Type VII
Type VII (10 built)
The original ten Type VIIs (often erroneously referred to as a Type VIIA) were grouped into a single flotilla - Saltzwedel - before the outbreak of war. Built by Bremen's AG Weser and Kiel's Germaniwerft and numbered between U27 and U36, the first generation Type VII was a single hull and single ruddered medium sized submarine, with four bow torpedo tubes and a distinctive externally mounted - and thus not reloadable - stern tube. The deck weapon was a quick-firing 8.8cm naval cannon (not to be confused with the more famous '88' of the Army and Luftwaffe with which ammunition was not interchangeable). The design incorporated saddle tanks slung outboard of each flank providing external ballast tanks allowing the heavy hull to be fully surfaced and giving the submarine its characteristic bulges. Above the pressure hull a substantial deck casing was constructed with sleek tapering bow and stern, numerous flooding and drainage holes allowing the free passage of both seawater and compressed air. The interior was divided into six compartments, with internal trim tanks beneath compartments 1 and 6 (Stern and bow torpedo rooms respectively) and the main diving and fuel tanks beneath the control room (compartment 4). But the Type VIIA soon suffered under the exigencies of operational combat. Foundation mountings for the engines often deteriorated rapidly, fracturing and curtailing patrols as boats were forced to return to base. The single rudder resulted in poor underwater manoeuvrability and the stern torpedo tube, the result of only a single rudder below the waterline, was open to the elements leading to frequent malfunction of the stored torpedo when it was used. The gyro angle could not be altered for this single torpedo and the U-boat had to 'point and shoot' - not the easiest way to score success! But despite these deficiencies the Type VII design showed enormous promise. On 11 January 1937 the first two Type VIIs to make an Atlantic voyage departed Wilhelmshaven. U28 was temporarily placed under the command of the veteran Kaptlt Hans-Günther Looff while his brother-in-law Kaptlt Hans Rudolf Rösing, also an experienced submariner and naval officer since 1925, was placed in temporary command of U35 for the planned joint voyage. "This was to be the first time that the boats had been into the Atlantic. I took over from Michahelles, as Dönitz was of the opinion that Michahelles had not enough experience therefore one of the 'old horses' was put in. At that time there was the Spanish Civil war and our two submarines were initially to be sent to the Spanish Civil War, but when we were equipped and fully ready the Spanish war was practically over and so we were sent to the Azores." Their trip later deemed a success by both commanders and their superior Dönitz. "We made the first experiences in really heavy weather. We had a Force 11 to 12 and then we found out what excellent seagoing ships these submarines were. And when it was too wet we could go down and relax. "Of course, as usual, I was seasick. I used to be seasick for the first two days in the cruise. But later on I was okay. Normally I never did anything about it, in the war of course I took medicine." But although Dönitz's favourite design with its excellent balance of size and firepower he was mot blind to its limitations. He later wrote of the Type VIIA: For its size it had the greatest fighting power…Its weakness lay in the fact that it could carry only 67 tons of fuel oil and that its radius of action - 6,200 miles - was too small. Even so, this type seemed to me to come very near to meeting all of our somewhat conflicting demands and I felt that, if by adding only a very little to its size we could materially increase the amount of fuel it could carry and thus give it a greater radius of action, it would become the ideal U-boat for our purposes. My Chief Engineer [Otto] Thedsen came forward with a very practical suggestion. By skilful use of space available in the design as it stood, and by increasing its size by only 17 tons, according to Washington rules, he raised the amount of fuel oil it could carry to 108 tons, thereby giving it a radius of action of 8,700 miles. This became the Type VIIB - 517 tons. When war began in September 1939 the Saltzwedel Flotilla's Type VIIs were at the forefront of combat. The first sinking by U-boat - that of the Athenia - was made by U30, days later the carrier HMS Courageous falling to torpedoes from U29. Indeed the largest ship sunk by U-boat of the Second World War was torpedoed by Kaptlt Hans Jenisch in U32 when he destroyed the already damaged SS Empress of Britain on 28 October 1940. As the battle extended into the Atlantic with the capture of French Atlantic bases, the design's shortcomings became more and more obvious and by the end of 1940 those Type VIIs that remained were relegated to training; six of the ten had been lost in action.
Specifications:
Displacement: 626 tons/745 tons (surfaced/submerged). Submerged - fully loaded and manned - 915 tons.
Length: 64.51 m
Beam: 5.85m
Draught: 4.37m (Keel to Bridge: 9.5m)
Diving depth/Theoretical crush depth: 100m/200m.
Diving Time: 50 seconds (normal); 30 seconds (neutral buoyancy).
Engines:
2 MAN, 6 cylinder, 4-stroke M6V 40/46 diesels totalling 2,100 - 2,310bhp.
Max rpm: 470-485.
Motors:
2 BBC GG UB 720/8 electric motors, totalling 750shp.
Max rpm: 322.
Batteries:
U27, U31-U33, U35, U36: 2 X 62-cell AFA type 27 MAK 740, producing 6940 amp hours.
U28-U30, U34: 2 X 62-cell AFA Type 33 MAL 740, producing 8480 amp hours.
Speed: 16-17kts/8kts (surfaced/submerged)
Range (nm/kts) 6,200/10 surfaced (combined diesel electric drive range 6,800nm@10kts); 73-94/4 submerged.
Armament:
5 X 53.3cm TT (6 reloads, or 22 TMA or 33 TMB mines)
1 X 8.8cm C35/L45deck gun
1 X 2cm C30 AA gun
Crew: 44 (4/40)
Stored boats: One dinghy stowed under forward casing forward of torpedo loading hatch.
Builders: U27-U32 Deschimag, Bremen U33-U36 Germaniawerft, Kiel
Type VIIB (24 built)
As the flaws in the original Type VII became almost immediately apparent work began on an improved design - the Type VIIB, officially named as such on 24 November 1936. The benefits as prescribed by Otto Thedsen were improved underwater turning circle, greater range and an increased weapon load. The reworking of the rudder arrangement, two incorporated into the boat rather than just a single, resulted in the first of these enhancements. Each screw now had its own rudder, doubling the total available rudder area in the process and underwater manoeuvrability increased dramatically. Also, this allowed the installation of an internal stern torpedo with a single reload housed beneath the deking within the aftermost compartment and another stored in a pressure resistant canister between the stern deck and pressure hull. A second canister above the bow torpedo compartment raised the weapon load to fourteen torpedoes: five in tubes with nine reloads in total. The range of the Type VIIB was improved by simply increasing fuel bunkerage. The overall length of the vessel was increased by two metres which allowed a small expansion of the internal fuel tanks. Coupled with this was the installation of a self-compensating fuel bunker within each saddle tank. 'Self-compensating' refers to the fact that the bunker was open to seawater at the bottom, the lighter diesel floating on top of it. As the fuel was consumed it was replaced within the tank by seawater, allowing no air bubbles to form that may upset trim (but also requiring sharp eyes on behalf f the diesel room crew who had to monitor the bunker load and switch tanks before the first sign of seawater entering the system). This increased the amount of fuel that could be taken aboard the boat by 40 m³ and the VIIB's range by over 2,000 nautical miles. Alongside the outboard fuel bunkers (Regelbunkers) were newly installed compensating tanks (Regelzelle) designed to be partially flooded in the manner of normal ballast tanks to reduce the boat's roll as experienced in bad weather in the Type VIA and exacerbated by the increased surface weight of the expanded saddle tanks in the VIIB. Significantly, although the size increase raised the U-boat's surface displacement by 120m³, under the terms of 'Washington tonnage' (i.e. without fuel and supply) the weight increase was only 17-tons - extremely important to Kriegsmarine Fleet planners when still bound by treaty agreements. The final marked improvement was the installation of superchargers to the diesels, improving their performance by 20% and raising the boat's top speed by 1 knot despite the boat's increased weight. The first seven Type VIIBs (numbered consecutively U45 - U51) were ordered from Kiel's Germaniawerft shipyards on 21 November 1936, the keel for U45 laid on 16 February 1937. By 27 April 1938 she was launched, followed by the remaining six of the original order as well four additional boats, all forming the Wegener Flotilla based in Kiel. Renegotiation of the Anglo-German naval Agreement that limited the size of Germany's submarine force had allowed the increased order of Germaniawerft Type VIIBs, as well as further construction in two new U-boat yards: Bremer Vulkan at Vegesack and Lübeck's Flenderwerft. By the outbreak of war in September 1939 eight of the ten boats were ready for action. Within weeks Kaptlt Günther Prien would make his boat, U47, famous with the successful penetration of Scapa Flow and the torpedoing of HMS Royal Oak, an exploit attempted twice during the First World War ending both times in failure and the loss of the U-boats concerned. Indeed the most successful U-boat of the Second World War was a VIIB. U48 sank a total of 54½ ships totalling 320,429 tons under three separate commanders. Likewise, the most successful commander, Otto Kretschmer, captained a Type VIIB U99 until his capture in March 1941 on the same night that another 'Ace' VIIB, Joachim Schepke's U100 was lost with its highly decorated commander.
Specifications:
Displacement: 753 tons/857 tons (surfaced/submerged). Submerged - fully loaded and manned - 1040 tons.
Length: 66.5 m
Beam: 6.2m
Draught: 4.74m (Keel to Bridge: 9.5m)
Diving depth/Theoretical crush depth: 100m/200m.
Diving Time: 30 seconds (normal)
Engines:
2 supercharged MAN, 6 cylinder, 4-stroke M6V 40/46 diesels (except:U45-U50: 2 supercharged 6-cylinder, 4-stroke F46 diesels) totalling 2,800 - 3,200bhp. Max rpm: 470-490.
Motors:
2 AEG GU 460/8-276 electric motors, totalling 750shp. Max rpm: 295.
Batteries:
U45, U47, U51: 2 X 62-cell AFA type 27 MAK 800, producing 7500 amp hours.
U46, U48-U50, U52, U53-U55, U74-U76, U83-U85, U87, U99-U102: 2 X 62-cell AFA 33 MAL 800 W, producing 9160 amp hours.
U73, U86: 2 X 62-cell AFA 33 MAL 800 E, producing 9160 amp hours.
Speed: 17.2 -17.9kts/8kts (surfaced/submerged)
Range (nm/kts) 8,700/10 surfaced (combined diesel electric drive range 9,400nm@10kts); 90/4 submerged.
Armament:
5 X 53.3cm TT - except U83 which had no stern tube - (9 reloads, or 26 TMA or 39 TMB mines)
1 X 8.8cm C35/L45deck gun
1 X 2cm C30 AA gun
Crew: 44 (4/40) Stored boats: One dinghy stowed under forward casing forward of torpedo loading hatch.
Builders:
U45-55, U99-U102 Germaniawerft, Kiel. (These boats had originally been numbered U69-U72 but were redesignated at the outbreak of war to U99-U102 in an attempt to mislead the Allies as to genuine number of operational U-boats)
U73-U76 Vegesackerwrft, Vegesack.
U83-U87 Flnderwerft, Lübeck.
Type VIIC
Arguably the most famous U-Boat type of the Second World War, the Type VIIC came about not through any perceived deficiency in the VIIB design, but by a desire for increased internal space. As production of the VIIB proceeded, a new active sonar S-Gerät (Such Gerät, or Special Apparatus) was nearing projected completion and strongly desired to be fitted within new U-boats. While the VIIB was the perfect weapon for what Dönitz perceived as the backbone of his burgeoning U-boat service, it did not have enough internal space to carry the S-Gerät. Thus was born the Type VIIC. An extra frame was added to the central control room adding 30cm to either side of the periscope housing. This increased space for the new sonar equipment also allowed the conning tower to be enlarged 30cm in length and 6cm in width. Two pressure-tight negative buoyancy tanks (Untertriebzelle), one either flank, were included within the saddle tanks to enable improved diving time in combat by remaining partially flooded. The engines were also upgraded, an oil filtration system introduced to prolong the life of diesel lubricants and increase engine reliability. Also the starboard electrical compressor was replaced by a diesel-powered Junkers model, reducing the strain on the densely packed batteries. Finally, improved AEG-designed knob-switch electrical control system was introduced to replace the archaic BBC knife-switch system used on the VIIB. The first batch of Type VIICs (U93 - U100, although confusingly U99 and U100 were reallocated to VIIB boats, their numerical designation increased to fool the Allies into believeing there were more U-boats than actually were on strength) were ordered from Germaniawerft on 30 May 1938, U93 launched on 8 June 1940. In December 1938 further renegotiating of the Anglo-German naval agreement allowed many more VIIC units to begin construction, before Hitler renounced any intention of abiding by this treaty and the brakes were taken off production orders. By the end of 1939 after war had broken out, 144 additional VIICs were on order, spread between thirteen different shipyards. Ironically the S-Gerät - sole reason for the enhanced design - was deemed unready for installation and the Type VIICs sailed without it. Despite the fact that with the increased size there was no increase in performance, in fact a minor decrease in submerged range, the Type VIIC became the standard design, frequently modified as war progressed, but the firm backbone upon which Dönitz hung all hopes for his assault on the Allied convoy routes.
Specifications:
Displacement: 761 tons/865 tons (surfaced/submerged). Submerged - fully loaded and manned - 1070 tons.
Length: 67.1 m
Beam: 6.2m
Draught: 4.74m (Keel to Bridge: 9.6m)
Diving depth/Theoretical crush depth: 150m/250m
Diving Time: 30 seconds (normal)
Engines: U79-U82, U90, U132-U136: 2 supercharged MAN, 6 cylinder, 4-stroke M6V 40/46 diesels totalling 2,800 - 3,200bhp. Max rpm: 470-490.
All others: 2 supercharged Germaniawerft, 6 cylinder, 4-stroke M6V 40/46 diesels totalling 2,800 - 3,200bhp. Max rpm: 470-490.
Motors:
U69-72, U89, U93-U98, U201-U212, U221-U232, U235-U300, U331-U348, U351-U374, U431-U450, U731-U750, U1051-U1058, U1063, U1068, U1191-U1210: 2 AEG GU 460/8-276 electric motors, totalling 750shp. Max rpm: 296.
U77-82, U88, U90-92, U132-U136, U401, U451, U452, U551-U650, U751, U821-840, U929-U936, U951-U994, U1026-U1050: 2 BBC (Brown Boveri & Co) GG UB 720/8 electric motors, totalling 750shp. Max rpm: 296.
U301-U316, U329, U330, U375-U400, U701-U730, U752-U782, U1131, U1132: 2 GL (Garbe Lahmeyer) RP 137/c electric motors, totalling 750shp. Max rpm: 296.
U349, U350, U402-U430, U453-U458, U465-U486, U651-U698, U901-U912, U921-U928, U1101-U1106, U1161-U1162: 2 SSW (Siemens-Schuckert-Werke) GU 343/38-8 electric motors, totalling 750shp. Max rpm: 296.
Batteries:
U69-U72, U77-U80, U88-U90, U93-U95, U98, U99-102, U132, U133, U135, U136, U201-U212, U221-U226, U228-U232, U238-U240, U244, U25, U248, U251-U255, U257-U286, U291, U301-U304, U306-U313, U329-U345, U352-U366, U372, U374, U376, U378-U392, U401-U404, U406, U408-U412, U414-U419, U421-U425, U431-U434, U436-U440, U442-U449, U451, U452, U454-U458, U456, U466-U472, U474, U551, U553, U556, U557, U559, U560, U562-U571, U573-U583, U585, U587-U591, U594-U599, U602-U607, U609-U617, U619-U624, U626-U638, U640, U642-U668, U670-U675, U682, U684-U698, U701, U702, U710-U713, U715-U717, U720, U723-U743, U751-U757, U759-U762, U764, U769-U771, U777-U782, U905, U907, U922, U951-U957, U960, U963, U964, U967-U994, U1053, U1104, U1131, U1133-1146, U1201-U1206, U1208, U1209: 2 X 62-cell AFA 33 MAL 800 W, producing 9160 amp hours.
All others: 2 X 62-cell AFA 33 MAL 800 E, producing 9160 amp hours.
A small number of boats operated with some batteries of each type, the difference between them being the casing of the individual battery cells only.
Speed: 17 -17.7kts/7.6kts (surfaced/submerged)
Range (nm/kts) 8,500/10 surfaced (combined diesel electric drive range 9,700nm@10kts); 80/4 submerged.
Armament:
5 X 53.3cm TT (9 reloads, or 26 TMA or 39 TMB mines) - except: U72, U78, U80, U554, U555 each only had two forward torpedo tubes. U203, U331, U351, U401, U431, U651 had no stern tube. U88-U92, U333-U350, U352-U370, U374-U401, U404-U430, U435-U450, U454-U458, U657-U686, U702-U750, U754-U784 and all C/41s from U1271 upwards, had no mine carrying capability.
1 X 8.8cm C35/L45deck gun (removed from requirements during 1942)
Several different flak weaponry combinations were used by the Type VIIC, becoming more prevalent as the war progressed. The following combinations illustrate some of these:
1. 1 X 2cm C30 AA gun
2. 1 X 2cm C30 and 2 X MG151 machine guns
3. 2 X 2cm C30 (on twin LC30/37 mounting) and 4 X MG151 machine guns (2 X 2)
4. 1 X 2cm C30 and 4 X Breda machine guns (2 X 2)
5. 2 X 2cm C30 AA weapons, one on each Wintergarten level.
6. 4 X 2cm C38 (2 X 2 on upper wintergarten) and 4 X 2cm C38 Vierling (lower level)
7. 4 X 2cm C38 (2 X 2 on upper wintergarten) and 1 X 3.7cm automatic flak
There were many variations, some official some not, as Allied aircraft became the principle threat to U-boat activity.
Crew: up to 60 (4/56)
Stored boats: One dinghy stowed under forward casing forward of torpedo loading hatch. Four 5-man liferafts held in watertight canisters on fore-casing (1944 onwards).
Builders (completed boats only):
U69-U72, U93-U98, U201-U212, U221-U232, U235-U250, U1051-U1058, U1063-U1065 Germaniawerft, Kiel.
U77-U82, U132-U136, U251-U291 Bremer Vulkan, Vegesack.
U88-U92, U301-U316, U903, U904 Flenderwerft, Lübeck.
U331-U350, U1101-U1106 Nordsee-Werke, Emden
U351-U370 Flensburger Schiffbau Gesellschaft, Flensburg
U371-U400, U651-U686, U1131, U1132, Howaldtswerke, Kiel
U401-U430, U1161, U1162, Danziger Werft, Danzig
U431-U450, U731-U750, U825-U828, U1200 -U1210, F Schichau, Danzig
U451-U486, Deutsche Werke, Kiel
U551-U650, U951-U994, Blohm und Voss, Hamburg
U701-U722, U905-U908, H C Stülcken, Hamburg
U751-U782, Kaiserliche Marinewerft, Wilhelmshaven
U821 - U824, Stettiner Oderwerke, Stettin
U901, U902, Stettiner Vulcan Werke (also finishing work on U903-U908)
U921-U930, Neptun-Werft, Rostock
Type VIIC/41
By 1941 the war had gone global with Japan's attack on the United States and Hitler's subsequent declaration of war against President Roosevelt. With the opening of U-boat operations along the US Atlantic coast and within the Caribbean and Gulf of Mexico (all planned for early 1942) considerable thought was given to how best to modify the basic Type VIIC design, allowing improved performance and greater range while not upsetting current construction projects with any real change to the boat structural design. Type VIIC/41 was the result. The primary changes were to the boat's weight, pressure hull thickness and bow. In February 1942 SKL/Ib had asked Oberleutnant (Ing) Kiesewalter (Chief Engineer on the Type IXC U157) to compile a memorandum entitled: 'Technical Development of the U-boat in the Light of War Operations'. Keisewalter was mainly concerned with the fact that combat conditions would soon outpace current U-boat designs, an increased diving depth to escape depth charging a focus of his ideas: "If we cannot actually succeed in concealing U-boats from detection by ultrasonics, then only two possibilities remain: either one dives to 300 metres and waits until depth charging is over, or one must be equipped with an attacking weapon such as an acoustic torpedo with which to destroy the pursuer…At [300 metres] the effect of depth charges is greatly restricted and, furthermore, the time it takes for depth charges to descend to such a depth enables a boat to take avoiding action" Thus the VIIC design had various power and electrical systems replaced by smaller more compact designs saving a total of 11.5 tons of hull weight. This saved weight was then used to increase the thickness of the pressure hull from 18.5mm to 21mm, extending the test diving depth from 150 metres to 180 metres and the theoretical hull failure depth (frequently exceeded!) from 250 metres to 300. Coupled with this the forecastle was slightly widened and a 13cm extension to the bow - named the 'Atlantic stem' - fitted to improve seaworthiness and decrease water resistance. The first orders for the VIIC/41 were placed on 14 October 1941, applied to Type VIICs already under construction to utilise the new materials. However, the first VIIC/41, U293, was not launched until 30 July 1943.
Specifications:
Displacement: 759 tons/860 tons (surfaced/submerged). Submerged - fully loaded and manned - 1070 tons.
Length: 67.2 m
Beam: 6.2m
Draught: 4.74m (Keel to Bridge: 9.6m)
Diving depth/Theoretical crush depth: 180m/300m
Diving Time: 30 seconds (normal)
Engines:
2 supercharged Germaniawerft, 6 cylinder, 4-stroke M6V 40/46 diesels totalling 2,800 - 3,200bhp. Max rpm: 470-490.
Motors:
U1191-U1199, U1271-U1279, U1301-U1308: 2 AEG GU 460/8-276 electric motors, totalling 750shp. Max rpm: 296.
U995-U1025: 2 BBC (Brown Boveri & Co) GG UB 720/8 electric motors, totalling 750shp. Max rpm: 296.
U317-U328: 2 GL (Garbe Lahmeyer) RP 137/c electric motors, totalling 750shp. Max rpm: 296.
U1107-U1110, U1163-U1170: 2 SSW (Siemens-Schuckert-Werke) GU 343/38-8 electric motors, totalling 750shp. Max rpm: 296. Batteries:
U320, U328, U1166, U1168, U1169, U1171, U1172, U1192, U1194, U1196-U1199, U1272, U1306: 2 X 62-cell AFA 33 MAL 800 W, producing 9160 amp hours.
All others: 2 X 62-cell AFA 33 MAL 800 E, producing 9160 amp hours.
A small number of boats operated with some batteries of each type, the difference between them being the casing of the individual battery cells only.
Speed: 17 -17.7kts/7.6kts (surfaced/submerged)
Range (nm/kts) 8,500/10 surfaced (combined diesel electric drive range 9,700nm@10kts); 80/4 submerged.
Armament:
5 X 53.3cm TT (9 reloads, or 26 TMA or 39 TMB mines) - except: All C/41s from U1271 upwards, had no mine carrying capability.
Again, several different flak weaponry combinations were used by the Type VIIC, becoming more prevalent as the war progressed. The following combinations illustrate some of these:
1. 2 X 2cm C30 AA weapons, one on each Wintergarten level.
2. 4 X 2cm C38 (2 X 2 on upper wintergarten) and 4 X 2cm C38 Vierling (lower level)
3. 4 X 2cm C38 (2 X 2 on upper wintergarten) and 1 X 3.7cm automatic flak
There were many variations, some official some not, as Allied aircraft became the principle threat to U-boat activity.
Crew: up to 60 (4/56)
Stored boats: One dinghy stowed under forward casing forward of torpedo loading hatch. Four 5-man liferafts held in watertight canisters on fore-casing (1944 onwards)
Builders (completed boats only):
U317-U318 Flenderwerft, Lübeck.
U995-U1025 Blohm und Voss, Hamburg
U1107-U1110 Nordsee-Werke, Emden
U1163-U1172 Danziger Werft, Danzig
U1191-U1199 F Schichau, Danzig
U1271-U1279 Bremer Vulkan, Vegesack
Type VIID
During the First World War and in the early stages of the Second, U-boat-laid mines had proved more effective than torpedoes and there continued to be a desire for custom designed U-boat minelayers for the powerful moored SMA mines. Development of the TM 'torpedo mines' deliverable by orthodox tube shots had negated the urgency for the dedicated minelayers, particularly after SMA mines were discovered to be defective, design faults found that caused premature explosions. Requiring several months of modification to correct, an embargo was placed on their use until March 1943. However, there was still a desire at OKM for medium sized submarines to be able to deliver the SMA in coastal waters where the dedicated minelayers Type XBs would be too large and unwieldy when the mines became available. Given the proven reliability and versatility of the VIIC it was decided to develop this boat to serve the new purpose. Conversion to minelayer was facilitated by the simple expedient of adding an entire 9.8 metre long hull section aft of the control room which incorporated five vertical mineshafts. Each shaft could hold three stored mines giving a total load of fifteen mines. The shafts were covered with slatted sheeting to provide ventilation, while the tube bottoms remained open to the sea, the stored mines were inaccessible from inside the pressure hull. Space within the extension that was not used by the shafts was given over to additional compensating tanks (flooded to compensate the weight loss of a delivered mine), additional diving tanks and enlarged fuel bunkers giving the increased operational possibilities of extended range missions. However, because the VIID maintained the standard VIIC power plant and had the increased drag of the mineshafts performance was slightly impaired in speed, manoeuvrability and diving time. Coupled with the mine capacity, the Type VIID carried the same normal weapon load as a normal VIIC, allowing them to enter service as normal attack submarines (albeit with longer range) until the SMA mine was cleared for use. Six Type VIID minelayers (U213 - U218) were ordered from Germaniawerft on 16 February 1940, U213 launched on 24 July 1940, later commissioned into the 7th U-Flotilla (commanded by ObltzS Amelung von Varendorff, former IIWO on U47 at the time of the Scapa Flow attack).
Specifications:
Displacement: 965 tons/1080 tons (surfaced/submerged). Submerged - fully loaded and manned - 1285 tons.
Length: 76.9 m
Beam: 6.38m
Draught: 5.01m (Keel to Bridge: 9.7m)
Diving depth/Theoretical crush depth: 100m/200m.
Diving Time: 35 seconds.
Engines:
2 supercharged Germaniawerft, 6 cylinder, 4-stroke F46 diesels totalling 2,800 - 3,200bhp. Max rpm: 470-490. Max Fuel Oil: 169.4 tons (115.3 tons within pressure hull).
Motors:
2 AEG GU 460/8-276 electric motors, totalling 750shp. Max rpm: 285.
Batteries:
2 X 62-cell AFA 33 MAL 800 E, producing 9,160 amp hours (U217 W type cells).
Speed: 16-16.7kts/7.3kts (surfaced/submerged)
Range (nm/kts) 11,200/10 surfaced (combined diesel electric drive range 13,000nm@10kts); 69/4 submerged.
Armament:
5 X Mine chutes, carrying a total of 15 SMA mines.
5 X 53.3cm TT (7 reloads, or 26 TMA or 39 TMB mines)
1 X 8.8cm C35/L45deck gun with 220 rounds.
2 X 2cm (2x1) C30 AA guns with 4,380 rounds.
After 1942 defensive armament changed to: 1 X 3.7cm Flak with 1,195 rounds 4 X 2cm C38 (2x2) with 4,380 rounds.
Crew: 44 (4/40)
Stored boats: One dinghy stowed under forward casing forward of torpedo loading hatch.
Builders: Germaniawerft, Kiel. Type
Type VIIF
During 1941 Germany's naval supply network was devastated by the Royal Navy and Dönitz frantically ordered supply submarines constructed to enable his U-boats to spend longer at sea in action, or to extend their patrol radius. While the new Type XIV supply U-boat could provide fuel, food and other basic supplies to combat U-boats, the large Milch Kuh had only enough storage for four extra torpedoes, causing Dönitz to demand a new boat to carry the ammunition necessary for total resupply at sea. Again he decided to use the trusted Type VIIC basic design and followed the example of the VIID, adding a 10.5 metre section aft of the conning tower. Inside this new area would be enough storage for twenty-four torpedoes to be carried, stacked in six columns of four, three columns each side of the boat's centreline. An additional torpedo loading hatch aft of the storage space allowed access to the stored weapons for loading and removal. Like the Type VIID, the VIIF also benefited from the additional space by having two extra bunks added and a pair of refrigerated food lockers. Again, like the VIID, there was also additional fuel and ballast bunkerage within the extended saddle tanks and main hull. The first four VIIFs (U1059 - U1062) were ordered from Germaniawerft on 22 August 1941 and U1059 was launched on 12 March 1943. However, by that stage of the war the U-boats had lost their advantage and the idea of tortuously long surface transfers of torpedoes was unrealistic in the face of smothering Allied air power, covering the entire Atlantic. The VIIF had retained the original weaponry of the Type VIIC and was soon put to work on long-range supply missions. Their performance was improved over the Type VIID as the boat's beam had been increased to match the extra length, raising its seaworthiness. Originally the boats were used to run supplies around Norway, before three of the four (U1059, U1060 and U1062) were earmarked during 1944 for torpedo transport missions to Penang to supply the large Type IXC/40 and Type IXD2s that had formed a Far Eastern U-boat presence there. Only U1062 survived the journey, delivering thirty-nine torpedoes to Penang (twenty-four stored plus its crammed-in weapon load of fifteen). She was sunk on her return voyage in September 1944. Only U1061 survived the war, damaged by grounding in February 1945 and surrendered in Bergen at the war's end.
Specifications:
Displacement: 1084 tons/1181 tons (surfaced/submerged). Submerged - fully loaded and manned - 1345 tons.
Length: 77.63 m
Beam: 7.3m
Draught: 4.7m (Keel to Bridge: 9.6m)
Diving depth/Theoretical crush depth: 100m/200m.
Diving Time: 35 seconds
Engines:
2 supercharged Germaniawerft, 6 cylinder, 4-stroke F46 diesels totalling 2,880 - 3,200bhp. Max rpm: 470-490. Max Fuel Oil: 198.9 tons.
Motors:
2 AEG GU 460/8-276 electric motors, totalling 750shp. Max rpm: 295.
Batteries:
2 X 62-cell AFA 33 MAL 800 E, producing 9,160 amp hours (U217 W type cells).
Speed: 16.9-17.6kts/7.9kts (surfaced/submerged) Range (nm/kts) 14,700/10 surfaced (combined diesel electric drive range 13,950nm@10kts); 75/4 submerged.
Armament:
5 X 53.3cm TT (9 reloads). No minelaying capability. 21 Torpedoes carried STORED ONLY in cargo room, 2 extra stored outboard beside tower.
1 X 3.7cm Flak with 1,195 rounds 2 X 2cm (2x1) C30 AA guns with 4,380 rounds.
Crew: 46 (4/42)
Stored boats: One dinghy stowed under forward casing forward of torpedo loading hatch.
Builders: Germaniawerft, Kiel.
Variants
The Flak Boats
U-boat Command experimented at converting seven U-boats into flak boats, designed to lure enemy aircraft into battle so as to destroy them, an idea that ultimately failed. Dönitz based the idea of the so-called 'Unterseebootflugzeugfalle' (submarine aircraft-trap) on the crew's ability to 'see' the enemy approach using radar detection equipmenty. U441 of Brest's 1st U-Flotilla was the first such flak boat, designated "U-Flak 1". A Type VIIC boat, as well as the usual anti-aircraft stations of the rear kiosk and 'Wintergarten' she had her conning tower extended forward, providing a third weapon position. In the stern-facing Wintergarten was a single-barrelled 3.7cm weapon, itself positioned beneath the four barrels of a shielded 2cm quad Flakvierling. The forward extension carried another fearsome Vierling, rounding out the lethal increase in firepower. The heavily armed U-boat, sacrificing some fuel storage capacity for the increased weaponry, was intended to either sail independently as a 'trap' or to escort other U-boats heading for the Atlantic. In total U211, U256, U263, U271, U441, U621 and U953 all underwent some conversion work to enable them to operate as Flakfalle before the idea's abandonment on 11 November 1943 after operations resulted in meagre returns for severe damage to several of the U-boats concerned and those they escorted.
PROJECTED DESIGNS:
Type VIIC/42
This design was brought about primarily in an attempt to increase the range and speed of the VIIC model by adding a second stage of boost to the already singly supercharged engines. Range was to have been increased with 35cm widening of the saddle tanks, adding nearly 70 tons to the maximum fuel load. Coupled with these performance issues was the thickening of the pressure hull by another 30cm, giving the Type VIIC/42 a normal diving depth of 300m and failure depth of a staggering 500m. Armour plating for the conning tower, an integral schnorchel and numerous flak weapons rounded out the design which would have taken the basic Type VIIC structure to its absolute limit. The first orders were placed on 16 July 1942 with Germaniawerft although within a year the entire conditions of the Atlantic battle had changed to such a degree that those boats of the 174 total number ordered that had been laid down within the shipyards, were cancelled in favour of Type XXI construction. Ironically it was the Russians who completed the only known examples of the VIIC/42 post-war when they finished the construction of U1174, U1176 and U1177 at the Danziger Werft, Danzig. It is though that they may also have finished several examples from the ordered U2301-U2318 series at Danzig's F Schichau yard as well.
Type VIIC/43
This planned expansion of the capabilities of the projected Type VIIC/41 would have seen the increase of the boat's offensive power. With redesigned bow and stern compartments the torpedo tube armament was to have been increased to six tubes forward (two banks of three) and four tubes aft (two banks of two). However, with the deteriorating convoy war, design work on the VIIC/43 was cancelled on 11 May 1943.
Type VIIE
This sub-type of the VIIC was a design project only. The VIIE was intended for use as a test machine for the installation of Deutz V12 two-stroke diesel engines. Apart from the lightweight engines, the design would have resembled the VIIC, although weight saved within propulsion unit would have allowed the strengthening of the pressure hull. However, delays and the eventual abandonment of the Deutz engines led to the VIIE design being scrapped before construction.