Icebreaking

Ice resistance and hull form

When an icebreaker is designed, one of the main goals is to minimize the forces resulting from crushing and breaking the ice, and submerging the broken floes under the vessel. The average value of the longitudinal components of these instantaneous forces is called the ship's ice resistance. Naval architects who design icebreakers use the so-called h–v curve to determine the icebreaking capability of the vessel. It shows the speed (v) that the ship is able to achieve as a function of ice thickness (h). This is done by calculating the velocity at which the thrust from the propellers equals the combined hydrodynamic and ice resistance of the vessel. An alternative means to determine the icebreaking capability of a vessel in different ice conditions, such as pressure ridges, is to perform model tests in an ice tank. Regardless of the method, the actual performance of new icebreakers is verified in full-scale ice trials once the ship has been built.