GORDON WILLIAMSON, illustrated by IAN PALMER
KRIEGSMARINE U-BOATS 1939-45
The Type VII was a single-hulled boat, the pressure hull in places forming the outer hull of the boat. It differed principally from earlier designs in that its bunkerage was contained within the pressure hull rather than in saddle tanks, giving additional protection to the precious fuel. A single central ballast tank was provided, together with bow and stern ballast tanks out with the pressure hull, and two large saddle tanks on either side of the hull. Outside the pressure hull was a streamlined external casing, the area between the two being free-flooding. Between the deck and the top of the pressure hull a considerable amount of ducting and trunking was fitted, as well as the mounting for the deck gun, ready-ammunition locker for the deck gun, a small dinghy and, ultimately, storage for spare torpedoes. All could be accessed via hatches or by removal of deck plating. An 8.8 cm naval gun was fitted on the foredeck just in front of the conning tower and a 2 cm flak gun just aft.
The first variant to be produced was the Type VIIA, of which ten were completed. These were allocated the numbers U-27 through to U-36. Four were built by Germaniawerft and six by AG Weser. Construction began in February 1935 with the first boat (U-33) of the type launched on 11 June 1936.
One of the most instantly recognisable visual characteristics of the Type VIIA was the hump of the external stern torpedo tube, clearly visible oil the aft decking.
SPECIFICATIONS
Length - 64.5 m
Beam - 5.8 m
Draft - 4.4 m
Displacement 626 tons surfaced, 745 tons submerged
Speed - 16 knots surfaced, 8 knots submerged
Endurance - 4,300 nautical miles surfaced, 90 nautical miles submerged
Powerplant - 2 × 1,160 bhp diesels coupled with 2 × 375 bhp electric motors
Armament - 5 torpedo tubes (4 bow, 1 stern), 1 × 8.8 cm gun, 1 × 2 cm gun
Crew - 44
The gun crew of a Type VIIC go through their loading drills whilst in port. Just in front of and to the left of the gun can be seen the white interior of the raised ready-ammunition locker hatch. This provided a small supply of readily accessible ammunition for the 8.8 cm deck gun whilst further supplies were brought up from the boat's magazine.
The Type VIIB was a marked improvement over the initial variant. It was given twin rather than single rudders to improve its turning circle, and the external stern torpedo tube of the VIIA was brought inside the pressure hull, firing out between the two rudders. The boat was given an increase in length of two metres to provide additional bunkerage, and additional fuel was now also carried in special fuel cells within the saddle tanks. These cells were self-compensating - as fuel was drawn from the top of the tank, sea water entered at the bottom, compensating for the loss in weight. Compensating tanks were also installed to help prevent the boat rolling when on the surface. Finally, turbochargers were fitted to the diesel engines to provide a modest increase in speed. All of these changes increased the size and weight of the boat significantly.
A total of 24 Type VIIBs were built: the first seven (U-45 to U-51) by Germaniawerft, a second tranche of four, also from Germaniawerft, and a third tranche consisting of four boats each from Germaniawerft, Vulcan, with five from Flenderwerft.
SPECIFICATIONS
Length - 66.5 m
Beam - 6.2 m
Draft - 4.7 m
Displacement - 753 tons surfaced, 857 tons submerged
Speed - 17.2 knots surfaced, 8 knots submerged
Endurance - 6,500 nautical miles surfaced, 90 nautical miles submerged
Powerplant - 2 × 1,400 bhp diesels coupled with 2 × 375 bhp electric motors
Armament - 5 torpedo tubes (4 bow, 1 stern), 1 × 8.8 cm gun, 1 × 2 cm gun, 15 mines
Crew - 44
The third and most significant variant of the Type VII was the 'C'. It was originally proposed as a vessel for the new sonar search equipment known as the Such-Gerät (S-Gerät), with an increase in length to both the control room and the conning tower to accommodate the necessary equipment. Other smaller, but nevertheless welcome, modifications were also incorporated. A small buoyancy tank was fitted within the saddle tanks, which could also be flooded to improve diving time. A new filtration system for the diesel engines, a new diesel rather than electric-powered compressor for the air tanks - to ease demands on the electrical system - and more modern electrical switching systems were all added to this model.
U-30, a Type VIIA, returns to base after a war cruise. This boat is generally credited with starting the fashion of painting an emblem on the side of the conning tower. Note the single central stern jump wire; most boats had two, one to port and one to starboard. The very dark grey colour of the saddle tanks is once again apparent.
SPECIFICATIONS
Length - 67.1 m
Beam - 6.2 m
Draft - 4.8 m
Displacement - 761 tons surfaced, 865 tons submerged
Speed - 17 knots surfaced, 7.6 knots submerged
Endurance - 6,500 nautical miles surfaced, 80 nautical miles submerged
Powerplant - 2 × 1,400 bhp diesels coupled with 2 × 375 bhp electric motors
Armament - 5 torpedo tubes (4 bow, 1 stern), 1 × 8.8 cm gun, 1 × 2 cm gun
Crew - 44
The first major sub-variant of this type was the VIIC/41. This variant featured extensive replacement of existing electrical equipment by newer, more compact models. The weight thus saved (some 11 tons overall) was utilised in thickening the steel plate used for the pressure hull by a further 2.5 mm, thus allowing an increase in diving capabilities from a maximum depth of 250 m to 300 m. The bow was also lengthened slightly to increase seaworthiness.
SPECIFICATIONS
Length - 67.2 m
Beam - 6.2 m
Draft - 4.8 m
Displacement - 759 tons surfaced. 860 tons submerged
Speed - 17 knots surfaced, 7.6 knots submerged
Endurance - 6,500 nautical miles surfaced, 80 nautical miles submerged
Powerplant - 2 × 1,400 bhp diesels coupled with 2 × 375 bhp electric motors
Armament - 5 torpedo tubes (4 bow, 1 stern), 1 × 8.8 cm gun, 1 × 2 cm gun
Crew - 44
U-boat ace Kapitänleutnant Gunther Prien on the bridge of U-47. This was an early Type VIIA boat. Note the outward flare of the conning tower edge common to most early Type VIIs and later replaced by a more effective form of spray deflector. Also visible are the snorting bull emblem adopted by Prien as his boat's emblem and the attachment points at the side of the tower for the jump wires.
This projected sub-variant was an attempt to improve speed further by adding additional turbochargers, coupled with an increase in length to give greater fuel storage capabilities. Armour-plate was to be used rather than normal steel for the pressure hull, taking the maximum depth possible up to 500 m. None of this type was ever completed.
Another design that got no further than the drawing board, this was essentially a Type VUG/42 with armament upgraded to provide six rather than four bow torpedo tubes.
This version of the versatile VII design was a minelayer. The hull of the basic Type VII was extended by almost ten metres, just aft of the control room, to provide five vertical mine shafts. Additional benefits of the extension in hull length included space for additional fuel and extra trim tanks. These boats also had the luxury of refrigerated food storage. The full torpedo and gun armament of the standard Type VII was retained. On the down side, the additional weight and length, to say nothing of the raised decking required for the mine shafts, reduced overall speed and handling qualities, though overall endurance was increased.
SPECIFICATIONS
Length - 76.9 m
Beam - 6.4 m
Draft - 5.0 m
Displacement - 965 tons surfaced, 1,080 tons submerged
Speed - 16 knots surfaced, 7.3 knots submerged
Endurance - 8,100 nautical miles surfaced, 69 nautical miles submerged
Powerplant - 2 × 1,400 bhp diesels coupled with 2 × 375 bhp electric motors
Armament - 5 torpedo tubes (4 bow, 1 stern), 1 × 8.8 cm gun, 1 × 2 cm gun, 15 mines
Crew - 44c
A design project only, this version was to have been fitted with a new type of two-stroke V12 lightweight diesel engine made by the Deutz firm. The project was abandoned before any could be built.
The Type VIIF was a modification of the basic Type VII design similar to that of the VIID, in that a 10.5 m additional length of hull was inserted just abaft the control room. This allowed an extra 24 torpedoes to be carried, as well as additional refrigerated food storage and two extra crew members. The VIIF was to act as a resupply boat, carrying additional torpedoes to front-line boats that had expended their ammunition.
U-431, a newly launched Type VIIC, shows to good advantage the hull shape of the Type VII with its narrow foredeck, widening around the conning tower, to narrow again towards the stern and the bulge of the saddle tanks. The demarcation between the light grey upper works and the dark grey scheme below the waterline is also clearly visible.
Only four of this type were eventually built (U-1059 to U-1062), all produced by Germaniawerft.
SPECIFICATIONS
Length - 77.6 m
Beam - 7.3 m
Draft - 4.9 m
Displacement - 1,084 tons surfaced, 1,181 tons submerged
Speed - 16.9 knots surfaced, 7.9 knots submerged
Endurance - 9,500 nautical miles surfaced, 75 nautical miles submerged
Powerplant - 2 × 1.400 bhp diesels coupled with 2 × 375 bhp electric motors
Armament - 5 torpedo tubes (4 bow, 1 stern), 1 × 8.8 cm gun, 1 × 2 cm gun
Crew - 46
Of all of the Type VII models, none saw as much modification and improvement to the basic design as did the most common model of all, the Type VIIC. The variants mentioned above relate principally to internal modifications, which would not be obvious from photographs of the boats themselves. However, one major series of modifications that became necessary during the course of the war, and which drastically altered the appearance of each type, was made to the conning tower.
As Allied anti-submarine measures improved, the use of aircraft against U-boats took on a considerable significance and it quickly became apparent that the single 2 cm anti-aircraft gun carried on the basic Type VII was woefully inadequate. In fact, no matter how much the flak armament was beefed up, few U-boats would risk taking on enemy aircraft (although in several recorded cases, when left with no option but to remain on the surface, U-boats did take on enemy aircraft, and succeeded in shooting them down).
The various conning tower configurations, beginning with the basic circular platform to the rear of the tower, with its single 2 cm flak gun, were given numeric codes, the basic configuration being known as Turin 0.
The first major attempt to beef up flak defences was to widen the platform somewhat, and replace the single 2 cm flak gun with two twin 2 cm machine gun mounts.
Turm 1. This design was to see a second, lower, platform fitted to the rear of the conning tower (generally known to U-boat men as the 'Wintergarden') on which would be fitted a twin 2 cm flak. This design was approved in June 1942.
U-377, a Type VIIC, seen here after her bridge conversion. The armoured shelters, intended to give bridge crew some protection against enemy fire, can be seen welded to either side of the forward part of the tower. The deck gun has been removed and an extended 'wintergarden' platform fitted to the rear of the tower to take the upgraded flak armament. (Jak P. Mallmann-Showell)
Turm 2. Due to problems with the supply of the new weapons required for the Turm 1 design, a second new tower configuration was introduced in which the original round upper platform was joined by a similar lower platform, both of which were fitted with a single 2 cm flak gun. Installation of this type commenced in December 1942.
Turm 3. This little-used configuration saw two single 2 cm flak guns mounted side by side on the upper platform and was used only on the Type VIII).
Turm 4. This, destined to become the most common configuration, had two twin 2 cm guns fitted on a widened upper platform, and a single four-barrelled 2 cm flak gun, the Flakvierling, on the lower. The Flakvierling was gradually replaced by a single-barrelled 3.7 cm flak gun.
Turm 5. An experimental model, fitted to only one U-boat (U-362), this configuration had two twin 2 cm flak guns on the upper platform, a single twin 2 cm flak gun on the lower, and a fourth twin 2 cm gun on a special platform built on to the front of the tower.
Turm 6. Another little-used model, only two boats received this modification. This configuration had a single-barrelled 3.7 cm flak gun on the lower platform, two twin 2 cm flak guns on the upper, and a single twin 2 cm in front of the tower on a separate pedestal. Only L-673 and U-973 were so converted.
Turm 7. A 'concept' only and never actually built, this tower would have seen twin 3.7 cm flak guns on platforms both to the rear and in front of the tower.
Flak Boats. A small number of boats (seven only) were ordered to be converted into Flak Boats, and given heavy anti-aircraft armament to allow them to take on enemy aircraft on relatively even terms. U-441 was given a Flakvierling on a mount in front of the tower, another on the upper platform at the rear of the tower, as well as a 3.7 cm flak the rear lower platform. Although U-441 succeeded in shooting down a Sunderland flying boat, the adverse effect of the new bridge structure on diving times and handling, combined with the heavy armament now being installed on standard boats, saw the order cancelled with all Flak Boats to be reconverted back to Turm 4 configuration.
We have much more interesting information on this site.
Click MENU to check it out!
∎ cartalana.com© 2009-2024 ∎ mailto: cartalana@cartalana.com