The ''Hildur-class'' monitors consisted of seven

monitors Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West Vir ...

built for the

Swedish Navy The Swedish Navy ( sv, Svenska marinen) is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet () – as well as marine units, the Amphibious Corps (). In Swedish, vessels o ...

in the 1870s. They were sold in 1919 and most were converted into

fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...

barge Barge nowadays generally refers to a flat-bottomed inland waterway vessel which does not have its own means of mechanical propulsion. The first modern barges were pulled by tugs, but nowadays most are pushed by pusher boats, or other vessels ...

s. One such ship, , has been converted into a

museum ship A museum ship, also called a memorial ship, is a ship that has been preserved and converted into a museum open to the public for educational or memorial purposes. Some are also used for training and recruitment purposes, mostly for the small numb ...

Design and description

The ''Hildur''-class monitors were designed by Lieutenant John Christian d'Ailly, from a proposal by

John Ericsson John Ericsson (born Johan Ericsson; July 31, 1803 – March 8, 1889) was a Swedish-American inventor. He was active in England and the United States. Ericsson collaborated on the design of the railroad steam locomotive ''Novelty'', which com ...

, for the defense of Lake

Mälaren Mälaren ( , , or ), historically referred to as Lake Malar in English, is the third-largest freshwater lake in Sweden (after Vänern and Vättern). Its area is 1,140 km2 and its greatest depth is 64 m. Mälaren spans 120 kilometers from e ...

and the Stockholm archipelago. The ships were

long overall __NOTOC__ Length overall (LOA, o/a, o.a. or oa) is the maximum length of a vessel's hull measured parallel to the waterline. This length is important while docking the ship. It is the most commonly used way of expressing the size of a ship, an ...

and had a

beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...

of . They had a

draft Draft, The Draft, or Draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a vesse ...

of and displaced . The crew of the first two monitors, ''Hildur'' and ''Gerda'', numbered 42 officers and men, the others had 48-man crews. ''Hildur'' and ''Gerda'' only had a stern

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

, the other had rudders at bow and stern. Bow rudders were fitted to the older ships when they were reconstructed.Harris, pp. 30–32 The ''Hildur''s had a pair of two-cylinder horizontal-return connecting-rod steam engines, each driving a single propeller using steam from two cylindrical boilers. The engines produced a total of in the first two ships and in the later ones which gave the monitors a maximum speed of .Harris, pp. 30–31 The ships carried of coal.Campbell, p. 362 The monitors were equipped with one M/69

rifled breech loader A rifled breech loader (RBL) is an artillery piece which, unlike the smoothbore cannon and rifled muzzle loader (RML) which preceded it, has rifling in the barrel and is loaded from the breech at the rear of the gun. The spin imparted by the gun ...

, mounted in a long, fixed, oval-shaped

gun turret A gun turret (or simply turret) is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechani ...

. The gun weighed and fired projectiles at a

muzzle velocity Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball/shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately to i ...

of . At its maximum elevation of 7.5° it had a range of . The gun and its turret in ''Folke'' were oriented to the rear. ''Hildur'' and ''Gerda'' were rearmed with a

quick-firing gun A quick-firing or rapid-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. Quick-firing was introduced worldwide in the 1880s and 1890s and ...

as well as three quick-firing guns 1890; the other were similarly rearmed later in the 1890s or the early 1900s. Most of the ships of the ''Hildur'' class had a complete

waterline The waterline is the line where the hull of a ship meets the surface of the water. Specifically, it is also the name of a special marking, also known as an international load line, Plimsoll line and water line (positioned amidships), that indi ...

armor belt Belt armor is a layer of heavy metal armor plated onto or within the outer hulls of warships, typically on battleships, battlecruisers and cruisers, and aircraft carriers. The belt armor is designed to prevent projectiles from penetrating ...

wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag Inclusion (mineral), inclusions (up to 2% by weight), which give it a ...

that was thick with a deck. ''Bjorn'' and ''Ulf'' had a belt while ''Folke''s belt ranged from forward to 76 mm aft. The face of the

was protected by of armor, while its sides were thick. The

conning tower A conning tower is a raised platform on a ship or submarine, often armored, from which an officer in charge can conn the vessel, controlling movements of the ship by giving orders to those responsible for the ship's engine, rudder, lines, and gro ...

protruded from the top of the turret and was protected by of armor.Harris, pp. 31–32

Construction

Service

During ''Hildur''s gunnery

trials In law, a trial is a coming together of parties to a dispute, to present information (in the form of evidence) in a tribunal, a formal setting with the authority to adjudicate claims or disputes. One form of tribunal is a court. The tribunal, w ...

in 1872, her shells penetrated the walls of

Vaxholm Fortress Vaxholm Fortress ( sv, Vaxholms fästning) is a historic fortification on the island of Vaxholmen in the Stockholm archipelago just east of the Swedish town of Vaxholm. The fortress is accessed by the Kastellet ferry, an electrically powered ca ...

in three shots.Harris, p. 31

References

Bibliography

* * * {{Hildur class monitors

Design and description

Construction

Service

See also

References

Bibliography