Best submarine force in WW2

[PainRack]

During WW2, which of the combatents had the best submarine force?

[K. A. Pital]

USA and Germany. Germany had more worthwhile opponents though, the USA had more operational freedom. Overall, I'd give it to the United States of America, but the weakness of their foe Imperial Japan is not adequately factored in that judgement.

As for whys, hows... uh... I don't even know where to start. There's Clay Blair's "U-boat war" (despite all the criticism, the guy operates with solid statistical datasets and nothing but that; all the attempts of u-boat fans to challenge his thesis are basically just butthurt feelings), two volumes. There are also several articles at navy.mil regarding the efficiency of US and German submarine fleets, etc. One should read that, definetely.

[Sea Skimmer]

The Germans sank much more, and had more and longer to sink stuff, but accomplished less per submarine sent into action, never mind per submarine lost compared to the US. US submarines also of course, accomplished the mission of starving Japan, while the U-boats were never actually effective. They also successfully took on a number of special roles including beach reconnaissance, lifeguard duty and supplying guerillas. Meanwhile the Germans built like five different types of midget submarine and human torpedoes for special missions, all of which were spectacular failures except maybe the Seehund.

US submarines had one marked technological advantage over all other nations’ submarines too, in the form of the Torpedo Data Computer. The US’s TDC could actually track a target, and be ready to feed an accurate solution to the torpedo gyro at any time. Latter marks of the computer could maintain two tracks at once. The computer, by taking in radar range and bearing allowed a US submarine to actually attack blind, without ever seeing the target using periscope radar or the conning tower radars.

No one else had a calculator which could do more then generate a one time solution. You could either fed it immediately to the torpedoes and fired, or you had to wait and run the calculator all over again to generate an updated gyro angle. That meant the skippers skill in aiming was far more important, and he had to time exactly when he would fire. Course some nations subs were even worse off and had no real calculator at all, they did everything on a plotting board or else purely by the captains eye. That includes as I recall Japan and Russia.

US subs of course also had the usual allied advantage in radar, mounting air search sets as early as 1942, while by 1944 they had several different microwave surface search sets. Its also arguable that the USN built boats better suited to the war the USN fought then the KM built boats to the war the KM fought. The whole KM tonnage war strategy was also on very rocky grounds from a mathematical as well as practical standpoint, and become completely invalidated upon the US entry into the war.

On the matter of Japanese ASW sucking. It did in large part, but something worth considering is that the average speed of Japanese merchant ships was much higher then those of the allies. Allied ships which were fast, over about 10-12 knots, always sailed independently. Those defended convoys meanwhile traveled slow, often painfully slow at as little as 4 knots owing to the hoards of pre WW1 era scows floating around. 8 knots was a ‘fast’ convoy. This often meant the convoy was just a good collection of slow targets before adequate escorts could be provided mid war.

Japan meanwhile had far less shipping, but almost all ships were built with government subsidies for the specific reason of ensuring they had high speed for war service. This meant most of Japans ships could make more then 10-12 knots, often more like 15-17 knots which gave them a fair bit of protection from a submerged sub.

Even the US Liberty Ship hoard could only make 11 knots, (Victory Ship was much faster) but in neither mass produced type arrived in much strength before the U-boats had already been defeated.

[Force Lord]

Didn't the U.S. enter WWII with some shitty torpedoes?

[Stark]

Everyone who didn't test them beforehand did that. The US just took longer to fix the problem, AFAIK.

[erik_t]

The following is a set of excerpts from Frederick J Milford's The great torpedo scandal, 1941-43, from the October 1996 issue of THE SUBMARINE REVIEW.

The entire work can be found here.

The Great Torpedo Scandal emerged and peaked between December 1941 and August 1943, but some of its roots went back twenty five years. It involved primarily the Mk.14 and three distinct problems, depth control, the magnetic influence exploder and the contact exploder, whose effects collectively eroded the performance of the torpedoes. The scandal was not that there were problems in what was then a relatively new weapon, but rather the refusal by the ordnance establishment to verify the problems quickly and make appropriate alterations. The fact that after twenty five years of service the Mk.10 had newly discovered depth control problems adds weight to the characterization of the collection of problems and responses as a scandal. These comments should, however, be mitigated a little by the fact that each of the Mk.14 problems obscured the next. Although BuOrd did not identify the final problem, contact exploder malfunction when a torpedo running at high speed struck the target at ninety degrees, their response, once the difficulty had been identified, was notably prompt. In spite of the promptness of BuOrd's response, by the time it reached Pearl Harbor a number of relatively simple solutions to the problem had been proposed, and modifications had already been designed and implemented. This was, however, almost two years after the United States entered WW II.


...


Depth control problems with US torpedoes were suspected by the Newport Torpedo Station (NTS-Newport) and BuOrd even before the United States entered WW II. On 5 January 1942 BuOrd, based on earlier (1941) testing, advised that the Mk.10 torpedo, which had entered service in 1915 and was still used in S-class submarines, ran four feet deeper than set.... In a mood of desperation, the operating forces made their own running depth determinations, using fishnets for depth measurement, at Frenchman's Bay in Australia on 20 June 1942. These measurements indicated that the depth errors were probably more like eleven feet.... it was not until August of 1942, after intervention by the CNO, Admiral Ernest J.King, that they re-investigated and agreed that there was a ten foot depth error in the Mk.14 system. Interim instructions for fixing the problem were issued very quickly and kits to effect an official alteration were distributed in late 1942.... The Mk.14 problem required both a calibration modification and a modification to sense water pressure in the midships section and the latter was implemented beginning in the last half of 1943.

...

The magnetic influence exploder was unquestionably responsible for sinking some, perhaps even a large fraction, of the 1.4 million gross registry tons of Japanese merchant ships sunk by submarines between December 1941 and August 1943. Reports from submarine commanding officers of apparent magnetic influence exploder failure, mainly duds and prematures, finally led to CinCPac ordering the disabling of the magnetic influence feature on 24 June 1943. ComSubSoWesPac reluctantly followed suit in December 1943. CinCPac's order was issued eighteen months after Jacobs, on Sargo's first war patrol, ordered the deactivation of the magnetic influence portion of the Mk.6 exploders in his torpedoes and incidentally got into considerable difficulty for doing so. Magnetic influence exploders were not used by US Navy submarines through the balance of WW II.

...

Once the depth problem had been fixed and the magnetic influence feature of the Mk.6 exploder deactivated, it came the turn of the impact exploder to demonstrate its merit. Unfortunately the initial result was a plethora of duds, solid hits on targets without warhead detonations14. This problem was suspected earlier, but it was not until the other two problems had been eliminated that there was unequivocal evidence of a problem with the impact exploder. This difficulty was a further frustration for the operating forces, but fortunately it was quickly diagnosed. The key to the problem was again the increased speed of Mk.14. The impact portion of the Mk.6 exploder was exactly the same as that which had been used in the Mk.4 and Mk.5 exploders. The Mk.4 worked entirely satisfactorily in the 33.5 knot Mk.13 torpedo. What was overlooked was that in going from 33.5 knots to 46.3 knots the inertial forces involved in striking the target at normal incidence were almost doubled. These greatly increased inertial forces were sufficient to bend the vertical pins that guided the firing pin block. The displacement was sometimes enough to cause the firing pins to miss the percussion caps, resulting in a dud. In cases of oblique hits, the forces were smaller and the impact exploder more often operated properly. Several war patrols, especially those cited above, convinced ComSubPac, VAdm Charles Lockwood, that there was a problem and he again resorted to experiment. Firings at a cliff in Hawaii demonstrated that some torpedoes did not detonate when they hit the cliff. A rather risky disassembly of a dud revealed the distortion of the guide pins. It was a simple solution to make aluminum alloy (rather than steel) firing pin blocks and lighten them as much as possible thus reducing the inertial forces to a level that did not distort the guide pins. Another solution was to use an electrical detonator and a ball switch to fire the warhead. This too was relatively easy to implement and soon became standard.

...

Once these and other less significant problems were solved, the Mk.14 torpedo became a reliable and important weapon. After WW II, it was modified to accommodate electrical fire control settings, gyro angle, depth and speed, and as Mk.14 Mod.5 remained in service until 1980.

Certainly by the latter part of the war, USN submarine torpedos were perfectly serviceable.

[Thanas]

On the matter of Japanese ASW sucking. It did in large part, but something worth considering is that the average speed of Japanese merchant ships was much higher then those of the allies. Allied ships which were fast, over about 10-12 knots, always sailed independently. Those defended convoys meanwhile traveled slow, often painfully slow at as little as 4 knots owing to the hoards of pre WW1 era scows floating around. 8 knots was a ‘fast’ convoy. This often meant the convoy was just a good collection of slow targets before adequate escorts could be provided mid war.

Japan meanwhile had far less shipping, but almost all ships were built with government subsidies for the specific reason of ensuring they had high speed for war service. This meant most of Japans ships could make more then 10-12 knots, often more like 15-17 knots which gave them a fair bit of protection from a submerged sub.

Yes, but US subs were built for fast surface speed as well.

IMO it is a bit pointless to compare the two submarine forces. Both had far different enemies and had different levels of support to rely on as you said.

[CmdrWilkens]

On the matter of Japanese ASW sucking. It did in large part, but something worth considering is that the average speed of Japanese merchant ships was much higher then those of the allies. Allied ships which were fast, over about 10-12 knots, always sailed independently. Those defended convoys meanwhile traveled slow, often painfully slow at as little as 4 knots owing to the hoards of pre WW1 era scows floating around. 8 knots was a ‘fast’ convoy. This often meant the convoy was just a good collection of slow targets before adequate escorts could be provided mid war.

Japan meanwhile had far less shipping, but almost all ships were built with government subsidies for the specific reason of ensuring they had high speed for war service. This meant most of Japans ships could make more then 10-12 knots, often more like 15-17 knots which gave them a fair bit of protection from a submerged sub.

Yes, but US subs were built for fast surface speed as well.

IMO it is a bit pointless to compare the two submarine forces. Both had far different enemies and had different levels of support to rely on as you said.

Yet we should still eb able to ask the question of how well they performed their assigned misison within the constraints they were forced to accept as a matter of national strategy. That is which force better enacted their mission relative to its difficulty. The KM certainly had against British only shipping a much more difficult mission just in terms of raw tonnage and they did succeed for a few months prior to US entry in sinking more tonnage than was launched but they were never able to maintain that pace even before the US entry changed the mission parameters usfficiently as to render mission accomplishment impossible. Conversely the USN managed to sink more continuously and did accomplish their mission even though Japanese merchant tonnage production was significantly lower.

I'd hate to give a defined metric without having the numbers immediately handy but were I to try a comparison my thought would be to compare the % of tonnage sunk against tonnage launched and existing prior between the two navies during the periods in which they both had a reasonable chance of achieving their mission. That is the %of tonnage sunk against tonnage launched and existing for the KM between March 1939 and the end of 1941 while for the USN the equivalent period would be December 41 to August 45.

[Thanas]

Oh, I agree that the USN had the better submarine force for the job at hand. However, I very much doubt it would have performed as well as the KM did against British ASW, whereas I very much doubt, no scrap that, I am sure that the KM would not have been able to conduct such an anti-shipping campaign over those long distances.

[Sea Skimmer]

American subs did very well against the Atlantic ASW groups; the USN sent a number of subs over to play with the top groups in late 1945 when everyone was still fresh from war experience. The end conclusion was that the best counter to hunting down a submarine with equally high technology was another submarine, and the first trials of hunter killers began in 1946.

[Thanas]

American subs did very well against the Atlantic ASW groups; the USN sent a number of subs over to play with the top groups in late 1945 when everyone was still fresh from war experience. The end conclusion was that the best counter to hunting down a submarine with equally high technology was another submarine, and the first trials of hunter killers began in 1946.

That sounds very interesting. Do you have a link to that?

[PeZook]

Oh, I agree that the USN had the better submarine force for the job at hand. However, I very much doubt it would have performed as well as the KM did against British ASW, whereas I very much doubt, no scrap that, I am sure that the KM would not have been able to conduct such an anti-shipping campaign over those long distances.

Of course the KM wouldn't be able to operate in the Pacific Theatre, because it didn't have the proper boats for the job. All KM boats were built for the Atlantic, because that's where any conceivable tonnage war would be waged. If they had to fight a tonnage war over the Pacific, they'd build a completely different force.

When evaluating different forces operating in different conditions (both geographical and strategic), a more complex model is needed than a simple comparison of sunk tonnage. For example, we'd need to start by answering soft questions: Who formulated their goals better? Who had a more sound strategy for achieving those goals? Who prepared better for their tonnage war in preceding years? Who was better at managing all their support structures?

Training, preparation, quality of the boats and equipment, effectiveness in combat and the goals you set for yourself are all measures for comparison. Can you really say you have the best submarine force if its leadership routinely sets goals that are impossible to meet? What if it simply can't win the war it's supposed to fight?

Furthermore, all these questions tie to the overall picture. The Kriegsmarine, for example, would be severely constrained in their tonnage war if they didn't have French ports to operate from: every u-boat would have to break out into the Atlantic to run its patrols.

[Serafina]

Where are the differences between the Atlantic and the Pacific theatre? Why does a submarine for the pacific be build differently than one for the Atlantic?
Other than longer ranges in the Pacific, i do not really see the differences - so what are they?

[Stuart]

American subs did very well against the Atlantic ASW groups; the USN sent a number of subs over to play with the top groups in late 1945 when everyone was still fresh from war experience. The end conclusion was that the best counter to hunting down a submarine with equally high technology was another submarine, and the first trials of hunter killers began in 1946.

That sounds very interesting. Do you have a link to that?

Norman Friedman in Illustrated Design History of US Submarines (two volumes, one up to 1945, the other 1946+) goes into this whole area. Its in the last chapter of the first book and the first of the second.

[PeZook]

Where are the differences between the Atlantic and the Pacific theatre? Why does a submarine for the pacific be build differently than one for the Atlantic?
Other than longer ranges in the Pacific, i do not really see the differences - so what are they?

Why do you think that's such a minor difference? It's a massive problem for the majority of the German u-boat fleet equipped with dinky little Type VIIs, for which a 30-day patrol was long, and 90 days was absolute hell for the crews, who had no shower, one toilet for 40 men and little space for provisions.

In order to run long patrols, you need a bigger boat not just in order to accomodate more fuel: you need it to have plenty of torpedoes to provide adequate loiter time at the destination, you need better crew facilities and more space for provisions, you need a machine shop of some sort...lots of stuff. And to top it off, you need more boats per a given number of ships on patrol, due to long time taken returning to base/going out on patrol. Distance is a horrible tyrant.

[Vehrec]

Where are the differences between the Atlantic and the Pacific theatre? Why does a submarine for the pacific be build differently than one for the Atlantic?
Other than longer ranges in the Pacific, i do not really see the differences - so what are they?

Why do you think that's such a minor difference? It's a massive problem for the majority of the German u-boat fleet equipped with dinky little Type VIIs, for which a 30-day patrol was long, and 90 days was absolute hell for the crews, who had no shower, one toilet for 40 men and little space for provisions.

In order to run long patrols, you need a bigger boat not just in order to accomodate more fuel: you need it to have plenty of torpedoes to provide adequate loiter time at the destination, you need better crew facilities and more space for provisions, you need a machine shop of some sort...lots of stuff. And to top it off, you need more boats per a given number of ships on patrol, due to long time taken returning to base/going out on patrol. Distance is a horrible tyrant.

Don't forget the tropical climate in much of the pacific theater that would turn any non air-conditioned boat into a steam chamber. Conversely, the cold waters of the north atlantic would seem to make a heater of some sort an absolute necessity. You need more food-maybe refrigeration to preserve the non-canned goods. Your engines need to be able to go longer between maintenance in a dock, and they need to be able to cruise farther. So the engines need to be built to higher tolerences. You might begin to see now why it's a different thing to fight in the different oceans.

[PeZook]

Don't forget the tropical climate in much of the pacific theater that would turn any non air-conditioned boat into a steam chamber. Conversely, the cold waters of the north atlantic would seem to make a heater of some sort an absolute necessity. You need more food-maybe refrigeration to preserve the non-canned goods. Your engines need to be able to go longer between maintenance in a dock, and they need to be able to cruise farther. So the engines need to be built to higher tolerences. You might begin to see now why it's a different thing to fight in the different oceans.

Several Type IX uboats actually performed long tropical patrols along the African coast during the war, actually, and the crews came back alive. Of course, even for a Type IX, a 90-day patrol was horrible: like all uboats, they only had minimal crew facilities. The crew didn't have anywhere to wash their clothes or bathe...so you can imagine how much it stank inside after just a month, not to mention three

On the other hand, all US navy fleet boats had a stated endurance of at least two months, which means they were expected to actually patrol this long, whereas for a u-boat of any type save perhaps the XXI, a sixty day patrol was something extraordinary.

[Sea Skimmer]

As I recall certain models of the Type IX, and I think one model of the Type VII did have air conditioning, but it made the cramping even worse. It was introduced because snorkeling was hell on the crews under any conditions.

The Germans did have a design for the very large (over 3,000 tons) Type XI-B cruiser with four five inch guns, and absurdly, still just six torpedo tubes. Also an airplane and accommodations for troops. It would have been far more able to conduct long range operations then any other German sub, but high diving time and low speed are not likely to work out well in combat. The project was canceled in 1939 upon outbreak of war.

[CaptHawkeye]

Actually it's pretty funny to read about the differences just in MASS between US and German Submarines. The biggest common German Submarine was the Type IX and it had like, what, 6 torpedo tubes? Meanwhile the Americans frequently kicked out boats the size of fucking destroyers with 10 torpedo tubes and 2X reloads for all of them. Granted that's a fairly simplistic analysis, but it lets you know who's going to get a better start off on the race track.

Of course the Germans Subs were also constantly under threat of surprise air attacks and fast, co ordinated hunter-killer groups, so it might be understandable why small boats with short dive times like the Type VII were so favored at first. Of course by 1944 surface cruising for ANY period of time was pretty much suicide. So having a larger boat with greater battery life became all the rage as the war went on. Hence the Type XXI.

[MKSheppard]

US submarines had one marked technological advantage over all other nations’ submarines too, in the form of the Torpedo Data Computer. The US’s TDC could actually track a target, and be ready to feed an accurate solution to the torpedo gyro at any time.

To explain further:

US Torpedo Data Computers basically would continue updating their calculations for angle on bow, and gyro angles based off the target's last known course, and the submarines' present speed and course. What it basically meant was, you could do the following:

1.) Raise periscope, get bearing to target, target range, target speed, and target course -- punch them into TDC.

2.) 5 minutes pass; you raise scope again, check to see if your numbers concerning the range of the target, it's speed and course were right; and if not, input corrected information into TDC.

3.) 15 minutes later, the TDC says that range to target has closed to 6,000 yards based off it's own calculations of the submarine's motion (fed from sub's gyrocompass and knotmeter); and of the target's motion (based off the data you input 15 minutes ago).

4.) You load the bearings into your torpedoes and fire, without once raising your periscope. Six minutes later, your torpedoes will hit the target, assuming he hasn't changed his course.

This capability I suspect, was driven by pre-war US doctrine of executing very deep submerged attacks on targets via sonar bearings.

The German TDC on the other hand, did not provide this "track target along it's last known course" capability -- you had to manually dial in all the variables (bearing to target, target range, target speed, and target course) and crank them through the TDC before you fired your shot, which meant that in order to fire a torpedo, you needed a last-minute periscope check of the target -- because while you could theoretically track the target and do all the math required for updating the TDC by hand on your map chart; it would be just too much work involved.

On the other hand, German boats had built-in salvo firing.

You selected which tubes you wanted fired in the salvo, and then input the amount of offset you wanted between each torpedo in degrees, and then fired them all at once with a single button; for example:

Torpedo 1: Fired on a -2 Degree offset from computed bearing
Torpedo 2: Fired on computed bearing
Torpedo 3: Fired on a +2 Degree offset from computed bearing

creating a "fan" of torpedoes, and increasing the chances of hitting the target.

US boats on the other hand, didn't have this feature. Instead, the gyro-offsets had to be done by hand for each torpedo fired.

This is why in war movies; you hear the germans go: "LOS!" and a whole salvo goes flying off against the brave plucky convoy; while you hear americans go: "FIRE ONE! *pause* FIRE TWO! *pause*" and so on.