The shipping industry, a significant contributor to the global economy, serves a variety of customers across the world. From the largest containers ships to riverboats, the industry comprises tens of thousands of ships that perform a number of duties. While a major portion of the ships is being used for freight transport, cruise ships and ferries take a good share of the remaining part. However, there are few vessels that stand out from the majority due to its unique purposes. The luxurious private yachts owned by millionaires across the world and various type of marine research vessels are part of the list. In addition, one of the unique types of vessels in the list is the special-purpose ships called ice-breakers. As the world shrinks to a size smaller than we ever imagined, it makes sense to wonder about the technology that makes this possible. Providing access to even the remotest parts of the world, there is technology that is truly breath-taking. Icebreaker ships would definitely fall into that category.
Getting to know about the technology behind ice-breakers can only start with understanding the nature of their genius.
What is an icebreaker ship?
Icebreaker ships are a special class of ships that are designed to break even thickest of the ice and make some of the most inhospitable paths accessible to the world, navigating through the ice-covered waters, especially in the Polar Regions. The significant features that make the ice-breakers different from other vessels are its strengthened hull to resist ice waters, a specially designed ice-clearing shape to make a path forward and extreme power to navigate through sea ice.
The idea of an icebreaker ship has been around for a very long time, since the initial days of polar explorations. It is said that in times as long ago as the 11th century, an icebreaker ship was known to work. Of course, they were more of boats then. The earlier versions of icebreakers, known as kochi, were the contribution of the communities lived on the coasts of the Arctic Ocean. The ship they developed was a small one- or two-mast wooden vessel and was used to navigate through the icy waters of Arctic seas and Siberian Rivers. The features of Koch included a belt of ice-floe resistant flush skin-planking to protect the hull and rounded body lines below the water-line to help the vessel to be pushed up in case it was squeezed by ice fields. During the later centuries, new icebreakers were developed adopting similar design techniques. Even today, their basic design remains the same, although the modernization has certainly made them much more efficient.
The prime functions of an icebreaker ship nowadays include clearing the trade routes in the icy waters, especially during winters. Though the vessels taking these trade routes- such as the Baltic Sea, the Saint Lawrence Seaway, the Great Lakes and, and the Northern Sea Route- are designed to navigate through the icy waters, the seasonal ice conditions make it difficult for the vessels to manage themselves. Thus, the icebreakers escort commercials vessel while crossing these areas to make sure the easy navigation of the vessels. In addition to clearing passage for the fright vessels, the icebreakers are also widely used to support research programmes conducted in the Polar regions.
Major Characteristics of an Icebreaker ship
As said earlier, it is the special design of the icebreakers that makes them suitable for performing icebreaking duties. A strong-built hull is one of the important features of an icebreaker. A hull shape that features a low ice resistance and capable of performing different maneuvers according to requirements is extremely significant. Featuring a double hull, the icebreakers have two layers of the water-tight surface at the vessels’ bottom and the sides. The hull will be built with more thickness compared to other vessels and the steel used as a material for the construction will have the strength to resist low temperatures. In order to enhance manoeuvrability in the icy waters, the icebreakers feature a sloping stem, sometimes rounded stem, and sloping sides. Moreover, some icebreaking ships feature a hull that measures more width in the bow than in the stern in order to increase the width of the ice channel that it creates.
Similarly, despite having the strong-built hull, additional structural strengthening is also required for a shipbreaker to perform its duties efficiently. In fact, the design of the bow of icebreakers is a significant element since the vessel needs to cut through the ice-filled waters. While other vessels feature a pointed bow, the icebreakers’ bow will be designed in a more rounded structure to help the vessel break the ice using its weight and also to ride over it. The pointed hull of a normal ship helps it to slice through the waves and reduce friction between ship and water. While old icebreakers featured up to 50 millimeters thick shell plating, the modern vessels use high strength steel that has a yield strength of as much as 500 MPa, offering enhanced strength with less steel weight and thickness. The steel used on the vessels are also efficient to resist brittle fracture in low ambient temperatures as well as high loading conditions.
One of the other significant features of the modern icebreakers compared to other vessels is the power it brings to make ways for other vessels through the icy waters. Be it the coal- or oil-fired steamships used in earlier period, diesel-electric icebreakers or even the nuclear-powered icebreakers, the icebreakers feature a significantly enhanced power. With two propellers fitted both at the fore and the aft and bow thruster, these vessels stand out in the crowd and maneuverer on the ice efficiently. The United States Coast Guard’s powerful Polar-class icebreakers feature a diesel-electric and mechanical propulsion system that includes six diesel engines and three gas turbines, producing up to 13,000 kW and 45,000 kW respectively.
Nuclear icebreaker ships
Nuclear icebreaker ships are the example of the latest technology that has been brought into the ice breaking industry, making it more suitable for the harsh job that these ships are destined for. Ice breaker ships are employed in jobs that are not exactly cooperative, per se. This makes it a highly cost-intensive job, primarily because of the fuel cost.
On average, an icebreaker working in regions like Russian frozen water with 3-meter-thick ice would use up more than 100 tons of fuel per day- a massive input even for high return jobs like oil extraction. This is where nuclear-powered ships come to rescue. A nuclear-powered ship would use less than a pound of uranium under the same conditions, making it a much better fuel option. Also, this eliminates the need for fuel refilling which is exactly what is needed in the secluded ice-covered regions that these ships operate in. The overall returns from nuclear icebreaker ships easily surpass the initial cost of production.
Currently, Russia operates all nuclear-powered icebreakers in the world. With the first one launched in 1957 and the latest put into service in 2007, Russia operates eight nuclear-powered icebreakers for various purposes.
How does an icebreaker ship work?
As said earlier, the working of icebreaker ships lies in their design that is modified to suit their special purpose. Having a mammoth structure, with the advantage of weight, size, and power, the icebreakers can glide smoothly over even 3-meter thick ice and crush it making a path for other ships to tread. This makes them exceptionally useful piece of machinery in frozen regions of Arctic and Russia. Of course, calling them a ‘piece of machinery’ would be a farce but on the fair side, they can be reasonably called quite small as compared to the ships and tankers that carry out the final job of relaying the material back and forth a spot.
Getting back to how does an icebreaker ship works, it is because of their hull design. With the rounded shape bow unlike other vessels, the smoother portion of an icebreaker ship allows it to glide more easily over the thick ice coat, reducing the opposing forces greatly. As the ship glides over the ice, its weight comes down on the ice sheet, crushing it. Smooth hull design helps push this ice out of the ship’s way, preventing it from entering ship’s parts and causing damage. The double hull structure ensures the integrity of the hull even under harshest conditions. The outer hull is reinforced with additional materials and hull polymer paints that provides it more strength and reduces damage due to friction. So the ship moves forward, the ice is shoved aside and there is a path for other ships to move on to.
Limitations of Icebreakers
While the icebreaker ships rule the polar regions and ice-waters across the world, the vessels lack efficiency outside their specific regions. The slight negative aspect of this design is that it makes icebreaker ships good enough for purpose of ice breaking alone. They are definitely the best at their job. But their specialized design makes them highly unsuitable for normal waterways. With the rounded bow, the icebreakers are almost unseaworthy in the normal seas. When a typical hull shape can resist the waves, the design of icebreakers allows the waves to hit the vessel in full force, making the maneuvering a difficult job.
Some modifications in designs have made double acting ship design a possibility to overcome these limitations. The double-acting ships are provided with propellers that can be turned in all directions, allowing the vessel in its backward direction to generate enough thrust to break the ice. However, these are a specialized class of ships. Until they come into use, the icebreaker ships remain the most viable option for ice breaking.