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 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.