Type VIIC/41 U-Boote

Germany (Built 1941-45): 91 submarines commissioned

Development

In 1941, Karl Dönitz confered with his top atlantic flottilla commanders and some decorated U-Boat captains at his Lorient HQ, Villa Kerlilon, about U-boat performances and how they could be improved. Of course at the same time he was aware of Professor Walter’s work on a new type of chemical propulsion that would massively improve underwater speed, and his first prototype tested in 1939, V80, that was measured at 23 knots underwater despite Oberkommando der Kriegsmarine (OKM)’s initial skepticsm. However problems with the production, supply, and safe handling of hydrogen peroxide was dooming the development of a working operational submarine. Only the German Type XVII was somewhat operational, but in 1941 with the “happy time”, U-Boote commander all did wonders and the Battle of the Atlantic seems winnable under a short notice.

Thus, there was no rush for an alternative model. So far, the Type VIIC and Type IXA did wonders as they were. Still, the OKH allowed in 1941 some development to be done on Walter’s ideas, at first under low priority, but that would change in 1943. But back in 1941, only thing that was envisioned was a pragmatic inprovement of the existing Type VIIC. The first reunion was to settle on a serie of possible alleys of improvement, from first hand operational accounts. Some would be easy to achieve with little effort, other more long-run enterprises.

-The first of such major requirements difficult to achieve was for a higher surface speed. It could not be met without deep design modifications. Both for the hull with better streamlining and for the diesels, with extra room. However this proposal was cancelled, as a new design would disrupt current production. It would be filled eventually, but with the Type XXI, and mostly underwater.

-Next it was investigated how much the diving depth could be increased, as a life-saving measure to escape depht charge attacks. Strenght of the pressure hull seemed the easy option. This seemed more doable in general, and this was the firdst objectice reached: By saving 11.5 t (11.3 long tons) weight, using simpler diesel-electric engine installations, this would free some 10 tonnes (9.8 long tons). This would allow in turn to increase the hull thickness from 18.5 mm (0.73 in) to 21 mm (0.83 in) mm, making for a max diving depth greater of 20%.
-Seaworthiness was another issue, and the soluton was to rework and extended the bow by 13 cm (5.1 in).
These were the most spectacular improvement over the base design, alongside dozens of minor changes, affecting ballasts, water tanks, batteries, and erogonomics at large inside and out. The armament would remain the same, apart AA weaponry and the conning tower receiving a larger aft platform. There was to be also an improved radio set, a more advanced enigma machine to go with it, and a better sonar system, albeit it was not ready when it was decided to fix the design and transmit the changes to the numerous yards in task of building these submarines (see later).

This improved, albeit not revolutionary design, was called Type VIIC/41 from the year of adoption in 1941, and all boats laid down from the keel up, not yet too advanced for it, were to be modified with the new pressure hull among others. Upgrades were unequal due to bottlenecks to acquire improved sub-systems. But it was to be implemented in all yards for new submarines which numbers were defined precisely. The first Type VIIC/41 was indeed ordered on 14 October 1941. The yards were instructed to convert existing boats if practicable, but not yet lay down orders new VIICs under the new design.

The first Type VIIC/41 U-292 was delivered on 25 August 1943, and on 30 September it was decided to stop laying down new Type VIIC/41 U-boats, freeing up space for the Elektroboote, pushed ahead by Dönitz. Only Flender Werke yard in Belgium was allowed to continue, not equipped to manufacture the larger and more complex Type XXI U-boats. There, the last Type VIIC/41 U-1308 was laid down on 28 January 1944, commissioned in January 1945. In total 88 Type VIIC/41 were commissioned albeit it’s disputed and other sources (most in fact) states 91 boats were commissioned as VII C/41s. From U-1271 onwards, for simplificaton, fittings to handle mines was omitted. There is today a single preserved Type VII U-boat, U-995 on display at Laboe Naval Memorial today on the Schelswig Holstein coast, near Kiel.

Builders

Bremer Vulkan-Vegesacker Werft, Bremen-Vegesack: U-292 to U-300 (9 subs) and U-1271-U-1279(9) as werk 57-65, 66-74; 1941-1943, 1942-44.
Flender Werke AG, Lübeck: U-317 to U-328 (12) as wek 317-328 in 1941-1944.
F Schichau GmbH, Danzig: U-827 and U-828, U1590 and U1591 1942-1944.
Neptun Werft AG, Rostock: U-929 and U-902 as well as U516, U517 in 1942-1944
Blohm & Voss, Hamburg: U-995 and U195, U-997-U-1010 (14) in 1942-1945
F. Krupp Germaniawerft AG, Kiel: U-1063, 1062, 1065 (3) as werke 700-702 in 1941-1944
Nordseewerke, Emden: U-1103 to U-1110(8) as werke 225- 232 in 1941-1944
Danziger Werft AG: U-1163-U-1172(10) as werke 135-144 in 1941-1944
Flensburger Schiffsbau-Ges: U-1301-U-1308(8) as werke 494-501 in 1942-1945.

Succession: The Type VIIC/42

When it was clear by late 1942 that the planned Walter boats would be too complex to transmate into operations and before the alternative desgn Tpe XXI Elektroboote was worked out, a stopgap measure was taken, leading to the much improved type VIIC/42. The Type VIIC/42 traduce the fear of U-Boat commanders when submerged of detection by sonar. Engineers came with a simple solution, coating the outer hull with rubber anechoic tiles (a solution adopted much later in the 1970s). It was hoped these acoustic sonar waves would be absorbed by the material, instead of bouncing back. The problem was to find the right absorbent material and the right glue to resist both pressure, cold and salt water.

In 1941, tests with rubber coating on U-67 ended disappointing, so the project was abandoned. Instead, ithe solition of “brute force” was chosen, just allowing these boats to dive even deeper, notably by basically useing battleship armour, already combining excellent proterties of flexibility and harness, knowned and mature since WWI already. The fact of using thicker steel for the pressure hull using the rolled homogeneous technique at the builders yards, given what most were capable of, however limited this maximum thickness to 28 mm (1.1 in). That was still much better than 21 mm but the hull weight went from 68.3 t (67.2 long tons) to 154.3 t (151.9 long tons).

To compensate, engineers worked out an increase from 4.7 m (15 ft 5 in) to 5 m (16 ft 5 in) in beam to create more buoyancy. Saddle tanks were enlarged as well, enabling to carry more fuel oil and improved the range so much it now reached an amazing 12,600 nautical miles (23,300 km; 14,500 mi), as much as a large Type IX. Top speed remained moderate at 17 knots (31 km/h; 20 mph). It was however soon seen as insufficient for keeping pace with 1942 convoys, that were much faster. One reason was that once U-Boats sank all the “junk” cargo ships of before WWI, working on coal at barely 10 knots, new cargo ships were now available thanks to Kaiser Yards and many others, in the US, Britain and Canada, the Liberty and Victory ships, all fitted with 16-18 knots machinery. Even surfaced by night, U-Boats had a hard time gaining the center of the convoy to do their business. They had to work hard their diesels, “whiping them” until they broke down or wear out prematurely, further reducing service life.

There was no way around it, the new U-Boats needed a greater surface speed, but with a heavier hull and the same diesel engines there were bot many ways it could be achieved. Even though diesel manufacturers of the time like AEG and Daimler promised increased performances, engineers had the hull lengthened by 0.8 metres (2 ft 7 in), both to increas the lenght ratio for speed, and to provide extra space for more powerful superchargers, added to the diesels and reworked exhausts. With this additional power, it was hoped to reach 18.6 knots (34.4 km/h; 21.4 mph).

As the design was finalized on 10 November 1942, a preliminary order for twelve Type VIIC/42 was placed. Furthermore, six months later as plans were ready to be delivered, by 17 April 1943, a hundred and seventy four boats had been ordered from twelve shipbuilding yards. But due to production bottlenecks for this new nickel-rich steel alloy for the reinforced pressure hull, construction was not starting. Indeed, that type of allow was in high demand already for tank manufacturing that firecely competed for scarcier resources. The land war had all priority as Hitler wanted in mid-1943 to definitively win the war in the east.

The same year two “wunder panzer” had been introduced and great hopes placed in them notably at the monumental battle of Kursk, the Panther and Tiger, and both were well armoured using precisely high nickel-rich rolled homogeneous steel plating. despite Dönitz efforts in early 1943 and his promises to win the war at sea in late 1942, this never happened. So supplies to the Kriegsmarine, now managed by Speer, had to rule out and reduced cotas for shipyards. Speer even suggested to Dönitz dismantling surface ships badly damaged and in repair or even earlier U-Boats of little use, like the Type II and IIa, and Type VIIA and B still around. Assembly at the yards in any case had not yet even started (there was not enough steel) when all orders were cancelled on 24 July 1943. Dönitz found an agreement with Speer to obtain more steel, but the VIIC was ruled our in favor of the new Type XXI “Elektroboote” far more promising. Hitler also weighted on this when presented the project and Dönitz promised to reverse the battle of the Atlantic when enough would be available.

Last Gasp: The Type VIIC/43

Early in 1943 as the Type VIIC/42 was not even started, it became obvious that convoy battles demanded a better armament, with more pre-loaded torpedo tubes rather than fewer torpedo tubes and more reload, no longer adpated to the higher pace of operations when an attack was ongoing. Given the risk of entering a convoy by night, after a lot of preparation and a more fearsome that ever answer by ASW escorts, it was very unlikely that U-boat would have the leizure to withdraw to reload and attack again. The other reason was that the potential Elektoboote program was still in its infancy. Some in the OKH estimated it would not be ready before December 1943 at best.

The VIIC/43 seemed a good stopgap and it was based on the Type VIIC/42 (still not cancelled at this point) but with six bow torpedo tube, two at the stern, much more in conformity to what other nations built (The US Gato class had the same, and the British T class even had ten tubes). But on 11 May 1943 it was decided to cancel the VIIC/43 and concentrate on the Type VIIC/41 and VIIC/42 instead. Both would be cancelled in July for the new Elektroboote. None of the VIIC/42 or 43 was ever completed. Both were phased out for the XXI Elektro boat bylate 1943, albeir plans for mass production agreed upon by Speer were quite ambitious and long in coming.

Design of the class

The Type VIIC/41 were a slightly modified version of the successful VIIC with basically the same engine layout and power, same armament with 5 torpedo tubes (4 bow, one stern) but a stronger pressure hull for extra depth in order to evade attacks. Operational depht was 120m (), crush depth estimated 250m () versus a standard VIIC, 100m operational, 200m max. This alone, saved a lot of crews as the allies had no idea at first this could be the case. But it was later realized, both through combat reports and classic intel, that U-Boote did achieve that depth routinely, so this led to a new depth charge setup and revision of practices across the allied escorts.

As seen above, the Type VIIC/41 had a lighter machinery to compensate for the extra steel in the pressure hull. This was both through revised diesels more smartly engineered, and lighter batteries as well, provided they still procured the same underwater power.

Hull and general design

The Type VIIC/41 displaced 769 tonnes surfaced, light, and 871 tonnes submerged, then 1070 tonnes total submerged and fully laden. They were longer as seen above at 67,10 meters overall (220 feet) and 50,50 meters (166 ft) for the pressure hull. The beam reached 6,20 meters (20 feet) overall and the pressure hull diameter was now of 4,70 meters (15-1/2 feet). To compare a standard VIIC had a 67.20m long hull, 6.20 m wide, with 4.74 m draught, like the new VIIC/41. Total height from the keel to the portico above the conning tower, was 9,60 m. Externally, not much changed either but in the shape of the conning tower, which tail was elongated to installed a heavier AA.

Powerplant

The VIIC/41 continued the trend of the VIIC with more of the 2,800 bhp (2,100 kW) MAN M6V40/46, capable of giving them a top speed of 17 kn (31 km/h; 20 mph), while others retained the 3,200 bhp (2,400 kW) Germaniawerft F46 giving them a top speed of 17.7 knots (32.8 km/h; 20.4 mph) at least of paper. It seems the majority were completed with the latter.
Underwater they had either AEG GU 460/8-276 and BBC GG UB 720/8 but also the new Garbe, Lahmeyer & Co. RP 137/c and Siemens-Schuckert-Werke (SSW) GU 343/38-8. However even with 750 shp total, top speed was less stellar than the standard VIIC due to the extra displacement, down to just 7,6 knots underwater.

As for range, they were capable of 8,500 nautical miles at 10 knots surfaced (that’s 15,742 km, well enough to criss-cross the Atlantic or make a full patrol to the US east coast and back). Underwater, they were limited to 80 nautical miles (150 km) at 4 knots economical speed. That was the advantage of a longer hull with sightly larger blisters and thus, fuel tanks. As for max depht, this was the strong point of the design, as they were now able to operate down to 250 meters (820 feet), but actual crush depth was almost double. British or Allied intel at large believed their operating depth in 1942 of around 500-600 feet, so depth charges had corresponding max settings.

It was not very long in 1943 before their true operating depht was discovered and depth charges modified accordingly. It must be stressed that due to increasing water pressure, DC detonation range and surrounding damage was not the same depending on the depth. The deepest it went, detonation range was even more buffered and less efficient and that too, was taken in account with this decision on betting on a greater dive to survive more and more challenging operating conditions.

Armament

Type G7e(TII) captured in Scapa Flow (dud) after being fired at HMS Royal Oak, preserved at Birkenhead.

Five 533 mm torpedo tubes (4 bow and 1 stern). 14 reserve torpedoes or 26 TMA or 39 TMB mines.
One 37 mm gun as designed, replaced by a 88 mm C35 L/45 when available.
One 20 mm C30 machine gun in the CT aft platform.
From 1944: Enlarged CT for one 37 mm gun and a flakvierling (4x) 20 mm Flak.

Deck Gun: 8.8 cm/45 (3.46″) SK C/35

The type VIIA U-boats had the 8,8cm as deck gun. The Type IA and later Type IX had the larger 105 mm deck gun, and the small Type II had a 20 mm AA gun. This deck gun was produced by Krupp but had absolutely no relation to the famous German Army 8,8 anti-tank and anti-aircraft gun. They did not even share the same ammunition. The 8.8 cm/45 (3.46″) SK C/35 was also used on Type 40 minesweepers and sub-chasers. After 1942, many U-Boats had it removed to install more FLAK instead. Only in the Mediterranean and the Northern Sea, U-boats kept their guns for a few months longer. It seems the original 37 mm was only sported at completion but the first two boats and replaced, the 8,8 cm was installed at completion on all the others as the production at Krupp was ramped up.

This was a pure “marine guns”, with material resistant to corrosion, simpler mechanisms and lubrication was limited or made internal. The goal was to have a permanent deck gun that could stay very long periods underwater at great pressures that could damage mechanisms and smaller parts. It was tested in a pressure chamber to the equivalent of around 200m (650 ft) which was the max theoretical diving depth at the time. These constraints made for a completely different gun than the more complex land-based 8,8 cm FLAK gun.
The 8,8 cm caliber had been used for many decades in the German Navy, all the way back to the 1890s and saw many iterations over the years. Unlike its land-based counterpart, it was a pure anti-ship model as it was limited by its mount to 30°.

The model used on the Type VIIA and following was designed in 1935 and introduced in 1938 so it’s likely the Type VIIA U-Boats were completed without it. It was a very rugged gun, albeit not having the same punch as its land counterpart, and a AP round (AP 35) which was far weaker. At 700 mps (2,300 fps) versus 840 m/s (2,690 ft/s) it lacked the speed and range as well, but was very impressive an efficient as a naval gun, especially for such as “small” submarine. It’s just that from 1942, no U-Kaptain would be mad enough to try to sink a cargo while surfaced with this single gun, staying exposed for an hour or more. More

Specs 8.8 cm/45 (3.46″) SK C/35

Weight: 5,346 lbs. (2,425 kg), Barrel alone 1,711 lbs. (776 kg)
Length: 157 in. (3.985 m) bore 146.9 in (3.731 m).
Rate of fire: 15 rounds per minute
Shell: 33 lbs. (15 kg) 14 in (385.5 mm) HE, AP, Incendiary, Illumination (90-10.2 kgs).
Bursting charge: AP 35S 0.064 kg. HE L/4.5 0.698 kg, HE L/45 Inc. Brandkörper A
Propellant charge: 3.70 lbs. (1.68 kg) RP C/32, 3.90 lbs. (1.77 kg) RP C/38, 4.63 lbs. (2.1 kg) RP C/40N and PL/V41
Muzzle velocity: HE 2,300 fps (700 mps), Illum.: 1,970 fps (600 mps).
Range: 13,070 yards (11,950 m) at 30°. Depression -10° on Ubts LC/35 mount.
Ammunition stowage Type VII: 220 rounds.
Barrel life: 12,000 rounds.

Torpedoes

For the Torpedo tubes I-V, Piston was 70 kg, forward +25.25 with piston inserted, 1680m3 and aft: -26,15 without piston and 1740m3. There was an upper deck container forward and aft, with and without G7A. Torpedo in the tubes were the G7E/G7A models. There was also a reserve stowage forward, aft. Note: The “Torpedokrise” lasted until the end of 1941. The result were scores of duds or precocious detonations. It was less severe than the infamous USN Mark 14, but limited the effectiveness of the Type VIIA, B and C until solved.

G7A Torpedoes

Direct involvement of Spain in the development of German torpedoes started in the late 1920s when the Spanish businessman Horacio Echevarrieta decided to start a torpedo factory in Cádiz (Fábrica Nacional de Torpedos, F.N.T. / National Torpedo Factory) with a theoretical production capacity of 100 torpedoes per year and license-build German torpedoes. But the G7 was created in WWI. The lineage comprised the pre-WWII G7A (T1) using compressed air and thus leaving a visible trail of bubble.

The G7a (TI) torpedo calibre was the standard 533.4 mm (21 in), for a length of 7163 mm (23 ft 6 in), fitted with a Ka or Kb warhead, Pi1 or Pi2 pistol. The warhead carried 280 kg (617lbs) Schießwolle 36. The model remained standard issue from 1936 to the end of WW2. This model was of a straight-running unguided model only controlled by a gyroscope. It could be set at a variable speed, 5,000 m at 81 km/h or 7,500 m at 74 km/h (8,250 yd at 40 kt) but also “long course” 12,000 m at 55.6 km/h. The 44 knots model setting was only used by Schnellboote with a reinforced engine.
Later were introduced the G7a (T2) electric, T3, T4, T5 (Zaunköning), and T11, but the latter remained a prototype.
In 1940-41, the Type VIIA were likely upgraded with the G7a T2:

G7E Torpedo (T2)

They had a unique setting of 5000m at 30kts. Standard torpedo of the war, it suffered from early issues with the internal depth-keeping equipment and firing pistol, solved after the Norwegian Campaign, but only gradually implemented. The “torpedokrise” was thus only resolved in mid-1941 when all stocks had been changed or spent. Full effectiveness on the T2 was obtained when preheated electrically to 30 degrees Cent (86 F) before firing. If not, speed was down to 28 knots for 3000m.

The G7e(TII) already entered service in 1936 and was a “secret weapon” for the Germans as much as was the “long lance” (type 93) for the IJN. Its existence was virtually unknown to the British until fragments were recovered following the sinking of HMS Royal Oak in October 1939. The G7e was electric, no longer using a wet-heater (steam-driven) and was simpler and cheaper to manufacture (half the cost), as well as being virtually silent, leaving almost no visible trail of air bubbles.

The latter was by far its biggest advantage. It was virtually invisible in the dark North Atlantic and spotters needed to be posted high and have an excellent view to see them via the water disturbances they still create at this speed, so a very faint trail underwater, still. It was most often heard first but the hydrophones’ operator, getting a bearing.

The T2 had many issues, it was however less reliable and performed unpredictably compared to the G7a(TI). Just like the Mark 14, both the contact and magnetic detonators were unreliable. But the feedback loop was quicker and there was less inertia from the engineering department to solve these issues way quicker than in the US. The T3 became the Stradivarius of the G7 type in 1942.

G7E Torpedo (T3)

By mid-1942 the improved version had an increased battery capacity, asking for a 50% superior range as the T3a. Range was now, 7500m at 30 knots, but in a preheated state it was 4,500m at 28 knots. More detail to come for the next articles on the Type VII. Thy did not have the previous faulty exploders and had a brand-new system, with a perfected proximity feature. This enabled what the US and other navies looked for, a torpedo that can dive below the keel of a ship and explode, breaking it.

G7e Falke Torpedo (T4)

The Falke was the model allowing a sub to fire them while deeply submerged inside the convoy. Their main advantage was to start like a straight-running torpedo for the first 400 m (440 yd) to enable its acoustic sensors, then actively search for a target. Since this equipment was sentitive, the propeller needed to be as quiet as possible, by its shape, and also speed, at only 37 km/h (20 kn), while the Carrier sub was also to be dead silent. This model was mostly intended for merchant targets. Its use was limited, as it was merely a “proof of concept” for the acoustic homing torpedo.

G7e(TIII Fat II) Torpedo

FaT stands for Flächenabsuchender Torpedo. This model had a devise to changed the torpedo’s course over time so that it ran various patterns. Three versions: Fat I, II and III (Fat III was later redesignated Lut I).

Improvements in the design of the G7e called TII, were incorporated in production for this electric torpedo introduced in 1942. This TIII was a massive improvement over the TII with the following:
-The well known faulty exploders was upgraded to a brand new design.

-Range was the same as the TII, at 5,000 m (2.7 nmi).

But more was to come.

TIIIa

The TIIIa increased performed by fitting new batteries for a a range of 7,500 m (4.0 nmi) at 30 knots (56 km/h), still in straight line. Complement by the G7a(TI) wet-heater model only used at night for the rest of the war, the TIII was used for day-attacks thanks to its near invisible trail. It had better proximity feature so that an able U-boat captain could now in effect fire under the keel of a ship, breaking its back. The same “tactic” is still used today. And thanks to a single torpedo when in the past several were sometimes needed to sink buoyant cargos ships and even through tankers. This helpled massively increase overall effectiveness with an unchanged number of torpedoes.

TIII FAT II/LUT II

Soon, it was improved with the program steering FaT – G7e(TIII FaT II), and LuT – G7e(TIII LuT II) which were pattern running systems to be launched on well-defended convoys. The FaT (Flächen-Absuch-Torpedo or Federapparat-Torpedo) and LuT(LageUnabhängiger Torpedo) at first ran straight out and then started a circular or ladder-like pattern through the convoy lanes, being impredictable. Ships had no idea how to manoeuver. This not increased the probability of a hit but also completely distrupted the carefully laid ship lines, augmenting the risk of collisions, as deadly as a torpedo hit and making the work of escort much more difficult.

There was a single setting to regulate the length of the prerun, then four possible settings would be activated in sequences making the torpedo zigzag left or right over 1200 m or 2-3 nautical miles, or on a longer path of 1900 m or a full nautical mile o,ce fire. However this “wunderwaffe” was not without risk for oother U-Boats, and if one launched such weapon, other U-Käpitan needed to be warned in the vicinity. They were vividly encouraged to dive to avoid being struck by. These FAT torpedoes could be converted on the line, without too much complex items and became available in late-1942, just in time to be sported by the Type VIIC/41. They became a regular feature of the convoy battles of March 1943.

TIIId “Dackel”

Thus further modified pattern-running variant had a much greater endurance of 57 km (31 nmi), however at 9 knots (17 km/h) only. It weighted 2,216 kg (4,885 lb). Like the FaT and LuT, it started to run a ladder search pattern at the middle of a convoy, made of four lanes in general.

TIIIb

Additional variant, the TIIIb weighted 1,347 kg (2,970 lb) due to its new propulsion module based on the human torpedo types, Neger and Marder. Top speed was 18.5 knots (34.3 km/h), range 4,000 m (2.2 nmi) at full speed.

TIIIc

The TIIIc had the same weapon payload as above but for a reduced weight of 1,338 kg (2,950 lb). Top speed was also of 18.5 kn for 4,000 m (2.2 nmi). But there was an alternatove setting to 4 knots (7.4 km/h), greatly increasing range.

TIIIe “Kreuzotter”

A relative development which had the same payload by the midget submarines Molch and Seehund, over 1,343 kg (2,961 lb), top speed of 20 kn (37 km/h), range of over 7,500 m (4.0 nmi).

TMA Mines

In alternative to their torpedoes, the Type VIIC/41 U-Boats could also carry 22 TMA mines, two for one torpedo. The Type VIIs made in fact many minelaying missions, albeit crreating quite small minefields given the surface to wartime cover size so Captains had to decide to place them on very strategic points, helped by detail maps to be sure they will be across obligatory lanes for coastal traffic. Losses due to these were few however, both given the small minefields and low power. These TMA mines were shaped as cylinders, used as moored mines, attached by cable to float above the surface, while the anchor secured its position. The correct depth setting needed to be applied depending on the observed depths.
Two could be carried in each torpedo tube.
Length/Diameter: 11.1ft (3.38m)/21in (533mm)
Maximum Depth: 270m
Warhead: 215kg.

Sonars

Gruppenhorchgerät

The GHG was an early acoustic system, a hydrophone array used on all models, including the Type VII. It was developed in WWI already following Pierre Curie discovery in 1880 using the piezoelectric principle. Atlas Werke AG in Bremen and Electroacustik (ELAC) in Kiel worked on transducers, detectors and amplifiers and found the best being the Seignette crystal formed from a mixture of different salts. From 1935, crystal receivers were permanently installed on German submarines.

The GHG was the final product, GHG made of two groups of 24 sensors, one on each side of the boat. Each sensor had a tube preamplifier. These 48 low frequency signals were routed to a switching matrix and the sonar operator could determine the side and direction of the sound source. To improve resolution, a frequency of 1, 3 and 6 kHz could be setup. There was however a dead zone of 40° fore and aft, but range was 20 km to individual ships and 100 km against a full Convoy. The Search area was 2 × 140° with a resolution of less than a degree at 6 kHz, 1.5° for 3 kHz, 4° for 1 kHz and without crossover 8°. The Royal Navy in May 1942 captured a submarine and its ELAC equipment. Later the Balkongerät was tested on U-194 in January 1943 and installed a few Type VII/41 but became standard on the Type XXI.

Balkongerät

This ancestor of the linear bow arrays of modern western sonars, these models had much greater performance than allied sonars due to their perculiar design philosophy, for long range target aquisition. They were both were low frequency for long range instead of high frequency for good spatial discrimination like speed and direction on allied sonars. Their detection range could be as long as 30,000 yards in good conditions. This system consisted of a passive acoustic echo chamber enabling multiple targetting for attacks. It was born from the need to do better than the GHG, unable to be used while cruising on the surface due to the diesels, nor even at periscope depth with an optimum operating modus below 20 meter at 3 knots.

The Balkongerät (or lit. “balcony-device” given its looks) was developed, fixed-mounted at the chin a submarine, the spot with less interference from surface noise, but leaving a dead spot towards the stern. This Balkongerät was tested on U-194, a Type IXC/40, in January 1943. It was installed on a few chosen Type VIIC/41 before beng adopted as standard for the Type XXI.

⚙ Type VIIC/41 specifications
Displacement	769 tonnes surfaced, 871 tonnes submerged, 1070 tonnes total
Dimensions	67,10 x 6,20 x 4,74 m
Propulsion	2x diesels 3200 hp surfaced+ 2 EM, 750 hp sub.
Speed	17.7 knots surfaced, 736 knots submerged
Range	8500 nm at 10 kts surfaced, 80 nm underwater at 4 kts
Armament	1x 8,8cm/45 deck gun+ 4 bow, 1 stern TTs (14) or 26 TMA mines
Max depht	c250 meters (820 feet)
Sensors	GHG, see notes
Crew	44-52

Memorablia: U995 at Laboe

U-995, was a late VIIC/41 type now on display at the Laboe Naval Memorial near Kiel. Originally built by Blohm & Voss in Hamburg she was commissioned in September 1943. She would remain the only remaining Type VII U-boat in the world so far in her original condition. She Surrendered in May 1945, was transferred to Britain, then to Norway (renamed Kaura) remaining in service until 1952 and then versed to other roles. Decommissioned in 1965, she was offered to Germany for a symbolic single Deutsche Mark but declined by the then government.

U995 being lifted down in place by a barge at Laboe

However it was saved by the German Navy League (Deutscher Marinebund) which assembled former veterans, they paid for it. U995 was converted into a museum ship, placed at Laboe in October 1971 with an official handover in March 1972. It stands beside the Laboe Naval Memorial (Marine-Ehrenmal Laboe), a towered structure originally dedicated to WWI sailors and later rededicated in 1954 to all sailors who perished at sea, regardless of nationality. She is also a remainder how 30,300 men lost their lives in service in the Kriegsmarine on thise u-Boats alone. That was three quarter of the U-Boat force deployed in this war. Especially from 1943 onwards.

The Type VIIC/41 in action.

For obvious reason of time i will not dwelve into the career of every single of the 90 U-Boats right away but on the long run. To start with, here are the first 11 boats in class. Just this sample alows to appreciate the situation for U-Boats in 1944. Indeed, despite the fact some were built relatively fast, despite being ordered on 14 October 1941, construction time varied from yard to yard, from more than a year to below seven months. Large yard with many orders tend to have a better organization overall, with many U-Boats progressing side by side in the same drydock. However they tend to spent many moinths in training because crews were generally all rookies at this point when completed in late 1943 for the earliest, and finding surviving experienced captains was harder at this point.

In late 1943, the Battle of the Atlantic was almost won for the allies, with larger ASW assets than ever before, better intel (ultra) and tactics. Chance sof survival of a VIIC were slim, many made a single sortie and never came back. At the complete opposite of Typ VII A and Typ VII B which were completed prewar for many, and had very experienced crews at the start of WW2, their hunting board was excellent, not as great as their fiorefathers in WWI but still impressive nonetheless. By the time most Type VIIC/41 started real operations in mid to late 1944, the picture was totally unfavourable to U-Bootes. Most ended operating, like the surface fleet, from Norway, especially against Arctic convoys, in appealling climate and conditions. Sinking or even damaging a ship over several patrols was the exception, not the rule. At this stage it seems building and operating the VIIC was a complete waste of time and money. Only the Type XXI was a viable option at this point, provided it could be built at all in time in a context of non-stop allied bombings over shipyards, industries and infrastructures, and competition for ressources between the army, air force and navy, always the last in line. More precise stats will follow as this section is updated over time. Note also there are almost no photos of these boats, at least creative commons.

U-292 (1942)

Ordered on 14 October 1941 from Vegesacker Werft, Bremen-Vegesack, Yard nU-mber57, U-292 was the first Type VIIC/41 modified as such, laid down on 12 November 1942, launched on 20 July 1943 and commissioned on 25 August 1943. Her service life started with training with the 8th U-boat Flotilla from August 1943. She was transferred to the 1st flotilla on 1 May 1944. After a serie of missions from Kiel and Larvik, Norway, she left departed Bergen (also in Norway) on 24 May 1944. On the 27th, she was sunk by depth charges from a Liberator Bomber, “S” from No. 59 Squadron RAF, west of Trondheim. She sank with all hands.

U-293 (1943)

Ordered on 14 October 1941 from Bremer Vulkan Werft, Yard number 58, U293 was laid down on 17 November 1942 and launched on 30 July 1943, commissioned on 8 September 1943. After training with the 8th U-boat flotilla, U-293 remained in german waters for months, stationed in Trondheim, after Arendal, Bergen, and Stavanger. Her first wartime patrol under Oblt. Leonhard Klingspor was on 16 September 1944, a year after commission. For seven days, she sriss-crossed the Norwegian Sea and made it into Narvik on the 22th September, no spot, no kill. She started her seocnd patrol on the 25th to the Arctic Ocean over 10-day, no spot. On 4 October she entered Hammerfest. Her 3rd patrol from 14 October 1944 brought her in the Barents Sea, north coast of Russia over 24-day, but no contact. She was back at Narvik on 6 November. Same for her 4th patrol over 29 days same place, back on 19 December 1944. Next under Oblt. Erich Steinbrink she started her 5th Patrol from Narvik on 1 January 1945. At last on 20 January at 10:55 AM she spotted and engaged the Soviet destroyer Razyaryonny ecorting the convoy KP-1. While in the hunt with Razumny, she struck her once while she was at 16 knots on her stern. Her DCs likely exploded but her bulkheads hold and the crew managed to save her. She was later towed by T-117 to Liinahamari on 21 January. Back to Narvik on 15 February after 46 days at sea, U293 saw no further activity due to the lack of fuel oil. Back to Germany she surrendered on 11 May 1945 and sank in Operation Deadlight, 13 December.

U-294 (1943)

Ordered on 14 October 1941, U-294 was ordered from Bremer Vulkan Werft, Yard number 59, laid down on 22 December 1942, launched on 27 August 1943 and commissioned on 4 October 1943. She joined the 8th U-boat Flotilla in October 1943. In May 1944 she sailed from Kiel to Stavanger and was later transferred to the 11th flotilla on 1 August 1944. Her first patrol was northeast of the Shetland Islands. She had brief sojourns between Bergen, Flekkefjord and Kiel and her 2ns true patrol was between 18 and 24 September 1944. Her 3rd sortie was in the North Sea and she made a few short sorties from Flekkefjord, Horten Naval Base and Tönsberg in October-November 1944. She joined the 13th flotilla on 6 November followed by a 4th patrol from Bergen, with a stop in Trondheim. She was versed into the 14th flotilla on 1 March 1945. Her 5fth patrol from Narvik had a stop at Harstad, then to Skjomenfjord in April 1945. She surrendered to the allies on 9 May 1945, was interned to Loch Eriboll in northern Scotland on 19 May, moved to Lisahally for Operation Deadlight and sunk by gunfire (HMS Offa, Zealous) on 31 December. She sank no ship.

U-295 (1943)

U-295 was ordered on 14 October 1941 from Bremer Vulkan Werft, Yard number 60 and laid down on 31 December 1942, launched on 13 September 1943, commissioned on 20 October. She trained with the 8th U-boat Flotilla in October and was transferred to the 9th for operations on 1 August 1944, reassigned to the 13th flotilla on 1 October. Her 1st patrol was uneventful, followed by short journeys between Bergen, Kristiansand, Stavanger and Trondheim and a second patrol between Trondheim and Harstad where she torpedoed but only damaged the British Captain class frigate HMS Mounsey, east northeast of Murmansk, on 2 November 1944. Her 3rd and 4th patrols were uneventful. The first was in the Barents and Norwegian Seas from Harstad, back on 18 December and her 5th ended in Narvik after three days off Murmansk. Her 5th patrol was longer but went to naught. She entered the 14th flotilla on 1 April 1945, departed Narvik on 15 April 1945 to the Barents Sea, back on 7 May. She surrendered and moved to Skjomenfjord on 12 May, transferred to Loch Eriboll for Operation Deadlight, sunk on 17 December by ORP Błyskawica.

U-296 (1943)

She was ordered on 14 October 1941 from Bremer Vulkan Werft, Bremen-Vegesack, Yard number 61, laid down on 23 January 1943, launched on 5 September 1943 and commissioned on 3 November 1943. In short, she sank no ship, made 3 patrols from Norway bases, and in her last, was reported missing after leaving Bergen in late February 1945. Presumed sunk by a mine around 12 March in the North Channel.

U-297 (1943)

U-294 was ordered from Bremer Vulkan Werft, Yard number 62, laid down on 27 January 1943, launched on 9 October 1943 and commissioned on 17 November 1943. She trained like the orthers in the 8th flotilla, was transferred to 11th from November 1944, single patrol, failed to sink or damage any ship, sunk by a British aircraft c6 December 1944, all hands lost.

U-298 (1943)

U-298 was ordered on 23 March 1942 at Bremer Vulkan Yard number 63, laid down on 23 February 1943, launched on 25 October and commissioned on 1 December 1943 (10 months construction). Her 1st captain was Oberleutnant zur See Ortwin Hensellek when she started training in the 8th flotilla until July 1944, but wa stransferred to the U-boat Defense School until 8 May 1945. Surrendered, sunk on 29 November (Deadlight).

U-299 (1943)

Ordered on 23 March 1942 from Bremer Vulkan Werft, Yard N°64, she was laid down on 1 March, launched on 6 November, commissioned on 15 December (9 months construction). Trained with the 8th flotilla until 31 July, transferred to the 11th, 13th, 14th (last from 1st March 1945), 6th patrols from Norway, no kills, surrendered on 9 May 1945, sunk in Operation Deadlight, 4 December.

U-300 (1943)

Ordered on 23 March 1942 from Bremer Vulkan, yard N°65 she was laid down on 9 April 1943, launched on 23 November, commissioned on 29 December (8 months construction). Under Oberleutnant zur See Fritz Hein she trained in the 8th U-boat Flotilla, operated with the 7th (August-September 1944), 11th (October 1944-22 February 1945 making three patrols, sinking two ships on 10 November (Godafoss 1,542t and Shirvan 6017t), and damaged two on 17 February 1945 (Michael J. Stone (US) 7,176 and Regent Lion (UK) 9,551t). She was sunk on 22 February 1945 off Quarteira, Portugal, by gunfire from the Algerine-class minesweepers HMS Recruit and HMS Pincher, after being badly damaged by depth charges from the armed yacht HMS Evadne on 19 February. She surfaced and surrendered after being badly damaged, 41 survivors.

U317 (1943)

U-317 was ordered on 14 October 1941 from Flender Werke, Lübeck, the first Type VIIC/41 built there, as Yard number 317. She was laid down on 12 September 1942, launched on 1 September 1943 and commissioned on 23 October 1943 (13 months). She trained in the 4th flotilla under command of Oberleutnant zur See Peter Rahlf, transderred to the 9th in June, making a first patrol in May-June 1944 to Norway, and Egersund from 21 June, but was sunk with all hands on 26 June NE of the Shetlands, depth charged by a Liberator from No. 86 Sqn. RAF.