Atle class
 The eponymous Atle
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The Atle class is a series of icebreakers and, depending on your point of view, consists of three Swedish or an additional two Finnish ships. The Finnish ships are also known as the Urho class .
During the construction of these ships, major innovations were introduced in icebreaker construction; These include a high above the hull lying bridge with 360 degree visibility and a heliport. All crew quarters are housed in the deckhouse in order to keep the noise pollution low during ice breaking.
history
In 1971 the Swedish Reichstag decided to have icebreakers built to make the Bottenwiek navigable all year round. For the construction of the first ship 60 million Swedish crowns were approved. Wärtsilä received the building contract on May 10, 1971, and in 1974 the first of the ships, the Atli , was put into service. As a result, all ports up to Umeå can be kept open to traffic all year round.
In connection with the plans for a new steelworks in Luleå , two new icebreakers were required in the mid-1970s to keep the fairway there clear all year round. At the same time, Finland ordered two icebreakers of the class known in Finland as the Urho class. The four ships were delivered in 1975 and 1976.
technical description
The Atle class was dimensioned in such a way that the hull and machines are permanently able to break all ice types and thicknesses occurring in the Baltic Sea in continuous forward motion, even in a hard ice winter.
hull
The Atle class was the first type of icebreaker from Wärtsilä whose hull design could be optimized with the help of test models . Before, only theoretical calculations were possible; now the behavior of a model e.g. B. tested in solid ice or in channels. This meant that the ships, despite being 24 meters wide, had less ice resistance than, for example, the 21-meter wide Tor or Njord . The material thickness is 32 mm in the bow , 28 mm amidships and 30 mm in the aft; the distance between the frames is 800 mm. At the time of construction, the height of the ships was 47.3 meters from Kiel , i.e. around 40 meters from the waterline. After the construction of the Sandö Bridge , which has a maximum headroom of 42 meters, the masts were shortened to 38 meters in 1989.
drive
The ships are powered by diesel-electric technology with five Wärtsilä-Pielstick 12PC2-5V-400 V motors, each with 12 cylinders and a drive power of 15.2 MW, which each act on two generators. The entire drive power is distributed to 2 front and 2 rear fixed propellers; 40% of the front propellers have proven to be optimal for ice breaking. The forward propellers point inwards and move the water under the ship's hull, causing it to rise again around the hull and reduce friction. The rear propellers are directed outwards and push the broken ice under the intact ice cover so that the fairway remains free of ice.
Ships
| designation | Class / type | Construction year | Shipyard | Owner | period of service | Whereabouts | image |
|---|---|---|---|---|---|---|---|
| Atle | Atle class | 1974 | Wärtsilä, Helsinki | Swedish Maritime Authority |
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| FrejReceipt ? | Atle class | 1975 | Wärtsilä, Helsinki | Swedish Maritime Authority |
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| Ymer | Atle class | 1977 | Wärtsilä, Helsinki | Swedish Maritime Authority | since 1977 |
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| Sisu | Urho class | 1975 | Wärtsilä, Helsinki | Arctia Shipping Oy | since 1976 | ||
| UrhoReceipt ? | Urho class | 1975 | Wärtsilä, Helsinki | since 1975 |
crew
Swedish icebreaker ( Atle class)
The Swedish icebreakers are assigned to the Swedish Maritime Authority; at the same time they were also auxiliary ships of the Swedish Navy , Department of Invasion Defense until the 1990s . They served there as mine clearance boats . For this reason, in addition to the civilian part of the crew, there were also military personnel on board. The ships also served as training ships for other naval auxiliary vehicles. During this time the crew was divided into four blocks, three of these blocks were on duty at sea, while the fourth was on land. The rotating block swap was carried out regularly by helicopter in order not to have to interrupt the ships' icebreaker trips.
In the late 1990s, when the Cold War ended, the military part of the crew was replaced by members of the civil defense .
Finnish icebreaker ( Urho class)
The Finnish Maritime Authority icebreakers were manned by civilian personnel from the start. According to the Finnish-Soviet Treaty of 1948 , the Finnish Navy is limited to a strength of 4,500 men and a tonnage of 10,000 tons; the icebreakers are not covered by this quota.
See also
literature
- Staffan Fischerström: Isbrytare: with statens isbrytare under 80 år . Marinliteratur, Falkenberg 1997, ISBN 91-970700-9-2 .
Web links
Footnotes
- ↑ Specification Dnr M: SF M5799-061: 54/73 des Försvarets Materielverk , roughly translated as Material Administration of the Swedish Defense Forces
- ↑ THE WORLD ICEBREAKER, ICE BREAKING SUPPLY AND RESEARCH VESSEL FLEET Baltic Icebreaker Management, 2011, accessed on October 10, 2013 ( Memento of the original from September 2, 2012 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ THE DEVELOPMENT OF THE DOUBLE ACTING TANKER FOR ICE OPERATION , Aker Arctic, contribution to OKHOTSK SEA & SEA ICE, MOMBETSU, JAPAN, 24.-28. February 2002 , accessed on October 10, 2013 ( Memento of the original from September 4, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ IB Urho on the website of the shipping company Arctia Shipping Oy , accessed on October 10, 2013
