Abstract: Inclined plane protection boards are provided in a manner to cover an inclined plane of an artificial island whereby the inclined plane may be protected from ice force of growing or drifting ice bodies or wind and wave force.

Abstract: A floating offshore structure which is moored at a fixed position on the sea by means of mooring hawsers and anchors connected to the ends thereof respectively for conducting a submarine excavating operation from a deck of the structure. The structure includes a moorage hull part provided with a vertical through-hole formed therein for receiving an excavating drill pipe and the mooring hawsers and a movable hull part connected to the moorage hull part so as to be rotatable within a horizontal plane. The movable hull part is constituted as a hull defining the outer wall of the floating offshore structure and connected with the moorage hull part by inserting it into a moorage hull part receiving hole formed at a position closer to the bow thereof.

Abstract: A floating offshore structure which is moored at a fixed position on the sea by means of mooring hawsers and anchors connected to the ends thereof respectively for conducting a submarine excavating operation from a deck of the structure. The structure includes a moorage hull part provided with a vertical through-hole formed therein for receiving an excavating drill pipe and the mooring hawsers and a movable hull part connected to the moorage hull part so as to be rotatable within a horizontal plane. The movable hull part is constituted as a hull defining the outer wall of the floating offshore structure and connected with the moorage hull part by inserting it into a moorage hull part receiving hole formed at a position closer to the bow thereof.

Abstract: A floating-type offshore structure, of which the main body comprises a lower hull and plurality of struts mounted on the struts and supporting a platform above the sea level and is moored through mooring wire ropes or chains at a predetermined offshore location, and which is adapted for use under both of an ice-covered and an iceless conditions of the sea by adjusting the amount of ballast water contained in a ballast tank or tanks formed in the lower hull and/or the struts and adapted for causing ice floes to undergo downward flexural failure on account of bending stresses when they move into the sea water along the ice contacting face of the strut which is inclined inwardly toward below.

Abstract: An artificial island for installing oil drilling equipment in ice covered sea areas, comprising barricades against ice which surround oil drilling equipment installed in ice covered sea-water and whose respective top portions are projected above the surface of the sea-water, means provided at the bottom portions of the barricades so as to fix them to the sea-bottom, and inclined ice breaking walls provided at the outer sides of the barricades.

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.