Abstract: A relatively wide vessel is assisted through an ice field by an icebreaker having a relatively narrow hull. The icebreaker includes two steerable propulsion mechanisms at the opposite ends respectively of the hull, and the propulsion mechanisms are used to propel the icebreaker through the ice field in a direction at a substantial angle to its keel line, thereby opening in one pass of the icebreaker a passage having a width substantially greater than the waterline width of the icebreaker.

Abstract: A main propulsion device of a ship includes a turnable underwater propeller pod, a screw propeller journalled in the propeller pod at one end thereof and a substantially vertical turning shaft journalled at its upper end portion in the ship3 s hull and attached at its lower end portion to the propeller pod. The upper end portion of the turning shaft is offset relative to the lower end portion of the turning shaft perpendicular to the propeller plane toward the propeller.

Abstract: A floating semisubmersible off-shore drilling platform or the like comprises an upper working level portion and a lower pontoon portion. When the platform is transported from one place to another, it floats on the pontoon portion, but when it is working as a stationary unit in open water, it is submerged deeper, so that the pontoon portion is at a considerable distance below the water surface and the working level portion is at a considerable distance above the water surface. The platform is adapted to withstand ice pressure from ice occurring in the ambient water by giving the pontoon portion of the platform a form particularly advantageous in ice conditions. When ice occurs, the platform is lifted to such a position, that its pontoon portion comes to float at the water surface level.

Abstract: The invention relates to a ship that is adapted for operating in ice-filled waters and has a general frame form defining a substantially horizontal bottom surface, two side surfaces, a stern and a blow portion that breaks the ice advantageously. The bottom surface comprises one or a greater number of cavities, extending to or located on both sides of the longitudinal symmetry plane of the ship, in which cavity or cavities there are arranged movable sheetlike elements. The sheetlike elements have a first position, in which said elements form a generally continuous part of the bottom surface, and a second position, in which said elements form, below the bottom surface, a substantially vertical wedge-shaped structure that converges in the direction from the stern of the hull towards the bow of the hull. The elements are provided with power units which bring about movement of the elements from one position to another by turning around a swivelling axis arranged in the longitudinal direction of the elements.

Abstract: An off-shore drilling platform or the like supported by support legs standing on the bottom of the sea is converted to withstand ice pressure occurring in ice filled waters by providing those portions of said drilling platform, which are to be protected against ice pressure, with protective structures below the platform. The drilling platform and/or the protective structures are then, when ice occurs, lowered along the support legs to a level where the protective structures partly extend below the surface of the ambient water.

Abstract: A floating semisubmersible off-shore drilling platform or the like comprises an upper working level portion and a lower pontoon portion. When the platform is transported from one place to another, it floats on the pontoon portion, but when it is working as a stationary unit in open water, it is submerged deeper, so that the pontoon portion is at a considerable distance below the water surface and the working level portion is at a considerable distance above the water surface. The platform is adapted to withstand ice pressure from ice occurring in the ambient water by giving the pontoon portion of the platform a form particularly advantageous in ice conditions. When ice occurs, the platform is lifted to such a position, that its pontoon portion comes to float at the water surface level.