Abstract: A base frame for an offshore platform and a method for installing such a base frame includes a self-floating lower building structure having a stable trim, at least one tank in the lower building structure which is dimensioned such that the lower building structure sinks when the tank is flooded, mechanism for flooding at least one tank, and a mechanism for bearing piles in upright standing arrangement on the lower building structure. The method builds a base frame, transports the base frame to the sea in a self-floating manner and floods the base frame until it is on the sea floor and then anchors the base frame to the sea floor with piles.

Abstract: A platform topside for an offshore platform including a self-floating superstructure with a stable floating position, projections on the superstructure, means for mounting legs in an upright arrangement in the projections, wherein the projections and the means for mounting legs are arranged above the water line or not far below the water line, means for displacing the legs in the longitudinal direction of the legs in the means for mounting and means for fixing the legs in their positions in the means for mounting.

Abstract: A base frame for an offshore platform comprising a. a self-floating lower building structure having a stable trim, b. at least one tank in the lower building structure which is dimensioned such that the lower building structure sinks when the tank is flooded, c. means for flooding at least one tank, d. means for bearing piles in upright standing arrangement on the lower building structure.

Abstract: A ship according to the invention for conveying and setting up offshore structures having: a hull with a U-shaped cross-section having an open stern and projections of the side walls extending at the rear beyond the rear edge of the floor, jack-up leg systems with jack-up legs integrated in the hull that are movable in a vertical direction with their bottom ends in positions below the floor, and a crane that can move on the top edges of the side walls.