Abstract: An amphibian vehicle having a vehicle body, and at least a pair of floaters attached to the vehicle body, each of which floaters consists of a cylindrical body having a buoyancy, and a helical blade fixed to the outer circumferential surface of the cylindrical body. This amphibian vehicle is formed such that the water line of the amphibian vehicle at a front end surface of each of the floaters is not higher than the center line thereof, with the water line of said amphibian vehicle at a rear end surface of each of the floaters not higher than a level which is higher than the center line of each of the floaters by 30% of the diameter thereof.

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.