target tracking was concerned. Even if detected it was impossible with the technology of the day to direction find as the maximum strength methods could not work of the 3 short pulses.

The new G7e T11 passive homing torpedos had filters to bypass foxer noise maker but also a pre-programmed behaviour to do a half crescent around the seductive decoy that nonetheless still would impact a larger ship. There was also the wire guided T10 (Spinne) torpedo which could eventually expect to make its debut on submarines.

There was also “kurier” a burst mode signal transmission system. In one of its modes, the “3F” mode it used a single side band suppressed carrier transmission system. Not only did it suppress the carrier between the dashes and dots of a Morse message it transmitted them on different frequencies. Again this would be nearly impossible to direction find or to obtain a full message suitable for decoding.

Hence the Type XXI had a full range of devices and in every way was a submarine competitive with 1990s submarines. It was at this point, in the 90s, that the AIP (air independent propulsion) entered into service. At present submarines with Lithium Polymer Batteries are offering under water electric ranges of 1000 nautical miles with an additional 6000 cruising on their AIP systems.

I do not think allied advances could keep pace, the submarine based on Type XXI ideas remained a threat for decades.

Furthermore the Kriegsmarine regarded the Type XXI as an interim type on the way to full permanent submersibles using air independent propulsion. The Walther u-boats were likely to achieve the range and speed of a small destroyer (30 knots) only underwater using the hydrogen peroxide system. There were also systems based on compressed oxygen and diesels under development. The stealth materials were advancing, there was already work at combining Jaumann and Ferrite based absorbers.

Winning the war for the Germans requires, in my view the Type XXI, security of the German cypher system, the non 'abandonment' of the German microwave program in late 1942 and most importantly some fateful decisions on Atomic reactor development and atomic bomb development since even if the Germans were 'winning' in 1945 it all would change around around the time Hiroshima and Nagasaki played itself out.
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Re: Could the Type XXI U-boat have won the war?

Post by Dave Saxton »

Excellent information Siegfried. It really puts the spot light upon the importance of the strategic bombing campaign, particularly the bombing of military and industrial targets. May I make a few comments on your points,
5 The Type XXI had retractable Hohtenweil PPI radar (FuMO 63u). However a water proof version of the Berlin 9cm radar which could be used underwater was to be used.


The plans were to use Hohentwiel until the Berlin -U systems could prove superior performance. Of chief concern was greater reliable detection range for the 9cm system vs the 55cm system. All things being equal a longer wave length will have superior detection range than a shorter wave length system. Moreover, the current Berlin systems using exact copies of the Allied strapped magnetrons had an illumination energy of 8-11kw, while Hohentwiel had an illumination energy of 100kw. Telefunken was working on 100 kw magnetrons but the Navy wanted to see it proven first. Additionaly FuMO30 in tests with a 150 kw transmitter could detect destroyers to 20km or twice the range of any existing submarine radar system anywhere in the world.
This radar which saw some use on Torpedo Boats (very small German destroyers), e-boats as well as Prinz Eugen used dielectric rod radiator arrays in a disk shaped antenna perfectly suited for encapsulation in a streamlined lenticular antenna for extension while the submarine was underwater
.

Berlin operating on a wavelength of 5.8cm saw more widespread use and was operational much sooner than is generally known. It was operational on major warships as early as spring 1944, or before equalivalent late war Allied surface search sets.
the non 'abandonment' of the German microwave program in late 1942


This only applied to Telefunken as directed by Telefunken's appointed director Karl Rottgardt. Telefunken's microwave program was vital to the Navy's project Euklid, however. Therefore, Kuhnholt and the NVK took over direction of Euklid and microwave R&D continued at least for the Navy. Nonetheless, the Rotterdam Geraete was recovered in Feb 1943 and Berlin was operational only about a year later. Most of the elements (such as PPI) required for Berlin were already well along which helped to get Berlin operational surprizingly quickly. Rotterdam did slow development of Euklid throughout 1943 because they waited to see if the centimetric technology could be used. When it was finally tested at 9cm the performance was ironically inferior to the performance at 27cm.
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Re: Could the Type XXI U-boat have won the war?

Post by RF »

I might add to the discussion that if the Type XXI was operational in 1943 then its impact would not be confined to the Atlantic or Arctic convoy battles, though those would be the critical battle areas.

It is likely that a number of these subs would be sent further afield, into the Indian Ocean and the Pacific. Imagine the impact of a few Type XXI's if they got among the US carrier forces at Leyte Gulf?
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Re: Could the Type XXI U-boat have won the war?

Post by Siegfried »

Thanks Dave,

A.O.Bauer a Historian of German Electronics (including WW2) has written a paper in which he argues that the Germans produced between 500 and 1000 microwave radars. He notes that bombing severely damaged the Hareous Vacuum Schmelze works cutting of the supply of permanent magnets materials and high magnetic materials. The Germans had to resort to the unwelcome complication of electromagnets with precision power supplies. Furthermore the Sanitas company which made magnetrons (and had fairly powerful multicavity units of its own design on the Bench in 1940) was also bombed which cut of much of the magnetron supply for a few months.

Although the Germans sensibly copied the British 9cm magentron (apart from getter materials) they had to use bigger magnetrons with more cavities since their magnetis were weaker due to materials issues.

The advantage of the Berlin microwave radar (can't remember its FuMO nos, perhaps FuMO 83U or something) was that it could be used in PPI mode while the submarine was submerged. USN Submarines used their PPI radars to attack at night or in rain squalls in the Pacific. Since the Kriegsmarine was planning the use sonar to aim its torpedoes perhaps this ability was not so important.

The 5.8cm Frequency seems odd, neither 3cm or 9cm but almost exactly in between. Nevertheless I have come across it in the form of an active radar terminal homing seeker for the Wasserfall and Schmetterling missile known as MAX-A. (developed by Blaupunkt). Nevertheless it makes some sense in the context of the German microwave program which targeted around 25cm and also 5cm.

The decision at Telefunken (against General Martini's wishes) to abandon 'microwave' work needs to be considered in the context of Lorenz giving up hope of producing a FLAK radar in 1942 due to commercial considerations. Fritz Trenkle notes that in 1942 that Lorenz was 80% complete with development of a 30cm FLAK gun laying radar but left the field when it looked like orders were not going to come through. While not exactly microwaves these 25cm to 30cm radars would have given the Kriegsmarine the radars it needed to fit on smaller torpedo boats, e-boats, u-boats. It would have given the Luftwaffe FLAK forces radars with narrower beams that were harder to jam. Moreover it would have provided a base of engineers and technicians familiar with microwave issues. As it was Peter Schwann (an German engineer who immigrated into the US) in an IEEE interview claimed the engineers and technicians liberated from Telefunken ended up in the Army and that it took months to recall them.

As early as 1941 Telefunken was running a 21.5cm radar at 5kW on Wurzburg dishes using disk triodes. It was called "Eisbaer". These triodes were comfortably producing down to 15cm and were engineered with new cavities when the British CV64 Magnetron was captured and found to be able to produce 25kW at 9cm (this is the LD 6 disk triode).

Apart from Lorenz, which used anode modulation there was a sluggish move to anode modulation at GEMA and Telefunken which left the German radars precise but as little weak even though they found other ways of extending range and evading Jamming. The decision to concentrate on conventional radars seemed to have been based around the idea of making existing radars more powerfull as well as having better signal processing. For instance Wurzburg-Riesse was to become Wurzburg-Riesse Gigant with 160kW power instead of 8kW.
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Re: Could the Type XXI U-boat have won the war?

Post by Siegfried »

RF wrote:I might add to the discussion that if the Type XXI was operational in 1943 then its impact would not be confined to the Atlantic or Arctic convoy battles, though those would be the critical battle areas.

It is likely that a number of these subs would be sent further afield, into the Indian Ocean and the Pacific. Imagine the impact of a few Type XXI's if they got among the US carrier forces at Leyte Gulf?
The Kriegsmarine did opperate its "Monsun Gruppe" in Malaysia. (Penang or Georgetown).

The allies did have technologies in development to blunt the advances the type xxi would have. In development was active array sonar that could track sub as fast as the type xxi, MAD, exhaust sniffers, active sonar buoys etc but I suspect these were still not quite enough to win back the gains of the type xxi.
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Re: Could the Type XXI U-boat have won the war?

Post by RF »

Even with such tracking equipment the fact that the Type XXI is a much faster moving target would I think make it harder to hit with depth charges or even torpedoes.

Am I right in thinking that they could also run deeper than the normal U-boats?
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Re: Could the Type XXI U-boat have won the war?

Post by alecsandros »

RF wrote: Am I right in thinking that they could also run deeper than the normal U-boats?
Theoretical crush depth 290meters...
In reality, it could probably go deeper...
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Re: Could the Type XXI U-boat have won the war?

Post by Byron Angel »

A stupendous amount of cutting edge technology was clearly involved with the Type XXI. Had Germany been afforded time to get all the systems working as advertised, the XXI would have been a great threat to seaborne comerce. Possible short term Allied tactical and technical responses are interesting to ponder.

Attack upon industrial and production chokepoints (perhaps hydrogen peroxide facilities, torpedo factories, building/assembly yards) vulnerable to aerial bombing.

Massive mining and aerial interdiction of approaches to operational bases.

Increased deployment of escort carriers and land-based air patrols in support of convoys.

Acceleration in development of homing torpedo technology.


B
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Re: Could the Type XXI U-boat have won the war?

Post by Dave Saxton »

alecsandros wrote:
RF wrote: Am I right in thinking that they could also run deeper than the normal U-boats?
Theoretical crush depth 290meters...
In reality, it could probably go deeper...
The Germans were working in Wh materials into the pressure hull in place of regular ST-52 construction steel. Wh has ~ twice the strength.
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Re: Could the Type XXI U-boat have won the war?

Post by Dave Saxton »

Siegfried wrote:The 5.8cm Frequency seems odd, neither 3cm or 9cm but almost exactly in between. ...
The KM's use of this wave length may have been so that it would not interfere with listening for Allied 9cm and 3cm emissions using radar detectors such as Tunis, Naxoz ZM, and Athos. Another possible factor is that 6cm magnetrons produced more power (15kw) than the 9cm magnetrons (10kw).
Apart from Lorenz, which used anode modulation there was a sluggish move to anode modulation at GEMA and Telefunken which left the German radars precise but as little weak even though they found other ways of extending range and evading Jamming.


GEMA was slow to put into operation anode modulation because their existing coherent signal processing techniques did not work well with it, although high power transmitter modules had been developed by late 1943. For example, Seetakt (1943) with grid modulation had a range accuracy of 25 meters, and artillery specific sets had a resolution for range as fine as 10 meters! With the anode modulated 125kw transmitter modules the fine ranging system could still work but the precision suffered some. It would not work at all with the 400kw transmitter module. With a new pulse keyed fine ranging system developed during 1944 by Dr Kober, called Paris-II, the range accuracy, and resolution, while using the anode and spark modulated high powered transmitters for 80cm was 100 meters. This was really good precision, but inferior to existing grid modulated sets, nonetheless.

Coherent signal processing has an automatic resistance to some forms of jamming, it is now known. This probably explains the surpizing revealation after the war that Allied jamming during bombing raids was mostly ineffective against Freya (sister radar to Seetakt)-The Luftwaffe just pretended it was effective so that the Allies would not find better methods. Against chaff, more power only increases the amplitude of the returns from the foil strips. This is why Wuerzburg needed MTI signal proccessing techniques to go to high power.
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Re: Could the Type XXI U-boat have won the war?

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Byron Angel wrote:A stupendous amount of cutting edge technology was clearly involved with the Type XXI. Had Germany been afforded time to get all the systems working as advertised, the XXI would have been a great threat to seaborne comerce......
B
HMMM...''had Germany been afforded time'' - there is another aspect to this. Namely Hitler and the way Germany was run from 1933 onwards. Nazi rule was based on divide and rule, physical strength rather than brain power.... not really conducive to scientific and technological development, or to raising labour productivity, or to achieving an optimum allocation of resources....

Had Germanys' economy from 1938 onwards been as well organised and directed as in Britai or the USA, then by 1943 Germany would have had Type XXI submarines, V2 rockets and be well on the way with the A10 rocket and the development of an atomic bomb. Submarine launched rockets would be in the course of seious development. And all before Allied bombing could have built up - and that threat would have been met with the Luftwaffes' new generation of jet fighters.
All for want of a savvy Fuhrer with brain cells, rather than an ignorant thug living off the abilities of others... who because of their abilities weren't allowed to make the best use of them.
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Re: Could the Type XXI U-boat have won the war?

Post by Dave Saxton »

The advent of the Type XXI following the operational deployment of German active and passive centimetric radar technology came just as the Royal Navy's own radar effort was hitting a rough patch.

This rough patch came as the result of a pissing match between fleet command, and the Admiralty Signals Establishment or ASE which over saw all things radar within the RN. The fleet command wasn't happy with the new radar sets that ASE was forcing upon them. Publications about how great these radars were are from the ASE themselves as they tryed to convince the fleet to trust the new sets, and these have been used as sources in secondary accounts about radar performance. But decalssified Admiralty documents such as ADM220/221 paint a different picture.

Especially controversal is the new search sets (warning sets by RN nomenclature) Type 277 and 293 replacing Type 271 and Type 273 on all warships from corvettes to battleships from mid 1944. The new sets had inferior performance than the ones they were replacing in several key areas. Type 277 was primarly to be air search with a tiltable antenna (AUK) while Type 293 was mounted on the foremast head primarily for surface search. Combined they could not pickup surface targets below IIRC 3 1/2 * line of sight, so they were useless for picking up surfaced submarines, or aircraft above 20,000 feet. The fleet complained that they were unreliable and nightmare to keep servicable. The size of the 293 antenna was increased to 8' then 12' but reliable detection ranges remained less than 30,000 yards.

ASE told the Fleet that they just didn't know how to use them properly and education of operating personal and techs was key. However, by the late 40s this remedy failed to solve the problems. Fleet was sarcastic in the typical British way (I'm paraphrasing):

" There's no doubt that this radar system isn't very good, but ASE says that it is the last word on the matter and if we can't make it work up to standard that is just tough. It's better than nothing they say."

Even by 1960 the issue remained unresolved.
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Re: Could the Type XXI U-boat have won the war?

Post by CPL Punishment »

Generally I find these counterfactual weapons arguments unenlightening. They almost always take the form of 'What if the Germans had more of these cool (fill in the blank) that really kicked ass? Wouldn't that make the Nazis victorious?' The ones that deal with real weapons aren't as tedious as the those interminable and pointless rants about weapons that never materialized into anything but ink on paper, but only just. Personally I prefer hypotheticals than turn on command decisions, like what if Holland had not chosen to close on Bismarck thus allowing Lindemann to cross his T...

I was going to argue that you guys have forgotten that the Battle of the Atlantic was won by superior intelligence which allowed the Allies to route convoys away from danger, and also helped Allied sub hunters to intercept and destroy the wolfpacks. I was further going to argue that if Type XXI boats had been used in large numbers then the Allies would have taken a variety of countermeasures. One that has not been mentioned heretofore is semi-rigid airships. If a Type XXI peril emerged then the Allies would have used blimps more extensively than they actually did.

I was going to argue these thing when I realized extraordinary countermeasures would probably not have been needed. If you're going to deploy extraordinary countermeasures, deploy them against more plausible threats, not against floating crap.

The Type XXI was crap, influential crap mind you, but crap nonetheless. In the real world the Kriegsmarine wanted 1170 Type XXI boats. What they got was 118. Because of horrendous quality control issues of those 118 only four were ever combat-worthy, the rest were floating scrap metal. Of the blessed four only two made war patrols, fruitless war patrols, no sinkings. The way some here have raved one would think an Allied ship had only to be spotted in a XXI's periscope reticle to be as good as scuppered. Not so apparently. So now let's be counterfactual. Lets us give Germany every Type XXI she wanted, all 1170 electrified grey wolves. Out of those 1170 less than 4% can be expected to be commissionable; that's 46 boats given the benefit. With one third either deploying or returning, and one third refitting, that means 15 boats more or less on patrol at any given time. Big deal. But, but, but... you sputter, suppose they worked out the bugs (giant bugs, bugzillas) in the building! Then those 1170 boats would all be sharks instead of herrings! Ah, but that's another counterfactual! If you insist on two mulligans then I insist on one, that the Allies deploy a powerful millimeter airborne radar that can see even the stealthiest schnorkel at range.
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