Type VII submarine

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Type VII U-boats were the most common type of German World War II U-boat. 704 boats were built by the end of the war. The type had several modifications. The Type VII was the most numerous U-boat type to be involved in the Battle of the Atlantic.

The lone surviving example, Template:GS, is on display at the Laboe Naval Memorial located in Laboe, Schleswig-Holstein, Germany.

At the start of the Second World War the Type VII class wasTemplate:Sndtogether with the British U, S and T class and Dutch O 21 classTemplate:Sndone of the most advanced submarine classes in service.Template:Sfn

Design

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

Type VII submarines were the most widely used U-boats of the war and were the most produced submarine class in history, with 704 built.

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

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

Subclasses

Type VIIATemplate:Efn

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. 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

The boat was powered on the surface by two MAN AG, 6-cylinder, 4-stroke M6V40/46 diesel engines, giving a total of Template:Convert. When submerged it was propelled by two Brown, Boveri & Cie (BBC) GG UB 720/8 double-acting electric motors, giving a total of Template:Convert.Template:Sfn

Type VIIB

After evaluating and comparing the commisioned 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 propellor 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

All these changes increased the surface displacement of the Type VIIB with Template:Cvt, but standard displacement rose only from Template:Cvt to Template:Cvt.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 first seven Type VIIB were ordered on 21 November 1936 from Template:Langr, followed by two more on 15 May 1937 and again two more on 16 July 1937.Template:Sfn After the revision of the Anglo-German Naval Agreement, further orders for four Type VIIB were given to Template:Langr, Template:Langr and Template:Langr each.Template:Sfn Template:Langr also built a fifth Type VIIB Template:GS under an export contract but the boat was taken over on 8 August 1938.Template:Sfn It lacked a stern tube.Template:SfnTemplate:SfnTemplate:Sfn A total of twenty-four Type VIIB entered service between 1938 and 1941: twenty were lost at sea and the remaining four were scuttled at the end of the war.Template:Sfn

Type VIIC

File:SRH009-p58.jpg

A cross-section of a Type VIIC U-boat

File:Type VIIc.jpg

Miniature model of a Type VIIC

File:Type VIIC U-boat schematic drawing.png

Detailed drawing of a Type VIIC U-boat

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

They had the same torpedo tube arrangement as their predecessors, except for Template:GS, Template:GS, Template:GS, Template:GS, and Template:GS, which had only two bow tubes, and for Template:GS, Template:GS, Template:GS, Template:GS, Template:GS, and Template:GS, which had no stern tube.Template:Sfn

A few of the early Type VIIC U-boats were equipped with the Template:Convert MAN M6V40/46, which gave a top speed of Template:Convert, others had the Template:Convert Germaniawerft F46 which gave a top speed of Template:Convert.Template:SfnTemplate: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

The first VIIC boat Template:GS was commissioned on 30 July 1940.Template:Sfn

Type VIIC/41

File:U-995 Marineehrenmal Laboe.jpg

Type VIIC/41 U-995. Laboe Naval Memorial

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%. This improved design was called Type VIIC/41; the first were ordered in October 1941, and delivered in August 1943.Template:Sfn A total of 87 were delivered.Template:Sfn All of them 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 enlargened so that range increased to Template:Convert. The maximum speed of Template:Convert of a Type VIIC proved to be unsufficient 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: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 TypeVIIC 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 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 presurre 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 battleship 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

Specifications

Class	VIIATemplate:Sfn	VIIBTemplate:Sfn	VIICTemplate:Sfn	VIIC/41Template:Sfn	VIIC/42Template:Sfn	VIIDTemplate:Sfn	VIIFTemplate:Sfn
Displacement surfaced	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt
Displacement submerged	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt
Length overall	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Length pressure hull	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Beam overall	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Beam pressure hull	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Draft	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Power surfaced (diesel)	Template:Convert	Template:Convert or Template:Convert
Power submerged (Electric)	Template:Convert
Surface speed	16 knots (29.6 km/h; 18.4 mph)	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Submerged speed	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Surface range at 10 knots	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Submerged range at 4 knots	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Maximum operating depth	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Crush depth	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert	Template:Convert
Complement	42–46	44–48	44–52	44–52	44–52	46–52	46–52
Deck gun	8.8 cm SK C35 naval gun, with 220 rounds						none
Anti-aircraft guns	2 cm FlaK 30		Various			2 × 2 cm Flak C30 with 4,380 rounds	3.7 cm Flak, with 1,195 rounds 2 × C30 20 mm, with 4,380 rounds
Bow tubes	4
Stern tubes	1
Torpedoes (maximum)	11	14	14	14	16	14	14 / 34Template:Efn
Mines	22 TMA mines or 33 TMB mines	26 TMA mines				15 SMA mines and either 26 TMA mines or 39 TMB mines	none
Number commissioned	10	24	568	91	0	6	4

References

• Template:Cite magazine