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  • Writer's pictureSarah Whiteford

What is an icebreaker?

Updated: Jan 25

First things first, what is an icebreaker? An icebreaker is a vessel built to move through ice-covered waters, such as those near the North Pole and Antarctica. Their design is different from most other ships to accommodate harsh weather conditions and break ice over 16 feet thick! Some of the uses of these ships are for shipping, research, and defense. We’ll take a closer look at why icebreakers are needed, the first icebreakers, the biggest, and even nuclear-powered icebreakers.

Swedish Icebreaker Oden. Image Credit: Larry Larsson, U.S. Navy.

Why do we need icebreakers?

Although we can travel much of the ocean with normal ships, in areas near the poles, the sea is covered with a layer of ice. Regular vessels are strong enough to withstand ocean waves and storms, but ice can tear a hole in a ship’s hull and sink her in minutes. This is where ice-strengthened ships come in, they are able to travel in areas where there is ice without sustaining damage. However, ice-strengthening does not mean these ships can break through ice. Ice breaking requires a special class of ships built for this purpose, and frequently escort ice strengthened ships through shipping lanes that are frozen over. Icebreakers have a rounded hull and designed to break through ice and push it away from the ship so it doesn’t get stuck. They are very expensive to build, maintain, and run, sometimes using 100 tons of fuel in a day. Since these ships have to be strong and smooth to glide through icy waterways, the stabilizing fins found on most ships cannot be used on icebreaker ships, making them pitch and roll in the open sea. Even though these ships are specialized, countries that want to travel the north-east and north-west passages, as well as to the Arctic or Antarctic need the services of these vessels. According to Cool Antarctica, here are some of the features that differentiate icebreakers from other ships:

  • “Heavy for their size, to make them more effective at breaking through ice when they are pushed up above it by their engines.

  • Gradual upwards slope at the bow, particularly at the water line to allow the bow to ride up over ice before the weight breaks it.

  • Hull made from special steels designed for optimum strength at low temperatures.

  • Air bubbling systems to assist ice-breaking. Air is forced under pressure from 2m or so below the water line where ice is met, helping to break it and move it out of the way.

  • Heated water jets below the waterline to help when breaking through ice.

  • Ability to rapidly move large amounts of water ballast within the ship to shift the weight when needing to break ice. The ships can be rocked from side to side in this manner.

  • Hull divided by bulkheads into a series of watertight compartments in case it is holed.

  • Extra thick steel at the bow, also at the stern and at the waterline.

  • An "ice horn" to protect the rudder and propeller when in reverse, and an "ice knife" in front to protect it when in forwards motion.

  • Electric propulsion to the propellers. Electric motors can apply torque when not actually turning or when only turning slowly, so the propeller hitting a large piece of ice will not stop the engine.

  • Extra strong propellers with replaceable blades. There may also be a propeller inspection well to examine them in operation and the facility to change blades while at sea.

  • Very powerful engines. The engine may be diesel possibly with extra power supplied by gas turbines for ice breaking or even be nuclear powered.

  • Powerful searchlights for use in dark winter conditions.”

RRS Sir David Attenborough polar research vessel. Image Credit: ECO Magazine.

As you can see, there’s a lot of special features that go into icebreakers that don’t go into a normal ship! You might be wondering why ships don't just avoid ice-covered waters if they are so difficult to traverse. There are a few reasons, first of which is shipping. During some seasons sea ice makes passing areas difficult, which is one of the reasons Russia has built so many large and powerful ice breakers. Their ships can travel where even other icebreakers can’t, including to the top of the world, the North Pole. Second, militaries want the ability to travel around the world for protection and surveillance. Lastly, researchers study places like Antarctica, where they can learn more about Earth, our impact on it, and the history of it through the very thick ice sheet. It’s an almost untouched area, claimed by no country. But, to resupply the Antarctic bases, icebreakers are needed. Check out our article about the RSV Nuyina, Australia’s brand new icebreaker research vessel built for cutting-edge research and supply missions to Australia’s three Antarctic bases.

History of icebreaking ships

Before icebreakers were used in the ocean, they were used to clear ice from rivers and canals inland. The first icebreaker was used in 1392 to clear a town moat in Bruges, Belgium. Ice-strengthened ships have been used frequently since humans started exploring the polar regions. These early vessels were made of wood, but reinforced by double-planking the hull and installing reinforcing crossmembers inside the ships. According to Wikipedia, “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.” Being nipped meant that ice flowed around the ship and push in to trap the ship in place, causing damage and restricting movement.

Russian Yermak rescuing a trapped battleship. RadioFreeEurope RadioLiberty

Early icebreakers in the 11th century used an egg-shaped hull so that if they were stuck in the ice, the pressure would push the ship up and out of the water, rather than crushing it. That design was used on steam powered icebreakers later in the 19th century, including by the Norwegian ship Fram, which 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.” according to Wikipedia. Throughout the 1800s, Russia built steam-powered icebreakers with early hulls designed for riding up onto the ice and breaking it with the weight of the ship. The first modern design icebreaker was built in 1897, the Russian Yermak, powered by steam engines with 10,000 horsepower. It was the first polar icebreaker, capable of running over and crushing pack ice. It was in service for 66 years, until 1963 when it was decommissioned and scrapped a year later. Diesel icebreakers appeared in the 1900s, with the first being the Swedish Ymer in 1933. Diesel-electric icebreakers appeared in the mid 1900s, with diesel and electric the popular power plant for most icebreakers today.

Although diesel-electric is the popular power plant for most of the world, Russia operates multiple nuclear powered icebreakers. The NS Arktika, a nuclear icebreaker built by the Soviet Union in 1975, became the first surface vessel to reach the North Pole in 1977. The Project 22220 class of ships, including the Arktika, are the largest icebreakers in the world and capable of breaking through sea ice 2.8 meters thick with its solid steel 50-centimeter thick prow. Nuclear icebreakers not only have much more power than diesel, they can travel faster through ice that is much thicker. According to RadioFreeEurope RadioLiberty, “A full day of grinding through thick ice uses up just 300 grams of uranium in a nuclear icebreaker, compared to around 100 tons of fuel for an equivalent diesel-powered vessel.” The initial cost of building a nuclear icebreaker as well as continued upkeep is one of the biggest reasons they are not more popular.

Arktika class icebreaker 50 Years Since Victory. RadioFreeEurope RadioLiberty.

Icebreakers serve a very specific purpose: breaking through ice. They’re heavy, they pitch and roll on the open seas, and they use a lot of fuel, but if you want to get through ice covered waters, they get the job done. They support shipping, the military, supply, and research around the world, and have some really cool technology. Happy Friday!


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