The South Wales Ports at War 1939-41 ] The mine war in the Bristol Channel 1939-41 ] A background to U-boat operations in the Bristol Channel ] [ Types of U-boat ] U-boats that entered the Bristol Channel ]

Types of U-boat

"...the Type VII was a compromise; a boat small enough to be built quickly but large enough for Atlantic operations"













the Type VII was not a true submarine







































RAF Coastal Command lost almost 700 aircraft in confrontations with U-boats
















The gun was often the best way to finish off damaged vessels or sink smaller ships and economise on expensive torpedoes

Under the terms of the Treaty of Versailles Germany was not allowed to retain or build any submarines so that at the outbreak of war in 1939 the German U-boat fleet was comparatively modern, all the vessels having been built since 1935. Between 1919 and 1934 German submarine technicians had not been idle, and among those submarines built in various European shipyards to German design and with German technical assistance were r built in 1932 for the Turkish navy, and Vesikko built in 1933 for Finland. Gür was 72.4 m (237 ft 6 in) long and displaced 750 tons (surfaced) and 960 tons (submerged), and was armed with six torpedo tubes (four bow and two stern) and one 4-in (102-mm) gun. Vesikko was a smaller boat of only 250 tons (surfaced) and 300 tons (submerged); it was 40.8 m (134 ft) long, and armed with three bow 53-cm (21-in) torpedo tubes and a small gun.

Gür provided a prototype for an ocean-going submarine, suitable for operations of limited endurance in coastal areas or the Mediterranean, while Vesikko was the forerunner of the coastal submarines. In June 1935, Hitler renounced the Treaty of Versailles and announced an intention to rearm. The German government brought its U-boat builders back from Holland and set them to work at the shipyards at Kiel. In order to get the building programme under way as rapidly as possible to fulfil the need to have submarines at sea and to train future crews, it was the coastal submarines of Type II, as they were to be known, that were the first to be laid down. The first boat for the German navy, called U I, was launched in Kiel in June 1935, the remainder following shortly afterwards. Types II B and II C were similar, but were larger and carried additional fuel to increase their range. Type II D boats were introduced in 1940; they were still larger; and were fitted with saddle tanks to increase their range further. Although used for operations early in the war these boats were soon relegated to training duties, an essential part of the enormous expansion programme that the U-boat arm was to undertake.


The Type VII U-boat

Meanwhile the Type I, of which only two boats were built, gave the German navy a capability of operations in the Atlantic. Basically the same design and performance as Gür, these two boats in turn were to become the prototype, with the UB48 Class of 1917, of a new series of ocean-going submarines, the Type VII. This type, with its several variants, was undoubtedly the mainstay of the German submarine fleet throughout the war. The variants retained many structural characteristics of the original Type VII but were designed either for better performance or for more specialised roles. It should be emphasised that the Type VII was a compromise; a boat small enough to be built quickly but large enough for Atlantic operations. Whilst complex for its time, the Type VII was not a true submarine. In many respects it was a surface vessel with a capacity for short term underwater operations. U-boats were expected to attack on the surface. Underwater they were hampered by slow speed, blindness and poor endurance. These disadvantages were to prove fatal for 75% of U-boat crews when they came into conflict with Allied anti-submarine patrols. Although the Type VII was developed throughout the war with many technical innovations, usually far in advance of Allied developments, it was considered obsolete by 1944. In the final stages of the War, the German Navy started to use true submarines which were technologically superior to the Allied anti-submarine forces. Thankfully, the War ended before they were used to any great effect.

The first Type VII was U 27, launched in 1936, designed for operations in the Atlantic. It had good sea keeping qualities and easy handling both on the surface and submerged, and carried the best possible torpedo armament that could be fitted into a submarine of less than 65 m (213 ft) in length and only 626 tons surfaced displacement. Inevitably this was achieved at the expense of other factors, and habitability was spartan, to say the least. The Type VIIs were distinguished by their single external torpedo tube aft. U 30, a boat of this type, was responsible for sinking the liner Athenia early in the war. The boats were also given extra flexibility in attack with the development of the magnetic mine, which will be discussed later.

U 45, the first Type VII B, was launched in April 1938. The type had increased size and displacement to accommodate higher-performance engines and more fuel. The stern torpedo tube was made internal with the hull. A Type VII B, U 47 commanded by Korvetten Kapitän Günther Prien entered Scapa Flow in 1939 and sank Royal Oak, and later was to sink many thousands of tons of Allied shipping in the Atlantic.

The Type VII C, introduced in 1940, had a further increase in displacement and fuel capacity, more torpedo reloads, and a better AA armament. With better armament boats were encouraged to fight it out with aircraft on the surface, which they often did with substantial success. RAF Coastal Command lost almost 700 aircraft in confrontations with U-boats (sinking 220 in the process). Contracts were placed for 688 boats of this type, though later some of these were cancelled and others were destroyed by enemy action during construction. The Type VII C/41 differed only in that it had a stronger hull to give a greater diving depth. Eight boats of this type were to have been completed for the Italian navy, but they were taken into commission by the Germans themselves following the Italian surrender. U573 was interned in Spain at Cartagena after being badly damaged by depth charges dropped from an RAF aircraft in 1942. The following year she was sold to Spain and renumbered G.7. U570 surrendered after being damaged by an RAF aircraft south of Iceland, and later was commissioned as HMS Graph. Orders for a second variant, the Type VII C/42, were cancelled to allow production to concentrate on newer types. Had it entered service it would have had increased range and an even greater diving depth.

A mine laying variant, the Type VII D, was introduced in 1942. The six boats of this type had a 9.8m (32 ft 2-in) section added into the hull aft of the conning tower to take five free-flooding mine chutes carrying a total of 15 moored mines similar to those carried by surface mine layers. In the Type VII F this extra section was adapted to carry 25 torpedoes to replenish other submarines already on patrol. Four boats of this type were built, and they carried additional fuel to increase their range. In addition to the replenishment torpedoes for other boats they had their own establishment of torpedoes to carry out their own operations.


The Schnorkel

As mentioned earlier, the U-boat was designed to operate mostly on the surface and submerge only for evasion or for rare daylight attacks. In 1940 a surfaced U-boat was even more secure near a convoy than submerged as the Allied ASDIC was useless against a surface vessel. It was only with the continued progress of Allied anti-submarine inventions that the U-boat was forced to spend more and more time underwater, running on limited electric motors which only managed a few knots and had poor endurance. The Dutch navy had been experimenting as early as 1938 with a simple pipe system which enabled a submarine at periscope depth to operate its diesels and thus have almost unlimited underwater range. The German Navy paid little attention (they actually thought about this system in 1940 as a means to take fresh air into the boats but saw no need to run the diesels underwater) until 1943 when more and more U-boats were lost to Allied counterattacks. Then it was taken into service as an afterthought. Combat boats were fitted with schnorchels as part of their normal refits from July 1944.

There were several problems with the Schnorchels; first it turned the attacking/patrolling U-boat into a slow and almost deaf vessel. Six knots was the maximum speed for the Type VII otherwise the air mast would break off. Second were the various disposal problems associated with the permanently submerged boat, garbage had to be stored internally and further fouled up the boat. Third, the initial schnorchel masts tended to close up in rough weather and thus the diesels, being starved of air from above, sucked all available air from the boat itself and causing extremely harmful ear pains and sometimes even damaged ear drums.

Despite these problems, U-boat crews learned to use schnorchels to good effect Many boats owed their survival to effective use of the schnorchel, particularly in the closing months of the war.


Emblems and Markings

Hundreds of U-boats displayed emblems in the war, much like many other services from all sides. They varied from typical war emblems (swords, axes etc.) to cartoon characters such as Mickey Mouse. Many U-boat commanders had their own personal emblems which would be moved from boat to boat as they changed commands. A number of U-boats were adopted by cities and towns in Germany before and during the war and some of those boats displayed the crests of those towns on their tower. This was usually along with the main emblem of the same boat. Boats would often display their Flotilla emblem as an alternative or in addition to a boat emblem.  Many boats would also use grey camouflage or disruptive patterns to further conceal their low profiles. However, the weathering processes of the Atlantic usually wore away paint schemes very quickly.


Deck Guns

Early German U-boats of types I, VII, IX and X had a very powerful deck gun. A good crew could fire 15-18 rounds a minute. The gun normally had a crew of 3 to 5 and was usually commanded by the second watch officer (II WO). The gun was often the best way to finish off damaged vessels or sink smaller ships and economise on expensive torpedoes. The gun was normally not used when aircraft were suspected to be around. It required a line of men (3 which were on the deck) to transport the ammunition from the main locker below the control room to the gun. The used rounds were taken back into the boat. The U-boats had a small water-proof ammunition locker for the gun on the deck in order to be able to start firing almost immediately when the order was given.

Type VII U-boats had the 8,8cm gun. This weapon is not to be confused with the famous German Army 88mm anti-tank / anti-aircraft gun which was probably the best weapon of the war, they did not even use the same ammunition. The 8,8cm gun fired a 9 kilogram round. The boat usually carried 250 rounds. From June 1943 the Atlantic-boats left their bases without the deck gun. The boats rarely being in a position to shell targets without experiencing air attack. and many crews exchanged their artillery pieces for increased anti-aircraft armament.

Back to the U-boat campaigns in the Bristol Channel



The View for Sunday October 15 2000

If you want to navigate the site come to the Home Page  © Swansea History Web 2000

Up ] The South Wales Ports at War 1939-41 ] The mine war in the Bristol Channel 1939-41 ] A background to U-boat operations in the Bristol Channel ] [ Types of U-boat ] U-boats that entered the Bristol Channel ]

The History Web Bookshop    Search the Site  Contact us   The Swansea History Web CD ROM