The ''Sjöormen'' class (''Sea serpent'') was a class of
submarine
A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...
s built for the
Swedish Navy in the late 1960s. They had a
teardrop hull shape and were capable of diving to . At the time of their deployment they were regarded as one of the most advanced non-nuclear submarine-classes in the world, incorporating many new features including x-rudder and
anechoic tiles. Both speed and underwater endurance was at this time very high for a conventional submarine. The submarines were retired by Sweden in the early 1990s. In the late 1990s, all five submarines were acquired by the
Republic of Singapore Navy (RSN) and four were relaunched as the following modernisation and tropicalisation. The fifth was never relaunched as it was used for spare parts and subsequently scrapped in the 2000’s. As of November 2024, the Challenger-Class has been decommissioned.
Description
As built, the ''Sjöormen'' class were designed with a
teardrop hull shape, based on the United States' . They had
bow planes on the
sail
A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may b ...
and their stern diving planes were configured in a x-shape. They had a
standard displacement of and when dived. The submarines had a
waterline length of and a
length overall
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, and is also ...
of . They had a
beam of and a
draught of . The ''Sjöormen'' class was powered by a
diesel-electric propulsion system composed of two
Pielstick diesel engine
The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...
s providing power to an
ASEA electric motor driving one shaft with a five-bladed
propeller
A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working flu ...
. The entire system was rated at . This gave the submarines a surfaced speed of and submerged. Designed for the confined waters of the
Baltic sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...
, the vessels had an endurance of 21 days and a test depth of .
As built the ''Sjöormen'' class were equipped with surface search
radar
Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
and
sonar. The submarines were armed with four
torpedo tubes located in the
bow for surface attack and two torpedo tubes in the stern for either
anti-submarine warfare
Anti-submarine warfare (ASW, or in the older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations ar ...
or for
naval mine
A naval mine is a self-contained explosive weapon placed in water to damage or destroy surface ships or submarines. Similar to anti-personnel mine, anti-personnel and other land mines, and unlike purpose launched naval depth charges, they are ...
s. The ''Sjöormen'' class had a
complement of 23 officers and enlisted.
Swedish upgrades
In 1984–85, the ''Sjöormen'' class received upgraded Ericsson IBS-A17
fire control system and CSU-83 sonar suite. In 1992, refits began on ''Sjölejonet'' and ''Sjöhunden'' that improved their electronics and their towed sonar array.
Ships
Service history
The ''Sjöormen'' class were ordered by the
Swedish Navy in 1961. The first boat in the class, ''Sjöormen'', entered service in 1968. In 1992, two vessels in the class, ''Sjölejonet'' and ''Sjöhunden'', underwent modernisation. The remaining three were supposed to remain in service until the became operational, but due to lack of funding, all were laid up in 1993.
All five submarines were sold to the
Republic of Singapore Navy (RSN) in the late 1990s and four entered service as the following modernisation and tropicalisation,
while the fifth was used for spare parts and subsequently scrapped in the late 2000’s.
References
Notes
Citations
Bibliography
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External links
Official Kockums website on the Challenger class submarines
{{DEFAULTSORT:Sjoormen class submarine
Submarine classes
Nuclear weapons programme of Sweden