Arrangement for Ice-Breaking

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.

1 .- 10 . (canceled) 
     
     
         11 . A device for icebreaking with a vessel, comprising:
 a vessel hull having two functionally separate elements of different widths, of which an upper and wider element is situated next to a water line for breaking unbroken ice and a lower and narrower element is configured to transport broken ice sideways and under the unbroken ice;   wherein the upper and wider element has a substantially flat inclined front part with a front frame angle and breaks ice downward, and has a substantially flat stern part with a stern frame angle, and has between the front and stern parts a substantially flat lower portion that is situated underneath an underside of a thickest ice that the vessel is configured to break at a continuous speed and that is situated outside the width of the lower and narrower element;   the front part, the stern part, and the lower portion of the upper and wider element are situated at a maximal width of the vessel; and   the lower and narrower element has substantially vertical side portions and is wedge-shaped at the front and stern parts of the upper and wider element in a direction of travel of the vessel, the wedge shape having an opening angle and being configured to force broken ice sideways and at least partly under unbroken ice when the vessel moves forward and to force broken ice sideways along the stern part and lower portion when the vessel moves astern, thereby decreasing an amount of broken ice that contacts a main propeller of the vessel.   
     
     
         12 . The device of  claim 11 , wherein at least one of the front frame angle is less than 15°, the stern frame angle is less than 20°, and the opening angle is less than 40°. 
     
     
         13 . The device of  claim 11 , wherein the vessel includes at least two wing propellers mounted at a bottom of the side portions and directed so that the wing propellers direct water upward at a first angle to hit the lower portion of the upper and wider element, whereby broken ice is forced aftward and prevented from contacting the main propeller when the vessel moves ahead. 
     
     
         14 . The device of  claim 13 , wherein the first angle is less than 10°. 
     
     
         15 . The device of  claim 13 , wherein the vessel includes at least two bow propellers mounted at a bottom of forward side portions of the lower and narrower element and directed so that the bow propellers direct water upward at a second angle and sideways at a third angle to hit the lower portion of the upper and wider element, whereby broken ice is forced sideways under unbroken ice when the vessel moves ahead in flat ice at continuous speed; and the bow propellers and wing propellers direct water astern when the vessel moves ahead in ridged ice, a lower part of the ridged ice extending under the flat part of the upper and wider element, to force the ridged ice to an area abaft the vessel. 
     
     
         16 . The device of  claim 15 , wherein the second angle is less than 10° and the third angle is half of the opening angle. 
     
     
         17 . The device of  claim 15 , wherein the wing and bow propellers are mounted on extrusions to decrease contact between the vertical side portions and water directed by the wing and bow propellers. 
     
     
         18 . The device of  claim 17 , further comprising wing-like projecting elements arranged in front of the wing and bow propellers, wherein the projecting elements and extrusions rotate broken ice to reduce blockage of the wing and bow propellers by the broken ice. 
     
     
         19 . The device of  claim 18 , wherein a projecting element has a side length that extends at least to a center of a respective wing or bow propeller. 
     
     
         20 . The device of  claim 13 , wherein the wing propellers are rotatable on support points at sides of the vessel to direct water forward or aftward, upward or downward. 
     
     
         21 . The device of  claim 11 , wherein the main propeller is rotatable on a support point below the vessel's stern. 
     
     
         22 . The device of  claim 11 , wherein the vessel has a driving propeller driven by propulsion machinery situated in front of propellers in the lower and narrower element. 
     
     
         23 . The device of  claim 11 , further comprising a cantilever disposed on a deck of the vessel, the cantilever being configured to decrease risk of broken ice landing on the deck. 
     
     
         24 . The device of  claim 11 , wherein sides of the upper and wider element include inward-inclining side portions having frame angles between 45° and 60° and arranged to, when turning, break ice upward when the vessel moves in unbroken ice.