Quote from The Motor Ship: “Odense Staalskibsværft delivers the most powerful units in the Danish icebreaker fleet”. 58 years later, DANBJØRN and her one-year younger fleet mate ISBJØRN arrives under tow at Smedegaarden in Esbjerg for demolition.
“The first of two new icebreakers, contracted by the Danish Ministry of Trade in 1963, has been delivered from Odense Staalskibsværft. The delivery of a second ship in the series follows in January 1966. These ships, each with 10,500 hp., are the most powerful units in the Danish icebreaker fleet and meet a great need for icebreaking capacity in Danish waters after recent winters have put a pressure on the existing fleet of four icebreakers”.
This is how the British monthly specialist magazine The Motor Ship in 1965 began their feature article about a Danish newbuild in the September number. The ship in focus was DANBJØRN, yard number 171 from Odense Staalskibsværft. The sister ship ISBJØRN with the yard number 176 followed a year later.
1,500 tons of steel have been used for the hull alone, which has plate thicknesses of up to 3.2 cm. Greatest strength has been placed in the bow and stern, where ice knives provide extra protection.
Prior to the building of the two icebreakers, Hydro og Aerodynamisk Laboratorium i Kgs. Lyngby made extensive tank tests of the hull, just as the design of the funnel had also been tested in relation to soot deposition on the aft decks. Something that with previous icebreakers has proven to be an actual problem with slow sailing during icebreaking, the magazine noted.
The washdown effect
Not surprisingly, The Motor Ship had a particular focus on the newbuilding’s propulsion with two four-bladed propellers in both the bow and stern. The aft propellers are responsible for the general propulsion, while the two front ones mainly reduce the friction between the hull and the sea ice by means of a “washdown effect”. That is, a stream of water that guides the broken ice down the sides of the ship.
The distribution of output between the two ends is in the ratio 1-to-2, twice as much power on the aft propellers as on the two in the bow. The magazine pointed out that DANBJØRN’s diesel-electric machinery is in line with what could be expected on a modern icebreaker, if one disregards the barely ten-year-old Soviet nuclear powered icebreaker LENIN.
DANBJØRN’s machinery consists of a total of six Burmeister & Wain engines of the 1226-MTBM-40V type, each of which is connected to a Thrige direct current generator. Four of the generators feed the two electric motors aft, while the rest are connected to the two electric motors at the front.
The machines normally deliver 1,980 hp. at 600 rpm, but can be continuously driven with a maximum output of 2,100 hp. For short periods, if necessary, during icebreaking, they can also be boosted up to 2,340 hp.
The six Thrige generators therefore cover the range 1,370 kW, 750 volts up to 1,510 kW 775 volts for up to six hours. The two electric motors aft have 3,500 hp, while the two at the front each have 1,750 hp, The Motor Ship reported.
A fleet of five
Statens Istjeneste (The Danish State’s Ice Service), a department under the Ministry of Trade, operated up to the delivery of DANBJØRN four icebreakers. The oldest, ISBJØRN of 2,500 hp., from 1923, LILLEBJØRN of 1,560 hp. from 1926, STOREBJØRN of 5,000 hp. from 1931 and ELBJØRN from 1953 with 2,700 hp. In addition, was DSB’s (The State Railways) 6,000 hp. large ice-breaking ferry HOLGER DANSKE also an important part of the ice preparedness, not least on The Great Belt.
Thus, DANBJØRN and the sister ISBJØRN represented a considerable step forward for Statens Istjeneste, which in the year leading up to the newbuilding contract in 1963 had most recently experienced a severe ice winter, which completely closed Danish waters in February 1963.
The non-appearance of long periods of below-zero temperatures in Denmark in recent decades is a significant part of the history of DANBJØRN, ISBJØRN and the 15 years younger fleet mate THORBJØRN. The Royal Danish Navy’s ice service was thus closed down in 2010 and three years later the three icebreakers were put up for sale in connection with the Royal Danish Navy’s command of them being formally removed.
THORBJØRN, which was built by Svendborg Shipyard in 1980, returned home, so to speak, when it was sold to the Svendborg shipping company Nordane Shipping shortly after the ice service was closed. Here, the original plan with the icebreaker purchase included to offer it in Finland for lighter ice-breaking tasks, but THORBJØRN has since been laid-up in Svendborg, albeit in a nicely kept condition.
Seven years in Hals
The two remaining icebreakers arrived in Hals under tow from the Naval Station in Frederikshavn back in June 2016.
DANBJØRN’s delivery from Odense Staalskibsværft in 1965 was a small governmental interlude in a serial production of tankers, which characterized daily life at the Mærks-owned shipyard throughout the 1960s. ISBJØRN followed, as mentioned, the year after.
The period in which the two new state icebreakers were planned and built was characterized by relatively severe ice winters, when icebreaking in Danish waters was required.
“Many winters, one or none of the ships are mobilized. Based on experience, in Danish waters we only have ice of significant importance every fourth winter on average – that is, ice situations that require all our equipment. If we look back at the last 30 winters, 19 winters have involved preparing equipment. However, the situation improved several times before the “bears” (The suffix “BJØRN” in the names is the Danish word for bear) came into action.”
The head of the State’s Ice Service, ship inspector K. J. Hørning, told this in a large interview with the Danish maritime magazine Vikingen in the autumn of 1964 as a prelude to the delivery of the first of the two new state icebreakers.
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According to figures from DMI (Danish Meteorological Institute), his assessment was also fairly accurate in the coming years, only to be interrupted by some relatively warm 1970s, before a somewhat more active decade in the 1980s for the icebreakers. The last time all three icebreakers were in action was in the winter of 1995/96 – and the last time they were mobilized on a 24-hour notice was in the winter of 2009/10.
In 1996 – the same year that the significantly older and smaller fleet mate ELBJØRN was decommissioned after a technical breakdown, DANBJØRN, ISBJØRN and THORBJØRN were moved from the ministry organisation to The Royal Danish Navy in connection with a new political defence settlement, after which they became a permanent part of the scenery at the naval base in the Port of Frederikshavn.
DANBJØRN, Odense Staalskibsværft # 171
Length: 76.8 m
Length: b.p.: 67.9 m
Width: 17 m
Draft: 6,4 m
Displacement: 3,685 t
Service speed in open water: 18 knot
(as built 1965, according to The Motor Ship)
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