entitled 34 ice cutter for monopod drilling platform 34 assigned to the same assignee as the present invention there is described in detail a drilling platform of the type shown in fig1 the drilling platform includes a base 10 in the form of a hull constructed of bulkheads and outer plates providing a substantially watertight structure which may be ballasted to rest on the sea bottom at the drilling location or which may be sufficiently buoyant to float beneath the surface as a semi submersible a superstructure 12 providing an upper drilling deck 14 is supported above the water surface from the base 10 by a single vertical column indicated generally at 16 drilling is accomplished from the drilling deck 14 down through the column and base into the sea floor by means of conventional drilling equipment including a drilling derrick 18 mounted on the drilling deck 14 as shown in the cross sectional view of fig2 the column consists of a outer stationary cylindrical shell 20 which is rigidly attached at its lower end to the bottom of the base 10 inside the column 16 is a cylindrical casing 22 through which access to the ocean floor from the drilling deck is provided the opening through the casing is referred to as the 34.