Nuclear Icebreakers; the wrecking ball of the seas

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• published: 08 Oct 2013
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**History** The icebreaker dates back to the year 1200 when Kochi made their way through frozen seas. A Koch had an egg-shaped hull that allowed it to be lifted form the water line when wind forced sheets of ice to compress. The ships waterline also had a steel band that prevented it form getting damaged. The Fram (1893-1912) took design hints from Kochi, but improved upon it by implementing a retractable keel and rudder. The Fram was built to go to the north pole, but not through crushing ice, but instead to be lifted from the water and carried by ice flows. That seems like cheating to me. Fram was stuck near the north pole for three years, though she and the crew can survive being stranded for five. Even though the Koch and Fram were considered the first icebreakers, their design did not resemble a modern one, however, the Pilot (1864) did. She was the first to be able to clear a path by actually breaking the ice. Even with that, I don't think that Pilot is an icebreaker, but rather ice strengthened. A strengthened ship can survive ice 0.5-1m thick while an icebreaker can do much better than that. **Propulsion** In modern times, there are only two propulsion methods for icebreakers. Diesel Electric, and Nuclear Electric. Well, there's actually a third. There are times when a hovercraft is used in rivers to prevent thin ice from getting thicker, but that's a unique case. A diesel electric engine uses a diesel motor to power an electric one. This is because an electric engine can better withstand the resistance from ice stuck in the propeller. A nuclear electric engine does something similar. **Design** The Arktika was the first ship to reach the north pole. Her inner hull is 25mm while the outer one is 48mm. She also has a strengthened prow (front) at 50cm thick. Though the prow is thick, the biggest misconception about icebreakers is that plows through ice. The bow (front) of a typical icebreaker either has a small angle of attack or rounded, much like a ramp. This is because Icebreakers actually uses it's weight to glide over the ice and break it. Breaking ice like this causes a lot of friction between the hull and ice. This friction makes it energy intensive to go through ice, and it friction creates a lot of noise which makes it uncomfortable for the crew. To prevent friction, holes that release steam pepper the hull. The steam create water from the melted ice which is used as lubricant. Aside from steam, icebreakers also have special paint and wider bow (front) to mitigate friction. Because ice passes under the ship, the vessel's propeller and rudder are positioned behind the collapsed section of the hull near the rear. See the image for more info. An icebreaker also needs to easily go on reverse or even move to the side, so azimuth propellers are typically installed. An azimuth propeller sticks out form the hull and can rotate 360º. To further protect the propellers, ships have ice-horns or ice-knives which are basically a horizontal piece of strengthened metal. Icebreakers also don't have stabilizers sticking out the size of the hull which makes it uncomfortable to ride an icebreaker in rough seas. Ice sheets move depending on wind conditions. This means that if an icebreaker is stationary for too long, it will get pinched in between sheets. Because it's pinched, it cannot move forward and thus break ice. That's why they hold ballast tanks which are containers of water typically located under the ship and inside the hull. These tanks have pumps and are used to shift the ships weight left to right or back to front in order to break from from ice. Icebreakers have to sometimes be moved from the north to the south and back again depending on the season. The lack of stabilizers makes icebreakers uncomfortable in rough seas, but the ballast tank can be used keep the vessel form risking too much. Another design that makes icebreakers unsuitable to the open ocean is the spoon shaped bow which causes the ship slam into waves instead of cutting through it. Fortunately, more modern designs have solved this problem. Newer ships actually have two bows. One bow for breaking ice and the other (on the opposite end) for cutting through the open seas. There are also bulbous bows that's so close to the water's surface that it's shape and velocity forces the water upward which breaks thinner ice and saves the ship's prow from getting too damaged. There are even ships that have a bow running the side of the ship. These ships are typically used to clear the way for even larger ships, and because it moves sideways instead of forward, the size of the ship can be greatly decreased.