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84-433: Sadko may refer to one of the following icebreakers named after Sadko , a hero of a Russian bylina : Icebreaker 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

168-582: A combined propulsion power of 34,000 kW (46,000 hp). 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

252-625: A heavy icebreaker must perform Operation Deep Freeze , clearing a safe path for resupply ships to the National Science Foundation ’s facility McMurdo in Antarctica. The most recent multi-month excursion was led by the Polar Star which escorted a container and fuel ship through treacherous conditions before maintaining the channel free of ice. Icebreakers are often described as ships that drive their sloping bows onto

336-535: A hull that is wider in the bow than in the stern. These so-called "reamers" increase the width of the ice channel and thus reduce frictional resistance in the aftship as well as improve the ship's maneuverability in ice. In addition to low friction paint, some icebreakers utilize an explosion-welded abrasion-resistant stainless steel ice belt that further reduces friction and protects the ship's hull from corrosion. Auxiliary systems such as powerful water deluges and air bubbling systems are used to reduce friction by forming

420-524: A lubricating layer between the hull and the ice. Pumping water between tanks on both sides of the vessel results in continuous rolling that reduces friction and makes progress through the ice easier. Experimental bow designs such as the flat Thyssen-Waas bow and a cylindrical bow have been tried over the years to further reduce the ice resistance and create an ice-free channel. Icebreakers and other ships operating in ice-filled waters require additional structural strengthening against various loads resulting from

504-417: A nuclear-powered icebreaking cargo ship, Sevmorput , which had a single nuclear reactor and a steam turbine directly coupled to the propeller shaft. Russia, which remains the sole operator of nuclear-powered icebreakers, is currently building 60,000 kW (80,000 hp) icebreakers to replace the aging Arktika class. The first vessel of this type entered service in 2020. A hovercraft can break ice by

588-518: A short parallel midship to improve maneuverability in ice. However, the spoon-shaped bow and round hull have poor hydrodynamic efficiency and seakeeping characteristics, and make the icebreaker susceptible to slamming , or the impacting of the bottom structure of the ship onto the sea surface. For this reason, the hull of an icebreaker is often a compromise between minimum ice resistance, maneuverability in ice, low hydrodynamic resistance, and adequate open water characteristics. Some icebreakers have

672-711: A southern inlet of the Barents Sea located on the northwest coast of Russia . It is surrounded by Karelia to the west, the Kola Peninsula to the north, and the Kanin Peninsula to the northeast. The whole of the White Sea is under Russian sovereignty and considered to be part of the internal waters of Russia. Administratively, it is divided between the Arkhangelsk and Murmansk oblasts and

756-641: A vertical axis. These thrusters improve propulsion efficiency, icebreaking capability and maneuverability of the vessel. The use of azimuth thrusters also allows a ship to move astern in ice without losing manoeuvrability. This has led to the development of double acting ships , vessels with the stern shaped like an icebreaker's bow and the bow designed for open water performance. In this way, the ship remains economical to operate in open water without compromising its ability to operate in difficult ice conditions. Azimuth thrusters have also made it possible to develop new experimental icebreakers that operate sideways to open

840-499: 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 Eskimos . 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 have no icebreaking capabilities, but they are light and well fit to carry over

924-593: A wide channel through ice. The steam-powered icebreakers were resurrected in the late 1950s when the Soviet Union commissioned the first nuclear-powered icebreaker , Lenin , in 1959. It had a nuclear-turbo-electric powertrain in which the nuclear reactor was used to produce steam for turbogenerators , which in turn produced electricity for propulsion motors. Starting from 1975, the Russians commissioned six Arktika -class nuclear icebreakers . Soviets also built

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1008-676: 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 koch's hull

1092-652: Is a developing seaweed industry. The White Sea is an important traffic centre of northwestern Russia, interconnecting various economic regions and providing an outlet to the foreign routes. The White Sea–Baltic Canal links it through Lake Onega to the Baltic Sea and the major city and port of Saint Petersburg . The Baltic Sea, in turn, is connected by the Volga–Baltic Waterway to the Volga River , Black , Caspian , and Azov seas. The major ports on

1176-570: Is an underwater ridge in the northern part of the gorlo , resulting in maximum depths of 40 metres in that part. This hinders water exchange between the White and Barents seas. The exchange is assisted by the tides , which are semidiurnal (rising twice a day), with the amplitude increasing from 1 metre on the south to 10 metres in Mezen Bay. Currents are rather weak in the open seas with the speed below 1 km/h, but they significantly strengthen in

1260-589: Is brought during the snow melting in May, and the inflow is minimal in February–March. This inflow raises and lowers the sea level that promotes the water exchange with the Barents Sea. As a result, annually, about 2,000 km and 2,200 km flow in and out of the White Sea, respectively. The inflow of fresh water in spring decreases the surface salinity in the top 5–10-metre layer to 23‰ (parts per thousand) in

1344-402: Is low enough that the ice breaks usually without noticeable change in the vessel's 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

1428-520: Is one of the four seas named (not only in English) after common colour terms —the others being the Black , Red and Yellow seas. The International Hydrographic Organization defines the northern limit of the White Sea as "A line joining Svyatoy Nos ( Murmansk Coast, 39°47'E) and Cape Kanin ". There are four main bays or gulfs on the White Sea. These bays connect with the funnel-shaped opening to

1512-451: Is to perform model tests in an ice tank . Regardless of the method, the actual performance of new icebreakers is verified in full scale ice trials once the ship has been built. In order to minimize the icebreaking forces, the hull lines of an icebreaker are usually designed so that the flare at the waterline is as small as possible. As a result, icebreaking ships are characterized by a sloping or rounded stem as well as sloping sides and

1596-614: The Baltic Sea , the Great Lakes and the Saint Lawrence Seaway , and along the Northern Sea Route , the main function of icebreakers is to escort convoys of one or more ships safely through ice-filled waters. When a ship becomes immobilized by ice, the icebreaker has to free it by breaking the ice surrounding the ship and, if necessary, open a safe passage through the ice field. In difficult ice conditions,

1680-523: The Republic of Karelia . The major port of Arkhangelsk is located on the White Sea. For much of Russia's history this was Russia's main centre of international maritime trade, conducted by the Pomors ("seaside settlers") from Kholmogory . In the modern era it became an important Soviet naval and submarine base. The White Sea–Baltic Canal connects the White Sea with the Baltic Sea . The White Sea

1764-529: 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  D'Iberville (1952), were built for this dual use (St. Lawrence flood prevention and Arctic replenishment). At

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1848-526: The United States Coast Guard , have a combined diesel-electric and mechanical propulsion system that consists of six diesel engines and three gas turbines . While the diesel engines are coupled to generators that produce power for three propulsion motors, the gas turbines are directly coupled to the propeller shafts driving controllable pitch propellers. The diesel-electric power plant can produce up to 13,000 kW (18,000 hp) while

1932-535: 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. Since the mid-1970s, the most powerful diesel-electric icebreakers have been

2016-667: The 'gorlo', opposite to the Kola Peninsula , is Mezen Bay . It receives the Mezen River and the Kuloy River . Other major rivers flowing into the sea are the Vyg , Niva , Umba , Varzuga and Ponoy . The seabed of the central part and Dvina Bay is covered in silt and sand, whereas the bottom of the northern part, the Kandalaksha Gulf and Onega Bay is a mixture of sand and stones. Ice age deposits often emerge near

2100-619: The 15th century the use of ice breakers in Flanders ( Oudenaarde , Kortrijk , Ieper , Veurne , Diksmuide and Hulst ) was already well established. The use of the ice breaking barges expanded in the 17th century where every town of some importance in the Low Country used some form of icebreaker to keep their waterways clear. Before the 17th century the specifications of icebreakers are unknown. The specifications for ice breaking vessels show that they were dragged by teams of horses and

2184-529: The 2000s, International Association of Classification Societies (IACS) has proposed adopting an unified system known as the Polar Class (PC) to replace classification society specific ice class notations. Since the Second World War , most icebreakers have been built with diesel-electric propulsion in which diesel engines coupled to generators produce electricity for propulsion motors that turn

2268-680: The Baltic Sea. From the 1920s, most northern Russian sea shipments diverted from the White Sea to the new port of Murmansk (officially founded in 1916), where the waters did not freeze in winter. The entire water area of the White Sea is the territorial waters of the Russian Federation. Any movement of foreign vessels on the White Sea is carried out in accordance with the legislation of the Russian Federation. The sea hosts more than 700 species of invertebrates , about 60 species of fish, and five species of marine mammals, including

2352-577: The Barents Sea via a narrow strait called " Gorlo " ( Russian : Горло , meaning "throat"). Kandalaksha Gulf lies in the western part of the White Sea; it is the deepest part of the sea, reaching 340 metres (1,115 feet). On the south, Onega Bay receives the Onega River . To the southeast, the Dvina Bay receives the Northern Dvina at the major port of Arkhangelsk . On the east side of

2436-502: The Soviet Union. Two shallow-draft Taymyr -class nuclear icebreakers were built in Finland for the Soviet Union in the late 1980s. In May 2007, sea trials were completed for the nuclear-powered Russian icebreaker NS 50 Let Pobedy . The vessel was put into service by Murmansk Shipping Company, which manages all eight Russian state-owned nuclear icebreakers. The keel was originally laid in 1989 by Baltic Works of Leningrad , and

2520-579: The White Sea route. Dutch ships soon followed the English, and the port of Kholmogory became busy with shipments of fur and fish. Local and foreign shops and factories were established in the city at that time. The port was reinforced with a fortress which sustained a siege by the Polish-Lithuanian army in 1613. Increasing traffic overloaded the port, which relied on shallow river-waters and had limited ship-capacity. However, instead of expanding

2604-596: The altered bow Pilot ' s 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 1899 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

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2688-735: The bays. The tidal waves are much faster than the regular currents and reach the speeds of 9 km/h in Mezen Bay, 3.6 km/h in Onega Bay and 1.3 km/h in the Kandalaksha Gulf. Rivers bring annually about 215 km of fresh water, on average, mostly to the Onega, Mezen and Dvina bays. The Northern Dvina alone may contribute up to 171 km in some years, with the Mezen, Onega, Kem and Vyg rivers adding up to 38.5, 27.0, 12.5 and 11.5 km , respectively. About 40% of this volume

2772-602: 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. Before the first diesel-electric icebreakers were built in the 1930s, icebreakers were either coal- or oil-fired steam ships . Reciprocating steam engines were preferred in icebreakers due to their reliability, robustness, good torque characteristics, and ability to reverse

2856-510: 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 and 1890 for navigation in the Gulf of Finland between Kronstadt and Oranienbaum thus extending

2940-404: The central part, but remains relatively cold in the north, at 7–8 °С, due to the water exchange between the surface and the cold bottom part which is enhanced by the shallow depths in the northern parts. Deep sea (about 100 m or more) is characterised by stable temperature (−1.4 °С) and salinity (30‰). The depth distribution of water temperature is very inhomogeneous across the sea. For example, at

3024-501: The command of Hugh Willoughby , his crew had sought a northern route to the Indies , especially India and China. The expedition, sponsored by King Edward VI of England and a group of about 240 English merchants, had London's authorisation to establish trade connections. The ships of Willoughby were separated and the other two were lost at sea, but Edward Bonaventure managed to pass the White Sea and reach Kholmogory, from where Chancellor

3108-466: The contact between the hull of the vessel and the surrounding ice. As ice pressures vary between different regions of the hull, the most reinforced areas in the hull of an icegoing vessel are the bow, which experiences the highest ice loads, and around the waterline, with additional strengthening both above and below the waterline to form a continuous ice belt around the ship. Short and stubby icebreakers are generally built using transverse framing in which

3192-422: The creation of the first polar icebreaker, which was able to run over and crush pack ice . The ship displaced 5,000 tons, and her steam- reciprocating engines delivered 10,000 horsepower (7,500 kW). The ship was decommissioned in 1963 and scrapped in 1964, making her 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

3276-628: The diesel-electric powertrain is the preferred choice for icebreakers due to the good low-speed torque characteristics of the electric propulsion motors, icebreakers have also been built with diesel engines mechanically coupled to reduction gearboxes and controllable pitch propellers . The mechanical powertrain has several advantages over diesel-electric propulsion systems, such as lower weight and better fuel efficiency. However, diesel engines are sensitive to sudden changes in propeller revolutions, and to counter this mechanical powertrains are usually fitted with large flywheels or hydrodynamic couplings to absorb

3360-407: The direction of rotation quickly. During the steam era, the most powerful pre-war steam-powered icebreakers had a propulsion power of about 10,000 shaft horsepower (7,500 kW). The world's 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

3444-744: The eastern and 26–27‰ in the western parts of the sea, reaching 10–12‰ in Dvina Bay; it also increases the content of silicon and silicates in water, which is a characteristic feature of the White Sea. Storms are the strongest in October–November. Shallow sea depths reduce the wave height to the average of 1 metre, sometimes reaching 3–5 metres. The sea is quiet in July–August. The climate varies between polar and subarctic with frequent fogs and clouds. Winds are predominantly southwestern in winter with speeds of 4–8 m/s. They bring cold air from

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3528-572: 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°57'N) and farthest south (78°41'S), 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

3612-402: The exit from Dvina Bay, water temperature drops to 0 °C at the depth of only 12–15 m, but the same temperature is reached at 65 m at the exit from the Kandalaksha Gulf. Residents of Novgorod knew of the White Sea from at least the 11th century and rapidly explored its commercial significance for navigation and its coastal forests rich in fur animals . One of the earliest settlements near

3696-619: 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. It is now planned to be kept in service through the 2020s pending the introduction of two new polar icebreakers, CCGS  Arpatuuq and CCGS  Imnaryuaq , for the Coast Guard. Russia currently operates all existing and functioning nuclear-powered icebreakers. The first one, NS Lenin ,

3780-511: The fixed pitch propellers. The first diesel-electric icebreakers were built with direct current (DC) generators and propulsion motors, but over the years the technology advanced first to alternating current (AC) generators and finally to frequency-controlled AC-AC systems. In modern diesel-electric icebreakers, the propulsion system is built according to the power plant principle in which the main generators supply electricity for all onboard consumers and no auxiliary engines are needed. Although

3864-403: The formerly Soviet and later Russian icebreakers Ermak , Admiral Makarov and Krasin which have nine twelve-cylinder diesel generators producing electricity for three propulsion motors with a combined output of 26,500 kW (35,500 hp). In the late 2020s, they will be surpassed by the new Canadian polar icebreakers CCGS  Arpatuuq and CCGS  Imnaryuaq , which will have

3948-533: The friendly beluga and the white whale. Several other dolphin species, such as harbour porpoises , appear less frequently while larger whales such as bowhead , humpback and rorquals , northern bottlenose , orcas have been considered as rare visitors to the waters while actual frequency of occurrences within White Sea basin is not specified. The fishing industry is relatively small, mostly targeting harp seal , ringed seal , herring , saffron cod , European smelt , Atlantic cod and Atlantic salmon . There

4032-503: The gas turbines have a continuous combined rating of 45,000 kW (60,000 hp). The number, type and location of the propellers depends on the power, draft and intended purpose of the vessel. Smaller icebreakers and icebreaking special purpose ships may be able to do with just one propeller while large polar icebreakers typically need up to three large propellers to absorb all power and deliver enough thrust. Some shallow draught river icebreakers have been built with four propellers in

4116-429: The heavy weight of the ship pushed down on the ice breaking it. They were used in conjunction with teams of men with axes and saws and the technology behind them didn't change much until the industrial revolution. 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

4200-412: 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

4284-416: The hull and the ice, and allowed the icebreakers to penetrate thick ice ridges without ramming. However, the bow propellers are not suitable for polar icebreakers operating in the presence of harder multi-year ice and thus have not been used in the Arctic. Azimuth thrusters remove the need of traditional propellers and rudders by having the propellers in steerable gondolas that can rotate 360 degrees around

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4368-423: The ice and break it under the weight of the ship. In reality, this only happens in very thick ice where the icebreaker will proceed at walking pace or may even have to repeatedly back down several ship lengths and ram the ice pack at full power. More commonly the ice, which has a relatively low flexural strength , is easily broken and submerged under the hull without a noticeable change in the icebreaker's trim while

4452-717: 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

4536-455: The icebreaker can also tow the weakest ships. Some icebreakers are also used to support scientific research in the Arctic and Antarctic. In addition to icebreaking capability, the ships need to have reasonably good open-water characteristics for transit to and from the polar regions, facilities and accommodation for the scientific personnel, and cargo capacity for supplying research stations on

4620-576: The level of ice strengthening in the ship's hull. It is usually determined by the maximum ice thickness where the ship is expected to operate and other requirements such as possible limitations on ramming. While the ice class is generally an indication of the level of ice strengthening, not the actual icebreaking capability of an icebreaker, some classification societies such as the Russian Maritime Register of Shipping have operational capability requirements for certain ice classes. Since

4704-412: The more spread-out hull loads. While the shell plating, which is in direct contact with the ice, can be up to 50 millimetres (2.0 in) thick in older polar icebreakers, the use of high strength steel with yield strength up to 500 MPa (73,000 psi) in modern icebreakers results in the same structural strength with smaller material thicknesses and lower steel weight. Regardless of the strength,

4788-588: 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

4872-405: The nation's presence in the Arctic and Antarctic regions. As the icecaps in the Arctic continue to melt, there are more passageways being discovered. These possible navigation routes cause an increase of interests in the polar hemispheres from nations worldwide. The United States polar icebreakers must continue to support scientific research in the expanding Arctic and Antarctic oceans. Every year,

4956-429: The old port, Ivan IV established a new one down-river in 1584, called New Kholmogory, which from 1596 began to become known as Arkhangelsk. Between the 15th and early 18th centuries, the White Sea served as the major trade route in and out of Russia. This role decreased later after the foundation of Saint Petersburg (1703), which opened a more direct ice-free connection between Russia and the bulk of Western Europe via

5040-528: The protected object. In the past, such operations were carried out primarily in North America, but today Arctic offshore drilling and oil production is also going on in various parts of the Russian Arctic. The United States Coast Guard uses icebreakers to help conduct search and rescue missions in the icy, polar oceans. United States icebreakers serve to defend economic interests and maintain

5124-400: The resonance method. This causes the ice and water to oscillate up and down until the ice suffers sufficient mechanical fatigue to cause a fracture. White Sea The White Sea ( Russian : Белое море , romanized :  Beloye more ; Karelian and Finnish : Vienanmeri , lit.   'Dvina Sea'; Nenets : Сэрако ямʼ , romanized:  Serako yam ) is

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5208-646: The sea shores grew up in the late 14th century at Kholmogory , on the Northern Dvina . From there, in 1492, a merchant fleet laden with grain and carrying ambassadors of Ivan III of Russia sailed to Denmark, marking the establishment of the first international seaport in Russia . The first foreign ship to arrive in Kholmogory was the English Edward Bonaventure commanded by Richard Chancellor in 1553. Together with two other ships under

5292-485: The sea shores. Northwestern coasts are tall and rocky but the slope is much weaker at the southeastern side. The White Sea contains a large number of islands, but most of them are small. The main island group is the Solovetsky Islands , located almost in the middle of the sea, near the entrance to Onega Bay. Kiy Island in Onega Bay is significant due to a historic monastery. Velikiy Island, located close to

5376-449: The sea, which increases from 24 to 26‰ in the centre to 30.5‰ in the gorlo , reaching 34.0–34.5‰ toward the Barents Sea. The freezing period varies from year to year as shown in the satellite image to the right. The ice is not stationary, but 90% of it is floating and is continuously removed to the Barents Sea. Ice thickness is usually about 40 cm but may reach 150 cm in cold winters. In summer, surface water warms up to 15 °С in

5460-399: The shell plating is stiffened with frames placed about 400 to 1,000 millimetres (1 to 3 ft) apart as opposed to longitudinal framing used in longer ships. Near the waterline, the frames running in vertical direction distribute the locally concentrated ice loads on the shell plating to longitudinal girders called stringers, which in turn are supported by web frames and bulkheads that carry

5544-489: The ship was launched in 1993 as NS Ural . This icebreaker is intended to be the sixth and last of the Arktika class. Today, most icebreakers are needed to keep trade routes open where there are either seasonal or permanent ice conditions. While the merchant vessels calling ports in these regions are strengthened for navigation in ice , they are usually not powerful enough to manage the ice by themselves. For this reason, in

5628-649: The shore, is the largest island in the Kandalaksha Gulf. The White Sea is a water-filled depression in the block of a continental shelf known as the Baltic Shield . Its bottom is very uneven and contains the Kandalaksha Hollow in the northwest and the Solovetsky Islands in the south. Also, the Onega Bay has many small underwater elevations. The opening and the gorlo of the sea are rather shallow, with depths about 50 metres or less. There

5712-511: The shore. Countries such as Argentina and South Africa , which do not require icebreakers in domestic waters, have research icebreakers for carrying out studies in the polar regions. As offshore drilling moves to the Arctic seas, icebreaking vessels are needed to supply cargo and equipment to the drilling sites and protect the drillships and oil platforms from ice by performing ice management, which includes for example breaking drifting ice into smaller floes and steering icebergs away from

5796-455: The so-called h - v -curve to determine the icebreaking capability of the vessel. It shows the speed ( v ) that the ship is able to achieve as a function of ice thickness ( h ). This is done by calculating the velocity at which the thrust from the propellers equals the combined hydrodynamic and ice resistance of the vessel. An alternative means to determine the icebreaking capability of a vessel in different ice conditions such as pressure ridges

5880-614: The south, establishing the temperature of about −15 °C (February) over most of the sea. The northern part is warmer at about −9 °C, sometimes reaching −6 °C, due to the warm air masses from the Atlantic. Arctic anticyclones, however, change winds to the northeastern ones, bringing much colder weather with temperatures of about −25 °C. Summers are cold, cloudy and relatively humid, with northeastern winds and frequent rains. Average July temperatures are 8–10 °C. Occasional southeastern winds bring warm air from Europe, raising

5964-425: The steel used in the hull structures of an icebreaker must be capable of resisting brittle fracture in low ambient temperatures and high loading conditions, both of which are typical for operations in ice-filled waters. If built according to the rules set by a classification society such as American Bureau of Shipping , Det Norske Veritas or Lloyd's Register , icebreakers may be assigned an ice class based on

6048-415: The stern. Nozzles may be used to increase the thrust at lower speeds, but they may become clogged by ice. Until the 1980s, icebreakers operating regularly in ridged ice fields in the Baltic Sea were fitted with first one and later two bow propellers to create a powerful flush along the hull of the vessel. This considerably increased the icebreaking capability of the vessels by reducing the friction between

6132-523: 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

6216-439: The temperature to 17–19 °C and sometimes even to 30 °C. Annual precipitations increase from 282 mm in the north 529 in the south. In winter, from October–November to April–May, the sea freezes, with the average January water temperatures of −1.9 °C in the north, between −1.3 and −1.7 °С in the centre, and between −0.5 and −0.7 °С in the bays. These variations are due to the distribution of water salinity across

6300-490: The torque variations resulting from propeller-ice interaction. The 1969-built Canadian polar icebreaker CCGS Louis S. St-Laurent was one of the few icebreakers fitted with steam boilers and turbogenerators that produced power for three electric propulsion motors. It was later refitted with five diesel engines, which provide better fuel economy than steam turbines. Later Canadian icebreakers were built with diesel-electric powertrain. Two Polar-class icebreakers operated by

6384-406: The vessel moves forward at a relatively high and constant speed. When an icebreaker is designed, one of the main goals is to minimize the forces resulting from crushing and breaking the ice, and submerging the broken floes under the vessel. The average value of the longitudinal components of these instantaneous forces is called the ship's ice resistance. Naval architects who design icebreakers use

6468-490: The vessel. The external components of the ship's propulsion system ( propellers , propeller shafts , etc.) are at greater risk of damage than the vessel's 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. Prior to ocean-going ships, ice breaking technology was developed on inland canals and rivers using laborers with axes and hooks. The first recorded primitive icebreaker ship

6552-590: Was a barge used by the Belgian town of Bruges in 1383 to help clear the town moat. The efforts of the ice-breaking barge were successful enough to warrant the town purchasing four such ships. Ice breaking barges continued to see use during the colder winters of the Little Ice Age with growing use in the Low Country where significant amounts of trade and transport of people and goods took place. In

6636-506: Was built for the city of Philadelphia by Vandusen & Birelyn in 1837. The ship was powered by two 250- horsepower (190 kW) steam engines and her wooden paddles were reinforced with iron coverings. With a 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 . She had

6720-452: 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. Canada's largest and most powerful icebreaker, the 120-metre (390 ft) CCGS  Louis S. St-Laurent ,

6804-471: 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 propulsion power. On 22 August 1994 Louis S. St-Laurent and USCGC  Polar Sea became

6888-633: Was escorted to Moscow to meet the Russian Tsar , Ivan IV . Returning from Russia in 1554, Chancellor brought back a detailed description of Moscow and the Russian north, which were largely unknown to Europe, as well as a letter from the Tsar expressing desire to establish trade relations with England. In 1555 Queen Mary issued a charter authorising the Muscovy Company to trade with Russia via

6972-581: Was launched in 1957 and entered operation in 1959, before being officially decommissioned in 1989. It was both the world's first nuclear-powered surface ship and the first nuclear-powered civilian vessel . The second Soviet nuclear icebreaker was NS Arktika , the lead ship of the Arktika class . In service since 1975, she was the first surface ship to reach the North Pole , on August 17, 1977. Several nuclear-powered icebreakers were also built outside

7056-452: 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

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