Icebreaking vessel and method of breaking ice
AssigneeMaersk Supply Service A/S
InventorNiels Peter Elmbo
Life of this patent
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Abstract
To keep the water around an off-shore installation (1) free from a harmful impact of ice, a vessel (5) is used to deploy an anchor (6) in a position at a distance from the off-shore installation (1) and in a direction which, seen from the off-shore installation (1), is substantially in parallel with the direction of movement (P) of the ice. By means of the machinery of the vessel, which preferably comprises azimuth propellers, the direction of the anchor line is adjusted and so is the orientation of the vessel relative to the anchor line to the effect that then propellers can be used to crush and dispose of the ice without using energy to hold the vessel up against the pressure of the ice.
Claims20
A vessel with an icebreaking hull to eliminate ice or to render ice harmless in a surface area of water in proximity of an off-shore installation, said vessel comprising:
- an anchor which can be deployed in an anchor line at a distance from the vessel;
- an anchor handling winch capable of winding or unwinding an anchor line through an opening in the vessel;
- motive power means for moving the vessel while it is anchored;
- said vessel being capable of performing icebreaking tasks while it is anchored, said vessel being, by means of the motive power means or the anchor handling winch, movable across a surface area of the bed of the sea which has a significantly larger expanse than the expanse of the vessel, whereby the vessel is capable of eliminating or rendering the ice harmless in a surface area of the sea, wherein the opening through which the anchor line passes into the water is arranged below (deeper than) the propeller shaft of the vessel.
A Method for breaking ice in proximity of an off-shore installation, comprising:
- providing a vessel that includes:
- an anchor which can be deployed in an anchor line at a distance from the vessel;
- an anchor handling winch capable of winding or unwinding an anchor line through an opening in the vessel;
- motive power means for moving the vessel while it is anchored, wherein said vessel is capable of performing icebreaking tasks while it is anchored, said vessel being, by means of the motive power means or the anchor handling winch, movable across a surface area of the bed of the sea which has a significantly larger expanse than the expanse of the vessel, whereby the vessel is capable of eliminating or rendering the ice harmless in a surface area of the sea, wherein the opening through which the anchor line passes into the water is arranged below (deeper than) the propeller shaft of the vessel;
- positioning the vessel at a distance from the off-shore installation and in a direction which, as seen from the off-shore installation, is substantially in parallel with the direction of movement of the ice to the effect that the vessel is capable of breaking ice drifting towards the off-shore installation,
- deploying the anchor in an anchor line which is conveyed through an internal passage in the vessel and out through an opening which is arranged under the sea level,
- positioning the vessel such that a holding force of the anchor can be transferred from the anchor to the vessel via anchor line and one or more anchor handling winches,
- adjusting the direction of the anchor line and/or its length via machinery and/or an anchor handling winch of the vessel to the effect that the vessel can be moved across a surface area of the sea bed which has a considerably larger expanse than the expanse of the vessel, whereby the vessel is capable of eliminating ice and/or rendering ice harmless in a surface area of the water.
Dependencies are inferred from the claim text.