The class was a group of six coastal defense ships built by the German ("Imperial Navy") in the late 19th century. The ships were intended to protect the German coastline from naval attacks. The class comprised the lead ship , along with her sisters , , , , and . All six ships were named after Norse mythological figures. Two further vessels, the , were built to a similar design but were not identical.
The -class ships were obsolete by the outbreak of World War I, and saw only limited service in their intended role before they were withdrawn from active duty. The ships then served in a variety of secondary duties, including barracks ships, target ships, and in the case of , an icebreaker in the Baltic Sea. All six ships were struck from the naval register on 17 June 1919, days before the Treaty of Versailles was signed. Five of the ships were sold for scrapping immediately after they were struck from the register (with being lost in transit), but was purchased by a shipping company, and converted into a freighter. She served in this capacity until she too was scrapped in 1930.
Background
In 1883, Albrecht von Stosch, the (Chief of the Admiralty) of the German (Imperial Navy), resigned. He was replaced by General Leo von Caprivi, an army officer with little experience in naval matters. He inherited from Stosch a naval construction program outlined in 1873 that stated the fleet's requirements to be fourteen sea-going ironclad warships, along with seven monitors and two floating batteries, among other cruising vessels and other, smaller ship types. By that time, the fleet had acquired thirteen of the large ironclads (the fourteenth, the ironclad , having sunk in an accidental collision in 1878), but none of the monitors or floating batteries.
Caprivi faced a number of obstacles to any new capital ship construction. The loss of generated considerable displeasure in the (Imperial Diet), and thus resistance to expensive naval projects. The general consensus for the expected service life of existing capital ships was thirty years, which meant that even the oldest ironclads that had been built in the 1860s could not be replaced before the mid-1890s. Lastly, the 1880s was characterized by general confusion amongst naval experts in all navies. The question of tactics in the ironclad age had not been settled, and end-on ramming attacks (as had been done successfully at the Battle of Lissa in 1866) required a heavy forward-firing armament, while the traditional line of battle emphasized heavy broadside firepower. For his part, Caprivi also vacillated between viewing the navy as critical to Germany's value as a potential ally to another power, and seeing it as a potentially unnecessary drain on resources that would be better used by the army.
To address these issues, Caprivi established the (Admiralty Council) in January 1884, which included a number of experienced naval officers. He ordered (Rear Admiral) Max von der Goltz to begin investigating the characteristics that best suited a new ironclad for the needs of the German fleet. Goltz prepared a survey for the navy's design departments for basic parameters such as the optimal top speed, the most effective armament, and size constraints of the existing naval infrastructure. In the meantime, in his first memorandum to the in late 1884, he assured the deputies that he would not request funding for new capital ships for at least three or four years. Instead, he requested only limited funding for modernization of existing vessels to make them more effective.
Goltz, who was appointed as the "Head of the Naval Department", organized a series of meetings to determine the requirements for the next class of capital ships. During one such meeting in October 1885, the members agreed to a set of specifications, including an armament of four guns, six torpedo tubes, a maximum speed of , and draft low enough to allow passage through the confined waters between Denmark and Sweden. The latter requirement was specified due to fears of a future war with Denmark, which the planners viewed as a possibility owing to Denmark's defeat in the Second Schleswig War in 1864. Additionally, displacement was limited to a maximum of .
By March 1886, the chief naval designer, Alfred Dietrich, had completed a broad design study titled "Memorandum on the Construction of Armorclads", which included series of general proposals for vessels of varying sizes and characteristics. Caprivi in turn requested more detailed proposals from the memorandum, including cost estimates, which Dietrich completed on 8 June. These ranged from a "heavy battleship" armed with seven guns, which cost 10 million marks, down to a small coastal defense ship armed with a pair of guns and displacing just , which cost 3.92 million marks. The price of the new ships was at the forefront of Caprivi's considerations, as the was opposed to increases in naval spending and the cost of the impending construction of the Kaiser Wilhelm Canal loomed over future naval budgets. At the same time, increasing international tensions in the mid-1880s, due to the scramble for Africa and perennial conflicts between Greece and the Ottoman Empire, strengthened Caprivi's resolve to request funding for new capital ships by mid-1886.
Discussions had begun for the requested naval budget of the 1887–1888 fiscal year. Having been unable to secure parliamentary approval for naval increases for new vessels in previous years, Caprivi instead submitted a request for a large-scale program that included new battleships, cruisers, coastal defense ships, and torpedo boats. The rejected almost all of his requested budget, allocating funds for only a single coastal defense ship, though Caprivi had asked for ten of the vessels, as this was the cheapest option available, and it was apparent that the canal would require local defenses once it was eventually completed.
Development
Dietrich's proposal for a 2,500-ton coastal defense ship from the 1886 memorandum was selected for development into the ship that was to be built. The vessel was to incorporate the following set of characteristics: a main battery of two guns supported by a secondary battery of six Hotchkiss revolver cannon; four torpedo tubes; a speed of . This was to be achieved at a cost of 3.5 million marks. The two heavy guns were carried in open barbettes side-by-side forward, as German naval theorists still favored ramming attacks that required a capability for end-on fire. They carried the guns in individual barbette mounts that could be independently aimed, rather than a single rotating barbette as had been done with the s. In addition, the hull was given a pronounced tumblehome shape to provide as wide a field of fire as possible. German tactical doctrine envisioned the ships breaking through an enemy line of battle, and the arrangement would have allowed each ship to engage multiple targets.
Displacement quickly rose to , which permitted the installation of a third 24 cm gun aft. The third gun was deemed necessary to improve the ability to fire astern if the ships were forced to retreat into the rivers near the ends of the canal. Weapons tests were held at the Krupp testing grounds at Meppen in 1888, using mock-ups of contemporary torpedo-boat designs. It was determined that the 37 mm Hotchkiss was unable to inflict serious damage at the expected battle range of , and so the secondary battery was replaced with guns, though these had not performed entirely adequately in the tests either. The first vessel received six of the new guns, while all subsequent ships were fitted with eight.
As construction work on the initial vessels proceeded in the early 1890s, alterations to the program continued. Of the ten vessels initially requested and slowly approved, the last pair were removed from the building program. Vessels seven and eight were altered slightly, becoming the , which Dirk Nottelmann and David Sullivan refer to as "somewhat of a sub-class." The most radical proposal for the Odin class would have seen them rearmed with four 24 cm guns, but placed in a pair of twin-gun turrets, as German tactical doctrine had returned to the line of battle by that time, meaning that a heavier broadside of four guns was seen as more important than two guns able to fire ahead independently. Additional changes would have been made to the hull to compensate for the weight of the fourth gun, including the adoption of lighter Krupp armor instead of the old compound armor used in the earlier ships, but the plan came to nothing, and the two Odins were completed with the basic Siegfried layout.
Design General characteristics and machinery
The ships of the class were long at the waterline and long overall. The ships had a beam of and a draft of between forward and aft. The ships had a designed displacement of , and a maximum displacement of . The ships used transverse and longitudinal steel frames in the hull. They had eight watertight compartments and a double bottom that ran for 60% of the hull. The hulls had a pronounced ram bow and tumblehome shape, and their upper deck extended from the bow to the main mast, where it stepped down one level. Their superstructures consisted of an armored conning tower forward and a smaller secondary platform further aft. Each ship was fitted with a pair of pole masts for signaling purposes.
The ships were described as good sea boats; they had gentle motion and were very responsive to commands from the helm. Steering was controlled via a single rudder. The ships lost significant speed in heavy seas, however, and suffered from severe weather helm. The ships had a crew of 20 officers and 256 enlisted men, with an additional 6 officers and 22 men when serving as a flagship. The ships carried a number of smaller boats, including one picket boat, one pinnace, two cutters, one yawl, and one dinghy.
The ships were powered by two sets of 3-cylinder triple-expansion engines, each in its own engine room. This was the first use of triple-expansion machinery in a major German warship. These engines drove a pair of three-bladed screws that were in diameter. The ships had eight marine type boilers, with the exception of , which was equipped with eight Thornycroft boilers. On all vessels, the boilers were vented through a single funnel located amidships. The ships' propulsion systems produced between , which produced top speeds of ; was the fastest and was the slowest. The ships stored up to of coal and of fuel oil, which enabled a range of at a cruising speed of . At , the ships could only steam . Each ship had three electric generators that provided between 29–26 kilowatts at 67 volts.
Armament
The ships' primary armament consisted of three 24 cm K L/35 guns. These were placed in an unusual arrangement for such large guns, two of which were mounted in a pair of rotating barbettes forward side-by-side, while the third was mounted in a single barbette aft. The barbette mounts were the MPL C/88. Each gun had a range of elevation from -3 to +25 degrees, and at maximum elevation, the guns had a range of . Ammunition storage amounted to 204 rounds, or 68 shells per gun. The ships were initially supplied with C/80 armor-piercing and common shells, which weighed ; these were later replaced by C/01 shells and eventually a C/01/07 semi-armor-piercing shell that weighed . Muzzle velocity for the guns was initially , using the C/80 shell, but increased to with the C/01 and later variants.