Magnetic Anomaly Detection

As early as 1917, alternatives to the detection of submarines by hydrophones were being studied. One such area for consideration was the use of magnetism. In 1918 the U.S experimentally tried a ship towed magnetic detection device. This device was found to have too limited a detection range and also suffered from the presence of the magnetic signature of the towing ship. For the time being, magnetic detection was abandoned as impractical.
With the outbreak of WW II, renewed interest occurred in alternative detection systems for anti-submarine warfare. For aircraft there was a pressing need to devise a means for them to be able to detect a submerged submarine. One of the devices that received renewed attention was the use of magnetic anomaly detection.
As early as 1941 magnetic detection devices (which measure changes in the Earth's magnetic field) had been developed in both Britain and the U.S. The first airborne use of these devices was in U.S. K type blimps. This was followed by much wider installation of MAD devices in ASW patrol aircraft. By 1943 most ASW aircraft were equipped with MAD.
Initially, the U.S. thought that MAD would be a primary means of detecting submerged submarines. In use MAD was found to be a system of limited usefulness. This was due to its very limited range and, its inability to distinguish between sources of magnetic variance. Frequently, wrecks or local magnetic disturbances were classified as submarines. This was particularly true earlier in the war before experience with the system had discovered its limitations.
By late war, MAD in combination with sonobuoys proved more useful. In combination, MAD allowed an aircraft to localize a contact made with sonobuoys and, the sonobuoys provided confirmation that the contact was, indeed, a submarine. In this combination MAD became the secondary system to the sonobuoy, the reverse of what was originally expected and it double the threat for a u-boat.
Source:www.uboat.net,with necessary changes.

Web Design

1. Navigation
When people come to our website they are generally looking for something that special.Example: recipe for a low diet, healthy and look for it and prepare it for less than a few minutes or what is the best business to start online. No matter what visitors want, we must have an answer for that. So ask yourself, why people come to our website? When we find out then we should make it easy for them find what they are looking for.
2. Graphics
If we run a professional site, and do not use graphics / pictures are fun, so do not expect people will want to linger on our website. People have come to seek information. Not to click on an ad or have their brain scrambled. Make your website a pleasant environment for visitors to enjoy. Think about when you go to the mall. We want to get a clean shop, which is prepared, have a great customer service and product that is being sought. Your website should reflect this. If there is what we expect in it like the shopping experience, visitors will enjoy what they are looking for on our website.
3. Color
Color is an individual choice, but studies show that color has an influence on the public's emotions. If we have a financial investment location, choose a conservative color. Or if we sell the material the beach, then choose soft colors.
4. About Us
People usually want to know basic things before they do business with us. Who we are, how they get a hold of us, what our product guarantee or warranty, when they will get the product, and others. We must answer these questions to create trust between us and potential customers.
5.Sitemap
Suppose we have a lot of resources and pages or products. A sitemap helps visitors to find what they're looking for quickly without having to search the entire site. This is especially useful for large sites, because it helps search engines to know what you are about very quickly.
6. Rapid loading
Nothing worse than a slow loading web pages. We can optimize your graphics for the website. People hate to wait. You can check the load time of pages and pages belonging to the Alexa.Com. Slow pages equal death to an online business.
7. Shopping Cart
If you are selling items or services, we need something that can be organized well and can trusted.We see some websites have a lot of products to register and email for reservations. What a nightmare! Yes, shopping carts will charge you a fee, but it is worth it to handle the transaction. There are many shopping carts available and we will research them based on business needs.
8.Templates or Original Design
People often think that to have a website designed is going to cost thousands. So they opt for the templates and arrange the location. There is nothing wrong with this approach except I can tell the difference between what I call "canned" site and that was created from scratch. While I do not think a website that uses templates will reduce the visitors, we think may not be appealing.
 9.Customer Service
Ok,and therefore how the customer service of a website designed? well, customer service should be writing our location. From the tips, free reports, collateral, to speed up and shop . People want to know a lot about what we are talking about and send their goods and guaranteed we will get ten times that.

ASDIC

ASDIC / Sonar

ASDIC, developed through the work of the Anti-submarine Detection Investigation Committee , from which its name is derived, was the primary underwater detection device used by Allied escorts throughout the war.
The first versions, crude to say the least, were created near the end of World War One and further developed in the following years by the Royal Navy.

How it works

The ASDIC, known to the Americans as Sonar, was basically a transmitter-receiver sending out a highly directional sound wave through the water. If the sound wave struck a submerged object it was reflected back and picked up by the receiver. The length of the time from transmission until the echo was received was used to measure the range, which was shown as a flickering light on the range scale. By mounting the transmitter head so that it could be directed almost like a searchlight, the bearing of the target could be read from the compass receiver.
The transmitter (sound) head extended beneath the ship, and was encased in a large metal done to minimize the noise of the water rushing past the ship while at moderate speed. This dome was filled with water, through which the sound passed, although this water was stationary and acted almost like a bumper. Noise level remained relatively low at moderate speeds, but anything above 18 knots resulted in too much noise and good contacts were difficult to find. The same results also resulted from bad weather when the ships were rolling, pitching and heaving.

The search pattern

During screening operations the ASDIC operator searched through an arc of roughly 45 degrees each side of the base course of the vessel. The ASDIC had to be stopped at regular intervals on this arc long enough to allow the relatively slow underwater sound waves to return should they locate a submerged target. Normally the head would be stopped on a bearing and a sound pulse would be transmitted, which would be heard as a "ping" noise. If no echo was received after several seconds the head would be rotated a few degrees (usually 5) and the process repeated throughout the watch.
If the outgoing impulse stuck a submerged target the echo would be heard as a distinct "beep". If this occurred the ASDIC operator would sound the alarm, feed the range and bearing to the bridge and then immediately start left and right cuts to try to determine the width of the target and trying to see if it was moving from one side to another. He could also determine if the target was closing or opening the range.
Echoes would bounce back from many things besides the U-boats such as whales, schools of fish, vertical sea currents and ship's wakes. This caused many false alarms, especially with the inexperienced operators. The veteran operator was much better at figuring out these bad signals and hunting down the intended target. The commanding officers quickly learned which operators were reliable.
Another problem was that often a real U-boat could not be detected due to water conditions. ASDIC was not very reliable in rough water, nor when layers of different temperature deflected the sound waves. U-boats could dive beneath such layers to avoid detection. Modern submarines use this tactic to this day.

ASDIC in a passive role

The device could also be used to listen as well as pinging. The propeller noises of the U-boat would sometimes be heard as well as its operation of various machinery and its use of compressed air in the ballast tanks to change depths. This was not very usual as one of the standard German tactics, when located, was to dive deep, rig for silent running and hide beneath a thermal layer at speeds slow enough to eliminate any cavitation from the propellers.

The attack

When the U-boat was located the attacking vessel would rush directly towards contact, usually at the speed of 15 knots. This run was used to determine the final movements of the target and further plot the final attack. The attacking vessel had to very sure where the boat was and estimate where it would be when the depth charges (or Hedgehogs) would reach its depth. Thus the attacking vessel would have to take a lead on the U-boat much as a hunter does on a bird. At 500 yards the allied commander hoped to know what the U-boat was doing and then he finalized his attack.
As the range closed the U-boat would pass under the beam of the ASDIC and be lost to the escort. The deeper the U-boat was the longer the range of the lost contact and thus more difficult to attack accurately. Normally a good and firm contact was lost at 300 yards. This did not affect the forward-throwing Hedgehogs as much as the depth charges.
Even if the attack was delivered with the correct lead angle and firing time there was no guarantee of damage to the U-boat since its depth could differ from the settings at which the depth charges were set to explode. The correct depth of the U-boat could only be guessed or estimated based on the range at which contact was lost.

U-boat's evasive maneuvers

The U-boats of course used tactics to evade the depth charges and Hedgehogs. The best time to act was when the attacking vessel had taken its lead angle and the ASDIC contact was just lost.
A very common German move was to run away from the escort and force it on a stern chase pinging through the wake of the U-boat which could give the ASDIC a hard time. Then at the moment of the ASDIC loosing contact the U-boat took a radical turn to left or right and more often than nor escaped out of the attacking pattern.
Another one was to turn radically with great power and disturb the water in order to confuse the ASDIC sometimes causing the attacker to be shaken off. The Germans also often released chemical pellets, which would produce clouds of bubbles to reflect the sound waves of the ASDIC.
Yet another tactic was to dive very deep and under a thermal layer or beneath the depth at which depth charges were normally set to explode. From 1942 onwards depths of 200 meters (600 feet) were not uncommon in an evasive tactic.

Source : www.uboat.net ,with necessary change.

The Deck guns

        
               The 88mm deck gun of Type VIIC boat U-486 seen in front of the tower.

The German U-boats of types I, VII, IX and X had a very powerful secondary weapon which was the deck gun. Each boat had one in front of the conning tower and with a good crew they could fire 15-18 rounds a minute. Often used to finish off damaged vessels or sink smaller ships the gun normally had a crew of 3 to 5 and was usually commanded by the second watch officer (IIWO).

                         
                                                Close-up of the 88mm deck gun.

In order to use the weapon the U-boat had to be on the surface naturally and it was normally not used when aircraft were suspected to be around. It required a line of men (3 which on the deck) to transport the ammunition from the main locker below the control room to the gun. The used rounds were taken back into the boat. The U-boats had a small water-proof ammunition locker for the gun on the deck in order to be able to start firing almost immediately when the order was given.
The smaller Type II coastal U-boats had no deck gun.
In 1937 plans were drawn up for type XI U-boat cruisers. Those huge boats would have had 4 pieces of 12,7cm guns in two separate towers. They were not built (see our "U-boat projects and proposals" page).

The 8,8cm gun

The type VII U-boats had the 8,8cm gun. This weapon is not to be confused with the famous German Army 8,8 anti-tank / anti-aircraft gun which was probably the best weapon of the war, they did not even use the same ammunition. The 8,8cm gun fired a 12-14 kilogram round (9kg warhead), on board were usually 250 rounds. From June 1943 the Atlantic-boats left their bases without the deck gun. Only in the Mediterranean and the Northern Sea boats kept their guns for a few months longer. In July 1944 some of the VIIC boats from the 8th Flotilla in Königsberg got their guns back for the patrols in the Baltic Sea against the Russians.
The 88mm naval deck gun was not capable of anti-aircraft fire since its maximum elevation was only 30 degrees.

The 10,5cm gun

The much wider deck of the larger I, IX, and X U-boats could accomidate the much more powerful 10,5cm/45 gun than 8,8 cm /45 on the narrow deck of the VII boats. These larger boats normally had 110 rounds of ammunition, although the IXD variant had 150 rounds, and one boat, the U-196, had 240 rounds.

The crew of U-124 during a drill.

Examples of use

Few commanders used the deck gun with better results than Reinhard Hardegen of U-123 did on his first 2 missions off the American coast in early 1942. His boat was of type IXB and thus had the larger 10,5cm version of the gun.

U-123 during a deck gun attack, note the merchant ship ahead.

The crews had some problems using the guns. There were several instances of barrel detonations, which killed or wounded some crew members. Often the reason was that the gun crew forgot to take away the muzzle protector from the gun - resulting in cartoon like blown up barrel if the gun gun was fired like that.
Sometimes the gun was used to shell shore-based targets like in the Caribbean where they fired at various installations like oil storage's and alike or in the Northern Sea where they damaged some radio stations. An excellent hit was landed by U-242 on 10 Oct, 1944 when it shot down a Russian aircraft with her 8,8cm deck gun!
19 Apr, 1942 In the Caribbean Sea U-130, under Korvkpt. Ernst Kals, successfully bombarded the oil refinery and storage on Curacao with his 105mm deck gun.
18 Sept, 1943 In the Northern Sea U-711, under Kptlt. Hans-Günther Lange, destroyed with the 8,8cm gun the Russian radio station "Pravdyi" near by the town Indiga, approx. 68.00N, 49.00E.
24 Sep, 1943 U-711 destroyed a few days later the Russian radio station "Blagopolncija" on the east of the island of Waigatsch, approx. 70.00N, 60.00E.

The end of the deck guns

After the massive anti-submarine build-up by the allies in 1942 and 1943 the deck guns were removed from almost all the boats in 1943 and 1944. A few commanders were allowed to retain them though, esp. the ones who commanded the boats in the Indian Ocean (the Monsun boats). But, in effect, from 1943 the deck gun was, for most boats, a thing of the past.

Source : www.uboat.net ,with necessary change.

The Electroboats

The Origins and Development of The Wonder U-boat

                               
                                       Type XXI Elektro boats after the surrender.

In the very last moments of the Second World War new U-boats, based on a completely new concept, saw action. Had they arrived earlier, they might have changed the outcome of the Battle of the Atlantic and more. The concept itself inspired the submarine design for the next two decades. Even more, the hull design of one of the Electroboats was adopted and used in the development of the world first nuclear submarine.

1. Origins

The development of the German U-boat fleet in 1935-39 was based entirely on the First World War principles. However, it had already been known that England was in possession of the underwater location device ASDIC(Anti Submarine Detection Investigate Comitee) which was to counter the submarine threat. Not surprisingly, the Second World War started with great speculations about the effectiveness of the U-boats.
Soon it had become apparent, that ASDIC was not so effective as claimed and certainly it was of no use against a surfaced U-boat. And it was a surfaced group attack at night, known as Rudeltaktik, that proved itself so lethal to convoys. Without a surface location device the escorts were not able to see a narrow silhouette of the surfaced U-boat at night or in bad weather. The same applied to aircraft.
The U-boat training programme was adopted to the principle of Rudeltaktik. The emphasis was on the skills of the commander and crew as it was believed that the experience was the main decisive factor in the battle.
The technical development was somewhat left behind. Doenitz got acquainted with Professor Walter and was quite impressed with the idea of a closed circle engine. Such an engine required no air intake and therefore could run when a submarine was submerged and at the same offered enough power to achieve speed around 25 knots. The idea was further developed and in 1940 the prototype V80 indeed travelled submerged at the speed of 26 knots! Therefore, the concept was regarded as the right answer for the need of high underwater speed. The amount of technical difficulties made it clear that it would take a long time to convert the prototype into an ocean-going attack U-boat. At that time, however, no one seemed to be worried as the conventional U-boats still enjoyed a high rate of success when operating on the surface at night.
However, there were early warnings that this situation might change dramatically. On the pitch black night 30th November - 1st December 1941 while attempting to penetrate the Straits of Gibraltar, U-96 was accurately located and bombed by the radar-equipped Sqdn. 812 Swordfish. Her commander, Heinrich Lehmann-Willenbrock, insisted that the aircraft must have been using a new location device. In spite of the fact this statement was made by one of the most experienced U-boat commanders, no one believed it was the case. In particular, no one believed an accurate radar set can be so small, it could fit in an aircraft.
Another warning came also in December 1941. It was the convoy battle around HG-76. The convoy was protected by an aggressive support group including an aircraft carrier,  lead by an ASW expert, Capt. Walker. Although a total of 14 U-boats were assembled in the area, only 5 ships were sunk at a cost of 4 U-boats directly involved in the operation (U-131, U-434, U-574 and U-567). A shocking exchange rate which later became normal. In fact a few more were sunk in the area at the same time. U-567 was commanded by Engelbert Endrass, an experienced Knight Cross Holder, while other boats by relatively inexperienced commanders. BdU was convinced that the success was entirely depending on the experience of attacking U-boats. This is why when Doenitz was sending Endrass, in whom he had great confidence, he had also signalled: "Hold on to that convoy. I'm sending Endrass". In vain.
There were a few more warnings. It was clearly demonstrated that with the arrival of the radar-equipped aircraft and escorts, especially when put together in a support group with a carrier, the conventional U-boats may achieve nothing but heavy losses. Unfortunately for the Germans, these warnings were not taken into consideration serious enough to affect the development plans for new U-boats, their weapons and electronic equipment. It was almost a year later, when the loses in the North Atlantic convoy battles became alarmingly high, when something finally happened.
November 1942 was the best month in the in terms of tonnage sunk during the U-boat War. The majority of sinkings happened along the North Atlantic convoy routes, in the so-called Atlantic Gap, out of the reach of land-based Allied aircraft. U-boats returned to the North Atlantic in the second half of 1942, when gradually stronger US anti-submarine forces made operations in the Western Atlantic and the Caribbean impossible. However, the British had enough time to increase the number of escorts, aircraft and develop new techniques. The Germans also increased the number of U-boats and in the second half of 1942 on average a hundred were at sea every day. All these factors inevitably lead to fierce convoy battles of previously unknown proportions.

2. Development

The scope of the November 1942 meeting was to examine the progress of the Walter U-boat which was the only possible solution to the situation that developed in the North Atlantic. Although the Walter concept and the first prototype V80 initially demonstrated remarkable performance, it had also delivered a whole range of new technical problems. These were particularly related to fuel required by the closed circle Walter engine - highly flammable Perhydrol. Due to the high rate of Perhydrol consumption a combat Walter U-boat would require a massive fuel tank, otherwise the underwater performance would not be satisfactory. The existing hull designs could not offer adequate fuel bunkerage. Therefore, Professor Walter presented a new double-hull design, forming a figure 8 in section. The upper part accommodated the crew, engines and torpedoes. The lower part used entirely as a fuel tank. The design was later known as Type XVIII.
However, it became clear that in spite of the advanced planning, the new Walter U-boat was not going to be operational in any foreseeable future. Moreover, any prospect on the Walter project would require a diversion of the shipyard resources from Type VII and IX building, which was at that time out of question. Therefore, it was decided to carry on the Walter projects but still on a limited research scale.
The meeting would end up in disappointment if it was not 2 engineers, Schuerer and Broecking, who realized a very simple solution, utilizing the new Walter hull design. Instead of using the lower section for Perhydrol, the idea was to install additional batteries there. This would effectively triple the battery capacity of the boat. Initial calculations showed that the performance of the new concept is far better than of the conventional U-boat, although not as good as of the Walter one. This however fully satisfied Doenitz and the development went ahead. The only problem was that the displacement of the boat was around 1600 tons - and at that time smaller boats around 1000 tons were preferred as much easier too handle and more resistant to depth-charges.
By the end of January 1943 detailed theoretical calculations were finished and by the end of June 1943 a preliminary design was completed. The following are the the most important features of the Type XXI design:

• Displacement of 1620 tons
• Streamlined hull with 6 forward torpedo tubes
• Full submerged speed of 18 knots for 1.5 hours
• Submerged speed of 12-14 knots for 10 hours
• Silent submerged speed of 5 knots for 60 hours
• Water-pressure controlled depth keeping equipment
• Semi-automatic hydrolic torpedo reload system
• New improved underwater listening device
• Sonar
• Radar-search receivers (to detect enemy radar)
• Radar
• Deep freezer
• No deck gun
• No external torpedo storage containers
• Schnorkel

The Type XXI design was presented to Hitler at a conference on the 8th July 1943 in order to obtain his approval for additional demands on the industry. The approval was given and on 13th August 1943 an order was given for the transition to building Electroboats. At the same time the building programme of the conventional boats was to be carried on, in order to make up for the expected losses till the arrival of new boats. The development of Walter boat was to continue, and in addition to 4 prototypes being built and order for additional 24 Type XVIIB and 2 Type XVIII boats was given.
Together with the development of Type XXI work had started on a small Electroboat for coastal operation. The large Electroboat was initially supposed to replace Type IX boats but after the May 1943 disaster it was obvious that it should also replace Type VII convoy attack boat. However, because of the size, Type XXI boat was not suitable for shallow water operations, particularly the North Sea, Black Sea and the Mediterranean. Therefore, a small Electroboat was proposed with the following features:

• displacement of 234 tons
• streamlined hull with 2 forward torpedo tubes (torpedoes in the tubes, no reloads)
• full submerged speed of 12 knots
• new improved underwater listening device
• easy to control
• Schnorkel

The plans for the small Electroboat, Type XXIII, were presented together with Type XXI and got approved.
Author could not positively established wether the Schnorkel was the inherent part of the Electroboat design from the very beginning or was added later, after experience was gained from the heavy losses in the first part of 1943. Certainly, Schnorkel was studied and added to the Walter U-boat concept at about that time. However, whenever the Schnorkel was considered, the final design of both Electroboats were equipped with the most modern telescopic device and were able to use it at much greater speeds than conventional Schnorkel U-boats.
A detailed production plan was worked out between July and December 1943.
At least 18 months were required to build a Type XXI U-boat under a conventional construction procedure (with boats built from start to finish on a single slip). This effectively meant that prototypes would be ready only in November 1944 and regular production boats would be ready for operational use in 1946. This was not acceptable.
Therefore the Minister for Armaments, Albert Speer, decided to consult the matter with Otto Merker, with experience in the mass production gained in the car industry. Eventually, an alternative production method was proposed with the following assumption:

• no prototypes
• pre-fabricated sections manufactured in parallel, in distributed works around the country
• sections to be transported to the shipyard by water (big Type XXI sections) or rail (smaller Type XXIII sections)
• final assembly of sections at the shipyard

The detailed building plan for the Type XXI consisted of the following stages:

acquisition of raw materials and transport to steel works	16 days
steel work	40 days
transport to the section building plant	5 days
section building	50 days
transport to the yard	4 days
assembly at the yard	50 days
final work after launching	6 days
total building time per boat	171 days (6 months)

The method eliminated the bottleneck caused by the limited shipyard resources. Instead of occupying a slip for the entire building process (18 months mentioned) it was required only for approximately 80 days of final completion (as it turned out to be). Hence the shipyard building effectiveness was multiplied by almost 7.
The following are the detailed descriptions of Type XXI and XXIII sections.

Type XXI section description

Section	description	weight (tons)	length (meters)
1	Stern with stern compartment	65	12.7
2	Electric motor room	130	10
3	Diesel engine room	140	8.4
4	Aft living quarters	70	5.3
5	Control room and galley	140	7.6
6	Forward living quarters	165	12
7	Torpedo stowage room	92	6.8
8	Bows with torpedo tubes	110	14
9	Conning tower superstructure		14.1

Type XXIII section description

Section	description	weight (tons)	length (meters)
1	Stern, steering installation, silent speed motor, gearing	11.5	9.2
2	Main engines and motors	14	6
3	Control room, forward living quarters (part)	18	7.5
4	Bows with torpedo tubes, forward living quarters (part)	16.25	10

On 30 September 1943 the building of some already obsolete boats was stopped (selected boats were already stopped on the 10th July). Subsequently, these boats were cancelled on the 6th November 1943 (the majority) or later (some particular boats). This applied to all Type VII C/42 boats and selected Type VII C/41, IX C/40, IX D/42, XVII B and XVII G boats.
Also, on the 6th November 1943 a final order for the construction of Type XXI boats was submitted to the following 3 shipyards:

Blohm & Voss, Hamburg	130 U-boats (U-2501 onwards)
Deschimag AG Weser, Bremen	87 U-boats (U-3001 onwards)
Schichau, Danzig (Gdansk)	70 U-boats (U-3501 onwards)

An order for the construction of Type XXIII boats was submitted slightly earlier, on 20th September 1943 to Deutsche Werft AG, Hamburg (U-2321 onwards) and later on 7th July 1944 to Germaniawerft, Kiel (U-2332-3, U-4701 onwards).
It is interesting to note that there had been some preliminary orders for Type submitted earlier, to other shipyards (e.g. order dated 6th July 1943 to Deutsche Werft AG for 24 Type XXI boats, cancelled on 30th September 1943).
From February 1944 onwards separate sections became systematically available. The first Electroboat to be laid down was a Type XXIII boat U-2321 on 10th March 1944. She was launched on the 17th April (after 38 days in the yard) and commissioned on 12th June 1944. The first Type XXI boat to be laid down was U-2501on 3rd April 1944. She was launched on 12th May 1944 (well ahead of the schedule) and commissioned on 27th June 1944.
The commission progress of Type XXI and XXIII boats is presented below:

Electroboat commission progress

Time	Type XXI	Type XXIII
June 1944	1	1
July 1944	3	3
August 1944	7	4
September 1944	8	6
October 1944	12	4
November 1944	13	7
December 1944	20	6
January 1945	22	12
February 1945	11	7
March 1945	18	6
April 1945	4	4
May 1945	-	1
Total	119	61

Type XXI commission progress

Time	Blohm&Voss	AG Weser	Schichau	Total
June 1944	1		-	1
July 1944	1	1	1	3
August 1944	3	3	1	7
September 1944	5	1	2	8
October 1944	6	3	3	12
November 1944	6	3	4	13
December 1944	6	6	8	20
January 1945	5	11	6	22
February 1945	5	6	-	11
March 1945	6	7	5	18
April 1945	4			4
May 1945				-
Total	48	41	30	119

Type XXIII commission progress

Time	Deutsche Werft AG	Germaniawerft	Total
June 1944	1	-	1
July 1944	3	-	3
August 1944	4	-	4
September 1944	6	-	6
October 1944	4	-	4
November 1944	6	1	7
December 1944	5	1	6
January 1945	9	3	12
February 1945	4	3	7
March 1945	3	3	6
April 1945	3	1	4
May 1945	-	1	1
Total	48	13	61

It is interesting to compare the technical data of both types of Electroboat and The Type XVIIB Walter U-boat:

	Type XXI	Type XXIII	Type XVIIB
Displacement surfaced (tons)	1621	232	312
Displacement submerged	1819	256	345
Dimensions (meters) - length	76.7	34.1	40.9
beam	6.6	3.0	3.4
draught	6.3	3.7	4.7
Machinery	2-shaft 6-cylinder MAN diesel/electric motors 4500/5000 bhp/shp silent speed electric motors 226 shp	1-shaft 6-cylinder MWM diesel 576 bhp AEG main electric motor 580 shp BBC silent speed electric motor 35 shp	Walter single-shaft turbines 2500 shp 8-cylinder Deutz diesel motor 210 bhp electric motor 77 shp
Fuel Capacity (tons)	250	18	75 (Perhydrol)
Batteries		62 double-cell 2x21MAL 740 E/23 5400Ah	4560 Ah
Maximum speed (knots) - surfaced	15.5	10.0	8.5
submerged	17.0	12.5	21.5 Walter 4.5 electric
max schnorkel speed		10.75
max silent speed		4.5
Endurance (miles) - max surfaced	15,500 @ 10 knots	4,450 @ 6 knots
surfaced	11,500 @ 12 knots	2,600 @ 8 knots	3,000 @ 8 knots
max sustained surfaced	5,100 @ 15.5 knots	1,350 @ 10 knots
max schnorkel endurance		3100 @ 6 knots
Endurance (miles) - max submerged	365 @ 5 knots	194 @ 4 knots
submerged	110 @ 10 knots	43 @ 10 knots	150 @ 20 knots
max sustained submerged		21 @ 12 knots	40 @ 4.5 knots electric
Diving depth - safe
Diving depth - max
Armament	6 bow tubes 23 torpedoes 2 twin 20 cm AA (3cm on later models)	2 bow tubes 2 torpedoes no guns	2 bow tubes 4 torpedoes no guns
Crew	57	14	19

It is important to remember that although the Walter U-boat possessed greater maximum speed and range, it was only of single use. Once the Perhydrol fuel was burn out, the boat could only bank on the conventional diesel-electric propulsion. The Electroboats could always recharge the batteries and therefore could benefit from the high underwater speed many times. On the other hand, the maximum speed was needed only for an attack - and with just 2 torpedoes the Walter U-boat indeed could practically attack only once. But having an ability to sprint away in the event of danger is always an advantage in the submarine warfare and therefore the Electroboats offered steady safety in comparison to the Walter ones.

3. Getting ready

The initial trials with the first available Type XXIs showed that the theoretical performance was almost met. The full submerged speed was slightly lower (17 instead of 18 knots) and could be maintained for a shorter time (60-80 minutes instead of 100). Overall, the performance was outstanding and offered much better prospects for attacking convoys and evading escorts than conventional U-boats.
At the silent submerged cruising speed the Type XXI had to schnorkel for only 3 hours a day to keep the batteries charged. This speed of 5 knots with a range of 365 miles meant that a U-boat would pass the dangerous waters between Norway and Iceland in 5 days schnorkeling shortly only 5 times. The radar-search receiver Tunis fitted to schnorkel and anti-radar rubber coating offered additional safety. Even when located, an alteration of speed and course would help to evade escorts or aircraft-dropped sonar buoys. When escaping at high speed, the Type XXI was almost as fast as most of the Allied escorts and bubbling of water rushing along the hull would make ASDIC location difficult. The potential area where a hunted Type XXI, escaping at the silent speed of 5 knots, would be forced to raise the schnorkel again was some 10-13 times greater than an area for conventional U-boat (escaping at 2 knots with a range of 100 miles). With the existing anti-submarine forces search abilities a chance for a kill was therefore greatly reduced.
The attack tactics was based on the following principles:

• location of a convoy by the listening device
• high-speed approach to the convoy
• penetration of the escort screen at silent speed and maximum depth
• getting underneath the convoy
• collecting firing data for the LUT looping torpedoes by echo-ranging
• firing spreads of torpedoes in order to cover the whole convoy

Special equipment was provided to facilitate the tactics, in particular a special echo-ranging plotting-table and an echo-ranging data converter which automatically calculated and set torpedo firing parameters. Due to the quick reload mechanism the Type XXI would need only one convoy encounter to fire all the torpedoes.
The preparation of the battle instructions for Electroboats was an interactive process with constant feedback and verification coming from the training units. The final battle instructions were written by experienced commanders: Erich Topp (for the Type XXI) and Carl Emmermann (for the Type XXIII). Others contributed though, among them Emil Klusmeier who later volunteered for a command in order to verify his ideas in practice and with U-2336 scored hits.
Although the first Type XXI was launched almost on time, the Electroboat building programme was eventually delayed by various means and the planned production figures had not been met. The following is the summary and status at the end of the war:

	Type XXI	Type XXIII
Planned for delivery by 1/05/45	381	95
Not produced because of the internal organization defects	202	13
Not produced because of Allied bombing on shipyards	60	19
Commissioned	119	61
Destroyed after commission  (trials, training, transit)	20	2
Training, fitting-out or on trials	86	38
Almost ready for combat	12	15
Fully ready for combat	1	6

The failure to achieve the objectives was mainly caused by organization troubles, faulty design and bad workmanship. It was particularly annoying, when sections did not fit to each other because the specified tolerances were exceeded. All these took place mainly in the first half of 1944 and was fixed in the second half of the year. At that time, however, the Allies realized the danger and started regular bombing raids, particularly on shipyards and water transport installations (needed for transportation of massive Type XXI sections).

Training for the new boats

Further delay in the project was caused by the extended training required for crews. The complexity of the design and new tactics meant that 6-7 months of training was required instead of usual 3-3.5 needed for conventional U-boats. Moreover, the training facilities were affected by the Allies actions, particularly the mining of the Bay of Danzig, the primary trial and training waters. The first mines were laid on 26/7 August 1944 by Bomber Command and continued regularly that eventually lead to the total abandoning of the area. The trials and tests were moved to the Bay of Luebeck which was much inferior, particularly because the area was within the range of Coastal Command.
The disruption of training caused that the Type XXI boats with practically one exception could not became fully operational in early 1945. Also, a number of boats that almost finished their training and awaited transfer to the Norwegian bases were lost in the dangerous Bay of Luebeck.

Operational Type XXI boats

The following Type XXI U-boats were almost ready for operations (on passage or in the operational bases, undergoing final preparations):

Place	Flotilla	Boat	Commander
in transit	11th Flotilla Bergen	U-2503 *	Oblt Raimund Tiesler
Bergen	11th Flotilla Bergen	U-2506	Kptlt Horst von Schroeter
Bergen	5th Flotilla Kiel	U-3514	Oblt Guenther Fritze
Stavanger	4th Flotilla Sttetin	U-3035	Oblt Ernst-August Gerke
Kristiansand	31st Flotilla Hamburg	U-2529	Kptlt Fritz Kalipke
Horten	11th Flotilla Bergen	U-2502	Kptlt Heinz Franke
Horten	11th Flotilla Bergen	U-2513	Korvkpt Erich Topp
Horten	11th Flotilla Bergen	U-2518	Kptlt Friedrich Weidner
Horten	4th Flotilla Sttetin	U-3017	Oblt Rudolf Lindschau
Horten	4th Flotilla Sttetin	U-3041	Kptlt Hans Hornkohl
Horten	5th Flotilla Kiel	U-3515	Oblt Fedor Kuscher
Wilhelmshaven	11th Flotilla Bergen	U-3008	Kptlt. Helmut Manseck

* U-2503 was badly damaged by aircraft on 3rd May 1945 and later scuttled.
The following was the only one Type XXI U-boat fully ready for operations at the end of the war:

Bergen

11th Flotilla Bergen

U-2511

Korvkpt Adalbert Schnee

It is sometimes reported that U-3008 also was ready for operations. She indeed sailed from Wilhelmshaven on 3rd May 1945, when the artillery bombardment was already heard. The U-boat may probably been supposed to call in one of the Norwegian ports for final provisioning before the patrol. In the North Sea, shortly after the order to surrender which was issued on 4th May 1945, she encountered a convoy, made a pass under it and sailed away undetected.

First war patrol by type XXI boat, the U-2511

U-2511, with a crack crew, sailed from Kiel on 16 March 1945 for the Norwegian base Horten in Norway. The war patrol was supposed to start on 26 March, but during deep dive test she sustained a periscope damage and was delayed. She sailed from Horten on the 18 April she was forced to put to Bergen on 21 April, due to diesel troubles. At last she sailed on 30 April 1945 with the orders to go to the Caribbean.
The first contact with the enemy was made on 1 May. On the following day U-2511 was detected by an escort group north of Scotland but easily got away with the increased underwater speed. She evaded other ships, too, as her objective was to get to the operation area first. Depth-charges were dropped but were helplessly wide. Soon after receiving the surrender message on 4 May 1945, U-2511 detected a Suffolk class cruiser, HMS Norfolk, with destroyer escort at a long range. She made a text-book approach, closing at high-speed first, then diving deep and passing the destroyer screen at silent-speed. Finally, Schnee had the cruiser in sights 500 meters away with a perfect attacking position inside the destroyer screen and undetected - impossible  to miss. U-2511 did not fire but dived deep again, and still undetected returned to base, arriving at Bergen on 5 May 1945.

4. Aftermath

What may be a sort of surprise is that the technology used in the design was by no means new. To characterize the concept, the following 3 features should be listed:

1. streamlined hull
2. snorchel
3. huge battery capacity

The benefits of the streamlined hull had been known long before the era of Electroboats. In fact, the very first submarines including original Holland's vessel were more streamlined than their WW1 and WW2 successors. Schnorchel was developed in the 30's by the Dutch, but the concept was known to the others. Adding more battery capacity is just a matter of space, not technology.
Therefore, it should be noted that the technology used for Electroboats was actually available already in the 30's. Why it was not exploited? There was no need to do so as long as the U-boat was safer and performed better on the surface at night than under the surface. This was clearly demonstrated in the first few years of the U-boat War. Only when the relative safety of staying on the surface was taken away by radar and aircraft, the German Naval High Command started looking for an alternative solution.
The reason for the late introduction of Electroboats should be primarily related to the underestimation of radar technology. In this particular field the Germans were significantly behind England. Had the German radar technology been more advanced, it would have probably been realized that it was just a matter of time before the small silhouette of the surfaced U-boat was indeed big enough for the radar to be located. And then the Electroboats could have come earlier.
Also, outstanding was the production process of the Electroboats, particularly the larger one. It was one of the few examples of the implementation of mass-production principle by the German industry during the Second World War. Of course, this too was affected by the Allied bombing, but the final number of commissioned Electroboats should be regarded as high. It is again a kind of surprise that the mass-production concept was not adopted earlier, particularly for the conventional U-boat production. A high number of conventional U-boats in the second half 1941, when the British counter-measures were not fully developed yet, instead of 1942, certainly would have made a difference.
The experience of U-2511 clearly demonstrates the outstanding performance of the Type XXI and  it is certain, that the Allied navies had no ready answer to the new threat. The operations of the Type XXIII constitute yet another proof of the fighting qualities of the Electroboats. Had the Allied progress on land been slower, the Type XXI U-boats might have appeared in numbers great enough to paralyze the Atlantic communication routes, even in spite of the increased bombing of production and training facilities.

Electro boat diary:

November 1942	The birth of the Electroboat idea
January 1943	Theoretical calculations finished
June 1943	Design completed
July 1943	Project approved
September 1943	Conventional U-boat building programme limited
November 1943	Orders placed
December 1943	Production design completed
30 April 1944	First Type XXIII launched (U-2321)
12 May 1944	First Type XXI launched (U-2501)
12 June 1944	First Type XXIII commissioned (U-2321)
27 June 1944	First Type XXI commissioned (U-2501)
August 1944	First aerial mines in the Bay of Danzig
29 January 1945	First Type XXIII sailed on war patrol (U-2324)
February 1945	Testing and training transferred to the Bay of Luebeck
14 February 1945	First success by an Electroboat (U-2322)
30 April 1945	First Type XXI sailed on war patrol (U-2511)
7 May 1945	Last success of an Electroboat and in the war (U-2336)

 Source : www.uboat.net ,with necessary change.

The Focke-Wulf Fw 200 Condor

An Fw 200C-8 with FuG 200 Hohentwiel Radar

On 27 July 1937 a new and graceful aircraft made its first flight, from the airfield of Neuenlander. The pilot was the designer of the aircraft, Kurt Tank, and the aircraft was the Fw 200 Condor. It belonged to a new generation of four-engined, long distance transports and/or scout.
The Condor had been designed for the Deutsche Lufthansa, which wanted a airliner for a route to South America. Its high aspect ratio, long-span wing was characteristic of long-range aircraft, sail planes, and the Condor bird that the aircraft was named after. Its modern, flush-riveted light alloy construction aimed for maximum efficiency. With four Pratt & Whitney Hornet S1E-G engines, later replaced by BMW 132L engines (licence-built Hornets) and up to 4360 liters of fuel the Condor was intended to fly 26 passengers over long distances. That it could do so was demonstrated in August 1938 by a flight from Berlin to New York in 20 hours, non-stop. Later that year a Fw 200 flew to Tokyo, with three stops, in 46 hours.
Production began in 1938 with the Fw 200A-0 transports. One of them became Hitler's personal aircraft, D-2600 Immelmann III. Other aircraft went to the Lufthansa, the Condor Syndicate (a German-owned airline in South America), and the Danish DDL. Focke-Wulf followed up with the more powerful, heavier Fw 200B and the Fw 200D that had even more fuel. But meanwhile, the Condor was developed in another direction.
The Imperial Japanese Navy had expressed an interest in a long-range reconnaissance version of the Condor. Tank modified a Fw 200B-1 to create the Fw 200V10 prototype, with more fuel, three machine guns, a short ventral gondola with fore-and-aft gunner positions, and a lot of additional equipment. It was never delivered to its customer. In 1939 the Luftwaffe decided that the Fw 200 could meet its own requirement for a long-range maritime reconnaissance aircraft, and instructed Focke-Wulf to develop the Fw 200V10 into a more robust aircraft with a bomb-carrying capacity.
The answer was the Fw 200C, with some modest structural reinforcements, improved cowlings containing 850hp BMW 132H-1 engines with three-bladed propellers, and bomb crutches on the wings. A longer ventral gondola, with a bomb bay, was planned but not fitted to the first production aircraft. When fitted, the gondola, which was offset to starboard, housed a 20mm MG FF cannon in front and a 7.9mm MG 15 machine gun aft. Another MG 15 was in a position above and behind the cockpit, and one in a dorsal position. The bomb capacity was 250kg in the gondola, two 250kg bombs under the outboard engine nacelles, and two more under the outer wing panels. The aircraft had a five-man crew.
The Fw 200s were delivered to Kampfgruppe 40, which from June 1940 operated from Bordeaux-Merignac. Systematic anti-shipping operations began in August. Flights lead over the Bay of Biscay, around Ireland, and ended in Norway. The sinking of 90,000 tons of shipping was claimed in the first two months, and 363,000 tons by February 1941. Churchill called it the "Scourge of the Atlantic".

An Fw 200C-1

But the Fw 200C-1 made itself very unpopular by breaking its back on landings. At least eight Fw 200Cs were lost when the fuselage broke, just aft of the wing. Obviously, the strength of the airframe was insufficient to cope with the additional weight and stress. The Fw 200C was always an improvised combat aircraft, with many deficiencies. The crews also complained about inadequate armament and an vulnerable fuel system.
The Fw 200C-3 introduced some more reinforcements, although still insufficient, a gun turret to replace the fairing above the cockpit, two beam guns, an increase in bomb load, and an additional crew member. It also had 1200hp BMW 323-R2 engines to compensate for the weight increase. Soon a number of variations in armament appeared, as the MG FF and MG 15 were replaced by far more powerful 15mm and 20mm MG 151 cannon, or the 13mm MG 131. With these changes, the later Condors were very well armed.
For offensive purposes the Fw 200C was equipped with the low-altitude Revi bombsight, or the Lofte 7D sight for attacks from between 3500m and 4000m. Radar appeared, on the Fw 200C-4, in the form of Rostock or Hohentwiel anti-shipping radars. These modifications increased the weight and reduced the speed. the max level speed of the Fw 200C-4 was a very unimpressive 330km/h at 4800m, down to 280km/h at sea level. The speed of 450km/h was not be exceeded, and brusque evasive manoeuvres could results in structural failures. Endurance was 14 hours, for a range of about 3860km, or 18 hours if additional fuel tanks were carried instead of bombs, and cruising speeds were around 250km/h. The common bomb load on long-range missions was just four 250kg bombs.
In mid-1941 a change of tactics occurred. The Fw 200 crews were now instructed not to attack, and to evade all combat unless unavoidable. The Condors were used to report allied shipping movements. To guide the U-boats to the convoys they shadowed they transmitted direction finding signal, but they did not directly communicate with the submarines. This was a more effective use of the available numbers, and it also helped to conserve the aircraft: Production was low, and some Fw 200s were diverted to other roles, notably VIP transports. But worse was to come. On 20 September 1941 a Condor was lost when it attacked a convoy escorted by HMS Audacity, the first escort carrier. During the second voyage of the carrier, four Condors were shot down. Although the Audacity was primitive, and soon sunk by U-751, it announced the beginning of the end. The vulnerable Condor was increasingly confronted by enemy fighters, based on catapult-equipped merchant ships (CAM ships), merchant ships with small flight decks (MAC ships), or small escort carriers.
In 1943 the Condors were recalled to be used as transports on the Eastern front, during the Battle of Stalingrad. They later returned to the Atlantic coast, but only a few continued to serve as maritime reconnaissance aircraft. In this role, the Condor was now being replaced by the Ju 290. The Fw 200s returned to anti-shipping strikes. For this purpose, the Fw 200C-6 and C-8 were equipped with the Henschel Hs 293A anti-ship missile, but the type's career was clearly over. The Condor served until the end of the war, but mainly as a transport aircraft.
Production ceased in early 1944, after the Luftwaffe had received 263 out of a total production of 276.

Specifications

Focke-Wulf Fw 200C-3/U4 :Four 1200hp BMW-Bramo 323R-2 Fafnir nine-cylinder radial engines

Wing span	:32.84m,length 23.46m,height 6.30m, wing area 118m2.
Empty weight	:12950kg, max take-off weight 22700kg.
Max. speed	:360km/h at 4800m, 306km/h at sea level.
Range	:3556km with standard fuel, 4440km with overload fuel.
Service ceiling	:5800m.
Armament:	:Forward dorsal Fw 19 turret with a 7.9mm MG 15   machine gun, 13mm MG 131 machine gun in aft dorsal position, two MG 131 guns in beam positions, one 20mm MG 151/20 cannon in front of the ventral gondola, and one MG 15 in the aft section of the gondola.
Maximum bomb load	:2100kg: two 500kg, two 250kg and two 50kg bombs.

Sources

• Incidental Combattant, by Ken Wixey, in Air Enthusiast No.66 and 67.
• Wings of the Luftwaffe, by Capt. Eric Brown, published by Pilot Press, 1977.
• The Encyclopedia of German Military Aircraft, by Brian Philpott, published by Arms and Armour Press, 1980.
• www.uboat.net

Depth Charges

The depth charge is the oldest anti-submarine weapon, being developed during World War One. Original idea dates back to the "dropping mine" concept of 1911. The Royal Navy Commander in Chief, Sir George Callaghan requested its production in 1914. The first effective depth charge (Type D) was the 300-pound (140 kg) barrel-like casing containing high explosives, normally TNT being developed in 1916. A "pistol" actuated by water pressure at a selected depth detonated the depth charge.
                                                                                        A K-gun just before firing
The 300-pound WWI depth charge could be detonated as deep as 300 feet (roughly 100 meters) but at the eve of that was the more formidable 600-pound (270 kg) version was developed.

                                                                           A depth charge in flight after being fired from a K-gun

The first means of delivery was to simply roll the "barrels" of a special rack at the stern of the escort vessel. Eventually a special depth-charge projector or "K-guns" were developed. These could, by means of an explosive propellant charge, hurl the depth charges out to the side of the escorts for a distance of roughly 50 meters.

When the K-guns and the stern charges were used together that enabled he escort to lay a pattern of 9 or 10 charges onto the suspected U-boat's position.

Even though the massive explosive power of the 600-pound charge was impressive to both the escort and the U-boat, highly unnerving to the later even, the depth charge was not the answer to the U-boat threat. The pressure hull of the U-boat was strong enough to withstand anything but a charge exploding 10 or 20 feet from its hull. To place the weapon this close to the U-boat was extremely difficult to say the least, especially since the U-boat normally took drastic evasive maneuvers at the very last moment. Thus most U-boats that were sunk by depth charges alone probably sank due to accumulated damage from repeated depth charge attacks. Many U-boats survived as many as 300 depth charges over a period of many hours.

In 1943, Torpex with a 50% more powerful explosive than TNT, was introduced along with a more streamlined depth charge casing that resulted in an improved sinking rate and speed of the weapon. This was of course an improvement yet a great deal of U-boats escaped its grasp.
The more appropriate answers to the U-boat threat were the "Hedgehog" forward-throwing charges and the American Mk. 24 Acoustic Torpedoes known as "Fido".
The greatest amount of depth charges dropped on a single U-boat during a single-hunt in the war is believed to be 678 dropped onto U-427 in April, 1945. Amazingly the boat survived the onslaught.

Source : www.uboat.net ,with necessary change.