The Type VII was a class of medium attack U-boats built for Nazi Germany'sScript error: No such module "Lang". from 1935 to 1945. Designed for attacking the North Atlantic convoy lanes, they formed the backbone ot the German effort in the Battle of the Atlantic during World War II. The Type VII came in several variants, apart from four types Type VIIA, Type VIIB, Type VIIC and Type VIIC/41, which were each time improvements of the previous version, there was also a mine laying version Type VIID and a torpedo supply U-boat Type VIIF.
After the defeat in World War I, the Treaty of Versailles forbade Germany to build submarines. Germany circumvented the treaty by setting up the Dutch dummy company NV Ingenieurskantoor voor Scheepsbouw Den Haag (I.v.S) which continued to design submarines. Based on the World War I design of the Type UB III and its never-built successors Type UF and Type UG, IVS designed the Vetehinen-class submarine and in 1931 built three submarines in Finland. Already in 1933 the Reichsmarine wanted to start the construction of a Template:Cvt medium attack U-boat, capable of operating in the North Atlantic. Parts were produced, but Hitler held back assembly not wanting to offend Great-Britain with an open breach of the Versailles treaty. The first orders for Type VII U-boats were only given in January 1935, well before Hitler openly renounced the Versailles treaty in March 1935.Template:Sfn This breach of the Versailles treaty was officialized with Great-Britain in the Anglo-German Naval Agreement, where Germany promised to limit the total tonnage of German U-boats to 45% of total tonnage of British submarines.Template:Sfn
The Type VII was designed a single hull submarine, meaning that the outer hull was also the pressure hull. Although there were saddle tanks, all fuel was stored within the pressure hull, which reduced significantly the risk of oil leaks in case of depth charge attacks. The saddle tanks contained only diving and trimming tanks. The main ballast tank was also located within the pressure hull, and more diving tanks were added outboard in the bow and stern which resulted in a very short diving time of 30 seconds.Template:SfnTemplate:Sfn The deck casing streamlined the pressure hull at the bow and stern.Template:Sfn
Type VII submarines were the most widely used U-boats of the war and were the most produced submarine class in history,Template:Sfn with 709 built.Template:Sfn
Armament
All Type VII U-boats were armed with four bow and one stern torpedo tubes. Five torpedoes were carried in the tubes; in the forward torpedo compartment four extra torpedoes were stored below the inner deck and two more were either suspended by chains or stored in cradles sideways. There was no aft torpedo room; the aft torpedo tube was located in the electrical engine compartment with one reload stored below deck between the two electrical engines. An extra spare torpedo was carried externally in a watertight container. There were torpedo hatches fore and aft through which torpedoes could be reloaded at harbour, but it was also possible to take on these external spares at sea through these two hatches, by mounting a collapsible trough and a tripod. When taking on spares, the U-boat was very vulnerable and this could therefore only be done in low-risk areas.Template:Sfn
At the start of the U-boat buidling program in 1935, the Germans were allowed to build only a limited number of U-boats and they could not afford to build specialized minelaying U-boats. Instead they developped sea mines that could be laid by any U-boat through the torpedo tubes. A TMA moored mine which could be laid in waters with a depth of maximum Template:Cvt, had a length of Template:Cvt and each internal torpedo could be substuted for two SMA mines. The TMB ground mine had a length of Template:Cvt so that for each torpedo, three TMB's could be loaded. In November 1939 a heavier TMC ground mine with a length of Template:Cvt came into service. At the beginning of the war, a Type VII U-boat would typically load eight TMA or twelve TMB in its torpedo tubes on a minelaying mission, and then continue its patrol with the spare torpedoes.Template:Sfn
The Type VII mounted a Template:Convert quick-firing deck gun.Template:Sfn This gun was intended for finishing off sinking ships, so that torpedoes could be economized. The gun could also be used in the beginning of the war to give stop sign to ships under the prize law. A U-boat was very vulnerable at the surface and not fit for gun duels as a single hit on the pressure hull could render it unfit to dive. From the end of 1942 onwards, the deck gun was removed to save weight for extra anti-aircraft guns.Template:Sfn
As a defense against aircraft, Type VII U-boats received one 2 cm C/30 anti-aircraft gun which was mounted on a platform at the back of the conning tower. By mid 1942 Allied aircraft attacks had become so frequent that an upgrade was needed. The platform was enlarged so that more guns could be mounted and a second platform was added behind and below the first one. A more powerful gun was needed but as intermediate solution, only an improved 2 cm gun the C/38 was available. This gun was more reliable and had a slightly increased rate of fire. The intention was to install two twin mountings on the higher platform and one quad mounting on the lower platform, but if not sufficient such mountings were available, single C/38 were installed instead. The first single C/38 were installed in mid-January 1943 and the first quad mounting in March. The first twin mountings became available on 15 June and were standard by October. On 30 June 1943 U-boats were ordered to delay their sailings until they had received an anti-aircraft gun upgrade. The 2 cm gun proved to be too weak, a heavier gun was needed but the existing 3.7 cm SK C/30 was not adequate and a naval version of the 3.7 cm Flak 43 was only ready for standard installation by November 1943. It replaced the quadruple 2 cm on the lower platform. There were some experiments with other anti-aircraft configurations, but these were not standardized as with the arrival of the Submarine snorkel the solution to avoid aircraft was to remain submerged.Template:SfnTemplate:Sfn
Ten Type VIIA boats were built between 1935 and 1937 in two batches: six at Deschimag AG Weser in Bremen and four at Friedrich Krupp Germaniawerft, Kiel.Template:Sfn The first Type VIIA was laid down on 11 November 1935, launched on 24 June 1936 and commisioned on 12 August 1936.Template:Sfn Six were lost in action, two were lost in accidents in the Baltic sea and the remaining two were scuttled on 4 May 1945.Template:Sfn
After evaluating and comparing the commissioned Type I and Type VII U-boats, the Template:Langr asked for an improved version of the Type VII which would be named Type VIIB. Four requirements were formulated: a smaller turning circle, better surface speed, larger range and more torpedoes. Manoeuvrability was improved by installing one rudder in line with each of the two propellers so that the wash of the propeller had much more effect on the rudder. This change fitted well with another requirement of improved armament and reserve torpedo capacity. The external stern torpedo tube could now be mounted within the pressure hull, between the two rudders. The internal tube allowed for reloading and for firing on the surface. One spare torpedo for the stern tube was carried internally and two more spare torpedoes, one below the forward deck and one below the afterdeck, were stored externally in pressure-tight containers.Template:SfnTemplate:Sfn
To improve the range, the hull was extended by Template:Cvt to increase the internal fuel storage, and saddle tanks with Template:Cvt of fuel added Template:Convert of range at Template:Convert. With the installation of saddle tanks, the advantage of having all fuel stored internally within the pressure hull, and hence avoiding the risk of oil leaks when the outer skin was damaged, was lost.Template:Sfn
Two types of diesel engines were installed in the Type VIIB : the first one was the same MAN M6V40/46 used in the Type VIIA, the second one was the near identical Germaniawerft F46. Power output of these engines was increased by installing superchargers. On the MAN engine the compressor of the supercharger was driven by exhaust gasses and power increased to Template:Convert. The Germaniawerft diesel had a compressor driven by the shaft of the engine itself, and delivered Template:Convert in total.Template:SfnTemplate:Sfn MAN powered U-boats reached a top speed of Template:Convert, with Germaniawerft diesels top speed was Template:Convert.Template:SfnTemplate:Sfn Some of the Type VIIB had the same Brown, Boveri & Cie GG UB 720/8 electric motors, others had the AEG GU 460/8-276, which was identical to the former.Template:SfnTemplate:Sfn
The Type VIIB was a very satisfactory design, but when a sonar needed to be installed, extra room had to be created by adding a full frame section of Template:Cvt in the control room, resulting in the Type VIIC. The extra weight reduced speed marginally, and the extra space in the saddle tanks was not used for fuel but for an extra buoyancy tank. One of the electrical air compressors was replaced by a Template:Langr diesel-powered air compressor in order to reduce the demands on the electrical systems of the U-boat.Template:Sfn
For submerged propulsion, electric motors were produced by four enterprises to the same design, and they had identical performance : the AEG GU 460/8-276 and BBC GG UB 720/8 which were already installed in previous types, and the Template:Langr RP 137/c or Template:Langr (SSW) GU 343/38-8.Template:Sfn
In 1941 it was examined how U-boats could be improved. A first requirement for higher surface speed could not be met without large modifications to the design. A new design would disrupt current production of U-boats too much, so it was investigated how the diving depth could be increased. By saving Template:Cvt weight on simpler diesel and electric engine installations, the weight of the hull could be augmented with Template:Cvt By increasing the thickness of the hull from Template:Cvt to Template:Cvt mm, diving depth increased by 20%. The bow was extended by Template:Cvt in order to improve seaworthiness. This improved design was called Type VIIC/41.Template:SfnTemplate:Sfn
The first TypeVIIC/41 were ordered on 14 October 1941 by instructing the yards to convert existing but not yet laid down orders of TypeVIIC to the new design.Template:Sfn The first TypeVIIC/41 Template:GS was delivered on 25 August 1943.Template:Sfn On 30 September 1943 it was decided to stop laying down new TypeVIIC/41 U-boats in order to free up space for the newer types of U-boats, the Elektroboote. Only the small Flender Werke yard was allowed to continue since it could not build the new, bigger U-boats. In this small yard the last TypeVIIC/41 Template:GS was laid down on 28 January 1944 and commissioned in January 1945. A total of 88 were commissioned.Template:Sfn All TypeVIIC/41 from Template:GS onwards lacked the fittings to handle mines.Template:Sfn The only preserved Type VII U-boat is the VIIC/41Template:GS that is on display at the Laboe Naval Memorial.Template:Sfn
Type VIIC/42
The greatest danger for a submerged U-boat was to be detected by Sonar. By coating the outer hull of a U-boat with rubber anechoic tiles, it was hoped that the acoustic waves of the sonar would be absorbed rather than reflected. During 1941, tests with the rubber coating were conducted with Template:GS, but these tests were disappointing and the project was abandoned. The only solution left was to increase once more the diving depth by using thicker steel for the pressure hull. The steel rolling equipment at the builders yard limited the maximum thickness to Template:Cvt. The weight of the hull increased from Template:Cvt to Template:Cvt needing an increase from Template:Cvt to Template:Cvt in beam, in order to create more buoyancy. The saddle tanks were also enlarged so that range increased to Template:Convert. The maximum speed of Template:Convert of a Type VIIC proved to be insufficient for keeping in touch with the enemy during convoy battles and an increase in top speed was also required. The same diesel engines were used, but the hull was lengthened by Template:Convert to provide space for superchargers for the diesels. With the additional power, it was hoped speed would increase to Template:Convert.Template:Sfn
Even before the design was finalized on 10 November 1942, a preliminary order of 12 boats had already been placed. By 17 April 1943 174 boats had been ordered from twelve shipbuilding yards, but due to problems with producing the new steel alloy for the reinforced pressure hull, construction was slow to start. Assembly at the yards had not yet started when all orders were cancelled on 24 July 1943 in favor of the new Type XXI.Template:Sfn
Type VIIC/43
Early in 1943 it became obvious that operations during convoy battles demanded a better armament with a higher number of ready-to-fire torpedo tubes rather than fewer torpedo tubes with more reloads. During convoy battles an attacking U-boat rarely got the occasion to withdraw to reload and attack again. Therefore a new design VIIC/43 was made based on the Type VIIC/42 but with six bow torpedo tubes and two at the stern. But as the new deep-diving U-boats were urgently needed at the front, it was decided on 11 May 1943 to cancel this project as it would delay production of the Type VIIC/41 and VIIC/42.Template:SfnTemplate:Sfn
Type VIID
At the beginning of World War II, there were four large Type XB minelayers under construction, intended for laying anchored SMA mines in distant waters. Any type of U-boat could lay TMB ground mines through torpedo tubes but still there was a need for a medium sized U-boat able to lay SMA mines on British and French coasts. In order to fill this gap, the Type VIIC was developed into a Type VIID SMA minelayer by simply adding a Template:Convert section with five mineshafts between the control room and the crew compartment of the petty officers. As the saddle tanks also covered the extra section, the fuel storage and range increased considerably. Six boats were ordered on 16 February 1940, and the first was laid down on 1 October 1940.Template:Sfn The six Type VIID U-boats were in service in early 1942, but the SMA mine had not yet been cleared for front usage. As the Type VIID had kept the same offensive capacities as their Type VIIC sisterships, they were used for regular combat patrols, where they could benefit from their extra range.Template:Sfn
Type VIIE
The Type VIIE was a project for trying out new lightweight Deutz V12 two-stroke diesel engines in a Type VIIC. The idea was again to try to save weight so that extra weight could go to the pressure hull. This project remained a design as this new engine was delayed and finally abandoned before any construction had started.Template:SfnTemplate:Sfn
Type VIIF
Up to mid-1941 it had been possible to provide U-boats with spare torpedoes through surface supply ships at remote locations. But after the sinking of the German battleshipScript error: No such module "WPSHIPS utilities".Script error: No such module "Check for unknown parameters". in May 1941 all supply ships were hunted down. Towards the end of 1941 attempts to resupply from the German auxiliary cruiser Atlantis ended in disaster when both the auxiliary cruiser and its supply ship Python were sunk by a British cruiser. The Type XIV supply boats were intended for fuel resupply and carried only four spare torpedoes. The large Type XB minelayer was also scheduled to be used as a supply boat but could carry only nine spares. Designing a whole new large torpedo transporter would eat away much resources both from the planning department and the shipbuilding yards, so the simplest and best idea was add an extra compartment to a Type VIIC, just like had been done before for the Type VIID minelayer.Template:Sfn The extra compartment measured Template:Convert and had an extra torpedo hatch to load twentyTemplate:Efn torpedoes, which were stored in four banks.Template:Sfn
The Type VIIF had the same engines as the Type VIIC, but was with Template:Cvt much heavier. With a more streamlined hull than the Type VIID, she did not loose much speed however. Just like with the Type VIID, the saddle tanks ran along the extra compartment and provided extra fuel and range up to Template:Convert.Template:Sfn
On 22 August 1941 four Type VIIF were ordered, with expected delivery beginning of 1943.Template:Sfn When these four boats entered service in early 1943, it was no longer realistic to use them in their intended role as Allied air power made supply missions in the battle zones too dangerous. Instead the boats were used to supply remote bases in Norway, and two were sent to resupply the Monsun Gruppe in Penang, Malaysia.Template:Sfn
In foreign service
File:U570 capture.jpgThe capturing of U-570, which was commisioned in the royal navy as HMS GraphOn 27 Augustus 1941 Aircraft surprised U-570 on the surface south of Iceland. Damaged by depth-charges the U-boat was unable to escape further attack and surrendered. British ships took the U-boat in tow to Iceland where she was beached. U-570 was repaired and entered service as Template:HMS with the Royal Navy on 31 October 1941.Template:Sfn
On 1 May 1942 Template:GS was heavily damaged by aircraft East of Gibraltar. She limped into the neutral Spanish port of Cartagena, Spain. She was allowed three months for repairs by the Spanish authorities but the U-boat could not be repaired in time and was finally sold to Spain where she entered service as S01.Template:Sfn
Template:GS was decommissioned on 20 August 1944, and disabled on 15 September 1944 in the port of La Pallice when the port fell to Allied forces. She was declared a war prize, repaired and recommissioned in the French Navy as Laubie.Template:Sfn
On the Schichau-Werke yard in Gdańsk, the Russians laid down at least three Type VIIC/41 with parts intended for the German U-1174, U-1176 and U-1177. Possibly also some Type VIIC/42 were built here.Template:Sfn
