Patent ID: 9352809
Filing Date: 2016-05-31
CPC Classification: B63B,E21B

Claim Text:
1. A semi-submersible vessel for offshore operations which is suitable to be operated in icy waters and in ice-free waters, said vessel comprising: an operating deck to accommodate equipment; at least one lower hull; an essentially vertical connecting structure between the at least one lower hull and the operating deck; and a ballast system to ballast or deballast the vessel, wherein the connecting structure has a water portion and an icebreaking portion being arranged on top of each other, wherein the water portion of the connecting structure is formed by multiple columns, wherein the vessel is configured to have an icebreaking draft for icy waters in which the water- or iceline is substantially level with the icebreaking portion, and a water draft for ice-free waters in which the waterline is substantially level with the multiple columns of the water portion, wherein the icebreaking portion has a single closed tapered contour, and wherein during the water draft the collective area of the water portion of the connecting structure intersecting the water surface is smaller than the collective area of the icebreaking portion of the connecting structure intersecting the water surface during the icebreaking draft.