U-43 class submarine (Austria-Hungary)

The U-43 class was a class

Ship class

A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....

of two coastal submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s or U-boats operated by the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

during World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. The two boats that comprised the class were Type UB II submarines

German type UB II submarine

The UB II type submarine was a class of U-boat built during World War I by the Kaiserliche Marine. They were enlarged from the preceding type UB I and were more effective vessels. The boats were a single hull design with a 50 metre maximum diving depth and a 30-45 second diving time...

of the Imperial German Navy, making the two classes identical. From the beginning of World War I, Austria-Hungary had been working to increase the size of its U-boat fleet, so the Imperial German Navy, which was finding it difficult to obtain trained submarine crews, sold two of its UB II boats, and , to its ally in June 1917.

The German Type UB II design incorporated improvements over Type UB I

German type UB I submarine

The Type UB I was a class of small coastal submarines built in Germany at the beginning of the First World War. Twenty boats were constructed, most of which went into service with the German Imperial Navy. Boats of this design were also operated by the Austro-Hungarian Navy and the Bulgarian...

boats, the first coastal submarines of the German Imperial Navy. Among these were twin engines and shafts for more redundancy during operations, a higher top speed, and larger torpedo tubes with double the complement of torpedoes. As a result the UB II boats were nearly twice as heavy as their predecessor UB I boats.

Both boats of the class were selected for German service in the Mediterranean while under construction. They were shipped via rail to Pola

Pula

Pula is the largest city in Istria County, Croatia, situated at the southern tip of the Istria peninsula, with a population of 62,080 .Like the rest of the region, it is known for its mild climate, smooth sea, and unspoiled nature. The city has a long tradition of winemaking, fishing,...

, assembled, launched, and commissioned in the German Imperial Navy, where both enjoyed great success against Allied shipping. In June 1917, the boats were decommissioned, handed over to Austria-Hungary, and then commissioned into the Austro-Hungarian Navy in July. The B in the designation of both boats was dropped, but the submarines retained the same numbers, becoming U-43 and U-47 under the Austro-Hungarian flag. At the end of the war and were ceded to Italy and France, respectively, and had been scrapped by 1920.

Background

Austria-Hungary

Austria-Hungary , more formally known as the Kingdoms and Lands Represented in the Imperial Council and the Lands of the Holy Hungarian Crown of Saint Stephen, was a constitutional monarchic union between the crowns of the Austrian Empire and the Kingdom of Hungary in...

's U-boat fleet was largely obsolete at the outbreak of World War I

World War I

. The Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

satisfied its most urgent needs by purchasing five Type UB I

German type UB I submarine

submarines that comprised the from Germany, by raising and recommissioning the sunken French submarine Curie

French submarine Curie (Q 87)

SM U-14 or U-XIV was a U-boat or submarine of the Austro-Hungarian Navy during the First World War. She was launched in 1912 as the French Curie , but captured and rebuilt for service in the Austro-Hungarian Navy...

as ,Curie

French submarine Curie (Q 87)

had been caught in an anti-submarine net

Anti-submarine net

An anti-submarine net is a device placed across the mouth of a harbour or a strait for protection against submarines.-Examples of anti-submarine nets:*Lake Macquarie anti-submarine boom*Indicator net*Naval operations in the Dardanelles Campaign...

while trying to enter the harbor at Pola

Pula

on 20 December 1914. See: Gardiner, p. 343. and by building four submarines of the that were based on the 1911 Danish Havmanden class

Havmanden class submarine (1911)

The Havmanden class was a class of six submarines built for the Royal Danish Navy from 1911 to 1914. Also later known as the A class, the boats were designed by the Austro-Hungarian firm Whitehead & Co. of Fiume...

.The plans for the Danish Havmanden class submarines

Havmanden class submarine (1911)

, three of which were built in Austria-Hungary, were seized from Whitehead & Co. in Fiume. See: Gardiner, pp. 344, 354.

After these steps alleviated the most urgent needs, the Austro-Hungarian Navy had adopted the German Type UB II design for what became known as the Austro-Hungarian U-27 class

U-27 class submarine (Austria-Hungary)

The U-27 class was a class of eight submarines or U-boats built for and operated by the Austro-Hungarian Navy during World War I. The class was based upon the German Type UB II design of the German Imperial Navy and was constructed under license in Austria-Hungary.After the Austro-Hungarian Navy...

in mid 1915, and had six of that class being built under license in Austria-Hungary by late 1916.A further two U-27 class boats

U-27 class submarine (Austria-Hungary)

were started in 1916. See: Halpern, p. 383. In November 1916, Germany had inquired to find out if Austria-Hungary were interested in purchasing existing German submarines because Germany was having a hard time finding trained submarine crews. After protracted negotiations, which had stalled over the outflow of Austro-Hungarian gold reserves to Germany, an agreement to purchase two submarines—UB-43 and UB-47—was reached in June 1917.

The UB II design

The German UB II design of coastal submarines was a development from the design of the UB I boats, which had been originally ordered in September 1914.The Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

's s were German-built UB I boats

German type UB I submarine

. Two of the U-10 class had, like the two U-43 boats, been originally commissioned into the Imperial German Navy. See: Gardiner, p. 343. During their trials, the UB I boats were found to be too small and too slow, but in-service use revealed another problem. The UB I boats had a single propeller shaft/engine combo such that if either component failed, the U-boat became almost totally disabled. The UB II boats featured twin propeller shafts and twin engines (one shaft for each engine) which not only alleviated this problem, but also had the added benefit of increasing the top speed. The new design also included more powerful batteries, larger torpedo tubes, and a deck gun

Deck gun

A deck gun is a type of artillery cannon mounted on the deck of a ship or submarine.The deck gun was used as a defensive weapon against smaller boats or ships and in certain cases where torpedo use was limited. Typically a crew of three; gunner, loader, and layer, operated the gun, while others...

. The UB II boats could also carry twice the torpedo load of their predecessors, and nearly ten times as much fuel. To contain all of these changes the hull

Submarine hull

The term light hull is used to describe the outer hull of a submarine, which houses the pressure hull, providing hydrodynamically efficient shape, but not holding pressure difference...

was larger, and the surface and submerged displacement

Displacement (ship)

A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...

was more than doubled.

The UB II boats were ordered from three manufacturers in groups that numbered between two and twelve. Each group had slight variations in design, resulting in differences in displacements, lengths, speeds, fuel capacities, and operational ranges.

The U-43-class design

The U-43 class consisted of two boats from a contracted group of six UB II boats built by AG Weser

AG Weser

Aktien-Gesellschaft Weser was one of the great German shipbuilding companies, located at the Weser River in Bremen. Founded in 1873 it was finally closed in 1983. Altogether, AG Weser built about 1400 ships of different types, including many war ships...

of Bremen

Bremen

The City Municipality of Bremen is a Hanseatic city in northwestern Germany. A commercial and industrial city with a major port on the river Weser, Bremen is part of the Bremen-Oldenburg metropolitan area . Bremen is the second most populous city in North Germany and tenth in Germany.Bremen is...

.The six boats were numbered sequentially from UB-42 to UB-47. Like all of the UB II boats from different manufacturers and contract groups, the U-43 group had distinct specifications. This group displaced 272 metric tons (299.8 ST) surfaced and 305 metric tons (336.2 ST) submerged. The boats had a single hull

Submarine hull

The term light hull is used to describe the outer hull of a submarine, which houses the pressure hull, providing hydrodynamically efficient shape, but not holding pressure difference...

with saddle tank

Saddle tank (submarine)

Saddle tanks are a type of ballast tank configuration fitted to mid-era submarines, those of World War II.Saddle tanks are fitted in pairs external to the pressure hull, one on each side, in a similar manner to that of a horse's saddle-bags, the positioning of which they resemble in appearance.-...

s (an early style of ballast tank

Ballast tank

A ballast tank is a compartment within a boat, ship or other floating structure that holds water.-History:The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or argonaut octopus, and the concept has been invented and reinvented many times by...

s), and were 121 in 1 in (36.91 m) long with a beam

Beam (nautical)

The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

of 14 in 4 in (4.37 m) and a draft

Draft (hull)

The draft of a ship's hull is the vertical distance between the waterline and the bottom of the hull , with the thickness of the hull included; in the case of not being included the draft outline would be obtained...

of 12 in 2 in (3.71 m). For propulsion, they featured two shafts, twin diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s of 270 bhp for surface running, and twin electric motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s of 280 shp for submerged travel. The boats were capable of 8.8 knots while surfaced and 6.2 knots submerged. The range of the boats was 6940 nautical miles (12,852.9 km) at 5 knots surfaced, and 45 nautical miles (83.3 km) at 4 knots submerged. The U-43 class boats were designed for a crew of 22.

The U-43 class boats were armed with two 50 cm (19.7 in) bow torpedo tubes and carried a complement of four torpedoes. They were each equipped with an 88 mm/26 (3.5 in) deck gun

Deck gun

and an 8 mm (0.31496062992126 in) machine gun

Machine gun

A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....

.

The two U-43-class U-boats were nearly identical to the eight boats of the Austro-Hungarian Navy's U-27 class, which were built to UB II plans. Despite the similarities, the two groups are identified in sources as distinct classes.

Construction

The six-boat group that included UB-43 and UB-47 was ordered in July 1915, and both boats had been laid down in early September. This group was selected by the German Admiralstab

German Imperial Admiralty Staff

The German Imperial Admiralty Staff was a military institution established in 1899 under the direct authority and command of the German Emperor, Kaiser Wilhelm II for managing the German Imperial Navy...

for deployment to the Mediterranean, but, unlike the smaller UB I boats, they could not as easily be transported overland by rail. Weser prepared the boats for rail shipment by cutting the boat sections longitudinally, and sent all the materials, along with German shipyard workers, to Pola

Pula

, where the boats were reassembled. UB-43 was launched in early April 1916, while UB-47 followed in June.

SM U-43

UB-43 was ordered by the Imperial German Navy on 31 July 1915 and was laid down by AG Weser

AG Weser

of Bremen

Bremen

on 3 September. While under construction, she was one of a group of six U-boats selected for service in the Mediterranean. UB-43 was broken into railcar-sized components and shipped overland to the Austro-Hungarian port of Pola

Pula

where Weser workers assembled her. She was launched on 8 April 1916 and commissioned into the Imperial German Navy as SM UB-43 on 24 April, under the command of Oberleutnant zur See Dietrich Niebuhr. Kapitänleutnant Hans von Mellenthin was assigned to the boat in late August 1916, and led the boat in sinking 19 ships over the next 8½ months. In April 1917, von Mellenthin was replaced by Oberleutnant zur See Horst Obermüller who commanded the ship for the next three months, sinking three more ships and damaging the British cruiser . UB-43 was decommissioned on 15 July and taken over by the Austro-Hungarian Navy.

Renamed U-43 for Austro-Hungarian service, the boat became the class leader of the U-43 boats when she was commissioned into the Austro-Hungarian Navy on 30 July 1917. The submarine's successes while under German command were not matched under Austro-Hungarian; she damaged a single ship in November 1917 in her only successful attack. U-47 was surrendered to France as a war reparation in 1920 and was broken up at Bizerta.

SM U-47

UB-47 was ordered by the Imperial German Navy on 31 July 1915 and was laid down at Bremen by AG Weser on 4 September. As one of six U-boats selected for service in the Mediterranean while under construction, she was broken into railcar-sized components and shipped overland to the Austro-Hungarian port of Pola

Pula

. Shipyard workers from Weser assembled the boat and her five sisters at Pola, where she was launched on 17 June.

SM UB-47 was commissioned into the Imperial German Navy on 4 July 1916 under the command of Oberleutnant zur See Wolfgang Steinbauer. Steinbauer and UB-47 sank 15 ships over the next nine months, including two Cunard Line

Cunard Line

Cunard Line is a British-American owned shipping company based at Carnival House in Southampton, England and operated by Carnival UK. It has been a leading operator of passenger ships on the North Atlantic for over a century...

steamers— and —serving as British troopship

Troopship

A troopship is a ship used to carry soldiers, either in peacetime or wartime...

s, as well as the French battleship . Steinbauer also damaged three ships with a combined gross register tonnage of 16,967. Under the command of Hans Hermann Wendlandt, who had replaced Steinbauer in April 1917, UB-47 sank an additional seven ships through 21 July, at which time the ship was decommissioned and handed over to the Austro-Hungarian Navy.

The B in her designation was dropped when she was commissioned as SM U-47 for the Austro-Hungarian Navy on 30 July 1917. U-47s success under Austro-Hungarian command was less than that under the German flag; only three ships were sunk through the end of the war. U-47 was surrendered to France as a war reparation in 1920 and was broken up at Bizerta.

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