An arctic jackup truss leg comprises a plurality of chords, an outer bracing network with a plurality of bracing elements connecting the plurality of chords, an internal bracing network with a plurality of bracing elements, and a bridge plate network with a plurality of bridge plates, wherein each bridge plate has two ends that are coupled with the bracing elements of the outer bracing network and the internal bracing network respectively.

An arctic jackup truss leg comprises a plurality of chords, an outer bracing network with a plurality of bracing elements connecting the plurality of chords, an internal bracing network with a plurality of bracing elements, and a bridge plate network with a plurality of bridge plates, wherein each bridge plate has two ends that are coupled with the bracing elements of the outer bracing network and the internal bracing network respectively.

A method for installation of an elongate element in a stretch of water, the method including reversible fastening of a connecting member (34) at a first end (16) of the elongate element (10); arranging the elongate element (10) in a substantially horizontal configuration; reversibly engaging the connecting member (34) in a retaining member (36); pivoting the elongate element (10) about a substantially horizontal axis to move the elongate element (10) into a substantially vertical configuration, while the connecting member (34) remains engaged in the retaining member (36); joint lowering of the retaining member (36), the connecting member (34) and the elongate element (10) in the stretch of water (12) with the help of a lowering line (152); detaching the connecting member (34) of the first end (16) of the elongate element (10), and joint raising of the retaining member (36) and the connecting member (34).

A method for installation of an elongate element in a stretch of water, the method including reversible fastening of a connecting member (34) at a first end (16) of the elongate element (10); arranging the elongate element (10) in a substantially horizontal configuration; reversibly engaging the connecting member (34) in a retaining member (36); pivoting the elongate element (10) about a substantially horizontal axis to move the elongate element (10) into a substantially vertical configuration, while the connecting member (34) remains engaged in the retaining member (36); joint lowering of the retaining member (36), the connecting member (34) and the elongate element (10) in the stretch of water (12) with the help of a lowering line (152); detaching the connecting member (34) of the first end (16) of the elongate element (10), and joint raising of the retaining member (36) and the connecting member (34).

A node structure (12, 14) for connecting two or more convergent members (16, 26) of a lattice frame to each other and to one or more other members of the lattice frame. The node structure (12, 14) comprises a pair of opposed spaced-apart faces (30) that are substantially planar and substantially parallel to each other. At least one pair of root formations (32) with respective central longitudinal axes define an interior angle between them, those axes diverging outwardly for alignment with respective members of the lattice frame and converging inwardly between the faces (30). An inner connecting wall (34) between the root formations (32) of the pair connects concave-curved inner edges (36) of the faces and extends in a concave curve around the interior angle to join the root formations (32) of that pair.

An offshore structure comprises a hull having a longitudinal axis, a first end, and a second end opposite the first end. In addition, the structure comprises an anchor coupled to the lower end of the hull and configured to secure the hull to the sea floor. The anchor has an aspect ratio less than 3:1. The hull includes a variable ballast chamber positioned axially between the first end and the second end of the hull and a first buoyant chamber positioned between the variable ballast chamber and the first end of the hull. The first buoyant chamber is filled with a gas and sealed from the surrounding environment. Further, the structure comprises a ballast control conduit in fluid communication with the variable ballast chamber and configured to supply a gas to the variable ballast chamber. The structure also comprises a topside mounted to the first end of the hull.

A jack-up crane vessel or semi-submersible crane vessel is provided including a hull with a deck, and a crane on the hull for hoisting a load outside the deck. The crane includes a slewing crane base with a first suspension, an elongated boom that is rotatable around a horizontal rotation axis with respect to the first suspension, at least two pendants between the boom and the first suspension that mutually converge toward the distal boom section, a boom spacer between the boom and the first suspension, and a boom luffing installation for driving the rotation of the boom around the horizontal rotation axis between a lowered transport position and a raised operational position. In the direction of the vertical rotation axis the first suspension extends at least in the lowered transport position of the boom above the boom heel of the boom.

A method for monitoring movement of a cantilever structure of an offshore platform, such as a jack-up platform or a self-elevating vessel, comprising providing a boundary model containing boundary limiting information of positions of the cantilever structure, wherein the boundary limiting information comprises at least position information of boundary limiting elements, such as obstacles; providing, during movement of the cantilever, position information of the cantilever representing an actual position of the cantilever; determining, during movement of the cantilever, a difference between the cantilever position information and the boundary limiting information of the boundary model; providing an output signal when the determined difference exceeds a predefined threshold value.

Method for stabilizing a jack-up platform unit, the unit including a hull, a plurality of legs which are extendible from and/or through the hull and which are arranged to support the platform unit during off-shore operations, and a jacking system arranged to move the legs between a transport position and an operational position, wherein the jacking system is also arranged to move the hull along the plurality of legs between a floating position and an operational position, the method comprising the steps of lowering the plurality of legs until the legs stand on or in the seabed, raising the hull substantially above the sea surface, temporarily applying a preloading on the plurality of legs, further raising the hull to an operational height above the sea surface.

The offshore jack-up has a hull and a plurality of moveable legs engageable with the seafloor. The offshore jack-up is arranged to move the legs with respect to the hull to position the hull out of the water. The method comprises moving at least a portion of a vessel underneath the hull of the offshore jack-up or within a cut-out of the hull when the hull is positioned out of the water and the legs engage the seafloor. A stabilizing mechanism mounted on the jack-up is engaged against the vessel. The stabilizing mechanism is pushed down on the vessel to increase the buoyant force acting on the vessel.