Icebreaker Informations

An icebreaker is a special-purpose ship or boat designed to move and navigate through ice-covered waters, and provide safe waterways for other boats and ships. Although the term usually refers to ice-breaking ships, it may also refer to smaller vessels, such as the icebreaking boats that were once used on the canals of the United Kingdom.

For a ship to be considered an icebreaker, it requires three traits most normal ships lack: a strengthened hull, an ice-clearing shape, and the power to push through sea ice.

Icebreakers clear paths by pushing straight into frozen-over water or pack ice. The bending strength of sea ice is low enough that the ice breaks usually without noticeable change in the vessels trim. In cases of very thick ice, an icebreaker can drive its bow onto the ice to break it under the weight of the ship. A buildup of broken ice in front of a ship can slow it down much more than the breaking of the ice itself, so icebreakers have a specially designed hull to direct the broken ice around or under the vessel. The external components of the ships propulsion system (propellers, propeller shafts, etc.) are at greater risk of damage than the vessels hull, so the ability of an icebreaker to propel itself onto the ice, break it, and clear the debris from its path successfully is essential for its safety.

Ice-strengthened ships were used in the earliest days of polar exploration. These were originally wooden and based on existing designs, but reinforced, particularly around the waterline with double planking to the hull and strengthening cross members inside the ship. Bands of iron were wrapped around the outside. Sometimes metal sheeting was placed at the bows, at the stern, and along the keel. Such strengthening was designed to help the ship push through ice and also to protect the ship in case it was "nipped" by the ice. Nipping occurs when ice floes around a ship are pushed against the ship, trapping it as if in a vise and causing damage. This vise-like action is caused by the force of winds and tides on ice formations.

The first boats to be used in the polar waters were those of the indigenous Arctic people. Their kayaks are small human-powered boats with a covered deck, and one or more cockpits, each seating one paddler who strokes a single or double-bladed paddle. Such boats, of course, have no icebreaking capabilities, but they are light and well fit to carry over the ice.

In the 9th and 10th centuries, the Viking expansion reached the North Atlantic, and eventually Greenland and Svalbard in the Arctic. Vikings, however, operated their ships in the waters that were ice-free for most of the year, in the conditions of the Medieval Warm Period.

In the 11th century, in North-Russia the coasts of the White Sea, named so for being ice-covered for over half of a year, started being settled. The mixed ethnic group of the Karelians and the Russians in the North-Russia that lived on the shores of the Arctic Ocean became known as Pomors ("seaside settlers"). Gradually they developed a special type of small one- or two-mast wooden sailing ships, used for voyages in the ice conditions of the Arctic seas and later on Siberian rivers. These earliest icebreakers were called kochi. The kochs hull was protected by a belt of ice-floe resistant flush skin-planking along the variable water-line, and had a false keel for on-ice portage. If a koch became squeezed by the ice-fields, its rounded bodylines below the water-line would allow for the ship to be pushed up out of the water and onto the ice with no damage.

In the 19th century, similar protective measures were adopted to modern steam-powered icebreakers. Some notable sailing ships in the end of the Age of Sail also featured the egg-shaped form like that of Pomor boats, for example the Fram, used by Fridtjof Nansen and other great Norwegian Polar explorers. Fram was the wooden ship to have sailed farthest north (85°57N) and farthest south (78°41S), and one of the strongest wooden ships ever built.

An early ship designed to operate in icy conditions was a 51-metre (167 ft) wooden paddle steamer, City Ice Boat No. 1, that was built for the city of Philadelphia by Vandusen and Birelyn in 1837. The ship was powered by two 250-horsepower (190 kW) steam engines and its wooden paddles were reinforced with iron coverings.

With its rounded shape and strong metal hull, the Russian Pilot of 1864 was an important predecessor of modern icebreakers with propellers. The ship was built on the orders of merchant and shipbuilder Mikhail Britnev. It had the bow altered to achieve an ice-clearing capability (20° raise from keel line). This allowed Pilot to push herself on the top of the ice and consequently break it. Britnev fashioned the bow of his ship after the shape of old Pomor boats, which had been navigating icy waters of the White Sea and Barents Sea for centuries. Pilot was used between 1864–1890 for navigation in the Gulf of Finland between Kronstadt and Oranienbaum thus extending the summer navigation season by several weeks. Inspired by the success of Pilot, Mikhail Britnev built a second similar vessel Boy ("Breakage" in Russian) in 1875 and a third Booy ("Buoy" in Russian) in 1889.

The cold winter of 1870–1871 caused the Elbe River and the port of Hamburg to freeze over, causing a prolonged halt to navigation and huge commercial losses. Carl Ferdinand Steinhaus reused the altered bow Pilots design from Britnev to make his own icebreaker,Eisbrecher I.

The first true modern sea-going icebreaker was built at the turn of the 20th century. Icebreaker Yermak, was built in 1897 at the Armstrong Whitworth naval yard in England under contract from the Imperial Russian Navy. The ship borrowed the main principles from Pilot and applied them to the creation of the first polar icebreaker, which was able to run over and crush pack ice. The ship displaced 5,000 tons, and its steam-reciprocating engines delivered 10,000 horsepower (7,500 kW). The ship was decommissioned in 1963 and scrapped in 1964, making it one of the longest serving icebreakers in the world.

In Canada, the government needed to provide a way to prevent flooding due to ice jam on the St. Lawrence River. Icebreakers were built in order to maintain the river free of ice jam, east of Montréal. In about the same time, Canada had to fill its obligations in the Canadian Arctic. Large steam icebreakers, like the 80-metre (260 ft) CGS N.B. McLean (1930) and CGS DIberville (1952), were built for this dual use (St. Lawrence flood prevention and Arctic replenishment).

At the beginning of the 20th century, several other countries began to operate purpose-built icebreakers. Most were coastal icebreakers, but Canada, Russia, and later, the Soviet Union, also built several oceangoing icebreakers up to 11,000 tons in displacement.

The worlds first diesel-electric icebreaker was the 4,330-ton Swedish icebreaker Ymer in 1933. At 9,000 hp (6,700 kW) divided between two propellers in the stern and one propeller in the bow, she remained the most powerful Swedish icebreaker until the commissioning of Oden in 1957. Ymer was followed by the Finnish Sisu, the first diesel-electric icebreaker in Finland, in 1939. Both vessels were decommissioned in the 1970s and replaced by much larger icebreakers in both countries, the 1976-built Sisu in Finland and the 1977-built Ymer in Sweden.

In 1941, the United States started building the Wind class. Research in Scandinavia and the Soviet Union led to a design that had a very strongly built short and wide hull, with a cut away forefoot and a rounded bottom. Powerful diesel-electric machinery drove two stern and one auxiliary bow propeller. These features would become the standard for postwar icebreakers until the 1980s.

In Canada, diesel-electric icebreakers started to be built in 1952, first with HMCS Labrador (was transferred later to the Canadian Coast Guard), using the USCG Wind-class design but without the bow propeller. Then in 1960, the next step in the Canadian development of large icebreakers came when CCGS John A. Macdonald was completed at Lauzon, Quebec. A considerably bigger and more powerful ship than Labrador, John A.Macdonald was an ocean-going icebreaker able to meet the most rigorous polar conditions. Her diesel-electric machinery of 15,000 horsepower (11,000 kW) was arranged in three units transmitting power equally to each of three shafts.

Canadas largest and most powerful icebreaker, the 120-metre (390 ft) CCGS Louis S. St-Laurent, was delivered in 1969. Her original three steam turbine, nine generator, and three electric motor system produces 27,000 shaft horsepower (20,000 kW). A multi-year mid-life refit project (1987–1993) saw the ship get a new bow, and a new propulsion system. The new power plant consists of five diesels, three generators, and three electric motors, giving about the same shp.

On 22 August 1994 Louis S. St-Laurent and USCGC Polar Sea became the first North American surface vessels to reach the North Pole. The vessel was originally scheduled to be decommissioned in 2000; however, a refit extended the decommissioning date to 2017.

Russia currently operates all existing and functioning nuclear-powered icebreakers. The first one, NS Lenin, was launched in 1957 and entered operation in 1959, before being officially decommissioned in 1989. It was both the worlds first nuclear-powered surface ship and the first nuclear-powered civilian vessel.

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