The Roon class was a pair of armored cruiser

Armored cruiser

The armored cruiser was a type of warship of the late 19th and early 20th centuries. Like other types of cruiser, the armored cruiser was a long-range, independent warship, capable of defeating any ship apart from a battleship, and fast enough to outrun any battleships it encountered.The first...

s built for the German Imperial Navy

Kaiserliche Marine

The Imperial German Navy was the German Navy created at the time of the formation of the German Empire. It existed between 1871 and 1919, growing out of the small Prussian Navy and Norddeutsche Bundesmarine, which primarily had the mission of coastal defense. Kaiser Wilhelm II greatly expanded...

 after the turn of the 20th century. The class comprised and , which closely resembled the earlier Prinz Adalbert class

Prinz Adalbert class armored cruiser

The Prinz Adalbert class was a type of armored cruiser built for the Imperial German Navy in the early 1900s. Two ships of the class were built, , and . Friedrich Carl was commissioned first, on 12 December 1903 and Prinz Adalbert followed on 12 January 1904. They were an improvement upon the...

 ships, but incorporated slight incremental improvements. The ships were easily distinguished from their predecessors by the addition of a fourth funnel. Like all of the armored cruisers built by Germany, they were intended to serve as station ships in Germany's overseas possessions. The ships did not compare well with their British rivals.

The two ships served with the High Seas Fleet

High Seas Fleet

The High Seas Fleet was the battle fleet of the German Empire and saw action during World War I. The formation was created in February 1907, when the Home Fleet was renamed as the High Seas Fleet. Admiral Alfred von Tirpitz was the architect of the fleet; he envisioned a force powerful enough to...

 in the reconnaissance squadrons after they joined the fleet in 1905–1906. At the outbreak of World War I in 1914, the ships served alongside the more powerful battlecruiser

Battlecruiser

Battlecruisers were large capital ships built in the first half of the 20th century. They were developed in the first decade of the century as the successor to the armoured cruiser, but their evolution was more closely linked to that of the dreadnought battleship...

s of the I Scouting Group

I Scouting Group

The I Scouting Group was a special reconnaissance unit within the German Kaiserliche Marine. The unit was famously commanded by Admiral Franz von Hipper during World War I. The I Scouting Group was one of the most active formations in the High Seas Fleet during the war; the unit took part in every...

. While returning to port after a raid of the English coast

Raid on Scarborough, Hartlepool and Whitby

The raid on Scarborough, Hartlepool and Whitby, which took place on 16 December 1914, was an attack by the Imperial German Navy on the British seaport towns of Scarborough, Hartlepool, West Hartlepool, and Whitby. The attack resulted in 137 fatalities and 592 casualties, many of which were civilians...

 on 16 December 1914, Yorck struck German mines and sank with heavy loss of life. Roon was disarmed in 1916 and intended to be converted into a seaplane carrier, though this was never carried out. The ship was eventually broken up for scrap in 1921.

Design

Design work on Roon and her sistership Yorck was completed in 1901. The design for the Roon class can be traced back to the first German armored cruiser, , built between 1896–1900, and the preceding Victoria Louise class

Victoria Louise class protected cruiser

The Victoria Louise class of protected cruisers was Germany's last class of ships of that type. They were designed for overseas cruiser duties. The class design introduced the clipper bow and blocky sides that typified later German armored cruisers....

 of protected cruiser

Protected cruiser

The protected cruiser is a type of naval cruiser of the late 19th century, so known because its armoured deck offered protection for vital machine spaces from shrapnel caused by exploding shells above...

s that came before it. The German armored cruisers were designed for overseas service, specifically to serve as station ships in the German colonies in Africa, Asia, and the Pacific.

Roon and her sister Yorck were improved versions of the preceding Prinz Adalbert class. The two ships German armored cruisers were slightly larger and faster than the Prinz Adalbert class and had a slightly different armor layout; the Roon class ships had thinner armor on the turret faces, and slightly thinner armored decks. They shared many of the same layout characteristics as the contemporary German pre-dreadnought battleships, including a smaller main armament but heavier secondary battery than their foreign equivalents. As a result, they likewise compared unfavorably with their British contemporaries. Taylor describes the ships as "poorly protected and not a successful class in service."

General characteristics

The ships of the Roon class were 127.3 metres (417.7 ft) long at the waterline and 127.8 m (419.3 ft) overall. They had a beam of 20.2 m (66.3 ft) and a draft of 7.76 m (25.5 ft). Roon and Yorck displaced 9533 metric tons (9,382.4 LT) normally, and 10266 metric tons (10,103.8 LT) at full load. Their 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...

s were constructed from transverse and longitudinal steel frames that formed a structure over which the steel hull plates were rivet

Rivet

A rivet is a permanent mechanical fastener. Before being installed a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole, and the tail is upset, or bucked A rivet...

ed. The hulls contained 12 watertight compartments and a double bottom

Double bottom

A double bottom is a ship hull design and construction method where the bottom of the ship has two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is somewhat higher in the ship, perhaps a few feet, which forms a...

 that ran for 60 percent of the length of the ship.

Like the preceding Prinz Adalbert class ships, Roon and Yorck were good sea boats; when the fuel bunkers were full they had a gentle motion. They also maneuvered well and were responsive to the helm. With the rudder

Rudder

A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

 hard over, the ships lost up to 60 percent speed. The ships' casemate

Casemate

A casemate, sometimes rendered casement, is a fortified gun emplacement or armored structure from which guns are fired. originally a vaulted chamber in a fortress.-Origin of the term:...

s were placed too low, and as a result they were exceedingly wet; the casemate guns were impossible to use in heavy seas. They had a metacentric height

Metacentric height

The metacentric height is a measurement of the static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre . A larger metacentric height implies greater stability against overturning...

 of 1.04 m (3.4 ft). Their standard complements numbered some 35 officers and 598 enlisted men. While serving as a squadron flagship the crew was augmented by 13 officers and 62 men, and as a second command ship 9 officers and 44 sailors were added to the standard crew.

Propulsion

Roon and Yorck were powered by the same engine system as the preceding class, which consisted of three 3-cylinder vertical triple expansion engines, each of which drove one of the ships' three screws. The central screw was 4.5 m (14.8 ft) in diameter while the outer screws were 4.8 m (15.7 ft) wide. Steam was provided to the engines by 16 Dürr boilers built by Düsseldorf-Ratinger Röhrenkesselfabrik. Each boiler had 4 fireboxes apiece for a total of 48. The propulsion system produced 19000 ihp, which delivered a top speed of 21 knots (41.2 km/h). The ships both had four turbo generators, which provided 260 kilowatts at 110 volts. The ships both had a single rudder.

Armament

The ships' primary armament consisted of four 21 centimetres (8.3 in) SK L/40 guns mounted two twin turrets, one fore and one aft.In Imperial German Navy gun nomenclature, "SK" (Schnellfeuerkanone) denotes that the gun is quick firing, while the L/40 denotes the length of the gun. In this case, the L/40 gun is 40 calibers, meaning that the gun is 40 times long as it is in diameter. These guns fired a 108 kilograms (238.1 lb) armored-piercing shell at a muzzle velocity of 780 metres (2,559.1 ft) per second, for a maximum range of 12300 m (13,451.4 yd) with their original maximum elevation of 16 degrees. The guns were later improved to 30 degrees, which extended the maximum range to 16200 m (17,716.5 yd).

Secondary armament included ten 15 cm (5.9 in) SK L/40 guns in single turrets and casemates and fourteen 8.8 cm (3.5 in) SK L/35 guns, also casemated. The 15 cm guns fired a 40 kg (88.2 lb) shell at a muzzle velocity of 800 m (2,624.7 ft) per second. The guns could be elevated to 30 degrees, which provided a maximum range of 13900 m (15,201.2 yd). The 8.8 cm guns fired a 7 kg (15.4 lb) shell at a muzzle velocity of 770 m (2,526.2 ft) per second. These guns had a maximum elevation of 25 degrees and a range of 9100 m (9,951.9 yd). The ships were also equipped with four 45 cm (17.7 in) torpedo tubes.

This armament was identical to that on the preceding Prinz Adalbert class

Prinz Adalbert class armored cruiser

The Prinz Adalbert class was a type of armored cruiser built for the Imperial German Navy in the early 1900s. Two ships of the class were built, , and . Friedrich Carl was commissioned first, on 12 December 1903 and Prinz Adalbert followed on 12 January 1904. They were an improvement upon the...

, with the exception of ammunition stores. The Roon class ships carried 380 shells for the main battery, 1,600 rounds for the 15 cm guns, and 2,100 shells for the 8.8 cm guns. The planned conversion for Roon to a seaplane carrier called for six 15 cm L/45 guns and six 8.8 cm Flak guns, with 2,400 rounds, though this was never carried out.

Armor

Roon and Yorck were protected by Krupp

Krupp

The Krupp family , a prominent 400-year-old German dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments. The family business, known as Friedrich Krupp AG Hoesch-Krupp, was the largest company in Europe at the beginning of the 20th...

 cemented steel armor. At the waterline, their armored belt was 100 mm (3.9 in) thick amidships were the ships' vitals were located. This was decreased slightly to 80 mm (3.1 in) on either ends of the central section of the belt. The belt was backed by 55 mm (2.2 in) of teak

Teak

Teak is the common name for the tropical hardwood tree species Tectona grandis and its wood products. Tectona grandis is native to south and southeast Asia, mainly India, Indonesia, Malaysia, and Burma, but is naturalized and cultivated in many countries, including those in Africa and the...

 planking. At the casemate deck the side armor was also 100 mm thick. Their armored deck ranged in thickness from 40–60 mm (1.6–2.4 in) and was connected to the belt by sloped armor that was 40–50 mm (1.6–2 in) thick.

The forward conning tower

Conning tower

A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

 had 150 mm (5.9 in) thick sides and a 30 mm (1.2 in) thick roof. The rear conning tower was less well-protected; its sides were only 80 mm thick and its roof was 20 mm (0.78740157480315 in) thick. The main battery gun turrets were armored with 150 mm thick steel plates on the sides and 30 mm thick roofs. The 15 cm turrets were protected by 100 mm thick sides and 80 mm thick gun shields.

Construction

Roon was laid down in 1902 at the Kiel Navy dockyard

Kaiserliche Werft Kiel

Kaiserliche Werft Kiel was a German shipbuilding company founded in 1867, first as Königliche Werft Kiel but renamed in 1871 with the proclamation of the German Empire...

. She was launched on 27 June 1903 and completed on 5 April 1906, at the cost of 15,345,000 marks

German gold mark

The Goldmark was the currency used in the German Empire from 1873 to 1914.-History:Before unification, the different German states issued a variety of different currencies, though most were linked to the Vereinsthaler, a silver coin containing 16⅔ grams of pure silver...

. Yorck was laid down in February 1903, at Blohm & Voss shipyard. Yorck was launched on 14 May 1904 and completed on 21 November 1905 at a cost of 16,241,000 marks. Roon was laid down as Ersatz Kaiser, as a replacement for the old armored frigate , which had been renamed Uranus and used as a harbor ship. Yorck was ordered as Ersatz Deutschland to replace , the sistership to Kaiser, which had renamed Jupiter and converted into a target ship

Target ship

A target ship is a vessel — typically an obsolete or captured warship — used for naval gunnery practice or for weapons testing.-Rationale:Sinking redundant warships is an effective way of testing new weapons and warships in as realistic a manner as possible. Whilst practice torpedoes are fired...

.All German ships were ordered under provisional names; additions to the fleet were given a letter, while ships that were intended to replace older vessels were ordered as "Ersatz

Ersatz

Ersatz means 'substituting for, and typically inferior in quality to', e.g. 'chicory is ersatz coffee'. It is a German word literally meaning substitute or replacement...

 (ship name)." An example of this practice is the s: the lead ship

Lead ship

The lead ship or class leader is the first of a series or class of ships all constructed according to the same general design. The term is applicable military ships and larger civilian craft.-Overview:...

  was considered an addition to the fleet, and was ordered as "K", while her sisters and were ordered as Ersatz Kaiserin Augusta and Ersatz Hertha, being replacements for two older ships. See: Gröner, p. 56

SMS Roon

After commissioning into the fleet, was assigned to the I Scouting Group

I Scouting Group

The I Scouting Group was a special reconnaissance unit within the German Kaiserliche Marine. The unit was famously commanded by Admiral Franz von Hipper during World War I. The I Scouting Group was one of the most active formations in the High Seas Fleet during the war; the unit took part in every...

. In 1908, she served as the flagship for Rear Admiral Jacobsen in the second division. Roon served here until 1912 when she was replaced by the new battlecruiser

Battlecruiser

Battlecruisers were large capital ships built in the first half of the 20th century. They were developed in the first decade of the century as the successor to the armoured cruiser, but their evolution was more closely linked to that of the dreadnought battleship...

 .

At the start of World War I, Roon was serving as the flagship

Flagship

A flagship is a vessel used by the commanding officer of a group of naval ships, reflecting the custom of its commander, characteristically a flag officer, flying a distinguishing flag...

 of the III Scouting Group. The ship participated in several actions during World War I, including the raid on Scarborough, Hartlepool and Whitby

Raid on Scarborough, Hartlepool and Whitby

The raid on Scarborough, Hartlepool and Whitby, which took place on 16 December 1914, was an attack by the Imperial German Navy on the British seaport towns of Scarborough, Hartlepool, West Hartlepool, and Whitby. The attack resulted in 137 fatalities and 592 casualties, many of which were civilians...

, during which she served in the cruiser screen for the dreadnought

Dreadnought

The dreadnought was the predominant type of 20th-century battleship. The first of the kind, the Royal Navy's had such an impact when launched in 1906 that similar battleships built after her were referred to as "dreadnoughts", and earlier battleships became known as pre-dreadnoughts...

s of the High Seas Fleet

High Seas Fleet

The High Seas Fleet was the battle fleet of the German Empire and saw action during World War I. The formation was created in February 1907, when the Home Fleet was renamed as the High Seas Fleet. Admiral Alfred von Tirpitz was the architect of the fleet; he envisioned a force powerful enough to...

. Roon also conducted operations against Russian forces in the Baltic Sea

Baltic Sea

The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

, including bombardments against the Russian positions at Libau

Liepaja

Liepāja ; ), is a republican city in western Latvia, located on the Baltic Sea directly at 21°E. It is the largest city in the Kurzeme Region of Latvia, the third largest city in Latvia after Riga and Daugavpils and an important ice-free port...

 in support of the army in May 1915. The Battle of the Åland Islands took place between Roon and several other German cruisers and Russian forces led by the powerful cruiser . in July 1915. In August Roon and bombarded Russian positions in the Baltic and briefly engaged several Russian 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...

s.

After 1916, Roon was disarmed and used as a guard ship and floating barracks in Kiel

Kiel

Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

 until the end of the war. Design work commenced in 1916 to convert the ship into a seaplane carrier; work was planned to last from 1917 to 1918 during a period of 20 months. The ship was struck from the naval register on 25 November 1920 and scrapped the following year at Kiel-Nordmole.

SMS Yorck

also served in the I Scouting Group with her sistership, in the second division. In 1908, the ship won the annual "Kaiser's Challenge Cups for Prize Firing" for the reconnaissance squadron. In 1911, the ship came under the command of Franz von Hipper

Franz von Hipper

Franz Ritter von Hipper was an admiral in the German Imperial Navy . Franz von Hipper joined the German Navy in 1881 as an officer cadet. He commanded several torpedo boat units and served as watch officer aboard several warships, as well as Kaiser Wilhelm II's yacht Hohenzollern...

, who would go on to command the I Scouting Group during the war. Hipper held this position aboard Yorck from 1 October 1911 to 26 January 1912. In early 1912 the ship was decommissioned and her crew was transferred to the new battlecruiser .

The ship had a short career during World War I. At the outbreak of war, Yorck was brought out of the reserve fleet and joined her sistership Roon in the III Scouting Group. After the raid on Scarborough, Hartlepool and Whitby, the ship made a navigational error upon returning to the Jadebusen

Jadebusen

The Jade Bight, is a bay on the North Sea coast of Germany. It was formerly known simply as Jade or Jahde.About 180 km² in area, the Jade was largely created by storm floods during the 12th and 16th centuries. During this period it was connected in the East to the river Weser...

, and accidentally sailed into a German defensive minefield. The ship sank quickly and only 127 men of her complement of 629 were rescued. The wreck was cleared over several periods between 1929 and the mid 1980s. The first period of work lasted from 1929–30; work commenced briefly in 1965. The final work on removing the ship began in 1982.