Icebreaker

"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.

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 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 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." - (en.wikipedia.org 13.05.2021)