Kraka, or UC2 Kraka was an amateur-built midget submarine completed in 2005, the first diesel–electric amateur sub in Denmark.[1] It was built by Peter Madsen, Claus Nørregaard[5] and several other people. The overall length was 12.6 meters (41 ft), 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).[6][7][2]Kraka is named after a woman in Norse mythology known for her intelligence.[3]
Construction
The sub was built at Peter Madsen's workshop in Farum, Denmark.[8] Construction took 2+1⁄2 years and over 3600 hours to build. It was built with two engines, a diesel and an electric, making the sub a diesel-electric. With a diesel drive, this theoretically allows the sub to have a 160 km (99 mi) range, and up to 130 km (80 mi) submerged. It can run at a speed of 9 knots (17 km/h; 10 mph) on the surface, and 3 kn (5.6 km/h; 3.5 mph) submerged, using the snorkel and with extra fuel aboard. The boat is 12.6 m (41 ft 4 in) long, 1.0 m (3 ft 3 in) wide, 1.7 m (5 ft 7 in) with dive planes, and 2.9 m (9 ft 6 in) high from keel to top of periscope. On electric drive, it has a range of 4.8 km (3 mi). On diesel drive, it has a range of 64 km (40 mi). It has a nominal dive depth of 15 m (49 ft), but the crush depth is theoretically 135 m (443 ft).[1] Maximum operational depth is 35 m (115 ft).[9] 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.[1][3] 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.[3] At the bottom of the sub is a dive lock, allowing emergency escape while submerged. The lock also allows use by divers while submerged.[3][10] Unlike predecessor Freya, Kraka is equipped with an air compressor allowing for extended dive times.[10] UC2 cost about 200,000 DKK to build.[3] The sub can hold 4 people.[5]
History
Construction started in 2002 and finished in 2005, when it was launched and put out to sea for voyages.[1] 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.[3]
After decommissioning, it was put on display, at Denmark's Technical Museum in Helsingor.[2][4]
