SM U-6 or U-VI was a U-5-class

U-5 class submarine (Austria-Hungary)

The U-5 class was a class of three submarines or U-boats that were operated by the Austro-Hungarian Navy before and during World War I. The class was a part of the Austro-Hungarian Navy's efforts to competitively evaluate three foreign submarine designs....

 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...

 or U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

 built for and 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....

  before and during the First World War. The submarine was built as part of a plan to evaluate foreign submarine designs, and was the second of three boats of the class built by Whitehead & Co. of Fiume after a design by American John Philip Holland

John Philip Holland

John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the U.S...

.

U-6 was laid down in February 1908 and launched in June 1909. The double-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...

ed submarine was just over 105 feet (32 m) long and displaced

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...

 between 240 &, depending on whether surfaced or submerged. U-6s design had inadequate ventilation and exhaust from her twin gasoline engines often intoxicated the crew. The boat was commissioned into the Austro-Hungarian Navy in July 1910, and served as a training boat—sometimes making as many as ten cruises a month—through the beginning of the First World War in 1914.

The submarine had only one wartime success, which was sinking a French destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

 in March 1916. Later that year, in May, U-6 became entangled in 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...

ting deployed as part of the Otranto Barrage

Otranto Barrage

The Otranto Barrage was an Allied naval blockade of the Otranto Straits between Brindisi in Italy and Corfu on the Albanian side of the Adriatic Sea in World War I. The blockade was intended to prevent the Austro-Hungarian Navy from escaping into the Mediterranean and threatening Allied operations...

. Coming under fire from drifter

Naval drifter

A naval drifter is a boat built along the lines of a commercial fishing drifter but fitted out for naval purposes. The use of naval drifters is paralleled by the use of naval trawlers....

s running the nets, U-6 was abandoned and sunk. All of her crewmen were rescued and were held in captivity through the end of the war.

Design and construction

U-6 was built as part of a plan 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....

 to competitively evaluate foreign submarine designs from Simon Lake

Simon Lake

Simon Lake was a Quaker American mechanical engineer and naval architect who obtained over two hundred patents for advances in naval design and competed with John Philip Holland to build the first submarines for the United States Navy.Born in Pleasantville, New Jersey, Lake joined his father's...

, Germaniawerft

Friedrich Krupp Germaniawerft

Friedrich Krupp Germaniawerft was a German shipbuilding company, located in the harbour at Kiel, and one of the largest and most important builders of U-boats for the Kaiserliche Marine in World War I and the Kriegsmarine in World War II.-History:The company was founded in 1867 by Lloyd Foster, as...

, and John Philip Holland

John Philip Holland

John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the U.S...

. The Austro-Hungarian Navy authorized the construction of U-6 (and sister ship, U-5) in 1906 by Whitehead & Co. of Fiume. The boat was designed by American John Philip Holland

John Philip Holland

John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the U.S...

 and licensed by Holland and his company, Electric Boat

Electric boat

While a significant majority of water vessels are powered by diesel engines, with sail power and gasoline engines also remaining popular, boats powered by electricity have been used for over 120 years. Electric boats were very popular from the 1880s until the 1920s, when the internal combustion...

. U-6 was laid down on 21 February 1908 in the United States, partially assembled, and shipped to Whitehead's for final assembly, a process which, author Edwin Sieche notes, "caused a lot of trouble". She was launched at Fiume on 12 June 1909.

U-6s design featured a single-hull

Hull (watercraft)

A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...

 with a tear-drop shaped body that bore a strong resemblance to modern nuclear submarines. She was 105 in 4 in (32.11 m) long by 13 in 9 in (4.19 m) abeam and had a draft of 12 in 10 in (3.91 m). She displaced

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...

 240 tonnes (264.6 ST) surfaced, and 273 tonnes (300.9 ST) submerged. Her two 45 centimetres (17.7 in) bow torpedo tubes featured unique, cloverleaf

Cloverleaf

-Places:*Cloverleaf, Louisville, Kentucky, a neighborhood*Cloverleaf, Texas, a suburb of Houston*Cloverleaf Local School District in southern Medina County, Ohio-Science and technology:*A representation of the chemical structure of a transfer RNA molecule...

-shaped design hatch

Hatch

Hatch may refer to:* Hatching, also called "cross-hatching", an artistic technique used to create tonal or shading effects using closely spaced parallel lines* Hatching, the emergence of a young animal from an egg...

es that rotated on a central axis, and the boat was designed to carry up to four torpedoes. For surface running, U-6 was outfitted with 2 gasoline engines, but suffered from inadequate ventilation, which resulted in frequent intoxication of the crew; her underwater propulsion was by two 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.U-6s gasoline engines were slated to be replaced by 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, but this was not accomplished before the boat sank in May 1916. The two engines ordered for U-6, were instead installed in which had to be lengthened to accommodate them. See: Baumgartner and Sieche, as excerpted here (reprinted and translated into English by Sieche). Retrieved 26 November 2008.

Service career

U-6 was commissioned into 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....

 on 1 July 1910, with Linienschiffsleutnant Georg Ritter von Trapp

Georg Ritter von Trapp

Korvettenkapitän Georg Ludwig Ritter von Trapp , known as Baron von Trapp, was an Austro-Hungarian Navy officer. His exploits at sea during World War I earned him numerous decorations, including the prestigious Military Order of Maria Theresa...

 in command. Over the next three years she served primarily as a training boat, making as many as ten training cruises per month. On 7 November 1911, she hosted a Norwegian naval delegation that inspected her. On 26 June 1912, U-6 was accidentally rammed by the submarine tender

Submarine tender

A submarine tender is a type of ship that supplies and supports submarines.Submarines are small compared to most oceangoing vessels, and generally do not have the ability to carry large amounts of food, fuel, torpedoes, and other supplies, nor to carry a full array of maintenance equipment and...

 Pelikan while surfacing after a deep diving trial.

At the outbreak of 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...

, U-6 was one of only four fully operational U-boats in the Austro-Hungarian Navy fleet, and was stationed at Cattaro by late 1914. U-6s activities over the early part of the war are not reported, but the boat's armament was augmented by a 3.7 cm/23 (1.5 in) quick-firing

Quick-firing gun

A quick-firing gun is an artillery piece, typically a gun or howitzer, which has several characteristics which taken together mean the weapon can fire at a fast rate...

 (QF) 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...

 in December 1915. Sister boat U-5 had her first radio receiver installed at the same time her deck gun was added, but it is not reported whether U-6 did, too.

On 23 February 1916, U-6 made an unsuccessful attack on an Italian , but she then managed to torpedo and sink the French destroyer Renaudin on 18 March off Durazzo. Renaudin went down with 47 of her 83-man complement.

On the night of 12 May, U-6 headed out to try to intercept shipping between Santa Maria di Leuca

Santa Maria di Leuca

Santa Maria di Leuca, often spelled simply Leuca, is a frazione of the comune of Castrignano del Capo, in the province of Lecce , southern Italy.A part of the town once belonged to the comune of Gagliano del Capo.- Description :...

 and Valona

Valona

The valona is a popular narrative song- and poetry-form of the Mexican state of Michoacán. Its main characteristics are: a bitter sense of humor, mainly with reference to erotism and social concerns; its lyrics are composed as groupings of ten-line strophes, each line made up of eight syllables;...

. Linienschiffsleutnant Hugo von Falkhausen, U-6s commander since November 1915, attempted to pass underneath two drifter

Drifter (fishing boat)

A drifter is a type of fishing boat. They were designed to catch herrings in a long drift net. Herring fishing using drifters has a long history in the Netherlands and in many British fishing ports, particularly in East Scottish ports....

s that formed a part of the Otranto Barrage

Otranto Barrage

The Otranto Barrage was an Allied naval blockade of the Otranto Straits between Brindisi in Italy and Corfu on the Albanian side of the Adriatic Sea in World War I. The blockade was intended to prevent the Austro-Hungarian Navy from escaping into the Mediterranean and threatening Allied operations...

. While submerged, von Falkhausen heard an unexplained noise on the hull of the boat, which was likely the sound of U-6 fouling one of the 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...

s deployed from the drifter Calistoga. The drifter's skipper was alerted to the submarine's presence when one of the indicator buoys had fired. Calistoga launched signal flares that attracted the attention of two nearby drifters Dulcie Doris and Evening Star II. In the meantime, von Falkhausen surfaced U-6 to try to cut loose the buoy being dragged behind his boat. When the hatch

Trapdoor

A trapdoor is a door set into a floor or ceiling .Originally, trapdoors were sack traps in mills, and allowed the sacks to pass up through the mill while naturally falling back to a closed position....

 was opened, the crew discovered the boat entangled in the net.
Though unable to submerge, von Falkhausen attempted to flee on the surface, but the port propeller shaft became fouled. Realizing that he was stuck, and with Dulcie Doris and Evening Star II beginning to shell his boat, U-6s captain ordered code books and confidential material thrown overboard and the submarine scuttle

Scuttling

Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

d. U-6s three officers and seventeen crewmen were all rescued, but spent the remainder of the war as prisoners of the Italians. In her career, U-6 sank one ship totaling .