U-boat questions.

[MTGian]

Hey everybody,

I have some u-boat questions for those significantly more knowledgeable.

1) Why were u-boats focused so much on shipping? Why not focus on sinking the RN? Was it because u-boats were ineffective against military targets? I have read that the torpedoes they used were rubbish.

2) If so, considering we are replaying history, could improving torpedo technology be a focus of playing as Germany? I was just watching a special on u-boats and it stated that it took 4! torpedoes to get one contact and explosion on the HMS Royal Oak. That shocked me. Would better torpedoes be a game changer?

3) Germany did try to develop "modern" submarines, i.e., a vessel that operated primarily underwater rather than for short stints, U-2511. Would such a vessel be more successful against military targets? Was the fact that uboats could only submerge for short periods the problem? Could this be an early focus to try and shift u-boat strategy to sinking the RN?

My point as a total layman is you would think that hundreds of vessels (Germany built over 1000 u-boats) that can be anywhere at anytime and sink anything should be a formidable weapon against anything. Why wasn't this even more dominant than it was?

Thanks!

 

[LordOfWar16]

Submarines are designed to avoid direct conflicts with the enemy fleet. Germanys plan was to avoid the RN and attack their trade routes and pretty much starve them untill they capitulate. Dönitz didnt got enough submarines for his plan however and the british developed quiet effective sonar and the allies eventually broke the enigma code. Submarines back then werent really suited to fight military vessels and even today arent.

First of all, they were very slow when they were underwater and an prime target when surfaced. They simply couldnt keep up with military vessels while submerged and couldnt surface because that would pretty much be their death. When the allies started to send their ships in convois to more effectively protect them the germans used the wolfpack tactic to inflict as much damage as they could before they disengaged, avoiding the enemy escorts. Merchant ships usualy cant spot submerged submarines and dont have any really countermeasure against them, while destroyers and light cruisers are perfectly suited to hunt them down and to destroy them.

Bigger military vessels also have big torpedo belts, which made it even harder to sink them with the limited amount of torpedoes carried by an submarine. It only took 1 well placed torpedo to sink unexpecting smaller unarmored vessels like cargoships or even destroyers or light cruisers, but you are very unlikely to do so with an battleship for example. That would simply alarm the enemy fleet and they would send the escort to hunt you down and destroy you.

All nations had alot of relieability issues with their torpedos. The early american Mark 14 are probably an great example for that. The Mark 14 torpedo had four major flaws.

• It tended to run about 10 feet (3.0 m) deeper than set.
• The magnetic exploder often caused premature firing.
• The contact exploder often failed to fire the warhead.
• It tended to run "circular", failing to straighten its run once set on its prescribed gyro-angle setting and instead, to run in a large circle, thus returning to strike the firing ship.

Dan Daspit documented his attempt of sinking an japanese whale factory ship. His first 2 torpedos hit the target rendering it unmanouverable. With no enemy anti-submarine combatants in sight, he then maneuvered into textbook firing position. He fired 9 more torpedos and all of them were duds.

With that said, i am not saying that the US torpedo were the worst or something like that, this is only supposed to show you how unrelieable torpedos back in ww2 really were. Even if you managed to hit your target, the risk of torpedos failing was very high.

 

[Hanitora]

U-boats attacked warships opportunistically. They could not keep pace with warships even on surface, so if the course of the warship taskforce was not favorable, the u-boat could simply not get in range. Another thing is that warships fight back and it's hell of a lot harder hitting a warship doing 30 knots than it is to hit a freighter casually moving along at a brisk pace of 10 knots going straight forward. Remember that the majority of torpedoes were completely unguided or patern guided at best. You needed to provide the torpedo data computer with accurate data to get a valid torpedo solution and getting this accurate data with the primitive instruments at the time was difficult and time consuming, and this made hitting a warship incredibly difficult because the time frame you had for plotting their course and speed was much smaller.

Torpedos could have been perfect and it still would have been difficult for an u-boat to sink a warship. Destroying convoys is a more efficient use of resources.

 

[Sprouts]

Everyone had early war torpedo problems. The things were precision instruments too valuable for lots of proper pre-war destructive testing. The flip side of that coin was the early war British ASDIC (active sonar) system on destroyers that the Admiralty was certain made submarines totally obsolete.

It’s good to remember how very many wrong assumptions went into that war. The bomber will always get through, fleet aircraft carriers are there to scout for the battle line, tanks don’t really need to move faster than the infantry they are supporting, Bushido is far more important than logistics, centimeter scale radar small enough to fit on aircraft was technically impossible (Germans all the way until they captured some) etc… We and our game designers know how all of those questions turned out, but the leaders we are playing didn’t at the time.

 

[Damiani]

US Torpedoes may have been awful, at least in the beginning of the war, but Japanese torpedoes were highly effective. In fact, it was a Japanese submarine that sunk/struck the Yorktown. I thought that it HOI3, however, subs were entirely useless against other ships in combat, even light cursers and destroyers. In that system the only capacity which submarines could perform in was convoy raiding and I agree with the OP that that seems odd and unrealistic.

 

[MTGian]

Thanks for the replies!

Followup questoin:

None of the responses mentioned the XXI U-boat (U-2511 was an example) that Germany developed toward the end of the war. The XXI could do 17 knots while submerged (according to wiki). Is that fast enough? It rarely needed to surface. Does that fix the U-boat issue that allowed the allies to stop the wolfpacks? From the brief bit that I have read, it inspired the modern sub. Are modern subs effective weapons against modern aircraft carriers and battleships? Or are they easier to detect than I think they are? Maybe I have watched Hunt for Red October one time too many.

So, if Germany re-engineers the U-boat early in the war to a more modern design (that is what the XXI is), which allows extended periods of submersion and relatively high submerged speed for short stretches (17 knots), then is it an effective weapon against the RN?

I am just curious. I know it is make believe, but so is Germany and USA being pals, which I think the game will allow. It wasn't like the XXI was researched in 1950.

 

[Caesar15]

Thanks for the replies!

Followup questoin:

None of the responses mentioned the XXI U-boat (U-2511 was an example) that Germany developed toward the end of the war. The XXI could do 17 knots while submerged (according to wiki). Is that fast enough? It rarely needed to surface. Does that fix the U-boat issue that allowed the allies to stop the wolfpacks? From the brief bit that I have read, it inspired the modern sub. Are modern subs effective weapons against modern aircraft carriers and battleships? Or are they easier to detect than I think they are? Maybe I have watched Hunt for Red October one time too many.

So, if Germany re-engineers the U-boat early in the war to a more modern design (that is what the XXI is), which allows extended periods of submersion and relatively high submerged speed for short stretches (17 knots), then is it an effective weapon against the RN?

I am just curious. I know it is make believe, but so is Germany and USA being pals, which I think the game will allow. It wasn't like the XXI was researched in 1950.

Well about modern usage. There was a Wargame awhile back and one of the results of it involved a French submarine going in undetected and successfully sinking a U.S Supercarrier. (The Ronald Reagan perhaps?).

 

[Premu]

Still, 17 knots is slower than 30 knots. Plus, you can't simply rush a sub with full speed towards an enemy fleet even submerged - it makes enough noise to be detected before the sub is even close to fire position. That's the reason the Germans attacked the convoys surfaced at night - because that way the risk of being spotted was far lower (at least until radar was used widely).

 

[AtParmentier]

Subs in WW2 were close to being unusable for anti-fleet operations. As being pointed out in the posts above, they were and still are too slow to be used effectively agains military targets. Japan and the USA wanted to use the subs alongside the surface fleet, however this failed. Apart from Japan, nobody had good torpedoes in the beginning of the war. Torpedoes were capable to at least inflict heavy damage, when shot directly under a battleship (with a magnetic detonator). German U-boot captains had in fact several possible kills on RN battleships, but so many of those torpedoes were duds. I believe there was one captain who had four perfect back breaking shot (shots under the keel of a ship) on a Elisabeth or Nelson class battleship, all of them were duds, he had a mental breakdown and had a couple of months of leave.

 

[Sun_Killer]

as is see it 17 knots should be enough to get an intercept. heavy units en route without an pressing mission, seldom did more then 17 knots. So if equal speed and infos from another unit you should be able to get the u-boat into position.

 

[Hanitora]

So, if Germany re-engineers the U-boat early in the war to a more modern design (that is what the XXI is), which allows extended periods of submersion and relatively high submerged speed for short stretches (17 knots), then is it an effective weapon against the RN?

It would be significantly more effective, but not just because of the speed. The main benefits of the XXI type were more quiet machinery, longer range and hydralic loading of torpedo tubes. It could reload torpedoes significantly faster than the preceeding types such as VIIc, and with quieter engines and longer endurance underwater it could escape warships looking for it more effectively. As far as speed goes, they would still have to attack task forces opportunistically. The type VIIc boats were capable of doing 17 knots surfaced, and most of the time the u-boat would sprint into position to attack on the surface and then submerge while waiting for the enemy ships to come into range.

These more advanced submarines could certainly pose a huge threat to surface warships, but to use them on purpose as hunter-killers against a surface navy would still be a questionable proposition. Japan tried to use their submarines as a fleet component and it had limited success and effect on the war compared to US and German submarines which were mostly used as commerce raiders. I mean why wouldn't you raid convoys and merchant shipping? It really hurts to have a 7000 ton ship sink into the bottom of the sea with a full load of war material or oil. They ain't gonna fight back either.

 

[MTGian]

I mean why wouldn't you raid convoys and merchant shipping? It really hurts to have a 7000 ton ship sink into the bottom of the sea with a full load of war material or oil. They ain't gonna fight back either.

Does it though? I'll have to go back and see if I can find it, but I recall a line from the U-boat special that I watched state something like, "For each convoy ship we sank, five more took its place". I know there is that line from Churchill about the U-boats being the greatest threat, but I wonder if it was an impossible task. That there simply were too many convoy vessels. Too many merchant vessels. That such ships and their cargo could be produced in such quantities that the U-boats just slowed things down a bit. They may have sank thousands of merchant/convoy vessels, but if there were tens of thousands, then it was all rather pointless

Meanwhile, how many RN vessels were there? Sink a few hundred of them and it might be a bit more irritating for the UK.

Of course, in reality, the U-boat was a poor weapon against the RN, so it was an obvious choice. However, with the knowledge of retrospect, if we know that the convoy quantities are essentially limitless, then the resources spent sinking them were wasted and we might contemplate a different use for those resources (like a sub that would be more effective against military targets).

 

[AaGuns]

Hey everybody,

I have some u-boat questions for those significantly more knowledgeable.

1) Why were u-boats focused so much on shipping? Why not focus on sinking the RN? Was it because u-boats were ineffective against military targets? I have read that the torpedoes they used were rubbish.

2) If so, considering we are replaying history, could improving torpedo technology be a focus of playing as Germany? I was just watching a special on u-boats and it stated that it took 4! torpedoes to get one contact and explosion on the HMS Royal Oak. That shocked me. Would better torpedoes be a game changer?

3) Germany did try to develop "modern" submarines, i.e., a vessel that operated primarily underwater rather than for short stints, U-2511. Would such a vessel be more successful against military targets? Was the fact that uboats could only submerge for short periods the problem? Could this be an early focus to try and shift u-boat strategy to sinking the RN?

My point as a total layman is you would think that hundreds of vessels (Germany built over 1000 u-boats) that can be anywhere at anytime and sink anything should be a formidable weapon against anything. Why wasn't this even more dominant than it was?

Thanks!

Sorry for the long quote, but I'm on mobile and can't really see the message and type at the same time unless I do this.

1.) as many others have said, submarines have never been very good against warships. Not so much the torpedoes being bad as the speed being bad. A submarine can't keep up with a fleet, even one of the monster subs like the XXI that Germany had developed by the end of the war.

2.) better torpedo technology wouldn't be a game changer, but it would help considerably. I think in the case of the Royal Oak, the torpedoes hit the bottom of the harbor? Not sure, don't have a source ready. Possibly the bulge deflected them, or they might have indeed been duds.

3.) they would be more successful against military targets, but maybe not how you're thinking. Battleships exceed 20 knots quite easily, especially if they're newer ones. So do carriers. And the XXI class could do 20 knots at its fastest, so it couldn't ever "hunt" capital ships. It could get lucky, like it happened a number of times throughout the war, and happen to be in the right place at the right time. And yes the fact that they couldn't remain submerged for long or maintain a decent speed was a huge problem, and often the limiting factor when diving deep to avoid depth charges. It would help to avoid destroyers that were hunting the sub though.

Destroying the RN isn't the biggest priority, nor is it possible, it being as large as it is.
The real target is the merchant shipping keeping Britain supplied and armed. And also preventing the invasion of German-occupied Europe. Had the XXI been developed and ready by say late 1941 or early '42, the war could have gotten very ugly for the allies. A fleet of 300 XXI subs could have caused serious problems. This is going to be my strategy for defeating the British, is investing very heavily in submarines and their tech. If you can take them out, the United States and their bombing is not a factor, and you can focus more materiel on the Mediterranean to prevent the fall of Africa.
But a complete answer to your question:
U-Boats were ineffective against warships because they simply weren't fast enough to keep up with them and they couldn't stay down long enough to evade them, nor were they fast enough below the surface.

 

[Nicolas I]

...this is only supposed to show you how unrelieable torpedos back in ww2 really were. Even if you managed to hit your target, the risk of torpedos failing was very high.

Maybe if the torpedoes instructions books were printed big bold underlined caracters they would have worked better ?

 

[Alias72]

Thanks for the replies!
Are modern subs effective weapons against modern aircraft carriers and battleships? Or are they easier to detect than I think they are? Maybe I have watched Hunt for Red October one time too many.

This is a difficult question to answer.

Modern Submarines are vastly more effective against warships then their ww2 counterparts. This is the result of a number of innovations.
1 - Modern submarines are extremely quite, especially ones equipped with anechoic tiles.
2 - Modern submarines are significantly faster then their ww2 counterparts
3 - Modern surface combatants are generally slower then their ww2 counterparts
4 - Modern submarines have a wide selection of advanced weaponry namely
- Homing Torpedoes with ranges out to 20 km
https://en.wikipedia.org/wiki/Type_53_torpedo
- Nuclear armed torpedoes
http://survincity.com/2012/02/russian-nuclear-torpedoes-t-15-and-t-5/
- Supercavitating torpedoes with a max speed of 200 knts
https://en.wikipedia.org/wiki/VA-111_Shkval
- Cruise missiles
https://en.wikipedia.org/wiki/P-700_Granit
- Some with Nuclear warheads
https://en.wikipedia.org/wiki/RPK-2_Vyuga
https://en.wikipedia.org/wiki/RPK-6_Vodopad/RPK-7_Veter

But all of this highlights a significant change in submarine role. Submarines are now launching platforms for autonomous and semi- autonomous weapons. The ability to launch these weapons and then disappear is more valuable in modern warfare then a protracted anti-shipping campaign.

But to answer your question. Modern subs can be highly effective against modern aircraft carriers and battleships. In fact they are one of the reasons why some people are saying the aircraft carrier is obsolete. The soviets positioned some of their submarines with the intent of destroying american carrier task forces at the onset of a war.

As for detection they are very easy to locate with active sonar but that gives away your position. If its a surface target pinging its in cruise missile range long before it detects anything. If its a submarine pinging then its asking for an aircraft to drop a sonobuoy and torpedo combo right on top of it. Most ships will use passive sonar systems and those can have great difficulty detecting modern submarines (though a type VIIC would stick out like a neon sign).

 

[Hanitora]

Does it though? I'll have to go back and see if I can find it, but I recall a line from the U-boat special that I watched state something like, "For each convoy ship we sank, five more took its place".

Yes. It's correct that uboats didn't manage to sink enough convoys to cripple Britain, but that had a lot to do with US aid. Britain was not capable of replacing its losses, it took US assistance in the form of emergency ship building program to get Britain out of its pickle. USA alone was capable of producing more equipment and material than Britain and Germany put together.

In 1942 USA built somewhere around 8 million tons of merchant ships. By comparison uboats sank somewhere around 14 million tons through the entire war. USA could have directed this colossal ship building industry into producing destroyers just the same if that's what Britain needed.

 

[MTGian]

Good stuff! Thanks!

Destroying the RN isn't the biggest priority, nor is it possible, it being as large as it is.
The real target is the merchant shipping keeping Britain supplied and armed. And also preventing the invasion of German-occupied Europe. Had the XXI been developed and ready by say late 1941 or early '42, the war could have gotten very ugly for the allies. A fleet of 300 XXI subs could have caused serious problems. This is going to be my strategy for defeating the British, is investing very heavily in submarines and their tech. If you can take them out, the United States and their bombing is not a factor, and you can focus more materiel on the Mediterranean to prevent the fall of Africa.
But a complete answer to your question:
U-Boats were ineffective against warships because they simply weren't fast enough to keep up with them and they couldn't stay down long enough to evade them, nor were they fast enough below the surface.

If you can keep the U.S. out of the war, then it sounds like this is plausible. However, if the U.S. is in the war, then whether it is vast numbers of convoys or vast numbers of destroyers, it doesn't sound like u-boats can be built in sufficient quantities to really stop the allies.

But all of this highlights a significant change in submarine role. Submarines are now launching platforms for autonomous and semi- autonomous weapons. The ability to launch these weapons and then disappear is more valuable in modern warfare then a protracted anti-shipping campaign.

But to answer your question. Modern subs can be highly effective against modern aircraft carriers and battleships. In fact they are one of the reasons why some people are saying the aircraft carrier is obsolete. The soviets positioned some of their submarines with the intent of destroying american carrier task forces at the onset of a war.

So, it isn't just a matter of staying submerged longer or being a bit faster while submerged, but rather the design of highly sophisticated weaponry that makes the modern submarine extremely dangerous. So, the XXI while an improvement on the U-boat class would not be this magic game changer. Makes sense!

Yes. It's correct that uboats didn't manage to sink enough convoys to cripple Britain, but that had a lot to do with US aid. Britain was not capable of replacing its losses, it took US assistance in the form of emergency ship building program to get Britain out of its pickle. USA alone was capable of producing more equipment and material than Britain and Germany put together.

In 1942 USA built somewhere around 8 million tons of merchant ships. By comparison uboats sank somewhere around 14 million tons through the entire war. USA could have directed this colossal ship building industry into producing destroyers just the same if that's what Britain needed.

I catch your drift. Once the U.S. is in the war, the battle of the Atlantic could not be won. Whether it is building vast amounts of convoys or military vessels, whatever the U-boats sink can be replaced and then some by U.S. production.

The U-boat was a greater threat when it was Britain alone against Germany with a "neutral" U.S. giving half-measures of support.

 

[keynes2.0]

Meanwhile, how many RN vessels were there? Sink a few hundred of them and it might be a bit more irritating for the UK.

Yeah the thing is that even a lowly destroyer-escort (US name) or corvette (British name) is as much a threat to a uboat as a uboat is to it. And corvettes could be made with the same shipbuilding as merchant ships (unlike uboats they could be made with bulky, inefficient power plants because they didn't need to be small). Uboats needed to attack where the corvettes and destroyers weren't and to spread the allied escorts out so they could achieve overwhelming numbers. If they attacked enemy navies head on they would be swarmed by escorts. Uboats were replacable but their trained crews weren't. Corvettes were expendable and their crews could be quickly replaced.

It should be noted that while the type XXI did a lot of stuff eventually, it didn't do those things before the war ended. So it didn't have an edge on it's contemporaries. It's contemporaries were post-war escort ships which had much better ASW.

Submarines could launch attacks of opportunity on warships when the circumstances were right. They also had more successes against the Japanese in the pacific but that was because the Japanese didn't have nearly enough escorts and didn't have good ASW.

 

[Hanitora]

The U-boat was a greater threat when it was Britain alone against Germany with a "neutral" U.S. giving half-measures of support.

In the context of HoI4 you can probably completely cripple both USA and Britain with submarines and sufrace navy convoy raiding because you have hindsight and you know that you need to focus heavily on convoy raiding. In HoI2, which is what I used to play a long time ago you could most certainly destroy Britains ability to wage war by convoy raiding to the point where Italy rolled them in Afrika without any German help on the ground. Their IC was completely tied up replacing convoy losses.

I also had surface raiders out in force, but I did not place much focus on them.

Maybe in HoI4 it's less crippling because equipment production and naval production is separated, but if I heard correctly I think one of the Paradox guys said in some thread that sinking a convoy will also destroy whatever it was carrying. So if it was carrying 10 tanks, you just lost 10 tanks. Which would make the effects of convoy raiding even worse than just losing the convoy itself. But even if you don't lose the equipment, tying up all the naval production of an enemy with convoys seems like a very beneficial thing. Every merchant ship they build, 1 cruiser remains unbuilt.

 

[Denkt]

Convoy raiding now take place as normal naval battles and allow the involved countries to send naval forces to the area. That can effect how effective raids will be.