Abstract: An ice platform suitable for multiseason use is constructed in a cold offshore region by accumulating ice on a portion of a floating natural ice sheet until the ice mass formed thereby becomes grounded on the marine bottom. A rigid wall element is driven through the ice and a preselected distance into the marine bottom so as to form a structural wall surrounding the ice mass. Subsequently an insulation jacket is installed over the top surface of the ice mass and between the ice mass and the wall. To dismantle the ice platform, the wall and at least part of the insulation jacket are removed to allow natural forces to restore the region to its natural state.

Abstract: Apparatus and method for mooring a tension leg platform at an offshore location wherein the tensioned cables of the platform legs are laterally supported by a plurality of rigid, fixed-dimensioned support members which interconnect the legs and are vertically spaced at predetermined positions along the cables to reduce the unsupported length thereof and to thereby increase the fundamental frequency of the cables to a value higher than the flutter frequencies likely to be encountered. Resonant fluttering of the cables due to vortex shedding is thereby prohibited and the useful life of the cables is extended. The support members can be variably buoyant and/or can be adapted to provide storage for fluids produced at the offshore location.