Abstract: A rotary ice-breaking body having a spiral rotary blade is attached to a structure for use in icy waters at a part falling in contact with an ice lump or ice floe. The rotary blade is actuated to bite into the ice lump and to lift up or press down the ice lump. The ice lump is broken by the flexural stress and the structure is protected from influences of the ice lump. One rotary ice-breaking body may be disposed to constitute the outer periphery of the structure. Alternately, a plurality of rotary ice-breaking bodies may be disposed to surround the structure so that they are driven and rotated simultaneously or independently.

Abstract: Disclosed are ice-breaking units for ships adapted to be installed at the bow and/or bottom portion of the ship's hull, consisting of two ice-breaking units each of which can be reversibly driven independently of each other, for performing ice-breaking and/or propulsion of the ship. The ice-breaking unit has a screw-like body having a spiral blade wound thereabout. The ice-breaking units may be disposed at the bow portion, at both sides of the longitudinal center line of the ship, in parallel with or normal to the latter, or may be arranged to have a propulsion portion and an ice-breaking portion, respectively. The two screw-like bodies may be driven simultaneously in the same direction or reversed, or may be rotated in the opposite directions, to provide thrusts to move the ship in any direction of ahead/astern and port/starboard.

Abstract: An ice-breaking apparatus for use in ships and barges operating on icy waters, including nozzles for jetting high pressure fluid, is disclosed. By impinging force or cavitation caused by the high pressure fluid jetted from the nozzles, grooves or cracks are formed on an ice floe, and then, the ice floe is broken from these grooves or cracks by the hull. This ice-breaking apparatus facilitates breakage of ice floes or the like, and when this ice-breaking apparatus is attached, ships or barges for operation on icy waters can be built without increasing dimensions or propulsion powers particularly for navigation on icy waters. The ice-breaking apparatus includes echo distance measuring apparatus for automatically controlling and maintaining the nozzles at optimum positions from the ice-surface.