HSwMS Thordön HSwMS " Thordön " was the second ship of the monitor s , built for the Royal Swedish Navy in the mid - 1860s . She was designed under the supervision of the Swedish - born inventor , John Ericsson , and built in Sweden . " Thordön " made one foreign visit to Russia in 1867 , but remained in Swedish or Norwegian waters ( at the time , Sweden and Norway were united in personal union ) for the rest of her career . The ship was reconstructed between 1903 and 1905 , but generally remained in reserve . She was mobilized during World War I , and sold in 1922 for conversion to a barge . Design and description . The " John Ericsson " - class ironclad s 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 and the much larger 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 the " Monitor " , had been born in Sweden , although he had become an American citizen in 1848 , and 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 . The ship measured long overall , with a beam of . She had a draft of and displaced . " John Ericsson " 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 . Initially her crew numbered 80 officers and men , but this increased to 104 as she was modified with additional weapons . Propulsion . The " John Ericsson " - class ships had one twin - cylinder vibrating lever steam engines , designed by Ericsson himself , driving a single four - bladed , propeller . Their engines were powered by four fire - tube boiler s at a working pressure of . The engines produced a total of which gave the monitors a maximum speed of in calm waters . The ships carried of coal , enough for six day ' s steaming . Armament . " Thordön " , and her sister ship " Tirfing " , were briefly armed with a pair of M / 66 smoothbore guns before being rearmed in 1873 with two M / 69 rifled breech loader s , derived from a French design . They weighed and fired projectiles at a muzzle velocity of . At their maximum elevation of 7 . 5° they had a range of . An improved version was developed in the 1870s ; the guns were heavier , , but had a higher muzzle velocity of . Coupled with the increased elevation of 11 . 29° , this gave them a range of . " Thordön " received her guns in 1882 . In 1877 each monitor received a pair of 10 - barreled M / 75 machine gun s designed by Helge Palmcrantz . Each machine gun weighed and had a rate of fire of 500 rounds per minute . Its projectiles had a muzzle velocity of and a maximum range of . These guns were replaced during the 1880s by the 4 - barreled M / 77 Nordenfeldt gun , which was an enlarged version of Palmcrantz ' s original design . The gun had a rate of fire of 120 rounds per minute and each round had a muzzle velocity of . Its maximum range was . Armor . The " John Ericsson " - class ships had a complete waterline armor belt of wrought iron that was high and thick . The armor consisted of five plates backed by of wood . The lower edge of this belt was thick as it was only three plates thick . The maximum thickness of the armored deck was in two layers . The gun turret ' s armor consisted of twelve layers of iron , totalling in thickness on the first four monitors . The inside of the turret was lined with mattresses to catch splinters . The base of the turret was protected with a glacis , 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 ( ) thick . The funnel was protected by six layers of armor with a total thickness of up to half its height . Service . " Thordön " had her keel laid down on November 1865 and was launched 1 December 1865 . She was commissioned on 14 August 1866 . In July 1867 Crown Prince Oscar , later King Oscar II , inspected " Thordön " , , , the steam frigate s " Thor " and , and the Norwegian monitor in the Stockholm archipelago before they departed for port visits in Helsingfors , later known as Helsinki , and Kronstadt in August , where they were visited by Grand Duke Konstantin Nikolayevich of Russia , head of the Imperial Russian Navy . This was the only foreign visit ever made by the ship . " Thordön " ( later spelled " Tordön " ) was laid up in reserve in 1868 and 1869 . She was rearmed with 240 - millimeter M / 69 guns ( serial numbers 5 and 6 ) in 1872 , but was laid up again from 1874 to 1882 . The ship ran aground and sank on Lilla Rimö Island , off Norrköping , on 23 July 1883 . She was salvaged on 4 August and managed to proceed under her own power to Karlskrona Naval Dockyard for repairs . The subsequent court - martial ordered the ship ' s captain to pay for the costs of the salvage and repairs , despite a misplaced buoy that caused the ship to ground . She was recommissioned in 1885 and 1888 – 89 before being placed back in reserve . " Tordön " was reconstructed in 1903 – 05 ; she received a pair of new Bofors M / 94 guns that were given elevation limits of −7° and + 15° . The ship also received eight 57 - millimeter guns and new boilers . She was reactivated during World War I and assigned to the Göteborg local defense flotilla in company with her sister " Tirfing " . Both ships were decommissioned in 1922 and sold the following year . Their new owner converted them into barges and used them in Stockholm harbor .