Type VII submarine#Type VIIC

The Type VII was based on earlier German submarine designs going back to the World War I Type UB III and especially the cancelled Type UG. The type UG was designed through the Dutch dummy company NV Ingenieurskantoor voor Scheepsbouw Den Haag (I.v.S) to circumvent the limitations of the Treaty of Versailles, and was built by foreign shipyards. The Finnish Vetehinen class also provided some of the basis for the Type VII design.

Type VII submarines were the most widely used U-boats of the war and were the most produced submarine class in history, with 704Westwood (1984), p. 9. built.{{cite web|url=http://www.uboataces.com/uboat-type-vii.shtml

|title=Type VII U-Boat|work=German U-Boat

|publisher=Uboataces.com|access-date=13 February 2010}} The type had several modifications. The Type VII was the most numerous U-boat type to be involved in the Battle of the Atlantic.

Type VIIA U-boats were designed in 1933–34 as the first series of a new generation of attack U-boats.{{cite web|url=http://www.uboat.net/types/viia.htm|title=Type VIIA|last=Helgason|first=Guðmundur|work=U-Boat War in World War II|publisher=Uboat.net|access-date=10 February 2010}} Most Type VIIA U-boats were constructed at Deschimag AG Weser in Bremen with the exception of U-33 through U-36, which were built at Friedrich Krupp Germaniawerft, Kiel. Despite the highly cramped living quarters, type VIIA U-boats were generally popular with their crews because of their fast crash dive speed, which was thought to give them more protection from enemy attacks than bigger, more sluggish types. Also, the smaller boat's lower endurance meant patrols were shorter. They were more heavily armed than the smaller Type II U-boats they replaced, with four bow and one external stern torpedo tubes. Usually carrying 11 torpedoes on board, they were very agile on the surface and mounted the {{convert|8.8|cm|in|adj=on}} quick-firing deck gun with about 220 rounds.

Ten Type VIIA boats were built between 1935 and 1937. All but two Type VIIA U-boats were sunk during World War II (famous Otto Schuhart {{GS|U-29|1936|2}} and {{GS|U-30|1936|2}}, which was the first submarine to sink a ship in World War II, both scuttled in Kupfermühlen Bay on 4 May 1945).

The boat was powered on the surface by two MAN AG, 6-cylinder, 4-stroke M6V 40/46 diesel engines, giving a total of {{convert|2100|to|2310|bhp}} at 470 to 485 rpm. When submerged it was propelled by two Brown, Boveri & Cie (BBC) GG UB 720/8 double-acting electric motors, giving a total of {{convert|750|hp}} at 322 rpm.

The VIIA had limited fuel capacity, so 24 Type VIIB boats were built between 1936 and 1940 with an additional 33 tonnes of fuel in external saddle tanks, which added another {{convert|2500|nmi}} of range at {{convert|10|kn}} surfaced.{{cite web|url=http://www.uboat.net/types/viib.htm|title=Type VIIB|last=Helgason|first=Guðmundur|work=U-Boat War in World War II|publisher=Uboat.net|access-date=13 February 2010}} More powerful engines made them slightly faster than the VIIA. They had two rudders for greater agility. The torpedo armament was improved by moving the aft tube to the inside of the boat. Now an additional aft torpedo could be carried below the deck plating of the aft torpedo room (which also served as the electric motor room) and two watertight compartments under the upper deck could hold two additional torpedoes, giving them a total of 14 torpedoes. The only exception was {{GS|U-83|1940|2}}, which lacked a stern tube and carried only 12 torpedoes.

Type VIIBs included many of the most famous U-boats of World War II, including {{GS|U-48|1939|2}} (the most successful), Günther Prien's {{GS|U-47|1938|2}}, Otto Kretschmer's {{GS|U-99|1940|2}}, and Joachim Schepke's {{GS|U-100|1940|2}}.

On the surface the boat was powered by two supercharged MAN, 6 cylinder 4-stroke M6V 40/46 diesels (except for U-45 to U-50, U-83, U-85, U-87, U-99, U-100, and U-102, which were powered by two supercharged Germaniawerft 6-cylinder 4-stroke F46 diesels) giving a total of {{convert|2800|–|3200|PS|kW|lk=in}} at 470 to 490 rpm. When submerged, the boat was powered by two AEG GU 460/8-276 (except in U-45, U-46, U-49, U-51, U-52, U-54, U-73 to U-76, U-99 and U-100, which retained the BBC motor of the VIIA) electric motors, giving a total of {{convert|750|PS|kW}} at 295 rpm.

File:SRH009-p58.jpg

File:Type VIIc.jpg

File:Type VIIC U-boat schematic drawing.png

The Type VIIC was the workhorse of the German U-boat force, with 568 commissioned from 1940 to 1945. The first VIIC boat commissioned was the {{GS|U-93|1940|2}} in 1940. The Type VIIC was an effective fighting machine and was seen almost everywhere U-boats operated, although its range of only 8,500 nautical miles was not as great as that of the larger Type IX (11,000 nautical miles), severely limiting the time it could spend in the far reaches of the western and southern Atlantic without refueling from a tender or U-boat tanker. The VIIC came into service toward the end of the "First Happy Time"U-boat ace Otto Kretchmer took issue with use of the term "Happy Time." He didn't see how the U-boat war could ever be characterized as having a "Happy Time" when losses of U-boats and crews were running at 50%. (See interview on YouTube.) near the beginning of the war and was still the most numerous type in service when Allied anti-submarine efforts finally defeated the U-boat campaign in late 1943 and 1944.

Type VIIC differed from the VIIB only in the addition of an active sonar and a few minor mechanical improvements, making them 2 feet longer and 8 tons heavier. Speed and range were essentially the same. Many of these boats were fitted with snorkels in 1944 and 1945.

They had the same torpedo tube arrangement as their predecessors, except for {{GS|U-72|1940|2}}, {{GS|U-78|1940|2}}, {{GS|U-80|1941|2}}, {{GS|U-554||2}}, and {{GS|U-555||2}}, which had only two bow tubes, and for {{GS|U-203||2}}, {{GS|U-331||2}}, {{GS|U-351||2}}, {{GS|U-401||2}}, {{GS|U-431||2}}, and {{GS|U-651||2}}, which had no stern tube.

On the surface the boats (except for {{GS|U-88|1941|2}}, {{GS|U-90|1941|2}} and {{GS|U-132|1941|2}} to {{GS|U-136|1941|2}} which used MAN M6V40/46s) were propelled by two supercharged Germaniawerft, 6 cylinder, 4-stroke M6V 40/46 diesels totaling {{convert|2800|to|3200|PS|kW shp|abbr=on}} at 470 to 490 rpm.

For submerged propulsion, several different electric motors were used. Early models used the VIIB configuration of two AEG GU 460/8-276 electric motors, totaling {{convert|750|PS|kW shp|abbr=on}} with a max rpm of 296, while newer boats used two BBC GG UB 720/8, Garbe, Lahmeyer & Co. RP 137/c or Siemens-Schuckert-Werke (SSW) GU 343/38-8 electric motors with the same power output as the AEG motors.

Perhaps the most famous VIIC boat was {{GS|U-96|1940|2}}, featured in the movie Das Boot.

==== U-flak "Flak Traps" ====

The concept of the "U-flak" or "Flak Trap" originated on 31 August 1942, when {{GS|U-256||2}} was seriously damaged by aircraft. Rather than scrap the boat, it was decided to refit her as a heavily armed anti-aircraft boat intended to combat the losses being inflicted by Allied aircraft in the Bay of Biscay. Two 20 mm quadruple Flakvierling mounts and an experimental 37 mm automatic gun were installed on the U-flaks' decks. A battery of 86 mm line-carrying anti-aircraft rockets was tested (similar to a device used by the British in the defense of airfields), but this idea proved unworkable. At times, two additional single 20 mm guns were also mounted. The submarines' limited fuel capacities restricted them to operations only within the Bay of Biscay. Only five torpedoes were carried, preloaded in the tubes, to free up space needed for additional gun crew.

Four VIIC boats were modified for use as surface escorts for U-boats departing and returning to French Atlantic bases. These "U-flak" boats were {{GS|U-441||2}}, {{GS|U-256||2}}, {{GS|U-621||2}}, and {{GS|U-953||2}}. Conversion began on three others ({{GS|U-211||2}}, {{GS|U-263||2}}, and {{GS|U-271||2}}) but none was completed and they were eventually returned to duty as standard VIIC attack boats.

The modified boats became operational in June 1943 and at first appeared to be successful against a surprised Royal Air Force. Hoping that the extra firepower might allow the boats to survive relentless British air attacks in the Bay of Biscay and reach their operational areas, Donitz ordered the boats to cross the bay in groups at maximum speed. The effort earned the Germans about two more months of relative freedom, until the RAF modified their tactics. When a pilot saw that a U-boat was going to fight on the surface, he held off attacking and called in reinforcements. When several aircraft had arrived, they all attacked at once. If the U-boat dived, surface vessels were called to the scene to scour the area with sonar and drop depth charges. The British also began equipping some aircraft with RP-3 rockets that could sink a U-boat with a single hit, finally making it too dangerous for a U-boat to attempt to fight it out on the surface regardless of its armament.{{cite book |last=Busch|first=Harald|title=U-Boats at War|url=https://archive.org/details/uboatsatwar00busc|url-access=registration|publisher=Ballantine Books |location=New York |year=1955}} In November 1943, less than six months after the experiment began, it was discontinued. All U-flaks were converted back to standard attack boats and fitted with Turm 4, the standard anti-aircraft armament for U-boats at the time. (According to German sources, only six aircraft had been shot down by the U-flaks in six missions, three by U-441, and one each by U-256, U-621, and {{GS|U-953||2}}.)

File:U-995 Marineehrenmal Laboe.jpg]]

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 11.5 tons weight on simpler diesel and electric engine installations, the weight of the hull could be augmented with 10 tons. By increasing the thickness of the hull from {{cvt|18.5|mm|in}} to {{cvt|21|mm|in}} 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.{{Sfn|Rössler|2001|pp=155-156}} A total of 87 were delivered.{{Sfn|Rössler|2001|p=160}} All of them from {{GS|U-1271||2}} onwards lacked the fittings to handle mines.

Today one Type VIIC/41 still exists: {{GS|U-995||2}} is on display at Laboe (north of Kiel), the only surviving Type VII in the world.

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, it was hoped that the acoustic waves of the sonar could be absorbed rather than reflected. During 1941 tests with the rubber coating were executed with {{GS|U-67|1940|2}}, 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 {{cvt|28|mm|in}}. The weight of the hull increased from 68.3 tons to 154.3 tons, needing an increase from {{cvt|4.7|m|ftin}} to {{cvt|5|m|ftin}} in beam, in order to create more buoyancy. The saddle tanks were also enlargened so that range increased to {{convert|12600|nmi}}. The maximum speed of 17 knots 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 0.8 m to provide space for superchargers for the diesels. With the additional power, it was hoped speed would increase to 18.6 knots.{{Sfn|Rössler|2001|p=157}}

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.{{Sfn|Rössler|2001|pp=158-160}}

Early in 1943 it became obvious that Operations during convoy battles demanded for 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.{{Sfn|Rössler|2001|pp=160, 234}}

At the beginning of World War II, there were four large Type XB minelayer 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 developped into a Type VIID SMA minelayer by simply adding a {{convert|9.8|m|ftin|abbr=on}} section with five mineshafts between the control room and the crew compartment of the petty officers. As the saddle tanks covered also the extra section, the fuel storage and range increased considerably. Six boats were ordered on 16 February 1940, the first was laid down on 1 October 1940.{{Sfn|Rössler|2001|pp=146-148}}

Up to mid-1941 it had been possible to provide U-boats spare torpedoes through surface supply ships on remote locations. But after the sinking of the German battleship {{ship|German battleship|Bismarck||2}} 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 intendend for fuel resuply and carried only four spare torpedoes. The Big Type XB minelayer was also scheduled to be used as a supply boat but could carry only nine spares. Designing a whole new big torpedo transporter would eat away much resources both from planning and 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. On 22 August 1941 four TypeVIIF were ordered, with expected delivery beginning of 1943.{{Sfn|Rössler|2001|p=162}}

{{Reflist|45em|group=Note}}

{{Reflist|30em}}

• {{cite book |last=Campbell |first=John |title=Naval Weapons of World War Two |location=Annapolis |publisher=Naval Institute Press |year=1985 |isbn=0-87021-459-4 }}
• {{cite book|last1=Gröner|first1=Erich|last2=Jung|first2=Dieter|last3=Maass|first3=Martin|translator-last1=Thomas|translator-first1=Keith|translator-last2=Magowan|translator-first2=Rachel|year=1991|title=German Warships 1815–1945, U-boats and Mine Warfare Vessels|volume=2|location=London|publisher=Conway Maritime Press|isbn=0-85177-593-4|ref={{SfnRef|Gröner|1991}}}}
• Rossler, Eberhard (1981). The U-Boat. Annapolis, Maryland (USA): Naval Institute Press. {{ISBN|0-87021-966-9}}.
• {{Cite book |last=Rössler |first=Gerhard |title=The U-boat : the evolution and technical history of German submarines |date=2001 |publisher=Casell |isbn=0304361208 |location=London}}
• Stern, Robert C. (1991). Type VII U-boats. Annapolis, Maryland (USA): Naval Institute Press. {{ISBN|1-55750-828-3}}.

• {{cite book |last=Nowarra |first=Heinz J. |date=1992 |title=Grey Wolves of the Sea: German U-Boat Type VII |series=Schiffer Military History |volume=63|location=West Chester |publisher=Schiffer Publishing |isbn=0-88740-401-4}}
• {{cite book |last=Showell |first=Jak P. Mallmann |date=2006 |title=The U-boat Century: German Submarine Warfare 1906-2006 |location=London |publisher=Chatham Publishing |isbn=9781861762412}}
• {{cite book |last=Sharpe |first=Peter |date=1998 |title=U-Boat Fact File: Detailed Service Histories of the Submarines Operated by the Kriegsmarine 1935-1945 |location=Leicester |publisher=Midland Publishing |isbn=1-85780-072-9}}
• {{cite magazine |last=van den Pol |first=E. |date=1989 |title=Aspects of submarines - Part I: Some notes on development|magazine=Schip en Werf|location=Rotterdam |publisher=Wyt & Zonen |volume=56|issue=10|issn= 0036-6099|pages=352-358}}
• {{cite book |last=Westwood |first=David |date=1984 |title=The Type VII U-boat |series=Anatomy of the Ships|location=London |publisher=Conway Maritime Press |isbn=0-85177-314-1}}
• {{cite book |last=Williamson |first=Gordon |date=2005 |title=Wolf Pack: The Story of the U-boat in World War II |location=Oxford |publisher=Osprey Publishing |isbn=1-84176-872-3}}

• {{commons-inline}}

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