Abstract: The invention provides a sub-structure (2) comprising at least one leg (4) having first buoyancy means (4a) arranged in a lower part of the at least one leg to provide a first buoyancy, and a float element (3) having second buoyancy means to provide a second buoyancy, wherein the sub-structure and the float element are constructed to allow relative wave induced motion with respect to each other in a substantially vertical direction wherein the leg is movable from a pre-installation position to an installation position by a substantially downwards movement of the leg with respect to the float element, and wherein during at least a second part of the downwards movement of the leg towards the installation position and/or in the installation position the first buoyancy means are substantially located below a wave zone to substantially decrease heave action on the first buoyancy means.

Abstract: The invention provides a sub-structure (2) comprising at least one leg (4) having first buoyancy means (4a) arranged in a lower part of the at least one leg to provide a first buoyancy, and a float element (3) having second buoyancy means to provide a second buoyancy, wherein the sub-structure and the float element are constructed to allow relative wave induced motion with respect to each other in a substantially vertical direction wherein the leg is movable from a pre-installation position to an installation position by a substantially downwards movement of the leg with respect to the float element, and wherein during at least a second part of the downwards movement of the leg towards the installation position and/or in the installation position the first buoyancy means are substantially located below a wave zone to substantially decrease heave action on the first buoyancy means.