Abstract: A device for ice-breaking with a vessel has two functionally separate upper and lower elements of different widths. The upper, wider element is situated next to the water line for breaking unbroken ice, and the lower, narrower element is situated below the upper element and for transporting broken ice sideways and under the unbroken ice. The upper wider element has a flat lower portion abaft an inclining front part with a small frame angle and breaks ice downward when moving ahead, and a flat stern part with a small frame angle and breaks ice downward when moving astern. The lower element has vertical side portions which in the forebody and the afterbody have a marked wedge-shape and shove broken ice sideways. Transport of broken ice sideways and astern can be augmented by bow propellers and wing propellers.

Abstract: An ice breaker vessel and a method for increasing maneuverability and protecting the propellers against broken ice when going backwards. The ice breaker has two stern propellers and a steering rudder aligned with each propeller shaft. Each of the rudders is individually rotatably mounted on a vertical rudder stock adjacent half the cord of the rubber blade profile length, and connected to a rudder gear, so that they e.g. may converge or diverge in the direction backwards, in abutment with end stops positioned on the stern of the ice breaker vessel, when the rudders are in their respective end positions. The method comprises turning the steering rudders in opposite directions until they cooperate and for backwards converging rudder surfaces.

Abstract: An ice-breaking vessel having a spoon-shaped bow portion and an obliquely downwardly/rearwardly extending reamer at each longitudinal side is provided with second reamers located above the water line, above the rear portion of the adjacent first reamer and extending further outward than the same. A plow-shaped extension projects downwards from the plane bottom of the vessel, and has a breadth less than the breadth thereof. The rearmost part of the deck of the aft portion of the vessel has a reduced breath, so two corners are formed at each side of the deck. The bilges at the bottom plating extend to the forward of these corners, while the bilges at the plow-formed extension extend to the rearward corners.