Icebreaker

Icebreaker, vessel designed to break channels through ice for other ships, chiefly in harbors and rivers. They are of special importance in Canada, the former USSR, and Scandinavia. An icebreaker has a very strong reinforced hull and is equipped with high-powered engines that transmit power to the rugged propeller by electrical means. This enables the vessel to develop maximum power from a standing start. When breaking thin ice, the ship rams its way forward, sometimes assisted by turbulence created by a propeller at the bow. For breaking thick ice the vessel moves fast enough to ride up onto the ice, which then breaks under its weight. The shape of the hull makes icebreakers roll heavily in open water, but this also helps to break the ice. Special canting tanks containing water can also induce rolling and prevent the ship from getting trapped. The U.S. Coast Guard has a number of these vessels, with their distinctive, sharp, upward-slanting bows. The world's first atomic-powered icebreaker, the 16,000-ton (7,258 kg) Lenin, was launched by the USSR in 1957.