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 .
133-454: 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 vessel's trim . In cases of very thick ice, an icebreaker can drive its bow onto
266-486: A conifer tree. From the 16th century, vessels were often built of a size requiring masts taller and thicker than could be made from single tree trunks. On these larger vessels, to achieve the required height, the masts were built from up to four sections (also called masts), known in order of rising height above the decks as the lower, top, topgallant and royal masts. Giving the lower sections sufficient thickness necessitated building them up from separate pieces of wood. Such
399-508: A full-rigged ship was one with a bowsprit and three masts, each of which consists of a lower, top, and topgallant mast. Most sailing ships were merchantmen , but the Age of Sail also saw the development of large fleets of well-armed warships . The many steps of technological development of steamships during the 19th century provided slowly increasing competition for sailing ships — initially only on short routes where high prices could be charged. By
532-433: A line of battle —coordinated movements of a fleet of warships to engage a line of ships in the enemy fleet. Carracks with a single cannon deck evolved into galleons with as many as two full cannon decks, which evolved into the man-of-war, and further into the ship of the line —designed for engaging the enemy in a line of battle. One side of a ship was expected to shoot broadsides against an enemy ship at close range. In
665-519: A steering oar as a rudder to control direction. Starting in the 8th century in Denmark, Vikings were building clinker -constructed longships propelled by a single, square sail, when practical, and oars, when necessary. A related craft was the knarr , which plied the Baltic and North Seas , using primarily sail power. The windward edge of the sail was stiffened with a beitass , a pole that fitted into
798-563: 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
931-450: A destination, sailing vessels may have to change course and allow the wind to come from the opposite side in a procedure, called tacking , when the wind comes across the bow during the maneuver. When tacking, a square-rigged vessel's sails must be presented squarely to the wind and thus impede forward motion as they are swung around via the yardarms through the wind as controlled by the vessel's running rigging , using braces —adjusting
1064-530: A fast passage secured higher rates of freight or passenger fares. Whilst many clippers were ship rigged, the definition is not limited to any rig. Clippers were generally built for a specific trade: those in the California trade had to withstand the seas of Cape Horn, whilst Tea Clippers were designed for the lighter and contrary winds of the China Sea. All had fine lines, with a well streamlined hull and carried
1197-419: A funnel, derrick, or mast . The line where the hull meets the water surface is called the waterline . There is a wide variety of hull types that are chosen for suitability for different usages, the hull shape being dependent upon the needs of the design. Shapes range from a nearly perfect box in the case of scow barges to a needle-sharp surface of revolution in the case of a racing multihull sailboat. The shape
1330-601: 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
1463-535: 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
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#17330930604521596-545: A hull with rounded bilges (the chine creates turbulence and drag resisting the rolling motion, as it moves through the water, the rounded-bilge provides less flow resistance around the turn). In rough seas, this can make the boat roll more, as the motion drags first down, then up, on a chine: round-bilge boats are more seakindly in waves, as a result. Chined hulls may have one of three shapes: Each of these chine hulls has its own unique characteristics and use. The flat-bottom hull has high initial stability but high drag. To counter
1729-463: A large sail area. To get the best of this, a skilled and determined master was needed in command. During the Age of Sail, ships' hulls were under frequent attack by shipworm (which affected the structural strength of timbers), and barnacles and various marine weeds (which affected ship speed). Since before the common era, a variety of coatings had been applied to hulls to counter this effect, including pitch, wax, tar, oil, sulfur and arsenic. In
1862-465: A load capacity of 7,800 tonnes. Ships transitioned from all sail to all steam-power from the mid 19th century into the 20th. Five-masted Preussen used steam power for driving the winches , hoists and pumps , and could be manned by a crew of 48, compared with four-masted Kruzenshtern , which has a crew of 257. Coastal top-sail schooners with a crew as small as two managing the sail handling became an efficient way to carry bulk cargo, since only
1995-466: A lower-horsepower engine but will pound more in waves. The deep V form (between 18 and 23 degrees) is only suited to high-powered planing boats. They require more powerful engines to lift the boat onto the plane but give a faster, smoother ride in waves. Displacement chined hulls have more wetted surface area, hence more drag, than an equivalent round-hull form, for any given displacement. Smooth curve hulls are hulls that use, just like
2128-523: 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
2261-417: 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
2394-400: A section was known as a made mast , as opposed to sections formed from single pieces of timber, which were known as pole masts . Starting in the second half of the 19th century, masts were made of iron or steel. For ships with square sails the principal masts, given their standard names in bow to stern (front to back) order, are: Each rig is configured in a sail plan , appropriate to
2527-515: 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
2660-433: A small number of roles, such as towing sailing ships and providing short route passenger and mail services. Both sailing and steam ships saw large technological improvements over the century. Ultimately the two large stepwise improvements in fuel efficiency of compound and then triple-expansion steam engines made the steamship, by the 1880s, able to compete in the vast majority of trades. Commercial sail still continued into
2793-641: 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
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#17330930604522926-582: 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
3059-655: 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
3192-399: Is a centerline longitudinal member called a keel . In fiberglass or composite hulls, the structure may resemble wooden or steel vessels to some extent, or be of a monocoque arrangement. In many cases, composite hulls are built by sandwiching thin fiber-reinforced skins over a lightweight but reasonably rigid core of foam, balsa wood, impregnated paper honeycomb, or other material. Perhaps
3325-459: 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 the ice. In
3458-622: Is chosen to strike a balance between cost, hydrostatic considerations (accommodation, load carrying, and stability), hydrodynamics (speed, power requirements, and motion and behavior in a seaway) and special considerations for the ship's role, such as the rounded bow of an icebreaker or the flat bottom of a landing craft . In a typical modern steel ship, the hull will have watertight decks, and major transverse members called bulkheads . There may also be intermediate members such as girders , stringers and webs , and minor members called ordinary transverse frames, frames, or longitudinals, depending on
3591-423: Is easily unsettled in waves. The multi-chine hull approximates a curved hull form. It has less drag than a flat-bottom boat. Multi chines are more complex to build but produce a more seaworthy hull form. They are usually displacement hulls. V or arc-bottom chine boats have a V shape between 6° and 23°. This is called the deadrise angle. The flatter shape of a 6-degree hull will plane with less wind or
3724-451: 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
3857-643: 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,
3990-631: The Borobudur temple, dating back to the 8th century CE. By the 10th century AD, the Song dynasty started building the first Chinese seafaring junks , which adopted several features of the K'un-lun po . The junk rig in particular, became associated with Chinese coast-hugging trading ships. Junks in China were constructed from teak with pegs and nails; they featured watertight compartments and acquired center-mounted tillers and rudders . These ships became
4123-649: The Indo-Pacific dates from at least 1500 BC. Later developments in Asia produced the junk and dhow —vessels that incorporated features unknown in Europe at the time. European sailing ships with predominantly square rigs became prevalent during the Age of Discovery (15th to 17th centuries), when they crossed oceans between continents and around the world. In the European Age of Sail ,
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4256-519: 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
4389-514: 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
4522-522: 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
4655-610: The Yngling and Randmeer . Hull forms are defined as follows: Block measures that define the principal dimensions. They are: Form derivatives that are calculated from the shape and the block measures. They are: Coefficients help compare hull forms as well: Note: C b = C p ⋅ C m {\displaystyle C_{b}=C_{p}\cdot C_{m}} Use of computer-aided design has superseded paper-based methods of ship design that relied on manual calculations and lines drawing. Since
4788-511: The after guard , who were stationed aft and tended the mainsail, spanker and manned the various sheets, controlling the position of the sails; the waisters , who were stationed midships and had menial duties attending the livestock, etc.; and the holders , who occupied the lower decks of the vessel and were responsible for the inner workings of the ship. He additionally named such positions as, boatswains, gunners, carpenters, coopers, painters, tinkers, stewards, cooks and various boys as functions on
4921-874: The barque , barquentine , and brigantine . Early sailing ships were used for river and coastal waters in Ancient Egypt and the Mediterranean . The Austronesian peoples developed maritime technologies that included the fore-and-aft crab-claw sail and with catamaran and outrigger hull configurations, which enabled the Austronesian expansion into the islands of the Indo-Pacific . This expansion originated in Taiwan c. 3000 BC and propagated through Island Southeast Asia , reaching Near Oceania c. 1500 BC, Hawaii c. 900 AD, and New Zealand c. 1200 AD. The maritime trading network in
5054-516: The structural arrangement . The uppermost continuous deck may be called the "upper deck", "weather deck", "spar deck", " main deck ", or simply "deck". The particular name given depends on the context—the type of ship or boat, the arrangement, or even where it sails. In a typical wooden sailboat, the hull is constructed of wooden planking, supported by transverse frames (often referred to as ribs) and bulkheads, which are further tied together by longitudinal stringers or ceiling. Often but not always there
5187-445: The waterline , giving less resistance and more speed. With a greater payload, resistance is greater and speed lower, but the hull's outward bend provides smoother performance in waves. As such, the inverted bell shape is a popular form used with planing hulls. A chined hull does not have a smooth rounded transition between bottom and sides. Instead, its contours are interrupted by sharp angles where predominantly longitudinal panels of
5320-467: The " Treasure Ship ", measured 400 feet (120 m) in length and 150 feet (46 m) in width, whereas modern research suggests that it was unlikely to have exceeded 70 metres (230 ft) in length. Sailing ships in the Mediterranean region date back to at least 3000 BC, when Egyptians used a bipod mast to support a single square sail on a vessel that mainly relied on multiple paddlers. Later
5453-545: The 11th century and was adopted by the Arab traders in the Indian Ocean. The compass spread to Europe by the late 12th or early 13th century. Use of the compass for navigation in the Indian Ocean was first mentioned in 1232. The Europeans used a "dry" compass, with a needle on a pivot. The compass card was also a European invention. At the beginning of the 15th century, the carrack was the most capable European ocean-going ship. It
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5586-503: The 14th century, but did not become common at sea until they could be reloaded quickly enough to be reused in the same battle. The size of a ship required to carry a large number of cannon made oar-based propulsion impossible, and warships came to rely primarily on sails. The sailing man-of-war emerged during the 16th century. By the middle of the 17th century, warships were carrying increasing numbers of cannon on three decks. Naval tactics evolved to bring each ship's firepower to bear in
5719-420: The 1870s to 1900, when steamships began to outpace them economically, due to their ability to keep a schedule regardless of the wind. Steel hulls also replaced iron hulls at around the same time. Even into the twentieth century, sailing ships could hold their own on transoceanic voyages such as Australia to Europe, since they did not require bunkerage for coal nor fresh water for steam, and they were faster than
5852-452: The 1880s, ships with triple-expansion steam engines had the fuel efficiency to compete with sail on all major routes — and with scheduled sailings that were not affected by the wind direction. However, commercial sailing vessels could still be found working into the 20th century, although in reducing numbers and only in certain trades. By the time of the Age of Discovery —starting in the 15th century—square-rigged, multi-masted vessels were
5985-444: The 18th century, the small and fast frigate and sloop-of-war —too small to stand in the line of battle—evolved to convoy trade, scout for enemy ships and blockade enemy coasts. The term "clipper" started to be used in the first quarter of the 19th century. It was applied to sailing vessels designed primarily for speed. Only a small proportion of sailing vessels could properly have the term applied to them. Early examples were
6118-525: The 19th century. Dana described the crew of the merchant brig, Pilgrim , as comprising six to eight common sailors, four specialist crew members (the steward, cook, carpenter and sailmaker), and three officers: the captain , the first mate and the second mate . He contrasted the American crew complement with that of other nations on whose similarly sized ships the crew might number as many as 30. Larger merchant vessels had larger crews. Melville described
6251-515: 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
6384-594: The 20th century, with the last ceasing to trade by c. 1960 . Early sea-going sailing vessels were used by the Austronesian peoples . The invention of catamarans , outriggers , and crab claw sails enabled the Austronesian Expansion at around 3000 to 1500 BC. From Taiwan, they rapidly colonized the islands of Maritime Southeast Asia , then sailed further onwards to Micronesia , Island Melanesia , Polynesia , and Madagascar . Austronesian rigs were distinctive in that they had spars supporting both
6517-672: 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
6650-452: The Americas with Christopher Columbus , and around the world under Ferdinand Magellan . Sailing ships became longer and faster over time, with ship-rigged vessels carrying taller masts with more square sails. Other sail plans emerged, as well, that had just fore-and-aft sails ( schooners ), or a mixture of the two ( brigantines , barques and barquentines ). Cannons were introduced in
6783-496: 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
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#17330930604526916-631: The United Kingdom and China after the East India Company lost its monopoly in 1834. The primary cargo was tea, and sailing ships, particularly tea clippers, dominated this long distance route until the development of fuel efficient steamships coincided with the opening of the Suez Canal in 1869. Other clippers worked on the Australian immigrant routes or, in smaller quantities, in any role where
7049-475: 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 was a barge used by the Belgian town of Bruges in 1383 to help clear the town moat. The efforts of
7182-586: 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 the creation of
7315-471: The basis for the development of Chinese warships during the Mongol Yuan dynasty , and were used in the unsuccessful Mongol invasions of Japan and Java . The Ming dynasty (1368–1644) saw the use of junks as long-distance trading vessels. Chinese Admiral Zheng He reportedly sailed to India, Arabia, and southern Africa on a trade and diplomatic mission. Literary lore suggests that his largest vessel,
7448-595: 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
7581-558: 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
7714-404: The bow. By the nineteenth century, ships were built with reference to a half model, made from wooden layers that were pinned together. Each layer could be scaled to the actual size of the vessel in order to lay out its hull structure, starting with the keel and leading to the ship's ribs. The ribs were pieced together from curved elements, called futtocks and tied in place until the installation of
7847-509: The clew of a square sail forward. The crew of a sailing ship is divided between officers (the captain and his subordinates) and seamen or ordinary hands . An able seaman was expected to "hand, reef, and steer" (handle the lines and other equipment, reef the sails, and steer the vessel). The crew is organized to stand watch —the oversight of the ship for a period—typically four hours each. Richard Henry Dana Jr. and Herman Melville each had personal experience aboard sailing vessels of
7980-465: 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
8113-421: The crew complement of the frigate warship, United States , as about 500—including officers, enlisted personnel and 50 Marines. The crew was divided into the starboard and larboard watches. It was also divided into three tops , bands of crew responsible for setting sails on the three masts; a band of sheet-anchor men , whose station was forward and whose job was to tend the fore-yard, anchors and forward sails;
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#17330930604528246-513: The curved hulls, a centreboard, or an attached keel. Semi round bilge hulls are somewhat less round. The advantage of the semi-round is that it is a nice middle between the S-bottom and chined hull. Typical examples of a semi-round bilge hull can be found in the Centaur and Laser sailing dinghies . S-bottom hulls are sailing boat hulls with a midships transverse half-section shaped like an s . In
8379-628: 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
8512-405: 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
8645-479: The earliest proper hulls were built by the Ancient Egyptians , who by 3000 BC knew how to assemble wooden planks into a hull. Hulls come in many varieties and can have composite shape, (e.g., a fine entry forward and inverted bell shape aft), but are grouped primarily as follows: At present, the most widely used form is the round bilge hull. With a small payload, such a craft has less of its hull below
8778-425: The early 1990s, a variety of commercial and freeware software packages specialized for naval architecture have been developed that provide 3D drafting capabilities combined with calculation modules for hydrostatics and hydrodynamics. These may be referred to as geometric modeling systems for naval architecture. Sailing ship A sailing ship is a sea-going vessel that uses sails mounted on masts to harness
8911-611: The early 19th century, until the advent of iron and steel hulls. Iron-hulled sailing ships , often referred to as " windjammers " or " tall ships ", represented the final evolution of sailing ships at the end of the Age of Sail. They were built to carry bulk cargo for long distances in the nineteenth and early twentieth centuries. They were the largest of merchant sailing ships, with three to five masts and square sails, as well as other sail plans . They carried lumber , guano , grain or ore between continents. Later examples had steel hulls. Iron-hulled sailing ships were mainly built from
9044-421: The early steamers, which usually could barely make 8 knots (15 km/h). The four-masted, iron-hulled ship, introduced in 1875 with the full-rigged County of Peebles , represented an especially efficient configuration that prolonged the competitiveness of sail against steam in the later part of the 19th century. The largest example of such ships was the five-masted, full-rigged ship Preussen , which had
9177-519: 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
9310-605: 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 ,
9443-406: 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
9576-510: 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
9709-419: The fore and aft angle of each yardarm around the mast—and sheets attached to the clews (bottom corners) of each sail to control the sail's angle to the wind. The procedure is to turn the vessel into the wind with the hind-most fore-and-aft sail (the spanker ), pulled to windward to help turn the ship through the eye of the wind. Once the ship has come about, all the sails are adjusted to align properly with
9842-562: The fore-sails required tending while tacking and steam-driven machinery was often available for raising the sails and the anchor . In the 20th century, the DynaRig allowed central, automated control of all sails in a manner that obviates the need for sending crew aloft. This was developed in the 1960s in Germany as a low-carbon footprint propulsion alternative for commercial ships. The rig automatically sets and reefs sails; its mast rotates to align
9975-402: 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
10108-502: 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
10241-412: The high drag, hull forms are narrow and sometimes severely tapered at bow and stern. This leads to poor stability when heeled in a sailboat. This is often countered by using heavy interior ballast on sailing versions. They are best suited to sheltered inshore waters. Early racing power boats were fine forward and flat aft. This produced maximum lift and a smooth, fast ride in flat water, but this hull form
10374-415: 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
10507-417: The hull meet. The sharper the intersection (the more acute the angle), the "harder" the chine. More than one chine per side is possible. The Cajun "pirogue" is an example of a craft with hard chines. Benefits of this type of hull include potentially lower production cost and a (usually) fairly flat bottom, making the boat faster at planing . A hard chined hull resists rolling (in smooth water) more than does
10640-422: 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
10773-433: 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 the hull and strengthening cross members inside
10906-409: 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 ship's propulsion system ( propellers , propeller shafts , etc.) are at greater risk of damage than the vessel's hull, so
11039-594: 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 the 15th century the use of ice breakers in Flanders ( Oudenaarde , Kortrijk , Ieper , Veurne , Diksmuide and Hulst )
11172-450: 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
11305-426: The implementation of center-mounted rudders, controlled with a tiller. Technological advancements that were important to the Age of Discovery in the 15th century were the adoption of the magnetic compass and advances in ship design. The compass was an addition to the ancient method of navigation based on sightings of the sun and stars. The compass was invented by Chinese. It had been used for navigation in China by
11438-468: The large-diameter line run around them, whilst multiple holes allowed smaller line— lanyard —to pass multiple times between the two and thereby allow tensioning of the shroud. After the mid-19th century square-rigged vessels were equipped with iron wire standing rigging, which was superseded with steel wire in the late 19th century. Halyards , used to raise and lower the yards, are the primary supporting lines. In addition, square rigs have lines that lift
11571-565: 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
11704-525: The lower corner of the sail, when sailing close to the wind. India's maritime history began during the 3rd millennium BCE when inhabitants of the Indus Valley initiated maritime trading contact with Mesopotamia. Indian kingdoms such as the Kalinga from as early as 2nd century CE are believed to have had sailing ships. One of the earliest instances of documented evidence of Indian sailing ship building comes from
11837-401: The man-of-war. 18-19th century ships of the line had a complement as high as 850. Handling a sailing ship requires management of its sails to power—but not overpower—the ship and navigation to guide the ship, both at sea and in and out of harbors. Key elements of sailing a ship are setting the right amount of sail to generate maximum power without endangering the ship, adjusting the sails to
11970-596: The mast became a single pole, and paddles were supplanted with oars. Such vessels plied both the Nile and the Mediterranean coast. The Minoan civilization of Crete may have been the world's first thalassocracy brought to prominence by sailing vessels dating to before 1800 BC (Middle Minoan IIB). Between 1000 BC and 400 AD, the Phoenicians , Greeks and Romans developed ships that were powered by square sails, sometimes with oars to supplement their capabilities. Such vessels used
12103-399: The mid 18th century copper sheathing was developed as a defense against such bottom fouling. After coping with problems of galvanic deterioration of metal hull fasteners, sacrificial anodes were developed, which were designed to corrode, instead of the hull fasteners. The practice became widespread on naval vessels, starting in the late 18th century, and on merchant vessels, starting in
12236-411: 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,
12369-569: 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
12502-538: The mural of three-masted ship in the Ajanta caves that date back to 400-500 CE. The Indian Ocean was the venue for increasing trade between India and Africa between 1200 and 1500. The vessels employed would be classified as dhows with lateen rigs . During this interval such vessels grew in capacity from 100 to 400 tonnes . Dhows were often built with teak planks from India and Southeast Asia, sewn together with coconut husk fiber—no nails were employed. This period also saw
12635-404: 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,
12768-418: The new tack. Because square-rigger masts are more strongly braced from behind than from ahead, tacking is a dangerous procedure in strong winds; the ship may lose forward momentum (become caught in stays ) and the rigging may fail from the wind coming from ahead. The ship may also lose momentum at wind speeds of less than 10 knots (19 km/h). Under these conditions, the choice may be to wear ship —to turn
12901-466: The norm and were guided by navigation techniques that included the magnetic compass and making sightings of the sun and stars that allowed transoceanic voyages. The Age of Sail reached its peak in the 18th and 19th centuries with large, heavily armed battleships and merchant sailing ships . Sailing and steam ships coexisted for much of the 19th century. The steamers of the early part of the century had very poor fuel efficiency and were suitable only for
13034-498: The other to form the whole, from bottom to top: the lower mast , top mast , and topgallant mast . This construction relied heavily on support by a complex array of stays and shrouds. Each stay in either the fore-and-aft or athwartships direction had a corresponding one in the opposite direction providing counter-tension. Fore-and-aft the system of tensioning started with the stays that were anchored in front each mast. Shrouds were tensioned by pairs of deadeyes , circular blocks that had
13167-407: The planking. Typically, planking was caulked with a tar-impregnated yarn made from manila or hemp to make the planking watertight. Starting in the mid-19th century, iron was used first for the hull structure and later for its watertight sheathing. Until the mid-19th century all vessels' masts were made of wood formed from a single or several pieces of timber which typically consisted of the trunk of
13300-455: The power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships , employing square-rigged or fore-and-aft sails. Some ships carry square sails on each mast—the brig and full-rigged ship , said to be "ship-rigged" when there are three or more masts. Others carry only fore-and-aft sails on each mast, for instance some schooners . Still others employ a combination of square and fore-and-aft sails, including
13433-513: 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
13566-441: 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. Hull (watercraft) A hull is the watertight body of a ship , boat , submarine , or flying boat . The hull may open at the top (such as a dinghy ), or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures , such as
13699-487: The s-bottom, the hull has round bilges and merges smoothly with the keel, and there are no sharp corners on the hull sides between the keel centreline and the sheer line. Boats with this hull form may have a long fixed deep keel, or a long shallow fixed keel with a centreboard swing keel inside. Ballast may be internal, external, or a combination. This hull form was most popular in the late 19th and early to mid 20th centuries. Examples of small sailboats that use this s-shape are
13832-427: The sail or the yard from which it is suspended that include: brails , buntlines , lifts and leechlines. Bowlines and clew lines shape a square sail. To adjust the angle of the sail to wind braces are used to adjust the fore and aft angle of a yard of a square sail, while sheets attach to the clews (bottom corners) of a sail to control the sail's angle to the wind. Sheets run aft, whereas tacks are used to haul
13965-410: The sail up and secure it with lines, called reef points . Dana spoke of the hardships of sail handling during high wind and rain or with ice covering the ship and its rigging. Sailing vessels cannot sail directly into the wind. Instead, square-riggers must sail a course that is between 60° and 70° away from the wind direction and fore-and aft vessels can typically sail no closer than 45°. To reach
14098-430: The sail, the crew uses clewlines , haul up the clews and buntlines to haul up the middle of sail up; when lowered, lifts support each yard. In strong winds, the crew is directed to reduce the number of sails or, alternatively, the amount of each given sail that is presented to the wind by a process called reefing . To pull the sail up, seamen on the yardarm pull on reef tackles , attached to reef cringles , to pull
14231-441: The sails with the wind. The sailing yachts Maltese Falcon and Black Pearl employ the rig. In the 21st century, due to concern about climate change and the possibility of cost savings, companies explored using wind-power to reduce heavy fuel needs on large containerized cargo ships . By 2023, around 30 ships were using sails or attached kites, with the number expected to grow. The following year, The Economist wrote that
14364-588: The schooners and brigantines, called Baltimore clippers , used for blockade running or as privateers in the War of 1812 and afterwards for smuggling opium or illegally transporting slaves . Larger clippers, usually ship or barque rigged and with a different hull design, were built for the California trade (from east coast USA ports to San Francisco) after gold was discovered in 1848 – the associated ship-building boom lasted until 1854. Clippers were built for trade between
14497-399: 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
14630-415: The ship away from the wind and around 240° onto the next tack (60° off the wind). A fore-and-aft rig permits the wind to flow past the sail, as the craft head through the eye of the wind. Most rigs pivot around a stay or the mast, while this occurs. For a jib , the old leeward sheet is released as the craft heads through the wind and the old windward sheet is tightened as the new leeward sheet to allow
14763-483: 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
14896-413: 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
15029-510: 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
15162-432: The size of the sailing craft. Both square-rigged and fore-and-aft rigged vessels have been built with a wide range of configurations for single and multiple masts. Types of sail that can be part of a sail plan can be broadly classed by how they are attached to the sailing craft: Sailing ships have standing rigging to support the masts and running rigging to raise the sails and control their ability to draw power from
15295-454: 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
15428-423: 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
15561-467: 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
15694-512: 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
15827-530: The technology was at an inflection point as it moved from trials and testing towards adoption by the industry. Every sailing ship has a sail plan that is adapted to the purpose of the vessel and the ability of the crew; each has a hull , rigging and masts to hold up the sails that use the wind to power the ship; the masts are supported by standing rigging and the sails are adjusted by running rigging . Hull shapes for sailing ships evolved from being relatively short and blunt to being longer and finer at
15960-488: 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
16093-590: The upper and lower edges of the sails (and sometimes in between), in contrast to western rigs which only had a spar on the upper edge. Large Austronesian trading ships with as many as four sails were recorded by Han dynasty (206 BC – 220 AD) scholars as the kunlun bo or K'un-lun po (崑崙舶, lit. "ship of the Kunlun people"). They were booked by Chinese Buddhist pilgrims for passage to Southern India and Sri Lanka. Bas reliefs of large Javanese outriggers ships with various configurations of tanja sails are also found in
16226-405: 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
16359-404: The wind direction on the course sailed, and changing tack to bring the wind from one side of the vessel to the other. A sailing ship crew manages the running rigging of each square sail. Each sail has two sheets that control its lower corners, two braces that control the angle of the yard, two clewlines, four buntlines and two reef tackles. All these lines must be manned as the sail is deployed and
16492-435: The wind. The running rigging has three main roles, to support the sail structure, to shape the sail and to adjust its angle to the wind. Square-rigged vessels require more controlling lines than fore-and-aft rigged ones. Sailing ships prior to the mid-19th century used wood masts with hemp-fiber standing rigging. As rigs became taller by the end of the 19th century, masts relied more heavily on successive spars, stepped one atop
16625-442: The yard raised. They use a halyard to raise each yard and its sail; then they pull or ease the braces to set the angle of the yard across the vessel; they pull on sheets to haul lower corners of the sail, clews , out to yard below. Under way, the crew manages reef tackles , haul leeches , reef points , to manage the size and angle of the sail; bowlines pull the leading edge of the sail ( leech ) taut when close hauled. When furling
16758-405: Was carvel-built and large enough to be stable in heavy seas. It was capable of carrying a large cargo and the provisions needed for very long voyages. Later carracks were square-rigged on the foremast and mainmast and lateen-rigged on the mizzenmast . They had a high rounded stern with large aftcastle , forecastle and bowsprit at the stem. As the predecessor of the galleon , the carrack
16891-476: 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 the heavy weight of the ship pushed down on
17024-498: 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
17157-452: 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 ,
17290-471: 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
17423-570: 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
17556-494: Was one of the most influential ship designs in history; while ships became more specialized in the following centuries, the basic design remained unchanged throughout this period. Ships of this era were only able to sail approximately 70° into the wind and tacked from one side to the other across the wind with difficulty, which made it challenging to avoid shipwrecks when near shores or shoals during storms. Nonetheless, such vessels reached India around Africa with Vasco da Gama ,
17689-451: 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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