Abstract: The immersion and positioning of a sink element on the sea bottom is controlled by providing a weight system suspended from the sink element. An auxiliary surface vessel has a control cable directly connecting the vessel with the weights system suspended from the sink element. The sink element is immersed with the weight system suspended therefrom and therebelow until the weight system contacts the sea bottom and the sink element reaches a preselected stabilized equilibrium elevational position above the sea bottom. Then the sink element can be laterally displaced while substantially maintaining the height of the sink element above the sea bottom by having the auxiliary surface vessel pull on the control cable connected to the weight system in a direction of movement towards the final location site. The weight system contacts the sea bottom during this movement to help control the movement of the sink element and minimize the influence of outside forces.

Abstract: An offshore platform structure of reinforced concrete for standing on the bottom of a sea as a consequence of its own weight. The structure includes a base supporting a tower for a platform deck. The lower part of the tower includes a cylindrical portion extending downwardly towards and through the base and providing a skirt. A frusto-conical annular wall extends coaxially with the tower between the tower and the top of the base to provide an annular chamber with a triangular cross section. Also a method of building a platform structure includes building the lower portion of the structure in a dry dock and floating the lower portion out into deeper water for continuing a casting operation for the remainder of the platform structure.

Abstract: Method for founding and stabilizing an off-shore platform which at its lower end is provided with skirts. The skirt or skirts are forced so deep down in the ground that a significant portion of the foundation area is transferred down to a depth where the load carrying strength of the ground is sufficient in regards to geotechnical stability and that it prevents an acceptable settlement.The platform (1) which is intended to be installed at very great depths, includes a foundation structure to be forced down in the sea bed, a cell portion that in its operational position is completely submerged, and an upper portion extending from the cell portion and up above the sea surface, where the submerged cell portion includes a centrally located cell surrounded by at least one cell portion.