Interesting and informative post, Librarian. Thanks. I never realized the Germans operated smaller coastal patrol types…
Oh, thank you very much, my dear Mr. Nickdfresh. I am assuring you that the pleasure was mine. 
Nevertheless, perhaps a tiny appendix to my previous post will be necessary as a truly finishing point to it. You see, one particular vessel of the Type II class, namely U-11, was distinctive in the whole history of submersible vehicles, due to the fact that she was the earliest submarine that actually used nowadays almost forgotten representative of a “modern” submarine technology – the very first synthetic rubber based anti – sonar coating called Alberich.
U-11 – another prematured high-tech demonstrator of the Type II class
Greatly interested for reduction of the sonar echo of their U-boats, the Germans experimented with sound absorbing synthetic rubber-like laminated coating of about 4mm thickness, intended for efficiency reduction of Allied active sonar devices, which also possessed significant sound absorbing properties.
The material was called Oppanol, an transparent, versatile polymer (in essence form of polyisobutene, even today highly renowned chemical with applications assortment varying from chewing gum, adhesive plasters and double-glazing sealants through to cable insulation, roofing sealants and protective coatings applied to pipelines), impervious to water and gases, resistant to chemicals, physiologically harmless and with elevated adhesive properties. Renowned German company BASF patented a synthetization process for polyisobutene in 1931, and the product was later called Oppanol after the Ludwigshafen suburb of Oppau, where it was developed and produced. However, another seven years of research and development work were needed before it could be produced on an industrial scale. The first Oppanol plant went into operation in 1938, but in those times its military potentials still were completely overlooked.
This laminated material was secured to the outer hull with different adhesives. Although no conclusive tests were performed, Germans claimed that the sonar echo reflection of a U-boat equipped with Alberich coating was reduced by some 15 percent, although absorption varied with depth, temperatue and salinity. In addition, this maetrial also acted as a sound dampener, containing the U-boat’s own engine noise. Basically, the thin two-ply synthetic coating slightly oscillated while the submarine moved through the water, thus providing partial absorption and phase-shifting of reflected sonar impulses.
Although the principle was a completely scientifically sound one, numerous problems were encountered with the adhesion capacity of the special glue (ethylene-vinyl), which was not strong enough to keep the rubber panels in place. This resulted in the sheets being partially washed off, or flapped in the wake of the ocean current, causing hydrodynamic resistance and additional noise. Over time wave action and salt made the rubber panels come lose and actually created more noise than a boat that did not have the coating. It was also discovered that coating is decreasing the speed of the vessel by 1.5 knots. A further deficiency was the fact that adequate treating of the submarine hull was a highly time consuming and very laborious task.
Further research into more reliable adhesives was conducted, but up to the end of the war only a few U-boats had received this treatment. These coatings were intensively investigated in the US after the WW2, but they were not employed due to constantly present adhesion complexity.
Nevertheless, it is highly intriguing that in the early fifties the Soviet Union began providing its own Malyutka-class (Малютка = little one) of coastal submarines with these anti-sonar and anti-echoic coatings. They successfully evolved into real multi-purpose coatings, capable not only to reduce echo-footprint of the submarine, but also to absorb noise of the internal machinery. Important distinction, however, is that these solutions were feasible in application on double-hall submarines only, where coatings could be placed upon multiple sufaces.
But that is a completely different story…
In the meantime, as always – all the best. 
I love Das Boot,I thought it was an awesome movie. I also read the book,which I thought was much better until the very end. I really got a sense of the boredoom,fear,and bravery of the crew.
I also watched U-571,I did enjoy it.But my enjoyment of it was tempered when I read how total B.S. The story was. I think the one thing that did disturb me was the scene of the U-Boat crew gunning down the crew in the lifeboat. From what I understand,the U-Boat crew’s would actually feed,give some medical attention and directions to the survivors,until Donitz put an end to that.
I will say I liked Thomas Fleischman’s portrayal of the U-Boat captain. He almost was as good as Jorgen Procknow’s portrayal in Das Boot.But,I am predjudiced as I think Fleischman is a teriffic actor.
I’m sorry,the actor in question is Thoman Kretcschman. My bad.
Saw this on another site and spent the last three weeks on vacation reading and studing it and comparing information to Rosselers excellent book “The Uboat”.
http://www.ibiblio.org/hyperwar/USN/rep/ASW-51/index.html
With regards the Type II Uboat I was reading about the on the “Uboat Net”
I got the following information about the Type II Uboats.
In the early war years they had 50 of these coastal boats and while 11 were dedicated to training the bulk were used on combat patrols until 1941. During that period the 39 remaining boats averaged 4 patrols each of average duration of ~ 31 days or a month. Each patrol sunk 1 enemy Merchant vessel plus had a chance of sinking an escort [mostly Auxiliary] or damaging another vessel.
According to the Uboat Net source, they sunk 149 merchant vessels 26 escorts and damaged 18 other ships while lossing about 11 Uboats in the process. Thats a staggering 11:1 kill ratio. The overall average of the Uboat fleet during this period was ~ 16-17:1 for the VII & IX types.
One is left with the impression that had Germany focused exclusively on building Type II Uboats in the 1930s plus overlapping Type II production into WW-II , while Type VII boats production was being ramped up , they would have faired alot better.
In order to reach Admiral Donitz mythical “300 Uboat fleet” they had to sacrifice building a surface fleet inorder to “fast track” Uboat production in the early war years…to make up for lost time.
Had they only built Type II in the 1930s, they could have produced 110-120 x type II before the war plus another hundred in 1940 and 1941, while Type VII production was being ramped up. Then when the War got going they would have filled the training role requirement through out most of the war. As it was 1/3 of the Uboat fleet had to remain at home at any give time to fill Uboat training role, which was far higher than they expected.
A note on arctic survival.
If you manage to kill a Polar Bear do not eat his liver.
Something I recall from a survival class in SFTG.
A lot of surviving U Boat vets poo-poo das boot.
Still probably the best movie on the subject.
U 571 is preposterous.
Akin to jumping into a flying saucer and flying it around.
Have you tried www.uboat.net.Yes Das Boot is a great film.
One has to be amazed by the bravery of the German U Boat crews.Only 10,000 out of an incredible 40,000 are said to have survived the war.Ther was many acts of bravery and selflessness on behalf of uboat captains,for example the famous Laconia Incident and Captain Hartenstein.
In Das Boot, the author writes, that everything in is based on something that really happened, not all in the same mission though. The book left the impression of a Boot as a noisy place.
There is both a movie and a TV series of greather length, but otherwise same content as the movie.
Librarian: If the Type II boats ordered by Yugoslavia became U 120 and U 121, do you know what happened to the two Type II boats stated to be ordered by China and stated to be launched in 1939?
Eric Groener in his massive volume on Uboats and Minewarfare ships for the Germans reports the boats destine for China were taken over by the Kreigsmarine.
Check out U564 on youtube.Reinhardt “Teddy” Suhrens genius method of transferring torpedoes from one UBoat to another.
Another very innovative Uboat type was XXI. It was the first submarine: before it there was only submersible boats, because they are able only to dive underwater for limitate period of time. Instead Type XXI was constructed with main objective to achieve a full underwater war machine. The streamlined hull is designed for high underwater speed (the main gun is removed, only a couple of antiaircraft small guns in a streamlined housin, antennas, schnorkel and periscope retract himselfs in the turret), can dive deeper than enemy boats and also offers a reduced sonar signature. Triple battery and new engine give to XXI type greater speed at less noise. Greater internal space means that finally Uboat crew can have some facilities, like freezer and shover, and also a greater number of torpedos carried. About torpedo, the new hydraulic reload system is a lot faster than previous one. High speed, good echo chamber, great diving depth, silent engine and reduced signar echo from hull means that XXI are a very hard prey to find for ASW boat.
This project was years ahead of current production, but his complessity, the intrusion of Hitler and damage done by USAF bomber doomed this project, of 120 submarine ordered only 2 reach operational status in April 1945.
This is completely wrong.
The Type XXI was not a true submersible in that it could NOT stay underwater indefinitely. It was merely the logical ultimate development of the conventional WW II diesel/electric boat powered by diesels on the surface and batteries when submerged. The only differences between the Type XXI and the Type VII for example, was that the Type XXI had about three times the battery cells that the Type VII had, and the Type XXI hull design was optimized for underwater high speed running and featured extreme streamlining. The Type XXI was equipped with a snorkel which allowed it to use it’s diesels to recharge it’s batteries while running just under the surface with the top of the snorkel extended above the surface.
This practice, however, was very unpleasant and hazardous to both boat and crew, and in the Type XXI, was very noisy, allowing Allied sonar to easily detect the boat at long range. Moreover, the head of the snorkel was large enough to be picked up with ease on both surface and airborne radars.
The Type XXI had other flaws in design and construction which rendered it little more than a coffin for it’s crew. The hull was constructed in sections by manufacturers who had little experience in shipbuilding, and the sections were then transported to a shipyard where they were welded together to form the completed submarine. The welds joining the sections (which themselves were not well built) were faulty and weak. Clay Blair, himself a WW II submariner, has studied the German U-boat war in great detail and reports in “Hitler’s U-boat War”, Vol. 2, page 710;
“Therefore the pressure hull was weak and not capable of withstanding sea pressure at great depths or the explosions of close depth charges. The Germans reported that in their structural tests the hull failed at a simulated depth of nine hundred feet. The British reported failure at eight hundred feet, less than the failure depth of the conventional German U-boats. In reality, the failure depth was much less.”
Blair also lists other flaws with the Type XXI.
The new design of six cylinder diesels were equipped with superchargers which were supposed to allow them to generate 2,000 HP. But in practice, the diesels and superchargers were so badly designed and manufactured, that the superchargers could not be used. This cut the available horsepower per diesel to just 1,200 HP. That meant that the Type XXI’s top surface speed was just 15.6 knots, less than conventional U-boats and slower than most Allied escort vessels. This lower horsepower also meant that it took significantly longer for the Type XXI to recharge it’s batteries, thereby increasing it’s vulnerability to surface and air attack.
The newly designed hydraulic system which operated the rudders, diving planes, torpedo tube outer doors, and antiaircraft gun turrets of the Type XXI was too complex and delicate and was located outside the pressure hull where it was vulnerable to saltwater leakage, corrosion, and enemy weaponry. This led to frequent failure of vital controls and functions of the U-boat. Furthermore, since the lines, actuators, accumulators, cylinders and pistons were located outside the pressure hull, they could not be repaired while submerged.
Finally, Blair says the Type XXI’s habitability was very poor and did not meet the minimum standards that prevailed in the US Navy. For example, the washing and drinking water systems were interconnected which was considered to be unsafe due to exposing the crew to increased hazard of infectious diseases.
Blair flatly states in “Hitler’s U-Boat War”, Vol 2, page 707;
“There was not the slightest possibility that, had they only come into play earlier, U-boats equipped with snorkels, or the new Type XXI and XXIII electro boats, with their high [underwater] sprint speed, could have won the Battle of The Atlantic or significantly intervened against Allied shipping.”
It’s a matter of pattern. Before Type XXI the pattern is to use battery to going under the see only as defense against daylight attacks, even when attack the Type VII has to surface to sprint to close distance (his submerged speed of 7.8 means that a merchant vessel can outrun it). Type XXI is created with the aim to keep underwater the boat for the larger time amount of mission possible, and with snorkel it can stay at 99% in water for all time mission.
If you say that submersible is the boat that stay underwater indefinitely, even nowadays most advanced US nuclear powered subs cannot stay underwater indefinitely. Ignoring the fact is not physically possible, because engine need fuel, please go to US Naval Accademy and explain this interesting concept, because in that accademy USN officer teach a slightly different version of this concept, the version that modern diesel-electric Uboat, like [U212](http://www.naval-
technology.com/projects/type_212/), that still use schnorkel is a true submersible boat.
Again, it depends on what you mean for submersible. The definition that you give is not so accurate for me. Anyway, check this “only differences”:
- the already know snorker;
- the already know streamlined hull;
- the facilities for crew;
- the faculty, granted by LUT-torpedo and new active and passive sonar, to launch a torpedo without surfacing and use periscope;
I think that is not “only differences” but truly changes.
If it’s noisy, it’s means that you are using passive sonar. In that case Type XXI produces at 15 knots less noise that USN Bailo class at 8 knots, not so bad i think. If you are talking of active sonar the Type XXI streamlined hull makes a smaller echo than Type VII. I’m very curious about this point, because German sources emphatize this aspect, for example in the only war mission of Type XXI U2511 it was able to approach HSM Norfolk, part of battle group, at 500 meters undetected.
While USN choise to simply scraps they war prays while Soviet use Type XXI as base for Whiskey and Zulu class.
Schnorkel is not stealth but anyway it present a smaller radar echo than a surfaced sub.
As i said in previous post, the poor quality manufacturing, caused by Allied bombing and decision by idiots to press Type XXI in service without sufficient quality test, doomed the project. One example: the first model of Type XXI was forced to be launched for Hitler birthday. Is so poorly made that it cannot stay on surface without buoyancy bags and after presentation was towed to dry dock.
I’m pretty sure that Clay Blair find the hull less resistent and some others flaws related to poor quality of materials. The quotes that you made suggest that he checks Type XXI against previous type, but he checks that the steel used for construction by 1943 Type VII and 1945 Type XXI has the same quality? And the connections between module are done with the same ability? Engine was reliable like the previous one? I don’t think so.
Again, if Nazi have the same resource of 1940 they will able to produce a well crafted engine. It wasn’t.
If you attack the armed convoy in Atlantic after 1943 from surface, you know that you cannot survive for long. Escort carrier and even merchant vessel launch airplane, and there is no way that a sub can beat an airplane: for an airplane that travels at 200 knots, if your sub travels at 10, 20 or 30 knots is the same. So surface speed of Type XXI is not a flaw.
Yes, an hazardous choice. But for example the Type XXI hydraulic system can reload 18 torpedos in 20 minutes while Type VII reload 1 torpedo in 10 minute. And putting outside some system make a lot of internal space available. Type VIIC for example keeps only 14 torpedos while XXI keeps 23. I don’t think it was so regretable this design.
For USN standard all uboats were under standard. Before Type XXI for example:
- the nazi uboat crew don’t take a shower for weeks;
- cannot refrigerate food;
- cannot have fresh water;
I don’t have read any source about crew accomodation on USN Bailo class, it offers the same facilities? Sure Bailo has more space than Type XXI.
Sorry, but the Type XXI’s only practical attribute that the Type VII lacked was the high underwater sprint speed, and that could only be employed in very limited circumstances. The Type XXI was operated in exactly the same way as a snorkel-equipped Type VII;, the only difference was that the Type XXI’s streamlining and larger batteries allowed it to travel much faster underwater for a short period of time. This underwater “sprint” capability did confer certain advantage when an attack approach was being made.
The ability to stay submerged for several days at a time was absolutely necessary by late 1944, due to the ubiquity of Allied aircraft patrols over the Atlantic, and almost every remaining operational U-boat of any type was, by that time, equipped with a snorkel. This allowed snorkel-equipped U-boats to remain submerged “for 99 % of it’s mission”, so the Type XXI was no different in that regard.
Actually, modern nuclear powered boats can stay submerged indefinitely. By “indefinitely” I mean that there is no imperative to surface to recharge batteries, vent the boat, refuel, or renew the air supply. So the decision to surface can be made by the captain independently of these considerations. No submarine can stay submerged forever, unless the crew is dead.
No, none were all that different. I’ve already mentioned the streamlined hull and the larger batteries, but even these were not real “innovations”; The Japanese and US navies had already made experiments with both of these factors in the inter-war years and the Japanese had already built two experimental submarines which had an even higher underwater sprint speed than the Type XXI. The US Navy had decided that the trade-offs necessary to achieve the underwater “sprint” capability were not worth the advantages. In the interwar years, the US Navy also practiced launching torpedoes from deep submergence; They found it was not practical until specially designed torpedoes with on-board guidance systems were developed near the end of the war.
My reference was to the noise generated by the Type XXI using it’s snorkel to run the diesel engines in order to charge it’s batteries, not the noise of it’s running on batteries alone. The Type XXI, like every other WW II diesel/electric boat, had to periodically run it diesels to charge it’s batteries; this typically took about four hours out of every twenty-four hours. But the fact that the Type XXI had extremely large batteries and under-powered diesels meant that it usually needed longer to fully recharge it’s batteries, so it spent far longer at this process than normal diesel/electric boats. Moreover, the Type XXI could only proceed at about four knots when charging batteries which meant that it would take weeks or sometimes months to arrive on it’s patrol station, and could only maintain a patrol for a very short time.
True, but by the end of the war it was only a small difference; the fact that the German U-boats, including the Type XXI, were forced to use snorkels slowed them down tremendously and made them almost irrelevant in convoy battles
No German U-boats had really reliable diesel engines, especially compared to the US Fleet boats, but the Type XXI’s diesels were particularly underpowered and troublesome which made the boat much less effective.
As for the steel used in the Type XXI’s hull, it made no difference since the hull was only as strong as the weakest weld in it’s structure. So you had a hull that was very strong in places but also very weak in others; once the hull starts flooding through a cracked weld, it doesn’t matter how strong the steel is elsewhere.
Oh, but the slow surface speed was a terrible flaw because before a sub could attack a convoy, it has to find and catch up to it. A slow surface speed meant that the Type XXI was even less able to intercept convoys than the Type VII and Type IX. Only if a Type XXI was directly in front of a convoy and the convoy was on a direct course for the sub, was surface speed of no import.
The problem was that the Type XXI’s hydraulics usually weren’t working properly, so it didn’t matter how fast the hypothetical reloads could be made. The Type XXI suffered from a poorly designed and engineered hydraulic system and it’s rudder and diving planes often jammed due to corroded hydraulic cylinders and pistons. This endangered the boat and crew even when no Allied forces were around. A slow surface speed, noisy and unreliable diesels, a snorkel that was dangerous to both crew and boat, and other design flaws meant that the Type XXI would have had trouble just getting into a position where it could have utilized it’s underwater sprint speed, or it’s fancy torpedo reloading system.
A submarine that was designed to stay underwater for weeks at a time required a far better habitability than the Type XXI offered if it’s crew is to remain effective. It’s not necessarily a matter of internal space, but of poor design and engineering; interconnecting the drinking and wash water systems is just plain stupid and asking for trouble with communicable diseases among the crew. There’s no getting around the fact that despite the hype that German sources put out about the Type XXI, it was simply NOT the war-winning design they wanted.
Looks like this Blair author is not worth wasting ones time over. Heres another assesment.
http://www.ibiblio.org/hyperwar/USN/rep/ASW-51/ASW-8.html
http://www.ibiblio.org/hyperwar/USN/rep/ASW-51/ASW-7.html
http://www.ibiblio.org/hyperwar/USN/rep/ASW-51/ASW-14.html
Remember that at most 1/3 of the UBoats had schnorkels in this last period and yet there is a sharp decline in kills from air.
Looks like schnorkeling and high underwater speeds had huge impact on WW-II technology ASW campaign. AS the other poster pointed out Type XX-I was rushed into service and only a couple actually were operational. Most problems with production was due to the actual end war situation and allied air dominance. The few patrols with Type XX-III seem to have been successful despite the fact their commanders and crew were new.
According to Rossler “The UBoat”, Their was a plan to upgrade the type VII uboat fleet by installing Schnorkel ; removing the guns and ammo bunkers streamling conning tower plus closing off some of the flooding slits. Combined that should have increased underwater sprint speed to ~ 12 knots and triple the battery capacity. Further the same sprint increase could have been achieved just by changing the properller to ‘variable pitch’ linked to RPM of the generator. In any case this was not done since it would delay the production of the Type XXI too much.
As Blair is the only historian to date to publish a book after meticulous research into both German and Allied records of every phase of the U-boat war and was himself a submariner during WW II, and his work is heavily footnoted, I’ll put my faith in Blair rather than Sternhill and Thorndike
German records show that nearly every operational u-boat from the fall of 1944 on had received the snorkel modification. Aircraft kills of U-boats declined during this period because the U-boats avoided the areas of heaviest air patrols and because there were simply far fewer U-boats going on war patrol
On the contrary, the patrols of the two Type XXI U-boats were failures compared to the hopes that were placed in them by the Germans. Their impact on Allied ASW technology was minimal and most telling, post-war submarine technology, except for hull streamlining, was not influenced by the Type XXI. The Type XXI’s were rushed into service, but this was responsible for only a few of the problems which plagued them, such as the poor welding that caused failure of the hulls. The other very real problems were simply due to poor design and engineering.
There were far more problems with the obsolete Type VII boats than just a lack of hull streamlining. Removing their deck guns and ammo magazines (not “bunkers”) would have helped marginally, but plating over the flooding ports would have caused extreme problems with the time it took to dive, something the German U-boat command took very seriously. Increasing the battery capacity would have entailed cutting down on the number of torpedoes carried, or the amount of diesel fuel, either of which would have reduced the time available on patrol. Increasing the underwater sprint speed of the Type VII to 12 knots, a matter of 3-4 knots, wouldn’t have made much difference because by the end of the war the minimum top speed of Allied escorts had been increased to a 20-knot standard.
You need to read Rosslers The UBoat then, since its considered by most to be the bible on German Uboats and more importantly its from a German using German sources. There is a basic rule of thumb in these types of historical research. Every writer is biased! So you can’t trust an american book on German Uboats to be better than a German book on the same subject matter.Like most people I’ll stick with German sources on their armaments etc !
Rossler shows in late 1943 140 schnorkeling units had been ordered but up to April of 1944 schnorkels had been installed on only 25 operational Uboats and by the summer this had increased to about 40 operational boats.Thats out of an total force of about 450 boats. According to OHara, ****son & Worth front line boat inventory ranged from 130-170 during 1944 and into 1945. Maybe by the end of the war most of the Type VII had schnorkels installed.
Rossler reports the schnorkel speed of the intial model to be 5-6 knots but by the end of the war a new prototype “Oelfken” type Schnorkel was begining to be installed that allowed schnorkel speeds of up to 10-11knots. I gather from Rosslers book, the Type XXIII regularly achieved schnorkel speeds of 10 knots or more. When the Uboats adopted Schnorkeling they spent the bulk of their transit time schnorkelling, which meant their was no need for rapid dive of the early period. Since life inside these boats was grim anyway they tolerated the discomfort of deisel fumes, rather than being exposed to deadly allied airpower.
BTW since most Uboat attacks in the second half of the war found they rearly got a second shot at torpedoe shots, the reduction of the Type VII from 14-10 reserve torpedos was meaningless. This is also why most designs of future Uboats in the 1943/44 period featured 6-8 bow torpedos and even investigated the midship torpedo tubes as well , boosting the TT to 12 in some cases.
Further if you study further you’d see that underwater dash speeds of even 10 knots cut ballistic ASW attacks effectiveness 1/2 of attacks on 7 knot submerged boats. Getting upto 12-14 knots submerged sprint speed would boost this to 1/3 ASW effectiveness. If they could get 16 knots that should boost this reduction to 1/4. By 19-20 knots submerged speed of the next generation boats to replace the Type VII, their is no point in ballistic ASW since the effectiveness would be around 1/10th.
This is your standard tactic of attacking any book that wasn’t written by a German and it is BS.
Blair spent nine years studying the writings of Jurgen Rowher, Gunther Hessler, and, of course, Karl Donitz. He had full access to the war diaries Of German Naval Headquarters, various U-boat Headquarters, and the surviving patrol reports all the U-boats. He enjoyed the collaboration of Horst Bredow, the director of the Stiftung Traditionsarchive Unterseeboote. Blair’s research is meticulous and comprehensive to the point of being boring. Blair is generally noted as the dean of submarine historians and his writings are anything but biased. Before you attack Blair, I suggest you read both Volumes of his “Hitler’s U-boat War”, something you obviously haven’t done.
I see this claim many times and always think it is a little ironic
“Originally posted by ubc”
You need to read Rosslers The UBoat then, since its considered by most to be the bible on German Uboats and more importantly its from a German using German sources. There is a basic rule of thumb in these types of historical research. Every writer is biased! So you can’t trust an american book on German Uboats to be better than a German book on the same subject matter.Like most people I’ll stick with German sources on their armaments etc !
So every writer is biased and you seem to be implying that a non German writer will ‘Downrate’ the effectiveness of the U Boats.
By your very statement though that ‘All writers are biased’ you imply that a German writer is no better as they would ‘Uprate’ the effectiveness of the U Boats.
Maybe we should be looking for writers from Non Combatant countries for our war historys then as they can not be classed as biased due to not being on the winning or losing side.