HNoMS Mjølner, named after the hammer of the god Thor, was the fourth of five ships of the John Ericsson-classmonitors built for the Royal Swedish Navy and the Royal Norwegian Navy in the mid-1860s. Influenced by the use of ironclads during the American Civil War, the design was based on that of USS Monitor. They were designed under the supervision of the Swedish-born inventor John Ericsson—coincidentally designer of Monitor—and built in Sweden. Mjølner was delivered in 1868. She ran aground the following year, without serious damage, and reconstructed in 1897 with later breech-loading guns. Mjølner was sold for scrap in 1909.
The John Ericsson-class ironclads were designed to meet the need of the Swedish and Norwegian Navies for small, shallow-draft armored ships capable of defending their coastal waters. The standoff between USS Monitor and the much larger CSS Virginia during the Battle of Hampton Roads in, early 1862, roused much interest in Sweden in this new type of warship, as it seemed ideal for coastal defense duties. John Ericsson, designer and builder of Monitor, born in Sweden—although becoming an American citizen in 1848—offered to share his design with the Swedes. In response, they sent Lieutenant John Christian d'Ailly to the United States to study monitor design and construction under Ericsson. D'Ailly arrived in July 1862 and toured rolling mills, gun foundries, and visited several different ironclads under construction. He returned to Sweden in 1863 having completed the drawings of a Monitor-type ship under Ericsson's supervision.[1]
The ship was 60.88 meters (199 ft 9 in) long overall, with a beam of 13.54 meters (44 ft 5 in). She had a draft of 3.4 meters (11 ft 2 in) and displaced 1,522 metric tons (1,498 long tons).[2]Mjølner was divided into nine main compartments by eight watertight bulkheads. Over time a flying bridge and, later, a full superstructure, was added to each ship between the gun turret and the funnel.[3] Initially her crew numbered 80 officers and men, but this increased to 104 as she was modified with additional weapons.[2]
Propulsionedit
The John Ericsson-class ships had one twin-cylinder vibrating lever steam engines, designed by Ericsson himself, driving a single four-bladed, 3.74-meter (12 ft 3 in) propeller. Their engines were powered by four fire-tube boilers at a working pressure of 40 psi (276 kPa; 3 kgf/cm2). The engines produced a total of 380 indicated horsepower (280 kW) which gave the monitors a maximum speed of 6.5 knots (12.0 km/h; 7.5 mph) in calm waters. The ships carried 110 tonnes (110 long tons) of coal, enough for six day's steaming.[4]
Armamentedit
Mjølner was initially armed with a pair of Armstrong 270-millimeter (10.6 in) rifled muzzle-loading guns. Each gun was constructed of steel and weighed 18.5 long tons (18.8 t). The ship also carried an 80-millimeter (3.1 in) gun. During Mjølner's reconstruction in 1897 her gun turret was fixed in place and modified to serve as a barbette for her two new breech-loadingCockerill 120-millimeter (4.7 in) guns. She also received two 124-millimeter (4.9 in) and 65-millimeter (2.6 in) Cockerill guns mounted in her superstructure. In addition two 37-millimeter (1.5 in) Hotchkiss 5-barrel revolving guns were mounted in the superstructure.[5] They fired a shell weighing about 1.1 lb (0.50 kg) at a muzzle velocity of about 2,000 ft/s (610 m/s), for a range of about 3,500 yards (3,200 m), with a rate of fire of about 30 rounds per minute.[6]
Armoredit
The John Ericsson-class ships had a complete waterline armor belt of wrought iron 1.8 meters (5 ft 11 in) high and 124 millimeters (4.9 in) thick. The armor consisted of five plates backed by 91 millimeters (3.6 in) of wood. The lower edge of this belt was three plates (74.2 millimeters (2.9 in)) thick. The maximum thickness of the armored deck was 24.7 millimeters (1.0 in) in two layers. The gun turret's armor consisted of twelve layers of iron, totalling 270 millimeters (10.6 in) in thickness on the first four monitors. The inside of the turret was lined with mattresses to catch splinters.[3] The base of the turret was protected with a 127-millimeter (5.0 in) glacis, 520 millimeters (20.5 in) high, and the turret's roof was 127 millimeters thick. The conning tower was positioned on top of the turret and its sides were ten layers (250 millimeters (9.8 in)) thick. The funnel was protected by six layers of armor with a total thickness of 120 millimeters (4.7 in) up to half its height.[2][3]
Serviceedit
The Norwegians had built one monitor-type ship of their own, Skorpionen, in 1865, and laid down several others, but the Norwegian Parliament authorized construction of Mjølner in 1867 in Sweden at the cost of 1,102,000 Norwegian krone.[Note 1] She was launched in 1868 and completed on 7 September of that year.[7]Mjølner ran aground at Kragerø on 21 June 1869, and could not be pulled off the rocks until the ship's ammunition, iron ballast and 120 long tons (120 t) of coal were removed. Her repairs were completed on 7 July 1869 by the Royal Dockyard at Horten, at the cost of 5,000 krone. The court of inquiry found the ship's commander and the pilot liable for the repairs, but the parliament released the two from their obligation two years later.[8] She was visited by King Charles XV of Sweden when visiting one of Sweden's west-coast ports in the early 1870s.[7]Mjølner was laid up after her refit in 1897, but was mobilized during 1905 when the personal union between Sweden and Norway was dissolved. She returned to reserve afterward, and was sold for scrap in 1909.[8]
Notesedit
^The exact relationship between the Norwegian Skorpionen class and the John Ericsson class is unclear. Harris 1994 says that the Skorpionen class merely had five, instead of four, boilers and were otherwise identical, see p. 34. But Gardiner cites slightly different dimensions and counts Mjølner as part of the class, see p. 368, as does Silverstone, p. 350
Bojerud, Stellan (1986). "Monitors and Armored Gunboats of the Royal Swedish Navy, Part 1". Warship International. XXIII (2). International Naval Records Organization: 167–180. ISSN 0043-0374.
Gardiner, Robert, ed. (1979). Conway's All the World's Fighting Ships 1860–1905. London: Conway Maritime Press. ISBN0-8317-0302-4.
Harris, Daniel G. (1994). "The Swedish Monitors". In Roberts, John (ed.). Warship 1994. Annapolis, Maryland: Naval Institute Press. pp. 22–34. ISBN1-55750-903-4.
Harris, Daniel G. (1995). "Warship Note". In Roberts, John (ed.). Warship 1995. London: Conway Maritime Press. pp. 171–178. ISBN0-85177-654-X.
Silverstone, Paul H. (1984). Directory of the World's Capital Ships. New York: Hippocrene Books. ISBN0-88254-979-0.
External linksedit
Naval History via Flix: Skorpionen
Naval History via Flix: Mjølner
April 27, 2024
hnoms, mjølner, 1868, hnoms, mjølner, named, after, hammer, thor, fourth, five, ships, john, ericsson, class, monitors, built, royal, swedish, navy, royal, norwegian, navy, 1860s, influenced, ironclads, during, american, civil, design, based, that, monitor, th. HNoMS Mjolner named after the hammer of the god Thor was the fourth of five ships of the John Ericsson class monitors built for the Royal Swedish Navy and the Royal Norwegian Navy in the mid 1860s Influenced by the use of ironclads during the American Civil War the design was based on that of USS Monitor They were designed under the supervision of the Swedish born inventor John Ericsson coincidentally designer of Monitor and built in Sweden Mjolner was delivered in 1868 She ran aground the following year without serious damage and reconstructed in 1897 with later breech loading guns Mjolner was sold for scrap in 1909 Drawing of Mjolner s sister SkorpionenHistory Norway NameHNoMS Mjolner NamesakeMjollnir OperatorRoyal Norwegian Navy Ordered1867 BuilderMotala Verkstad Norrkoping Cost1 102 000 Norwegian krone Laid down1867 Launched1868 Completed7 September 1868 FateScrapped 1909 General characteristics Class and typeJohn Ericsson class monitor Displacement1 501 metric tons 1 477 long tons Length60 88 m 199 ft 9 in Beam13 54 m 44 ft 5 in Draft3 4 m 11 ft 2 in Installed power380 ihp 280 kW Propulsion1 shaft 1 Vibrating lever steam engine 4 cylindrical boilers Speed6 5 knots 12 0 km h 7 5 mph Range950 nautical miles 1 760 km 1 090 mi Complement80 104 Armament2 270 mm 10 6 in Armstrong guns ArmorBelt 124 mm 4 9 in Gun turret 270 mm 11 in Deck 24 6 mm 1 0 in Conning tower 225 mm 8 9 in Contents 1 Design and description 1 1 Propulsion 1 2 Armament 1 3 Armor 2 Service 3 Notes 4 Footnotes 5 References 6 External linksDesign and description editThe John Ericsson class ironclads were designed to meet the need of the Swedish and Norwegian Navies for small shallow draft armored ships capable of defending their coastal waters The standoff between USS Monitor and the much larger CSS Virginia during the Battle of Hampton Roads in early 1862 roused much interest in Sweden in this new type of warship as it seemed ideal for coastal defense duties John Ericsson designer and builder of Monitor born in Sweden although becoming an American citizen in 1848 offered to share his design with the Swedes In response they sent Lieutenant John Christian d Ailly to the United States to study monitor design and construction under Ericsson D Ailly arrived in July 1862 and toured rolling mills gun foundries and visited several different ironclads under construction He returned to Sweden in 1863 having completed the drawings of a Monitor type ship under Ericsson s supervision 1 The ship was 60 88 meters 199 ft 9 in long overall with a beam of 13 54 meters 44 ft 5 in She had a draft of 3 4 meters 11 ft 2 in and displaced 1 522 metric tons 1 498 long tons 2 Mjolner was divided into nine main compartments by eight watertight bulkheads Over time a flying bridge and later a full superstructure was added to each ship between the gun turret and the funnel 3 Initially her crew numbered 80 officers and men but this increased to 104 as she was modified with additional weapons 2 Propulsion edit The John Ericsson class ships had one twin cylinder vibrating lever steam engines designed by Ericsson himself driving a single four bladed 3 74 meter 12 ft 3 in propeller Their engines were powered by four fire tube boilers at a working pressure of 40 psi 276 kPa 3 kgf cm2 The engines produced a total of 380 indicated horsepower 280 kW which gave the monitors a maximum speed of 6 5 knots 12 0 km h 7 5 mph in calm waters The ships carried 110 tonnes 110 long tons of coal enough for six day s steaming 4 Armament edit Mjolner was initially armed with a pair of Armstrong 270 millimeter 10 6 in rifled muzzle loading guns Each gun was constructed of steel and weighed 18 5 long tons 18 8 t The ship also carried an 80 millimeter 3 1 in gun During Mjolner s reconstruction in 1897 her gun turret was fixed in place and modified to serve as a barbette for her two new breech loading Cockerill 120 millimeter 4 7 in guns She also received two 124 millimeter 4 9 in and 65 millimeter 2 6 in Cockerill guns mounted in her superstructure In addition two 37 millimeter 1 5 in Hotchkiss 5 barrel revolving guns were mounted in the superstructure 5 They fired a shell weighing about 1 1 lb 0 50 kg at a muzzle velocity of about 2 000 ft s 610 m s for a range of about 3 500 yards 3 200 m with a rate of fire of about 30 rounds per minute 6 Armor edit The John Ericsson class ships had a complete waterline armor belt of wrought iron 1 8 meters 5 ft 11 in high and 124 millimeters 4 9 in thick The armor consisted of five plates backed by 91 millimeters 3 6 in of wood The lower edge of this belt was three plates 74 2 millimeters 2 9 in thick The maximum thickness of the armored deck was 24 7 millimeters 1 0 in in two layers The gun turret s armor consisted of twelve layers of iron totalling 270 millimeters 10 6 in in thickness on the first four monitors The inside of the turret was lined with mattresses to catch splinters 3 The base of the turret was protected with a 127 millimeter 5 0 in glacis 520 millimeters 20 5 in high and the turret s roof was 127 millimeters thick The conning tower was positioned on top of the turret and its sides were ten layers 250 millimeters 9 8 in thick The funnel was protected by six layers of armor with a total thickness of 120 millimeters 4 7 in up to half its height 2 3 Service editThe Norwegians had built one monitor type ship of their own Skorpionen in 1865 and laid down several others but the Norwegian Parliament authorized construction of Mjolner in 1867 in Sweden at the cost of 1 102 000 Norwegian krone Note 1 She was launched in 1868 and completed on 7 September of that year 7 Mjolner ran aground at Kragero on 21 June 1869 and could not be pulled off the rocks until the ship s ammunition iron ballast and 120 long tons 120 t of coal were removed Her repairs were completed on 7 July 1869 by the Royal Dockyard at Horten at the cost of 5 000 krone The court of inquiry found the ship s commander and the pilot liable for the repairs but the parliament released the two from their obligation two years later 8 She was visited by King Charles XV of Sweden when visiting one of Sweden s west coast ports in the early 1870s 7 Mjolner was laid up after her refit in 1897 but was mobilized during 1905 when the personal union between Sweden and Norway was dissolved She returned to reserve afterward and was sold for scrap in 1909 8 Notes edit The exact relationship between the Norwegian Skorpionen class and the John Ericsson class is unclear Harris 1994 says that the Skorpionen class merely had five instead of four boilers and were otherwise identical see p 34 But Gardiner cites slightly different dimensions and counts Mjolner as part of the class see p 368 as does Silverstone p 350Footnotes edit Harris 1994 pp 22 24 a b c Harris 1994 p 26 a b c Bjoerud p 169 Harris 1994 pp 26 27 Harris 1994 pp 27 34 United States of America 1 pdr 0 45 kg 1 46 37 mm Marks 1 through 15 Navweps com 15 August 2008 Retrieved 22 August 2010 a b Harris 1994 p 27 a b Harris 1995 p 172References editBojerud Stellan 1986 Monitors and Armored Gunboats of the Royal Swedish Navy Part 1 Warship International XXIII 2 International Naval Records Organization 167 180 ISSN 0043 0374 Gardiner Robert ed 1979 Conway s All the World s Fighting Ships 1860 1905 London Conway Maritime Press ISBN 0 8317 0302 4 Harris Daniel G 1994 The Swedish Monitors In Roberts John ed Warship 1994 Annapolis Maryland Naval Institute Press pp 22 34 ISBN 1 55750 903 4 Harris Daniel G 1995 Warship Note In Roberts John ed Warship 1995 London Conway Maritime Press pp 171 178 ISBN 0 85177 654 X Silverstone Paul H 1984 Directory of the World s Capital Ships New York Hippocrene Books ISBN 0 88254 979 0 External links editNaval History via Flix Skorpionen Naval History via Flix Mjolner Retrieved from https en wikipedia org w index php title HNoMS Mjolner 1868 amp oldid 1151224491, wikipedia, wiki, book, books, library,
