A method of assembling and deploying a floating offshore wind turbine (FOWT) platform includes floating a buoyant floater and a hollow outer tank in a floating assembly, placing permanent ballast material in the outer tank to define a mass, and sinking the mass to a seabed. The buoyant floater is moved to a position over the mass. Transit lines are attached between a lifting device in the buoyant floater and the mass to define a FOWT platform. The mass is lifted to a point directly under the buoyant floater and the FOWT platform is towed to an installation site. Mooring lines are attached between anchors in the seabed and the buoyant floater, and the mass is lowered to a depth wherein suspension lines attached thereto are taught, the mass with the suspension lines defining a suspended mass. The transit lines are then stored or removed from the mass.

A method of assembling and deploying a floating offshore wind turbine (FOWT) platform includes floating a buoyant floater and a hollow outer tank in a floating assembly, placing permanent ballast material in the outer tank to define a mass, and sinking the mass to a seabed. The buoyant floater is moved to a position over the mass. Transit lines are attached between a lifting device in the buoyant floater and the mass to define a FOWT platform. The mass is lifted to a point directly under the buoyant floater and the FOWT platform is towed to an installation site. Mooring lines are attached between anchors in the seabed and the buoyant floater, and the mass is lowered to a depth wherein suspension lines attached thereto are taught, the mass with the suspension lines defining a suspended mass. The transit lines are then stored or removed from the mass.

A method of ballasting a vessel comprises positioning a vessel having a first draft adjacent to or underneath an offshore installation. The vessel has at least one ballasting tank and at least one port in fluid communication with the at least one ballasting tank. The at least one ballasting tank is arranged to selectively adjust the flow of ballast water in and out of the at least one ballasting tank. The method comprises pushing down from the offshore installation on the vessel to increase the draft of the vessel from the first draft to a second draft. The method further comprises opening the at least one port when the vessel is at the second draft and the at least one port is below a waterline. The method also comprises filling at least part of the at least one ballasting tank.

A method of installing a wind turbine generator onto a floating foundation. The floating foundation has variable buoyancy and is pre-ballasted to float at a predetermined vertical position before installation of a wind turbine generator component onto the floating foundation. A wind turbine generator component supported by lifting equipment is brought towards the floating foundation until contact is made with the floating foundation. Ballast is removed from the floating foundation to increase the buoyancy of the floating foundation such that weight of the wind turbine generator component supported by the floating foundation is increased from substantially zero to substantially the entire weight of the wind turbine generator component. The vertical position of the floating foundation is substantially unchanged during transferring weight of the wind turbine generator component onto the floating foundation.

An offshore floating structure is provided including a floater with positive buoyancy and a keel with negative buoyancy, as well as active and passive suspenders connecting nodes of the keel and the floater with each other. When the keel at the offshore site is lowered by making the active suspenders longer, the passive suspenders, which have a fixed length and are held taut, causes the keel to rotate about the vertical during lowering.

An offshore floating structure is provided including a floater with positive buoyancy and a keel with negative buoyancy, as well as active and passive suspenders connecting nodes of the keel and the floater with each other. When the keel at the offshore site is lowered by making the active suspenders longer, the passive suspenders, which have a fixed length and are held taut, causes the keel to rotate about the vertical during lowering.

An assembly includes an object with a vertical height of at least 30 metres placed on a bearing frame and a motion compensation platform including a base attached to a vessel. The platform includes an x-y actuator system for rotating the bearing frame with respect to the base about an x-axis and a y-axis, a sensor system configured to detect an x-axis rotating movement, and a y-axis rotating movement, and to generate a corresponding sensor signal, as well as an x-y control system configured to adjust the position of the bearing frame with respect to the base, depending on the sensor signal. The bearing frame is supported at a vertical distance above the base by means of a three-point support having a hinged, fixed first support and hinged second and third supports which are telescopic in the longitudinal direction of the z-axis.

An assembly includes an object with a vertical height of at least 30 metres placed on a bearing frame and a motion compensation platform including a base attached to a vessel. The platform includes an x-y actuator system for rotating the bearing frame with respect to the base about an x-axis and a y-axis, a sensor system configured to detect an x-axis rotating movement, and a y-axis rotating movement, and to generate a corresponding sensor signal, as well as an x-y control system configured to adjust the position of the bearing frame with respect to the base, depending on the sensor signal. The bearing frame is supported at a vertical distance above the base by means of a three-point support having a hinged, fixed first support and hinged second and third supports which are telescopic in the longitudinal direction of the z-axis.

A method for installing an offshore wind power generation floating body may include manufacturing a lower structure including a damping plate, a guide beam including protruding portions, and a slot, coupling a temporary buoyancy tank to each protruding portion, installing a concrete block mounting structure in the slot, transporting the lower structure on the sea until a destination by a towing vessel, fixing the lower structure between a first work barge and a second work barge by a link bridge connected to each of the first work barge and the second work barge, and seating a concrete block connected to a second wire of a second crane seated on the second work barge on the concrete block mounting structure in a state in which first wires of a first crane are connected to the lower structure to maintain a tension equal to or greater than a set magnitude.

A method for installing an offshore wind power generation floating body may include manufacturing a lower structure including a damping plate, a guide beam including protruding portions, and a slot, coupling a temporary buoyancy tank to each protruding portion, installing a concrete block mounting structure in the slot, transporting the lower structure on the sea until a destination by a towing vessel, fixing the lower structure between a first work barge and a second work barge by a link bridge connected to each of the first work barge and the second work barge, and seating a concrete block connected to a second wire of a second crane seated on the second work barge on the concrete block mounting structure in a state in which first wires of a first crane are connected to the lower structure to maintain a tension equal to or greater than a set magnitude.