''Kraka'', or UC2 ''Kraka'' was an amateur-built

midget submarine A midget submarine (also called a mini submarine) is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, ...

completed in 2005, the first diesel–electric amateur sub in Denmark. It was built by

Peter Madsen Peter Langkjær Madsen (; born 12 January 1971) is a Danish convicted murderer and former entrepreneur. In April 2018, he was convicted of the 2017 murder of Swedish journalist Kim Wall on board his submarine, '' UC3 Nautilus'', and sentenced ...

, Claus Nørregaard and several other people. The overall length was , and it displaced 6 tonnes. The propulsion was diesel–electric with a 16 hp diesel engine and an 8 hp electric motor. ''Kraka'' can be seen at Denmark's Technical Museum in Elsinore (aka Helsingør). '' Kraka'' is named after a woman in Norse mythology known for her intelligence.

Construction

The sub was built at Peter Madsen's workshop in

Farum Farum is a town on the northeast of the island of Zealand in eastern Denmark, 20 km northwest of Copenhagen. The town has a population of 20,312 (1 January 2022).

, Denmark. Construction took years and over 3600 hours to build. It was built with two engines, a

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...

and an

electric Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...

, making the sub a diesel-electric. With a diesel drive, this theoretically allows the sub to have a range, and up to submerged. It can run at a speed of on the surface, and submerged, using the snorkel and with extra fuel aboard. The boat is long, wide, with dive planes, and high from

keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...

to top of

periscope A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. In its simplest form, it consists of an outer case with ...

. On electric drive, it has a range of . On diesel drive, it has a range of . It has a nominal dive depth of , but the

crush depth Depth ratings are primary design parameters and measures of a submarine's ability to operate underwater. The depths to which submarines can dive are limited by the strengths of their submarine hull, hulls. Ratings The hull of a submarine must b ...

is theoretically . Maximum operational depth is . It has a 40kW Volvo Penta MD 19 diesel and a 6kW Sauer Danfoss 24V DC electric motor. The marine diesel engine was 65 years old when it launched in 2005. Backing the electric is 24V 400Ah Sectronic-Fram GS gel battery. UC2 has two sets of balance tanks, two main tanks and two trim tanks. With its flooding system, it takes only 20 seconds to reach neutral buoyancy. At the bottom of the sub is a dive lock, allowing emergency escape while submerged. The lock also allows use by divers while submerged. Unlike predecessor ''Freya'', ''Kraka'' is equipped with an air compressor allowing for extended dive times. UC2 cost about 200,000 DKK to build. The sub can hold 4 people.

History

Construction started in 2002 and finished in 2005, when it was launched and put out to sea for voyages. At the time it was finished, it was one of only three diesel submarines in private civilian hands in the world, and one of only seven civil private sea-going submarines in the world. After decommissioning, it was put on display, at Demark's Technical Museum in Helsingor.

References

Midget submarines 2005 ships Individual watercraft Peter Madsen {{museum-stub